Advanced materials for fuel cells and electrolyzers

Resume : High temperature proton exchange membrane fuel cells (HT-PEMFCs) have certain advantage in the face of common PEMFCs. The use of a high temperature significantly increases the CO tolerance, enhances the oxygen reduction reaction kinetics and reduces the thermal and water management of the system. Platinum on carbon black is commonly used as catalysts in PEM fuel cells. However, the scarcity and high cost of this novel metal and the high corrosion suffered in this carbonaceous support made necessary to look for new materials which decrease the cost without compromising the catalytic activity. In this work, base Pt catalysts were prepared using a novel non carbonaceous support, SiC-TiC. The catalysts were synthesized by an impregnation method using NaBH4 as reducing agent. The catalysts were physical-chemically characterized by ICP-MS, XDR, TPR, SEM and TEM. Besides, cyclic voltammetries in hot phosphoric acid were carried out in a half cell to evaluate the electrochemical resistance in terms of the change of the electrochemical active surface area (EASA). After that, electrodes prepared with Pt based catalyst supported on the novel SiCTiC have been tested in an actual fuel cell of 25 cm2 at 160 ºC. The results are very promising in terms of durability but further work is required to increase the performance. Acknowledgements The authors thank the European Commission as this work was supported by the 7th Framework Programme through the project CISTEM (FCH-JU Grant Agreement Number 325262).

Resume : Considering a single electrochemical cell, the main challenge in the development of Unitized Regenerative Fuel Cells based on the PEM technology is the design of bifunctional oxygen electrodes (BOE) able to activate the oxygen reduction reaction (ORR) under fuel cell operation and the oxygen evolution reaction (OER) under water electrolyzer operation. Platinum – a performant ORR catalyst – is usually dispersed on high surface area carbonaceous materials to increase mass efficiency. Nevertheless, carbon cannot withstand the high potential (around 2V vs. RHE) of the oxygen electrode during water electrolysis. Several metal oxides and nitrides such as Sb doped SnO2 or TiN have been studied as carbon-free supports. Although their stability at high potentials is remarkable, their insufficient electronic conductivity impedes the overall performance of the cell. RuO2 performs well as an OER catalyst and exhibits sufficient electronic conductivity. In this approach, we propose to use RuO2 both as catalyst and as durable carbon-free support for Pt nanoparticles. Crystalline RuO2 nanoparticles have been prepared through various hydrothermal treatments with crystal size control. Then Pt nanoparticles were dispersed on the most suitable RuO2 support. After structural and electrochemical characterizations of the obtained bifunctional catalyst, the performances for both OER and ORR have been investigated using a 5 cm² surface area single cell.

Resume : The performance and durability of low-temperature fuel cells strongly depend on catalyst support materials. One of the most important challenges in the immediate future facing the development of polymer electrolyte fuel cells (PEFCs) is either to stabilize the carbon supports or to find new support materials that improve the durability of catalyst layer and catalyst kinetics [1]. Different types of catalyst support materials have been developed, such as conductive metal oxides, nitrides, carbides, carbon nano (tubes, fibres, dots, horns, coils), graphene, carbon paper, conductive diamonds, among others [1,2]. Eco-friendly ionic liquids (ILs) and deep eutectic solvents (DESs) can be used as promising precursors for functional carbon materials in the field of renewable energy or environmental science [3,4]. DESs have many characteristics of conventional ILs (e.g., low volatility), but exhibit additional advantages, such as low cost, being mainly useful for large-scale synthetic applications. However, relatively cheap ILs, derived from biomass, could also be used for functional carbon synthesis [5]. In the present work, we report for the first time a novel route for the synthesis of Pd supported on a carbon modified-DES and IL (1-ethyl-3-methylimidazolium tetrafluoroborate) using a one-step preparation via a microwave-based strategy in the absence of reducing agents. The preparation of the DES was carried out by heating a mixture of choline chloride and urea at a molar ratio of 1:2 at 70 ºC. The surface morphology and structure of the electrodes were characterized by SEM, HR-TEM/EDX and XRD. ORR activity, kinetics and durability were determined in acid perchloric medium. References [1] A. Rabis, P. Rodriguez, T.J. Schmidt, ACS Catalysis 2 (2012) 864; [2] K. Sasaki, Z. Noda, T. Tsukatsune, K. Kanda, Y. Takabatake, Y. Nagamatsu, T. Daio, S.M. Lyth, A. Hayashi, ECS Transactions 64 (2014) 221; [3] J.P. Paraknowitsch, A. Thomas, Macromolecular Chemistry and Physics 213 (2012) 1132; [4] M.-M. Titirici, R.J. White, N. Brun, V.L. Budarin, D.S. Su, F. del Monte, J.H. Clark, M.J. MacLachlan, Chemical Society Reviews 44 (2015) 250; [5] Z.-L. Xie, D.S. Su, European Journal of Inorganic Chemistry 7 (2015) 1137.

Resume : The instability of the carbon based support materials is one of the major causes of Polymer Electrolyte Membrane Fuel Cells (PEMFC) performance degradation. We investigated the performance stability of Pt electro-catalysts supported on a typical carbon black, a stabilized carbon support and a non- carbon. A robust synthesis method of Pt nanoparticles of <5nm particle size has been developed by modifying the well-known polyol method. With the synthesis process chosen, Pt nano-particles were successfully deposited on both carbon and the non-carbon supports. Electrochemical surface area by CV, Oxygen reduction reaction activity by RDE and degradation via potential cycling were measured for all catalysts. Finally, the catalysts were processed to MEAs and subject to single cell performance tests. The stable carbon supports showed improved corrosion resistance as compared to the traditional carbon black support under accelerated stress test (AST) condition. The membrane electrode assembly (MEA) performance test results of the stable carbon supported catalysts are also comparable with the carbon black supported catalyst. We developed a non-carbon (Sb doped SnO2) support material of reasonable electrical conductivity (10 times lower than Carbon black) and surface area of 50m2/g which showed comparatively low loss of electrochemical active surface as the stable carbon supports upon potential cycling. The MEA performance of Sb doped SnO2 supported catalyst is currently under investigation.

Resume : The current need for new solutions for waste management and clean energy production can find a concrete answer in the technology of microbial fuel cells (MFCs). MFCs are bio-electrochemical systems which allow producing electrical energy, using wastewater as fuel, eliminating at the same time some of the problems linked to their disposal . Current limitations and open problems related to MFC technology are the high costs associated to materials, cell configurations not yet suitable for scaling-up, and the complexity of wastewater. To address these issues, the research activity of our group is focused on the identification of innovative and cost-effective materials and components to fabricate lab-scale MFC prototypes, fed with wastewaters of different nature. Subject of this presentation will be an overview of our recent activity in the field of MFCs. Special emphasis will be given to the development of low cost and effective catalysts for the oxygen reduction reaction occurring at the cathode. The combination of carbon supports with electronically conducting polymers, non noble metals, ceramic oxides, and enzymes was investigated to boost catalytic activity, while reducing the adsorption of contaminant species. The use of food waste and agro-industrial wastewater as fuel of MFCs will be proposed, highlighting opportunities and constraints in terms of energy production as well as efficiency of wastewater treatment.

Resume : The use of lactate as fuel is very attractive due to their high energy density of 507 Wh/L in the oxidation for a single enzyme and complete oxidation of 3041 Wh/L. In this work, we evaluated a lactate biofuel cell (BFC) using like bioanode lactate oxidase with redox polymer dimethylferrocene-modified linear polyethyleneimine and two different cathodes enzymatic based on laccase (BFC-1) and bilirubin oxidase (BFC-2) coupled to MWCNT modified with anthracene and an abiotic catalyst Pt/C (BFC-3) estimated on sweat direct (lactate concentrations of 5 - 70 mM). The result shown a cell voltage (OCV) of 0.6 V (BFC-1), 0.56 V (BFC-2) and 0.36 V (BFC-3), with maximum of density current of 78 µA cm-2, 47 µA cm-2 and 4.9 µA cm-2 respectively with good stability. In conclusion, the performances of the BFCs evaluates would be apply for devices of low current and self-powered sensor as a supplemental power supply.

Resume : In this study, homogeneously dispersed gold particles onto carbon felt were fabricated by electrodeposition method followed by a thermal treatment at 1000 °C under nitrogen. The thermal treatment induced the dewetting of gold and the formation of well-crystallized gold particles that exhibited large surface area. The structural properties of the resulted Au@CF material were evaluated by SEM, XRD and TGA. We studied the electrocatalytic properties of this new gold material toward the abiotic glucose oxidation in alkaline medium and the enzymatic dioxygen electroreduction by the enzyme bilirubin oxidase. Finally, we showed the potentiality of the resulting Au@CF material to construct a 3-dimensional glucose hybrid biofuel cell by assemblying an abiotic anode with an enzymatic cathode. The system exhibited high electrochemical performance, by taking account of the projected surface area, with an open circuit voltage of 0.71 V and a maximum power density of 310 µW cm-2 at 352 mV, in spite of a low gold loading (0.2 wt%). The advance presented in this work is the efficiency of the synthesis technique to get a new free-standing material for electrocatalysis with macropores for diffusion transport and gold particles with high reactive surface area for electron transfer.

Resume : The microbial fuel cell is a device which allows both to generate bioelectricity and to treat wastewater [1]. The performance of this system is affected by several parameters, in particular the cathode material [2]. In this perspective, two cathodes, synthetised and caracterised, of non-stoichiometric ferroelectric material of formula Li0,95Ta0,57Nb0,38Cu0,15O3, were prepared according to two heat treatments modes (slow cooling-S- and rapid cooling -R-). The synthesized phases were characterized by XRD, TEM, specific surface area, laser granulometry (PSD) and density measurements. These phases have the principales characteristics as Curie temperatures,1215 and 1196°C and specific surface area 0.572 and 0.801 m2 /g for S and R phases respectivelty. These materials were tested as photocathodes in a microbial fuel cells single chamber for the treatment of wastewater. The performance of these photocatalysts in terms of electricity generation and wastewater treatment were evaluated by power density and rate of COD removal in the presence of a light source. For the samples S and R the values of the maximum power densities are 22.82 mW/m3 and 213.38 mW/m3, the COD removal are 74 % and 80% respectively. We noted the phases prepared by rapid cooling -R- are more successful in terms of powers generated and of the efficiency of the wastewater treatment improves significantly the photocatalytic activity of the material. Key words: Tantalo-niobate, phase, photocatalyst, slow cooling,rapid cooling,MFC, COD [1]. Liu, H. and B.E. Logan, Electricity generation using an air-cathode single chamber microbial fuel cell in the presence and absence of a proton exchange membrane. Environmental science & technology, 2004. 38(14): p. 4040-4046. [2]. A. Lu, Y. Li, S. Jin, H. Ding, C. Zeng, X. Wang, C. Wang, Microbial fuel cell equipped with a photocatalytic rutile-coated cathode, Energy & Fuels, 24 (2009) 1184-1190.

Resume : In this work, the experiments are conducted by cathodes composite based ferroelectric LiNbO3 catalyst and carbon cloth support conductor. It has been investigated in terms of power output in single-chamber MFCs, in the absence and in the presence of UV-Vis light. This material catalyst was synthesized, identified and characterized by XRD, MET and PSD techniques. Maximum values of open circuit potential (OCP) and power densities were observed in the presence of UV-Vis are 400 mV and 115,14 mW.m-3, respectively. This cathode configuration also offered the maximum chemical oxygen demand (COD) removal with a value of 76 % after 72 h of MFC operation using wastewater as fuel. Finally, the analysis of the removal of heavy metal from wastewater (63Cu, 66Zn, 111Cd,52Cr and 56Fe) shows removal efficiencies within the interval 60-85% for most of the metals studied in the case of irradiated LiNbO3 configuration.

Resume : The development of alkaline polymeric membranes has allowed that alkaline electrolysis becomes an attractive alternative because it permits the use in these devices of electrocatalysts with non-noble metals, such as Ni and Mo. These materials are stable in alkaline medium, have good resistance to corrosion and exhibit high activity not only in the reaction of hydrogen evolution (HER), but also the oxidation of alcohols when combined with low content of Pt or Pd, so they can be used both in electrolyzers and polymer electrolyte membrane (PEM) fuel cells. In this work Ni nanodisks supported on reduced graphene oxide (RGO) were prepared and modified with Mo and Pt for the study in alkaline media of the HER and alcohol oxidation reactions (AOR), respectively. Structure of synthesized materials was characterized by X-ray and microscopy techniques. Differential electrochemical mass spectrometry showed a negative shift of 150 mV towards negative potentials for the onset of the HER at Ni-Mo materials with respect to pure Ni and Mo. On the other hand, Ni@Pt/RGO catalysts were obtained by galvanic replacement developing a core-shell structure. The onset for AOR at these materials was established at more negative potentials for the catalysts with lower Pt content, which also presented the highest mass current densities. The high activities achieved with modified Ni/RGO nanodisks in alkaline media make then good candidates to be used as catalysts for PEM devices using alkaline membranes. Acknowledgments Financial support given by Spanish MINECO (ENE2014-52158-C2-1-R and 2-R, FEDER) and Fundación Cajacanarias (BIOGRAF project) was gratefully acknowledged.

Resume : Pt based nanostructures are the widely sought after metal-based nanomaterials for various catalytic applications including renewable energy harvesting, which, due to growing energy demand, is fast emerging as a key research area. Despite extensive investigations, certain Pt nanocrystals with excellent potential performance have remained elusive, giving rise to important research challenges. This talk will illustrate our recent successes in realizing such nanostructures that leads to enhanced energy harvesting. Earlier we established that by generating a secondary amine in-situ during their synthesis, sub 10 nm Pt nanotetrahedra (NTds with (111) surfaces that are thermodynamically unfavourable) exhibiting one of the highest electrochemical efficiencies towards fuel reduction can be obtained. Subsequently, we demonstrated a mechanochemical unzipping process of a nanotube structure to yield robust free-standing ~26 nm thick Pt nanosheets, a rare morphology for metals. Therein, shear forces (~2 N) and shear stress (~24000 Pa) generated by stirring in a solution was utilized to mechanochemically zip open an 1D nanostructure to form a nanosheet. Nanocrystals are crystallographically connected to each-other within the nanosheets and therefore can be used for electrochemical applications without using conducting supports. This alleviates the problems associated with catalyst masking by the catalyst-support and leads to high mass-activity in fuel cell reactions. Besides, a ‘support-less’ strategy involving Pt nanowire membrane recently developed by us will be discussed. Finally, a novel approach that uses carbon, a usual support material, as multifunctional material for hybrid energy storage shall be illustrated. References 1. “Mechanochemical Synthesis of Free-Standing Platinum Nanosheets and Their Electrocatalytic Properties”, M. Chhetri , M. Rana , B. Loukya , P. K. Patil , R. Datta , U. K. Gautam, Adv. Mater., 2015, 27, 4430. 2. “High-yield Synthesis of Sub-10 nm Pt Nanotetrahedra with Bare (111) Facets for Efficient Electrocatalytic Applications”, M. Rana, M. Chhetri, B. Loukya, P. K. Patil, R. Datta, U. K. Gautam, ACS Appl. Mater. Interfaces, 2015, 7, 4998. 3. Pd–Pt Alloys Nanowires as Support-less Electrocatalyst With High Synergistic Enhancement in Efficiency for Methanol Oxidation in Acidic Medium, M Rana, P. K. Patil, M. Chhetri, K. Dileep, R. Datta, U. K. Gautam, J. Colloid Interface Sci., 2016, 463, 99. 4. N-and S-doped High Surface Area Carbon Derived from Soya Chunks as Scalable and Efficient Electrocatalysts for Oxygen Reduction, M. Rana, G. Arora, U. K. Gautam, Sci Tech. Adv. Mater., 2015, 16, 014803.

Resume : Fuel cell is a clean power generator with high energy efficiency and low carbon emission. Benefiting from low operation temperature and high speed start-up and shutdown, polymer electrolyte membrane fuel cells (PEMFCs) have stepped in the demonstration stage. Over the past decades, the study of nanotechnology has brought in tremendous progress to PEMFC development, in particular on understanding catalytic mechanisms of fuel cell reactions on catalyst surfaces, and many new catalyst approaches have been reported. However, the only considered catalyst for commercialization is still the conventional Pt/C catalysts. This presentation will highlight the increasing concern of the gap between pure material research and fuel cell devices, and review the research activities undertaken in Birmingham by combing green chemical synthesis [1-3] and new plasma techniques [4] to create advanced catalyst electrodes for high performance PEMFCs. References 1. S. Du. J. Power Sources 195, 289-292 (2010) 2. Y. Lu, et. al, Appl. Catal. B 164, 389-395 (2012) 3. Y. Lu, et. al, Appl. Catal. B 187, 108-114 (2016) 4. S. Du, et. al, Sci. Rep. 4, 6439 (2014)

Resume : Hydrogen produced by water electrolysis is considered as the best energy carrier to adjust the balance between the generation of power source by renewable primary energy and energy demand for end-use. In assisted water electrolysis using carbon as anodic material (graphite, activated carbon and coal), the real operating voltage and the actual energy consumption would be lower than for conventional water electrolysis, with apparent reduction of the cost for hydrogen production. In this work, the low temperature and low pressure electrochemical gasification of graphite in alkaline solutions is explored, taking into account that above the thermodynamic potential for oxygen evolution the faradaic overall current might have a significant contribution from carbon oxidation reactions and seeking the production of synthetic liquid fuels via syngas. In a first stage, laboratory studies were conducted in an undivided planar cell with graphite electrodes with 25 cm2. Cyclic voltammetry and polarization curves were instrumental to establish optimum operational conditions for adequate molar gases fraction for the production of syngas. Gaseous product analysis was carried out using gas chromatography. A 45W prototype using a 5 cell stack with 150 cm2 was built allowing electrolyte recirculation, temperature control up to 80ºC and pressure control up to 1 bar with excellent results in both alkaline and acid media. A 1 kW prototype has been built for working with alkaline media with the molar fraction of gases is in excellent agreement with the found in the laboratory prototype for similar operating conditions. Integration with renewables for powering electrolysis and also with a reactor for the production of methanol is expected. Results and the technological implications of the obtained advances are discussed. KEYWORDS: Hydrogen, Carbon monoxide, Carbon dioxide; Electrochemical gasification; Graphite, Electrolysis. ACKOWLEDGEMENTS This work is co-financed by COMPETE, Portugal under project nº 38940. REFERENCES [1] J. Rodrigues, Portuguese Patent 106779 T: Obtenção de gás de síntese por eletrólise alcalina da água, 2013.02.13

Resume : Since 2013, transition metal phosphides (TMPs) have emerged as a new class of catalysts for the hydrogen evolution reaction (HER), whose catalytic performance was reported to favorably compare to that of Pt and outperform that of many metal sulfides, selenides, and carbides. Among various TMPs investigated by far, iron phosphide is particularly attractive because iron is the cheapest and most plentiful transition metal in the earth’s crust (the primary source of metal ores); moreover, it has low toxicity and negligible environmental impact. Up to now, many iron phosphide nano-catalysts have been reported for use to catalyze the HER, but its catalytic performance toward the oxygen evolution reaction (OER) has been rarely explored, even if TMPs were recently reported to be active OER catalysts as well. In this work, we report the fabrication of FeP nanorods (NRs) and their electrocatalytic performance toward the OER. The synthesis of FeP NRs was accomplished by a facile hydrothermal process modified according to a previous report, where iron oxyhydroxide (FeOOH) NRs were first obtained upon cooking 0.15 M FeCl3·6H2O and 1 M NaNO3 solution in a Teflon-line steel autoclave reactor at 100 °C for 24 h; this was followed by doctor-blade of FeOOH NRs on carbon fiber paper (CP) current collectors and subsequent phosphorization treatment in P vapor at 500 °C for 0.5 h. Phosphorization treatment further significantly enhances the OER activity, the CP@FeP exhibits higher current density and a more negative onset potential (1.52 V vs. RHE) than CP@FeOOH (1.65 V vs. RHE). We find that FeP NRs supported on carbon fiber paper (CP) current collectors exhibit OER activity (ηon = 290 mV, η10 = 350 mV, Tafel slope = 64 mV dec-1) superior to that of many transition metal based OER catalysts reported in the literature, and they also show excellent long-term stability (48 h) for the OER.

Resume : Novel telecommunications services must be supported by a widespread infrastructure and technological advances. Radio Base Stations (RBSs) belong to the mobile services infrastructure and, since they are connected to the grid, they represent a relevant source of costs and energy consumption to ICT operators. For this reason, ICT operators are working on internal power production in RBSs, instead of being passive loads to the electrical grid. In the framework of the ONSITE project (financed by FCH JU, Grant No. 325325, www.onsite-project.eu), which deals with a hybrid (fuel cell and batteries) RBS supply system, a modeling activity was carried out to optimize the system operations. The developed algorithms separately implement a SOFC system and a high temperature (SNC) battery for design purpose and collect them in a unique model for devices interaction (i.e. power production, storage, and control). Moreover, a CFD battery model was developed to analyze the heat transfer while the SOFC stack generates excessive heat during operation and outlet hot gases can be effectively used. Since the SNC batteries need heat during charging process (to maintain their operating temperature) and, conversely, the reactions are exothermic in discharge mode, the described approach aims at combining SNC batteries with micro-CHP unit to optimize the energy flows. The implementation required several alternative designs and variant analysis to secure proper operation of battery and power generation unit.

Resume : Solid oxide fuel cells (SOFCs) are a strong candidate for zero-emission electricity generation. However, the high temperatures necessary for operation lead to long start up times and short lifetimes. Decreasing this temperature leads to a decreased rate in the oxygen reduction reaction at the cathode site, leading to a need for new cathode materials active at reduced temperatures. Doped perovskite materials, such as LSCF, show great promise as IT-SOFC cathodes. However, optimisation of these materials can be difficult due to the large variation in stoichiometry that is possible. Here we present a detailed study of intrinsic point defects, substitutional defects and oxide ion migration in LaFeO3, a parent compound of LSCF. With an understanding of the chemistry of the base material it is possible to predict the effect of doping and therefore to be able to optimise this material for its purpose. Both molecular mechanical and density functional theory calculations have been employed in this work, with the majority of intrinsic defects investigated having high formation energies with the exception of O2- vacancies. A range of divalent dopants have been investigated for both the A- and B-site and the most appropriate for each will be discussed, along with their affect on the electronic properties of the material. Oxide ion conduction calculations revealed activation energies of 0.58 and 0.66 eV, agreeing well with the reported experimental value 0.77 eV.

Resume : Direct methanol fuel cells (DMFCs) can provide energy as long as the fuel is feeding the cell. Unfortunately, DMFC undergoes slow kinetics for alcohol oxidation at the anode and at the cathode both the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) occur simultaneously. To lessen the alcohol crossover issue, some binary and ternary Pt base catalyst with high activity for the ORR and low activity for the MOR has been synthesized. We have found that home synthesized catalyst PtCoRu/C can be active enough for ORR and almost no active for MOR, whereas PtCo/C is active for ORR and MOR. The electrochemical behaviour of the catalysts as prospective anode is analysed and compared with homemade PtRu/C. Thus, PtRu/C behaves as the best catalyst for MOR, and its Nyquist plot shows the smallest charge transfer resistance. The PtCo/C catalyst, which is very active for ORR and MOR at high potentials, behaves as a poor catalyst for MOR at low potentials. Finally, PtCoRu/C which has shown good ORR behaviour and also proves to be resistant to methanol oxidation shows the highest charge transfer resistance and consequently the poorest activity for MOR. EIS results have been modelled according a combined electrical circuit which represent the reaction mechanism of methanol oxidation. The chance of having Pt and Ru in the catalysts composition is not enough to ensure a higher catalytic activity for MOR.

Resume : In this paper, the integration of small SOFC commercial system into the fuselage of a mini Unmanned Aerial Vehicles (UAVs) is carried out from an experimental and computational point of view. As a design constrain, the SOFC generator has to be installed inside the UAV fuselage, with the lowest possible offset (about 20 mm all around the generator) to reduce the volume and mass of the UAV. SOFC systems operate at high temperature in the range of 800 – 1000 °C and even whether a good insulation of the system is designed, the external temperature is always about few hundred Celsius degrees. Due to high external surface temperature, malfunctioning of the electronics devices connected to the generator and hot spots on the fuselage shell can occur. For this reason, it is important to ensure a proper ventilation of the air volume inside the UAV fuselage. To deal with these issues, experimental and Computational Fluid Dynamic studies were carried out to evaluate the temperature distribution inside the UAV fuselage. Different air intake configurations and design are investigated and advises concerning a correct SOFC system integration inside the UAV fuselage are also provided.

Resume : Synthesis, structure, microstructure and electroconductivity of modified lanthanum gallate ceramics as perspective electrolytes for high temperature solid oxide fuel cells G.M. Kaleva, E.D. Politova, I.P. Sukhareva, A.V. Mosunov, and N.V. Sadovskaya L.Ya. Karpov Institute of Physical Chemistry, Obukha s.-st., 3, 105064, Moscow e-mail:politova@cc.nifhi.ac.ru Aliovalent substituted lanthanum gallate La0.9Sr0.1Ga0.8Mg0.2O3-y (LSGM) is being considered among the most perspective electrolyte materials for the intermediate temperatures solid oxide fuel cells because of its high ionic conductivity in the wide range of the partial pressure of oxygen (1 – 10-22 atm.) and insignificant electronic conductivity. Previously, we have studied the characteristics of the crystal structure, electroconductive and magnetic properties of LSGM ceramics with a perovskite structure by substituting of gallium cations by iron cations. Single phase samples with the orthorhombic structure were synthesized in the entire region of iron concentrations. Antiferromagnetic ordering at temperatures below 500 K was revealed for the composition (La0.9Sr0.1)(Fe0.8Mg0.2)O3-y. In this work ceramic samples in the system (La0.8Sr0.2){[Ga0.8-x(Si0.5Mg0.5)x]Mg0.2}O3-d (x=0 ÷ 0.8) were prepared by the solid state reaction method. The phase formation, crystal structure, microstructure and electroconductivity were investigated using the X-ray Diffraction, Scanning Electron Microscopy and Dielectric Spectroscopy methods. According to the X-ray diffraction data, perovskite structure phase was formed in the samples with x = 0 ÷ 0.6. These compounds are characterized by the orthorhombic structure (space group Pbnm). Fragments of diffraction patterns of the samples demonstrate a consistent shift of the diffraction peaks to smaller angles, indicating to the slight increase in unit cell parameters as a result of substitution of Ga cations by Si and Mg cations. It was found that the silicon-containing samples are characterized by a homogeneous microstructure of square shape with grain sizes (10x10) mkm. The temperature dependences of the total electroconductivity of ceramic samples confirmed their high values at temperatures near 1000 K. This work was supported by the Russian Foundation for Basic Research, project no. 16-03-00581.

Resume : Vanadium Redox Flow Batteries (VRFB) are electrochemical devices able to store energy using vanadium species dissolved in solution as electrolytes. VRFB are a promising technology for sustainable and environmental friendly large-scale energy storage. However, major challenges such as low energy density, low stability, and high cost limit further development of this technology. The polymer membrane used as separator is indeed a critical component for VRFB development. Perfluorosulfonic polymers, such as Nafion, are commonly used in VRFBs due to their high proton conductivity and good chemical and thermal stability but suffer from high cost and important vanadium ion crossover. Our approach to reduce costs and vanadium-ion crossover was based on the use of composite membranes based on sulfonated poly ether ether ketone modified with the addition of different loading of nanometric titanium oxide, either as a pure species or functionalized with surface acidic groups. The homogeneity of composite membranes was enhanced by using an air-spraying deposition technique and results were compared with those obtained with conventional solvent casting methods. Vanadium ion permeability through the membranes was evaluated by using a static H-type glass cell, measuring vanadium ion concentration by UV-Vis. Proton conductivity of membranes was measured by in situ-electrochemical impedance spectroscopy. Coulombic and energy efficiencies of the cell were studied by galvanostatic charge-discharge cycles. The overall performance of was further analyzed by polarization curve at different state of charge. Early insights on the understanding of battery capacity loss in long-term cycling tests is also reported in this work.

Resume : In the recent years, the nitrogen-containing carbon nanostructures (NCNS) have received increasing attention especially because of their applicability in the fabrication of new catalysts, electrocatalysts, and electrode material for supercapacitors. The aim of this study is the investigation of electrocatalytic activity toward oxygen reduction reaction of NCNS. The carbonization of polyaniline nanostructures as nitrogen containing precursors was used for the preparation of NCNS. Polyaniline nanostructures were synthesized using three different template free polymerization methods. In the present work we compared the efficiency of these materials for oxygen reduction reaction (ORR) in alkaline media. The electrochemical behavior was correlated with data obtained from X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy and Raman Spectroscopy. Acknowledgments This work is supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS – UEFISCDI, project number PN-II-RU-TE-2014-4-0221.

Resume : This work focuses on the synthesis of Tantalum (Ta) modified TiO2 mixed oxides and their structural and surface properties characterization using XRD, XPS, BET and H2-TPR techniques. Tantalum (Ta) modified TiO2 samples were synthesized using a sol-gel procedure and evaluated for potential application as electrocatalysts supports. The Tantalum (Ta) modified TiO2 mixed oxides showed unimodal nanoporous structure with pore sizes ranging from 3 to 5 nm. Concomitantly with their higher surface area and pore volume, the mixed oxides were nanocrystalline and significantly smaller than Ti and Ta single oxides prepared by the same method (7 to 8 nm). A dominant anatase phase was detected by XRD at low calcination temperature, while the crystallographic structure become ruthile when the sample was treated at 850°C. Lattice parameters were changed by incorporating Ta into TiO2. H2-TPR revealed that the oxidation state of surface cations decreased, and oxygen deficiency of the surface was significantly enhanced by introducing Ta into TiO2. The structural and surface modification by introducing Ta into TiO2 increased the reducibility of mixed oxides in H2-TPR. The present study clearly established that the structural (crystal phase, crystal size, nanoporosity, pore size) and surface properties (reducibility, oxygen deficiency, acidity, oxidation activity) of the Tantalum (Ta) modified TiO2 mixed oxides can be tailored by modifying the sol gel procedure and the thermal treatment.

Resume : In the last decade the worldwide interest on renewable energies researches of bio-fuels have been intensified to meet the increasing fuel demand and secure local energy. The attention was addressed toward the employment of third generation biofuels derived from algae that are a cheaper feedstock for chemicals and biofuels production. The pyrolysis process is considered a good and economical process and also shows higher efficiency than other process for conversion of algae into bio-fuels. Moreover, bio-oils can be upgraded in-situ by catalytic cracking to reduce its high acidity and oxygen content and increase the low heating value. For this reason, Ni based and Ni-Ceria catalysts have been utilized in pyrolysis processes mainly for their low cost and to promote deoxygenation reactions. Although, many papers are present in literature on catalytic pyrolysis, the researches on effect of catalysts to the pyrolysis of sea plants are really scarce. The aim of this work was to evaluate about the feasibility of the process to produce high quality bio-oil from a Mediterranean sea plant. In particular, the effects of pyrolysis parameters such as temperature and different prepared Ni based catalysts on product yields were investigated. The amount of char, gas and oil was determined and moreover bio-oil was studied in terms of oxygen and organic compounds content. The results showed that both temperature and catalyst had significant effects on conversion into the products.

Resume : Direct Methanol Fuel Cells (DMFCs) have received worldwide attention because of several intrinsic advantages, such as simplicity of operation, high theoretical energy density and easy refueling. Being Methanol a liquid fuel, DMFCs are simpler in construction than hydrogen fed fuel cells, and do not need pressurised hydrogen gas storage, delivery or processing. Additional simplification in DMFCs includes passive operation with air-breathing operation for low power applications. In recent years, technology developments have promoted interest around DMFC applications in small portable power devices, such as notebook computers, power tools and cellular phones, which need power sources with increasingly high energy density and easy recharging. In this work, an innovative DMFC fuel cell ministack, designed for operation at ambient pressure and temperature, under air breathing and using methanol diffusion by natural convection, has been evaluated in terms of performance, durability and reliability. The architecture of the ministack has been conceived as planar and modular; with each pair of current collectors, and clamping plates combined on a single component made with two PCBs. Four different geometries of cathode feeding widows have been designed and tested and the issues related to the reliability of PCB have been investigated.

Resume : The synthesis of mesoporous NiO via stable NiCO3 intermediate is achieved by a soft templating approach utilizing PEO-PB-PEO triblock copolymers and evaporation induced self assembly. The well known excessive crystallization behaviour of NiO is avoided by the complexation of the nickel precursor Ni(NO3)2 with citric acid. Thermal properties of the polymer template, the nickel precursor complex and the stable NiCO3 intermediate are investigated by TGA. The prepared films on different substrates were investigated in terms of morphology, pore ordering, crystallinity, surface species and surface area by SEM, TEM, SAXS, SAED, XRD, XPS and Kr-physisorption. The electrocatalytic OER activity is examined in order to achieve insights into structure-activity relationships. Furthermore, we will show that a calcination temperature of 250 °C leads to an amorphous, stable NiCO3 intermediate. An increase of the calcination temperature results in mesoporous templated NiO with low crystallinity and high BET surface area as well as high OER activity. We will elucidate that the BET surface area is an important reaction parameter in order to obtain highly active OER catalysts.

Resume : Microbial fuel cell(MFC) systems use electrochemically active biofilm which can exchange electron discharged from internal metabolic pathway into electrically conductive electrode as terminal electron acceptor and/or donor. Conventionally MFC has been applied to produce renewable energy such as electricity and hydrogen from various biodegradable organic materials, and biosensor for organic contaminant monitoring. We investigated the effect of Ti nano-particle on the electron generating efficient of MFC by deposition of nano-particles on the carbon paper electrode. Since the generated voltage and current from MFC are depend on the amount of microbes which are attached on the anode, a surface area and bioaffinity of electrode materials are important factor. By monitoring the voltage of MFC which employing Ti-nano-particle, we evaluated and compared performance enhancement with a case of general carbon paper anode. Also, an influence of nano-particle size and gap of inter-particle variation were investigated. To understand a mechanism of electron transport from alive microbe to conductive electrode, we need to observe an individual electrochemically active bacterium such as Shewanella oneidensis MR-1 by using nano-probing technique. The electrical properties such like resistance and dielectric constant of microbes were analyzed by conductive-atomic force microscopy(C-AFM) with conductive cantilever tip and mini-structured MFC were employed for the in-situ characterization of internal reaction and property of MFC. To investigate an interaction between microbe and anode electrode with Ti nano-particle would be a clue for understanding of electron generation and transmission mechanism.

Resume : The aim of this study is to evaluate the feasibility of producing a combined heat and power system from woody biomass gasification unit coupled with a solid oxide fuel cell (SOFC). In particular, a downdraft air-gasification unit for syngas production and a tubular SOFC for heat and power production were considered. Both gasification and SOFC-CHP units were modeled via ASPEN plus in order to determine mass and heat balances and were validated with literature data. The SOFC electrical performances (polarization, power density and SOFC AC efficiency) were evaluated. The TRNSYS dynamic modelling features have been used to evaluate the most suitable technical solutions and to calculate all the energy streams and relevant parameters. Considering a compromise between feedstock consumption and capital costs, a 200 mA/cm2 current cell density was selected for the SOFC and the required syngas flow rate was calculated. Through the simulation model of the gasification unit, the amount of semi-dry (12% water content) woody biomass has been estimated to be about 413 kg/h for 635 kW of electricity produced by the SOFC. The gross AC efficiency of 40% was obtained. Based on simulations results, it was proved the theoretical possibility to obtain an added value from the energetic exploitation of woody biomass, through an integrated downdraft gasification unit and a 635 kW SOFC-CHP system. Through the employment of TRNSYS environment, a design model suitable for the technical, energetic and economic evaluation of the system has been developed, which represents a viable tool for detailed analysis on such systems.

Resume : The heart of a fuel cell is the membrane-electrode assembly consisting of two porous electrodes (where the electrochemical reactions take place), and the ionomer conductive membrane (that allows the proton exchange from the anode to the cathode). The porosity of the electrodes plays an important role in the fuel cell performance. One of the drawbacks presented by the porous electrodes is the accumulation of water in their structure, which implies a hindrance for the reactive gas transport to reach the electrode active sites. Of the many parameters that play a part in improving the fuel cell behavior, the water content in the gas that fed the cathode is systematically studied in reference to fuel cell performance. In this work, a mathematical model is presented and discussed in which fuel cell operating under steady state and isothermal conditions together with a simple and uniform porous electrode structure is assumed. It is demonstrated that at low current densities, water accumulation has no effect in the fuel cell behavior, whereas at high current densities the cell performance is severely affected.

Resume : The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are very important processes in different energy conversion devices such as electrolysers, unitized reversible fuel cells and metal-air batteries. Both reactions occur on the same electrode during the charge and discharge processes, what requires a “bi-functional” material able to carry out both reactions. Recently, perovskites have shown outstanding activities as bifunctional catalysts for both the ORR and the OER in alkaline medium. In the present work, a perovskite with formula La0.6Sr0.4Fe0.8Co0.2O3 (LSFCO) was mixed with a carbon material and investigated for operation as both oxygen reduction (ORR) and oxygen evolution (OER) catalyst. The catalyst was investigated in half-cell by using a three-electrode configuration, in alkaline solution at ambient temperature, and compared to a noble metal catalyst, Pd/C. LSFCO was less active for the ORR, while the performance for the OER was significantly higher compared to Pd. Several accelerated stress tests were carried out in order to investigate the stability of the catalyst. The LSFCO-based catalyst showed a very stable behavior compared to the noble metal catalyst.

Resume : In the last few decades, direct methanol fuel cells (DMFCs) have been actively investigated from both fundamental and applied points of view. Recent results have shown interesting perspectives for the application in the fields of auxiliary power supply and portable power sources. Hundred-watt-class DMFC systems designed to supply power for medium-size electrical applications, such as small vehicles and emergency auxiliary power sources, have been investigated. The design and operation of these systems require the selection of proper components, stack design and experimental conditions. In this work, a new design of bipolar plates was developed for a 10-cell DMFC stack, with 100 cm2 cell area, for auxiliary power units (APUs) applications. The membrane-electrode assemblies (MEA) were manufactured by using a fumapem® F-1850 perfluorosulfonic acid membrane (from FUMATECH); whereas, nanosized carbon supported PtRu and Pt were used as anode and cathode electrocatalysts, respectively. To study the scalability of the DMFC stack and related components, a 5 cm2 single cell was used for the preliminary studies adopting the same MEA configuration of the 100 cm2 stacked cells. Different methanol feed concentrations were investigated both in single cell and stack configuration. The results obtained with the stack showed a good matching with the performance recorded with the small single cell, confirming the scalability of the DMFC device.

Resume : Hydrogen (H2) has been recognized as a high energy density, efficient, and environmentally clean in a variety of renewable energy sources. However, production, storage, and transportation of H2 it involves some problems with regard to cost, safety, low hydrogen gravimetric density, and difficulty in hydrogen extraction. The H2 produced by water electrolysis in the on-site place can be an alternative compared to other way to solve these problems. In the water electrolysis area, the numerous researchers have been focused on the oxygen evolution reaction (OER) because the OER is a key anodic process (slow kinetics) compared with another process as hydrogen evolution reaction (HER) to produce H2. On a point of view of a catalyst, slow kinetics in OER and the use of precious metal (platinum group metal) for high performance should be solved to popularize water electrolysis. The target of this study is the development of non-precious catalysts with high activity via simple and efficient synthesis method that is a wet-chemical based method. The 0 dimensional transition metal oxide catalysts were synthesized through the co-precipitation. The electrocatalysts were characterized by various physicochemical analyses such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). To investigate electrocatalytic properties of prepared catalysts, we carried out electrooxidation activity measurements such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), long-term stability test, and electrochemical impedance spectroscopy (EIS). The relationship between their physicochemical properties and electrocatalytic activities will be explored and discussed with respect to variation of dimension.

Resume : Environmental concerns due to the increasing use of energy power sources based on fossil fuels have driven the development of fuel cell technologies. Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising because their high performance and wide range of applications. To accelerate the inherent electrochemical reactions taking place inside the PEMFC: the anodic hydrogen oxidation and the cathodic oxygen reduction, the use of catalysts is required. Nowadays, platinum is still the catalyst of choice for both processes. However, its scarcity, high cost and some geopolitical issues could limit its availability and use in the future, preventing the large-scale commercialization of PEMFC systems. To overcome these potential difficulties and ultimately replace Pt in PEMFCs, R&D activities in non-platinum catalysts are carrying out. Particular attention is receiving those materials that contain Co and Fe transition metals, like chalcogenides, inorganic/nanocarbon hybrid materials, and metal/N/C catalysts, among others. Regarding transition metal chalcogenides, cobalt sulphides are one of the most active electrocatalysts towards the ORR in acidic media. In this investigation, we synthesized practical catalysts of composition MxS2/C, MxM’1-xS2/C (M = Co; M’ = Ni, Fe; C = MWCNTs), by one-pot synthesis hydrothermal method. Then, we studied their electrochemical behaviour towards the ORR in H2SO4 and H3PO4 aqueous solutions, to mimic the fuel cell environment found in low and high temperature PEMFC, respectively. The results showed an improved electrocatalytic activity using CoS2-based catalysts. Furthermore, effects of catalyst composition and stability issues were also discussed. Acknowledgement: The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2012-2015) for the Fuel Cells and Hydrogen Joint Undertaking under grant agreement ARTEMIS no. 303482.

Resume : High temperature polymer electrolyte membrane fuel cells (HT-PEMFC) can operate at temperatures up to 220 °C, resulting in an increase of the overall system volume power density and efficiency, which makes HT-PEMFC very attractive for different applications. However, there are some critical challenges related to the long-term operation of these fuel cells, which need to be addressed. In particular, degradation observed in the cathode catalyst layer results in a loss of performance yielded by the fuel cell. To overcome this issue, a new approach based on the use of modified carbonaceous support for Pt nanoparticles dispersion has been followed in this investigation. Pt/MOx(CNT) electrocatalysts were synthesized from commercial multiwalled carbon nanotubes, modified by chemical oxidative treatment, and then coated with different metal oxides, MOx (M= Ce, Co, and Ti). Electrochemical characterization in three-electrode cell with H3PO4 shown enhanced electrochemically active surface areas compared to Pt/CNT reference catalysts, denoting decreased phosphoric acid poisoning. Furthermore, their in-situ performance (V-j curves) in H2|air single cell at 140, 160 and 180 °C, gave promising results, which was attributed to the modified cathode catalyst support. Acknowledgement: The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2013-2016) for the Fuel Cells and Hydrogen Joint Undertaking under grant agreement DeMStack no. 325368.

Resume : Polymer electrolyte membranes (PEMs) have found useful applications in many energy-related fields, including hydrogen production by water electrolysis (WE) devices [1]. Electrolysis of water using a PEM, serving as both proton conductor and separator of gases, is considered an appealing alternative to more conventional alkaline water splitting technologies. State-of-the-art PEMs are perfluorinated systems, such as Nafion. These materials offer most of the needed properties for efficient PEM WE, i.e., high proton conductivity, good mechanical and electrochemical stability. However, they suffer from several drawbacks, mainly (i) cross-permeation phenomena, especially at high pressure, leading to contamination of oxygen by hydrogen and potentially to high risk levels and (ii) operating temperatures limited to 80 °C due to mechanical strength and proton conductivity losses. Goal of the present work is to develop new, more resistant PEMs exhibiting reduced gas permeation and operating in a wider temperature range, e.g., up to 100 – 120 °C. Indeed, extension of working temperatures may result in a better water and thermal management as well as in enhanced kinetics of the oxygen evolution reaction, which is the rate determining step of the whole process. To reach this goal, the modification of Nafion membranes by the incorporation of solid inorganic acid nano-particles has been considered [2]. As original contribution to the research on PEMs for water electrolysis, we here report on the use of sulfated titanium oxide, S-TiO2, having super-acidity properties and tunable morphologies, as membrane additives. The influence of the inorganic filler on the properties of composite Nafion membranes is investigated. Temperature-dependent electrochemical performances of SPE electrolyzers adopting bare or composite polymer electrolyte are here discussed in terms of polarization curves, cross-over currents and impedance response of the cells. [1] M. Carmo, D.L. Fritz, J. Mergel, D. Stolten Int. J. Hydrogen Energy, 2013, 38, 4901. [2] S. Siracusano, V. Baglio, M.A. Navarra, S. Panero, V. Antonucci, A.S. Aricò Int. J. Electrochem. Sci., 2012, 7, 1532.

Resume : Electrochemical investigations on 1-2 kW experimental short stacks, consisting of different modified electrode configurations, were carried out under enriched-air conditions (> 23.5 % Oxygen) by using the current design stack technology. The aim was the electrochemical performance evaluation as a function of the oxygen compatibility in order to guarantee high standard levels in terms of safety, durability and feasibility. The interest was focused towards the performance evaluation under a 30% in oxygen for naval applications. This value was selected thanks to a preliminary investigation activity based on a risk analysis carried out at different oxygen percentages, by using materials and components data, consisting in the present stack technology in terms of hardware and software. Electrochemical characterizations performed on the experimental stacks assembled with different Pt loading under enriched-air condition (30% oxygen) showed an electrical efficiency enhancement of about 2% with respect to a commercial stack operating under standard condition (21% oxygen). In the perspective of overcoming the technology safety limit due to the current stack hardware and software components, the obtained result can offer large margin of improvement for operating conditions under more high oxygen percentage (> 30%).

Resume : Polymer electrolyte fuel cells based on Nafion membranes are able to work in a relatively low temperature range (70–100 °C) but require operating relative humidity (RH) close to 100% in order to allow effective proton conduction. In order to develop proton-exchange membranes with adequate performances at low RH an attractive strategy consists of the incorporation of inorganic acidic materials into the host Nafion polymer. Sulfated metal oxides are actually attracting much interest as fuel cell membrane additives [1]. This communication reviews our recent results concerning the characterization of nanosized TiO2 and SnO2 powders with high acidic properties to be adopted as fillers in Nafion-based polymer electrolytes. Taylor-made synthetic procedures have been assessed in order to obtain nanosized oxide materials with controlled morphologies and phase purity. Moreover surface treatments to bond sulphate groups on the oxide surfaces have been optimized. The obtained fillers have been characterized by thermal analysis (TGA), X-ray diffraction, N2-absorption, transmission electron microscopy and vibrational spectroscopies (Raman and FT-IR). The sulphated oxide nanoparticles have been incorporated in Nafion polymer membranes by a solvent-casting procedure. Structural, morphological and vibrational properties of the sulphated composite membranes have been investigated by advanced techniques including TGA, atomic force microscopy, Raman and IR spectroscopies. Functionality of the proposed membranes has been demonstrated by electrochemical in-situ (as electrolytes in a fuel cell device) and ex-situ (for proton conductivity tests) characterizations. [1] A. D'Epifanio, M.A. Navarra, F. Weise, B. Mecheri, J. Farrington, S. Licoccia, S. Greenbaum, Chem. of Materials, 22 (2010) 813

Resume : Efficiency of Molten Carbonate Fuel Cells (MCFC) is strongly associated with the microstructural characteristics of their components. Design of MCFC materials demands determination of quantitative relationships between the structure and operational efficiency of the cell. All the elements including cathode, anode and matrix are highly porous in order to facilitate catalytic and transport phenomena. Required porosity level is strictly determined by kinetics of chemical reactions in case of the electrodes. Porosity, as a crucial feature for each of main MCFC components, can be obtained by tape casting of metallic powder suspended in the polymer based slurry and further firing. The present paper presents the results of the optimization of manufacturing parameters and characterization of the anode materials obtained herewith using tape casting technique. In this method green tapes are formed from a slurry with strictly defined composition and properties. Subsequent stages of the manufacturing process, including: slurry composition optimization, tape casting set-up and heat treatment parameters, were carried out. Proper combination of slurry ingredients allows to achieve optimal structural characteristics of final products. The influence of the slurry composition and heat treatment conditions are correlated with structural parameters such as porosity of final products. In order to establish structure-property relationships the materials fabricated here were tested in MCFC assembly with respect to their efficiency. Anodes of various porosity and thickness were tested. Performance tests demonstrated that an adequate architecture of the anode allow to generate the power in the unit cell from 3.7 mW/cm2 to 4.9 mW/cm2 at 650 °C in humidified hydrogen.

Resume : Proton exchange membranes (PEMs) are ionically conductive polymers, typically employed in a wide range of applications, as for instance fuel cells. In this kind of technology, the membrane acts as a separator through which protons migrate with different mechanisms, typically vehicle- or Grotthus ones, depending on both the chemistry and physics of the starting polymer. Generally, NafionTM is the most investigated membrane electrolyte for fuel cells and still represents a benchmark to consider when a new system is proposed as alternative PEM. The state-of-the-art of Nafion as part of a fuel cell is impressively wide. It was extensively employed either in chemical fuel cell or microbial ones. The reason lies in a number of advantages offered by such polymer, such as the high proton conductivity, the low internal resistance and a good chemical stability. On the other hands, PEMs based on NafionTM are expensive; therefore they are not economically sustainable. In addition, they show a number of critical drawbacks, depending on the type of applications, as for instance: i) conductivity drops at temperature exceeding 100°C and humidification issues in case of chemical fuel cells; ii) chemical/biological fouling and high transfer ratio of substrate cations to protons in case of microbial fuels cells. In both the systems, these factors hinder the cathode electrochemical processes and drastically reduce the device functional performances. The current target on PEMFC R&D is the overcoming of such constraints. To this aim, the investigation of innovative and advanced materials could be a successful approach, either in the field of chemical fuel cells or MFC. Polybenzimidazole is the more attractive alternative to NafionTM. It is a cheap polymer, easy to synthetize and process, chemically stable and is a good proton conductor. In case of chemical PEMFCs, acid-doped Polybenzimidazoles are actually considered as promising electrolytes to replace Nafion in HT-PEMFCs. Nevertheless, some relevant questions are still open: under which operating conditions (chiefly temperature) are the acid-doped PBI systems a real alternative to Nafion? What is the real durability of the PBI cells/stacks? For what concerns the microbial PEMFCs, very isolated information is still available in literature about PBI membranes as potential separator for MFCs. Here I will report the state of the art and most recent developments of my group on polybenzimidazole systems in two cutting-edge technologies of green economy and bioenergy, namely high temperature (HT)-PEMFCs and Microbial Fuel Cells. Particular emphasis is given to some questions, which are still critical and open, as well as to the strategies adopted in my laboratory to properly address these issues.

Resume : In recent years, polymer electrolyte membrane fuel cells (PEMFC) are attracting great interest due to the high power densities that are capable of reaching at relatively low temperatures. Hydrogen and methanol have been the most common fuels used in these devices but both have certain drawbacks1. Nowadays, one of the best alternatives to these fuels is the use of ethanol, easy to store and distribute, cheaper and less toxic than methanol. In addition, ethanol is considered a green chemical and it can be produced as a renewable biofuel from the fermentation of biomass in large quantities. However, direct ethanol fuel cells (DEFCs) have important drawbacks as the slow electrode kinetics or the high cost of electrocatalysts in acidic media2. The use of alkaline membranes could improve the reaction kinetics and facilitate the use of a range of non-precious metal catalysts both in the cathode and in the anode, reducing the dependence of platinum and so the cost of the catalysts, in addition to an important decrease of alcohol permeability3. These advantages are the main reason to change the common type of PEMFC devices to others with anion exchange membranes as electrolytes. However, the main issue of the improvement of the performance of these fuel cells was the limited development of the anion exchange polymeric membranes (AEMs). In the present research, we report a comparative study of new composite PVA/PBI membranes synthesized in different proportions (2:1, 4:1, 6:1 and 8:1) using the casting method and doped with KOH in order to study their suitability for fuel cell applications. These materials have been characterized by FT-IR/ATR and Raman spectroscopy. Thermal stability, water and KOH uptakes have also been determined. The ionic conductivity of the doped membranes is between 10 2 and 10 1 S·cm 1. These results are suitable to use these composite membranes in anion exchange membrane DEFCs. In fact, the highest power density value obtained in single cell measurements is 76 mW cm-2 for PVA/PBI 4:1, giving a power density 50% higher than the doped PBI in the same conditions. References: [1] Oliveira Neto A., Giz M.J., Perez, J. et al., Journal J. of the Electrochemical. SocietySoc., 149: A272-A279, 2002 [2] Geraldes A.N., Furtunato da Silva D., Martins da Silva J.C. et al., Journal of . Power Sources, 275: 189-199, 2015 [3] Varcoe J.R., Slade R.C.T., Yee E.L.H. et al., Journal J. of Power Sources.;, 173:194-9, 2007

Resume : Ionically conducting materials (ICM) are of great importance for the fabrication of portable batteries for electronic devices such as computers, tools, video and still cameras, and for the development of fuel cell and battery-powered electric vehicles, dye-sensitized solar cells, supercapacitors and sensors. It has been suggested that conductivity in ICMs occurs via a number of different processes. The predominant conductivity processes are attributed to: a) the charge migration of ions between coordination sites in the host materials; and b) the increase of conductivity due to relaxation phenomena involving the dynamics of the host materials. Ions “hopping” to new chemical environments can lead to successful charge migration only if ion-occupying domains relax via reorganizational processes, which generally are coupled with relaxation events associated with the host matrix. In the first part of this presentation will review the general phenomena and basic theory behind Broadband electric spectroscopy. Then an overviews of the application of BES in the study of the charge transfer mechanisms pristine and hybrid inorganic-organic proton-conducting and anion-conducting membranes for fuel cells, the models adopted for the interpretation of conductivity mechanisms are described and a unified conductivity mechanism is proposed. Acknowledgements The authors thank the Strategic Project “From materials for Membrane electrode Assemblies to electric Energy conversion and SToRAge devices” (MAESTRA) of the University of Padova for funding this activity.

Resume : Acidic polymer electrolytes based on perfluorosulfonic-acid membranes are extensively used as electrolytes (e.g. Nafion-type membranes) in many electrochemical power applications, but high cost, low operating temperature and high methanol crossover of Nafion membranes limit their wide applications [1,2]. These drawbacks are pressing scientists to develop new composite polymer electrolyte membranes (PEMs) based on sulfonated aromatic polymers as alternatives to Nafion for DMFC applications. This study reports on the synthesis and development of PEMs based on composite membrane of sulfonated polysulfone and modified silica materials for application in DMFC at different operating temperatures. The sulfonated polysulfone (SPSf) is easily synthesized by using trimethyl silyl chlorosulfonate as sulfonating agent in a homogeneous phase of chloroform [3] and, the functionalized silica was prepared by reacting silica with neat chlorosulfonic acid at room temperature[4]. The ion exchange capacities (1.2 -1.8 meq g-1) of sulfonated polymer samples were obtained changing the mole ratio between the sulfonating agent and monomer unit of polymer. The structural and physical chemical features of the composite membranes were assessed by scanning electron microscopy, infrared spectroscopy and NMR measurements. Besides, the transport properties of the water and methanol through the electrolyte membranes as a function of methanol concentration (e.g. 1M - 5M CH3OH) and temperatures from room temperature up to 80°C were obtained by NMR and methanol/water uptake methods. Instead, the electrochemical features of membranes in terms of proton conductivity and DMFC performance at various temperatures were evaluated by polarization and ac-impedance spectroscopy (EIS) measurements. The whole study involved (a) the choice of preparative conditions to optimize the synthesis and yield of produced sulfonated polysulfone polymer, (b) the modification of silica and the optimization of acidic silica content in the composite membrane, (c) the assessment of structural and water/methanol transport properties through the membranes by using pulsed-gradient spin-echo (PGSE) NMR diffusion method under variable temperature and d) DMFC single cell investigations at different methanol concentration (e.g. 1-5 M) and temperatures. The first important finding of the work was obtained by NMR measurements, which showed higher water diffusion than methanol diffusion in all the three investigated membranes (composites and bare SPSf) and for different methanol solution concentrations (1-5M) and temperatures (30-80°C). Moreover, the study showed that as the temperature increases, the difference in diffusion coefficient become larger for the composites, proving the beneficial methanol blocking effect of the silica nanoparticles dispersed in the polymer matrix. The lower diffusion coefficient of acidic silica composite membrane than other membranes was also confirmed by in-situ measurements such as linear sweep voltammetry, by the limiting crossover current, and EIS under potentiostatic mode at 0.3 V. Both techniques showed that the best DMFC performance of SPSf-SiO2Sulf membrane was due more to its low permeability than to the high proton conductivity. The comparison of polarization curves show clearly that the MeOH crossover is the controlling phenomena occurring in DMFC that maximize the electrochemical performance, at least in the experimental conditions of measurements. A power density of 30 mW cm-2 was recorded at 60°C feeding 5M methanol solution at the anode and dry air at the cathode, both at atmospheric pressure. These interesting electrochemical features are indicating good perspectives of these membranes in practical DMFC for auxiliary power unit applications. References [1] J. Martin, W. Qian, H. Wang, V. Neburchilov, J. Zhang, D. Wilkinson, Z. Chang, Journal of Power Sources, 164 (2007) 287-292. [2] C. Laberty-Robert, K. Valle, F. Pereira, C. Sanchez, Chemical Society Reviews, 40 (2011) 961-1005. 3. F. Lufrano, V. Baglio, P. Staiti, A. Stassi, A.S. Arico’, V. Antonucci, J. Power Sources 195 (2010) 7727-7733. 4. M.A. Zolfigol, Tetrahedron 57 (2001), 9509-9511.

Resume : The exploitation of agro-industrial residues for syngas production through gasification process has attracted many interests in the sustainable energy for future developments in order to reduce the dependence from fossil fuels. Fruits processing industries generate important amount of residues, which must be managed properly by recycling, incineration or land filling. Particular attention has been recently addressed toward the use of residual biomass and wastes as sources for syngas production by thermo-chemical processes for heat and power production. In this context, thermo-gravimetric measurements of citrus residues (under nitrogen and steam atmosphere) allowed the selection of suitable gasification conditions (T≥720°C; S/B≥1.5 wt/wt). Therefore, steam gasification process of citrus waste was investigated from thermodynamic and experimental point of view. Experiments were carried out in a lab-scale reactor in presence of different catalytic materials (Ni/Al2O3, MgO and dolomite mineral). Results highlighted the effects of catalysts on outlet gas stream compositions mainly in terms of hydrogen content. In particular, gasification tests performed with dolomite get an H2 selectivity of about 84 vol%. Experimental results were also compared to thermodynamic data by process simulator software (Aspen Plus).

Resume : The aim of this communication is to report on application of various plasma-assisted sputtering for the synthesis of electrocatalysts and electrocatalytic layers for proton-exchange membrane (PEM) electrochemical systems (fuel cells, water electrolysers, etc). Targets based on platinum metals have been sputtered over the surfaces of membrane, gas diffusion electrode (carbon cloth, carbon paper of porous titanium) or nano-dispersed catalysts carrier using several physical techniques such as ion-beam and pulsed laser deposition. Synthesized electrocatalytic materials have been studied by transmission and scanning electron microscopy, X-ray diffraction analysis, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and cyclic voltammetry. They were also tested in PEM water electrolysis and fuel cells. Features of plasma-assisted catalysts deposition are discussed. Development of magnetron-ion sputtering technique was executed with financial support of the Russian Science Foundation (project No. 14-29-00111). Investigations of developed electrocatalytic materials have been financially supported by the Ministry of Education and Science of the Russian Federation within the framework of government task No. 2014/123 for performance of the government works in scientific activities.

Resume : Large scale application of polymer electrolyte membrane (PEM) fuel cell system technology requires a reduction of its high cost as well as improvement of performance and stability. In particular, for engineering requirements, PEM fuel cells for automotive application need to operates under harsh condition such as high temperatures, i.e. 110 °C or above, and low relative humidification (R.H.) less than 50%. These extreme conditions require the development of catalysts with proper resilience to sintering and corrosion. In addition, to reduce the total cost it is necessary to minimize the platinum content in the membrane electrode assembly (MEA) maintaining at the same time good performance. With these aims, in the last years at the CNR-ITAE Institute the research activities were focused mainly on the development of various platinum-based eletrocatalysts characterized by a good performance and proper resistance to sintering and corrosion [1-3]. In the present work, carbon supported Pt-Ni (differently alloyed) catalysts have been prepared by using the formic acid reduction method and characterized in terms of bulk and surface composition, structure and morphology. They have been investigated in PEFCs under automotive conditions (high temperature and low R.H.) and compared to a benchmark Pt/C catalyst. Accelerated degradation tests were also carried out to evaluate electrocatalysts stability. Acknowledgements The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) for Fuel Cell and Hydrogen Joint Technology Initiative under Grant no 303452 (IMPACT). References 1. A. Stassi, I. Gatto, G. Monforte, V. Baglio, E. Passalacqua, V. Antonucci, A.S. Aricò, J. Power Sources 208 (2012) 35. 2. A. Stassi, I. Gatto, V. Baglio, E. Passalacqua, A.S. Aricò, J. Power Sources 222 (2013) 390. 3. A. Stassi, I. Gatto, V. Baglio, A.S. Aricò, Int. J. Hydrogen Energy 39 (2014) 21581.

Resume : Large scale production of proton-exchange membrane fuel cells (PEMFCs) is mainly limited by the high cost and the high environmental impact of platinum-based catalysts. A higher control on Pt nanoparticles (NPs) density and morphology are mandatory while preserving an easy, scalable and environmental friendly deposition method. The synthesis of Pt/C catalysts by (wet) chemical routes are difficult to upscale and frequently require the use of organic solvents and surfactants which can lead to device failure due to the poisoning of Pt NPs. In this work, catalysts for PEMFCs applications are synthetized by using low-pressure RF plasma treatments [1], ensuring a fast and easy synthesis not requiring any use of solvents. The plasma discharge is applied to generate structural and chemically active defects at the surface of different nanostructured carbon supports where the simultaneous nucleation of metal nanoparticles occurs from the degradation of an organometallic powder precursor (platinum acetylacetonate). Furthermore, gram quantities are achievable in a laboratory-scale reactor. The organometallic precursor and the carbon solid powders are mixed and then continuously stirred during the plasma treatment; this ensures a homogenous decoration of the high-surface-area carbon nanomaterial (graphene nanoplatelets, carbon nanotubes and xerogels) by metal NPs. The treatment conditions such as the plasma discharge power, treatment time and chemical environment have been optimized to end up with a uniform and dense distribution of metal NPs with a controlled size (around 5 nm) and low particle aggregation. The catalysts have been systematically characterized by electron microscopy (SEM, TEM and analytical STEM-EDX), X-Ray diffraction, and High Resolution X-Ray photoelectron spectroscopy (XPS). Measurements of the electrochemical activity versus the oxygen reduction reaction show equal or superior performances of plasma catalysts with respect to commercial Pt/C catalysts. An advantage of plasma synthesis is that nitrogen functionalization of the carbon material can be simultaneously performed by applying N2 plasma treatments: N loadings up to 5 at% (as measured by XPS) were achieved. Finally, Pt-Ni bimetallic catalysts have been realized by mixing the respective organometallic precursors. Interestingly, for a bimetallic Pt-Ni/C catalyst, a catalytic activity comparable to that of Pt/C catalysts with a higher Pt content has been obtained. [1] M. Laurent-Brocq, N. Job, D. Eskenazi, J.-J. Pireaux, Applied Catalysis B: Environmental, 147, (2014) 453-463

Resume : Hydrogen evolution reaction (HER) consumes massive electrical energy in an alkaline electrolyte system during water and chlor-alkali electrolysis. Therefore, development of an active Pt-based electrocatalyst is remained as the great challenge to overcome the sluggish kinetics of alkaline HER. Recently, several reports demonstrated a promising strategy for enhancing the alkaline HER kinetics by depositing Ni(OH)2 clusters on the surface of a Pt catalyst. In this bimodal surface, the edges of oxophilic Ni(OH)2 catalyze the dissociation of water and the formation of hydrogen intermediates, while the nearby Pt surface converts the hydrogen intermediate to H2 gas. In this presentation, we have developed effective electrocatalysts based on Pt-Ni octahedra, where Ni(OH)2 was naturally formed on their surfaces during a synthesis. The as-obtained Pt-Ni octahedra show greatly enhanced HER activity in an alkaline solution compared to that of a commercial Pt/C catalyst.

Resume : Direct alcohol fuel cells (DAFC) are attractive power generator systems for stationary and portable applications. The major drawbacks of DAFC technology stand with the sluggish anode/cathode reactions and the crossover of unreacted alcohol permeating through the membrane and reaching the cathode side, decreasing the entire fuel cell performance. The use of methanol-tolerant non-noble metal (NNM) catalysts based on transition metals (Fe, Co) and N-doped carbon is a costly and advantageous solution. NNM catalysts are less active than PGM ones, but they do not suffer from CO or methanolic species poisoning. In this work, Iron phthalocyanine (FePc) was used as Fe/N/C source and templated with an ordered mesoporous silica (SBA-15), followed by heat treatment and leaching of silica with hydrofluoric acid (sacrificial method) [1]. The catalyst was fully characterized and tested in an RDE configuration. Then, MEAs containing the Fe-N-C were prepared with Nafion® and PBI membranes and tested in single cell DMFC/DEFC under different alcohol concentrations and temperatures. A commercial Pt-Ru black was used at the anode side. The experiments were performed using 3 bar-g back pressure in the cathode compartment. The optimal operating condition was found to be 1 M (methanol) and 2 M (ethanol) at 90 °C, reaching 19.6 mW cm–2 for DMFC and 74.7 mW cm–2 for DEFC, respectively. Potentially, DEFC has larger activity performance than DMFC, using the same catalyst, suggesting system optimization progress to achieve activity increasing. At similar operating conditions, Pt-based cathodes are dramatically affected by permeated alcohol, by reducing their activity. [1] AHA Monteverde Videla, L Osmieri, M Armandi, S Specchia, Electrochim Acta 177, 2015, 43.

Resume : A Ni/TiO2 electrocatalyst was synthesized and evaluated for its application in methanol oxidation in alkaline media. In brief, TiO2 nanotubes (TiO2-NT) were synthesized by electrochemical anodization from Ti foil which were used as substrate to later be deposited with Ni nanoparticles by cyclic voltammetry. An experimental factorial design was carried out to know the influence of potential range, scan rate and cycle number for Ni electrodeposition in the response for MeOH oxidation. Further on, the impact of nanotube length and the pre-treatment in acid media for the same reaction was assessed. For optimized conditions, scanning electron microscopy (SEM) and XRD revealed the presence of spherical Ni particles of an average value of 200 nm over the surface of the NT. Potential range was the most critical value in the study, while the number of cycles and scan rate exhibited to be in a competition where at higher scan rate the yield in methanol electrooxidation was increased. The NT length showed an important role in the maximum peak current demonstrating that longer geometries in the substrate enhance the reaction yield. Such behavior suggests that the NT are available and exposed to the electrolyte and organic molecule. These observations lead to the optimized combination of parameters for both electrocatalyst and support in the methanol oxidation.

Resume : Depending from the energy density of the fuel, micro fuel cells could present an interesting alternative to batteries for powering of nomad devices. Various designs were proposed, all underlining the sensitivity of the breathing fuel cells performances to the environment. The water management in these breathing fuel cells is indeed even more pronounced since the cathode is in ambiant conditions. We developed a planar fuel cell array based on a printed circuit board as collectors, with integrated interconnection elements to be compatible with the voltages requirements of conventional electronic devices. The present design behave differently from the classical stack architectures since the interconnection elements are in the plane of the array. The obtained 6g fuel cell is able to deliver 5W in stable condition, at a yield of 48%. Neutron imaging studies have been performed at various yields during short term and long term operation. Nucleation mechanisms have been found hugely affected by the interconnection and packaging elements as well as natural convection. Understanding the nucleation mechanisms led also to the development of water management solutions for improved degradation rate, which is one of the limitation of fuel cells based on Printed Circuit Board designs. With this design, promising durability results have been obtained. We will discuss the correlation between water patterns and electrochemical performances. Degradation mechanisms during short term and long term operation will also be presented.

Resume : In this work, Pd nanoparticles as well as PdFe, PdAu and PdPt nanocatalysts were synthesized via a green reduction method using 2-hydroxy ethylammonium formate ionic liquids as an “all-in-one” reaction medium. Crystallite and nanoparticle sizes were in well concordance finding values of 10.1, 10, 11.8 and 7.9 nanometers for Pd, PdFe, PdAu and PdPt, respectively. For PdAu, it was observed the presence of planes related to palladium and gold indicating that, some proportion of the catalyst is only physically mixed. Moreover, the XRD of PdFe revealed that this material was mainly composed of Pd-Fe2O3. The electrocatalytic activity for the ethanol oxidation reaction was carried out as function of concentration and working temperature. AuPd/C showed the most negative oxidation potential and a current density almost two-fold higher than Pd/C, and similar than that obtained for PdFe/C. Furthermore, PdPt/C showed a lower poisoning effect than the other catalysts, this behavior was studied by Surface-Enhanced Raman Spectroscopy (SERS).

Resume : The use of liquid fuels can be an attractive solution for supplying energy in portable devices. Direct Methanol Fuel Cell (DMFC) offers high theoretical power density. One way to control reactants distribution and the fluid dynamic regime is the use of different types of flow field (FF), both at anode and cathode. FF allows both supplying fuels and controling the diffusion of reactants for the electrochemical reaction, and removing products. Fluid flow in the FF can greatly affect the performance and life span of DMFC. In this study, the influence of three conventional and a modified FF designs on the performance of a DMFC was analyzed using a 3D multi-physics, multi-phase, multi-component and non iso-thermal model. The model includes Stokes-Brinckman, Darcy-Law, Maxwell-Stefan, Flory-Huggins and non-linear Butler-Volmer/Tafel equations for simulating the performance of a DMFC single cell, and to perform the electrochemical, fluid-dynamics and thermal phenomena. The model uses Comsol® Multiphysics v4.4 platform. All experiments for the model validation were carried out using a small-scale laboratory single cell DMFC with external areas of 5 and 25 cm2, for 3 different commercial flow field pattern: serpentine, convective and labyrinth. Experiments were performed by varying temperature and backpressure, using Nafion membrane, a commercial catalyst at the anode and a non-noble metal catalyst at the cathode.

Resume : In recent years, electricity-driven hydrogen production by electrochemical splitting of water has received particular attention because of its potential applicability in decentralized energy storage concepts.1,2 Most of the efforts have been focused on the electrochemical reaction occurring at the anode side, the oxygen evolution reaction (OER), since it is source of large overpotentials. Advances in computational studies and in in situ characterizations can now offer novel insights into the OER mechanism, revealing new perspective in the search for advanced materials. In this study, we couple a cutting-edge synthesis method to produce highly active OER nano-catalysts with advanced, time resolved X-ray absorption spectroscopy measurements able to capture snapshots of the catalyst electronic and local structure during operando conditions. The use of nano-catalysts not only allows achieving outstanding performance, but also reveals electronic and structural changes at the catalysts surface (given the high surface to bulk ratio of nanoparticles) never observed before. At present most of the fundamental studies on OER catalysts have been conducted using bulk techniques and materials with low surface area, which is a questionable approach considering that the OER is a near-surface reaction. In here we show that substantial and mostly irreversible chemical and structural changes take place on the catalyst surface at potentials where the OER occurs, opening new views on the OER mechanism. 1. Fabbri E, Habereder A, Waltar K, Kotz R, Schmidt TJ., Catal Sci Technol 2014, 4: 3800-3821. 2. Fabbri E, Nachtegaal M, Cheng X, Schmidt TJ, Advanced Energy Materials 2015, 5(17) 1402033

Resume : As the world population is increasing continuously, the energy demand is becoming a major challenge for the world’s energy sector. At present, energy supply mainly depends on fossil fuels which are directly related to environmental pollution. Moreover, the nuclear disaster in Fukushima, Japan in 2011 has diverted world’s attention to alternative fuel resources. Under this situation, substitutes for conventional fuel sources are in major trust areas in current research and technology. One of the alternatives to fossil fuels is solid oxide fuel cells (SOFCs). SOFCs have attracted wide attention due to its high efficiency, fuel flexibility and minimum carbon emission. SOFCs are the class of fuel cells that are mainly based on solid oxide electrolyte. The most extensive electrolyte used for SOFC is YSZ, although high operating temperature nearly 800C is required to achieve sufficient oxide-ion conductivity. High operating temperature of these cells lead to many problems related with material stability and compatibility with other components of SOFCs and also thermal degradation of the electrolyte itself. Therefore, now considerable attention is given in developing solid electrolytes which can operate at intermediate temperature range (600-800C). Na-doped SrSiO3 has been investigated for its use as solid electrolyte. Sr1-xNaxSiO3- (x=0.0, 0.10, 0.20, 0.30 and 0.40) have been synthesized by simple solid state reaction method. The X-ray diffraction study indicated the formation of monoclinic phase. Raman analysis is performed to support the XRD results. AC impedance spectroscopy is used to study the conductivity of the system. Sr0.6Na0.4SiO3- showed highest conductivity of 22.8 mS/cm at 800 C in air. The SEM analysis indicated that secondary phase is co-formed, which is segregated along the grain-boundary regions. DSC analysis further supported the formation of amorphous phase.

Resume : Donor-doped strontium titanates demonstrate remarkable structural stability against redox cycling and are considered as promising components for SOFC anodes targeted for sulfur-contaminated and partially-reformed fuels. One important issue in the development of SrTiO3-based anode materials relates to the mechanism of adoption of excessive oxygen, which has do be introduced in perovskite lattice to compensate donor dopant. In the present work, we consider the formation of various types of defects in Sr(Ti,Ta)O3 solid solutions, including point defects as well as continuous cases: defect associations and intergrowth of strontium tantalate layer. The Monte-Carlo simulation and static lattice energy minimization techniques were used to find an optimal configuration of the lattice for solid solutions with Ta content up to 35 at.%. The perovskite lattice with embedded Sr2Ta2O7-like layers was found to be most stable, whilst the formation of the oxygen interstitials is rather improbable, neither in the form of 1D nor as 2D continuous defects. Charge compensation through the generation of cation vacancies demonstrated an intermediate thermodynamic stability. The results of atomistic simulations are discussed in combination with the experimental results on structural, electrical and redox properties of Sr(Ti,Ta)O3 solid solutions. Support from Polish Ministry of Science and Higher Education (stat. grant no. CPC/4/STAT/2016) is gratefully acknowledged.

Resume : Perovskite type (La1-xSrx)CoO3-δ (LSC113) has been studied as one of the promising candidates for the cathode of intermediate temperature (500-700 ˚C) solid oxide fuel cells (IT-SOFCs); they show extraordinary exchange properties and the best mixed conduction among all aliovalent doped perovskites. Despite its advantages, the main problem in utilization of perovskite type LSC113 in SOFCs is surface strontium segregation and high thermal expansion coefficient, two effects both of which are detrimental at intermediate temperatures. Nonetheless, anomalously enhanced oxygen reduction kinetic around the (La1-xSrx)CoO3-δ/(La1-ySry)2CoO4+δ interface has been reported such that hetero interfacial surface oxygen exchange coefficient is 3-4 orders of magnitude higher than both phases. Such an enhancement in exchange property has potential to lower temperature of SOFC from intermediate to low temperature so long as the only source of the resistance is this highly improved surface exchange process. At such low temperatures, namely around 400 ˚C, thermal expansion and surface strontium segregation problems can be negligible. This approach presumes thin film cathodes. However, this scenario also necessitates extremely densified and vertically aligned hetero interface through this thin film. In this way, cathodes with vertical interfaces were obtained by PLD using only one target obtained via mechanically mixing separately synthesized powders with some success [1]. This study resulted in 1000 Ωcm2 at 400 ˚C and 0.21 atm P_(O_2 ), constituting the only attempt to yield high density of vertical interfaces. In the present work, (La0.8Sr0.2)CoO3-δ, (La0.5Sr0.5)CoO3-δ and (La0.5Sr0.5)2CoO4+δ (LSC214) powders were separately synthesized through low temperature solution based methods, ensuring the absence of any undesired phase [2]. Three oxide sputtering targets have been obtained from these powders by pressing them into 2-inch diameter pellets. The present work, then, attempts to obtain finely mixed interfaces via simultaneous sputtering by of LSC113 and LSC214 phases. This was achieved via a magnetron sputtering technique yielding thin film cathodes where the relative amounts of (La1-xSrx)CoO3-δ and (La0.5Sr0.5)2CoO4+δ phases varied. These variations were obtained by placing the substrates (GDC) in positions whose distance varied with respect to sputtering targets. In this way, more than ten different films were obtained for ORR measurement, each of which has its own interface creation as well as phase compositions. Thin film half cells having submicron thicknesses were then fabricated. These were then characterized via in-situ electrochemical impedance spectroscopy (EIS) with a frequency range between 1 MHz-10 mHz and 10 mV perturbation voltage amplitude. In-situ EIS measurements were conducted under different oxygen partial pressure and temperature combinations. The study aims to identify conditions giving the highest density of interfaces, the best associated ORR and hence the lowest possible ASR at 400 oC which is critical threshold for surface Sr segregation. Acknowledgement: The work reported in this study was supported by ERAFRICA FP7 Program: No. RE-037 HENERGY –TUBİTAK Project 114M128. ** deceased on 03.04.2016 References: [1] Ma, W., Kim, J. J., Tsvetkov, N., Daio, T., Kuru, Y., Cai, Z., et al. (2015). Vertically aligned nanocomposite La0.8Sr0.2CoO3/(La0.5Sr0.5)2CoO4 cathodes-electronic structure surface chemistry and oxygen reduction kinetics. Journal of Material Chemistry A (3), 207-219. [2] Torunoğlu Z. Ç., Demircan O., Kalay Y. E., Öztürk T. and Kuru Y., Utilization of Enhanced Oxygen Reduction Rate at Hetero Interface of(La0,8Sr0,2)CoO3-δ/(La0,5Sr0,5)2CoO4+δvia Dual Phase Synthesis. International Symposium on Materials for Energy Storage and Conversion Ankara, Turkey.Oral Presentation, September 7-9, 2015

Resume : Large scale research efforts are still needed to meet the efficiency, durability and cost requirements for polymer electrolyte membrane (PEM) fuel cells (FCs). Developing electrolyte and electrode components that tolerate a wide range of operating conditions is particularly challenging. Desirable PEM must not only be highly proton conductive under hot and dry conditions, it should be thermally and dimensionally stable, impervious to fuels, as well as to electrons. At the same time, low noble metal-loaded catalysts with enhanced activity towards oxygen reduction and hydrogen oxidation are needed. We here propose a double-task strategy based on the use of highly acidic sulfated titanium oxide (S-TiO2) [1] as both additive in Nafion membranes and co-catalyst for the redox processes. Powerful investigation tools for the understanding of both micro- and macroscopic characteristics of the proposed materials will be presented. Proton conductivity of the hybrid organic-inorganic membranes, as well as the redox capability of S-TiO2-supported Pt-based catalysts, will be addressed together with performances of the proposed composite materials in working fuel cell prototypes. Particular care will be devoted to the functionality of the new PEMFC configuration under critical parameters, such as dry or low relative humidity conditions and temperatures up to 120 °C. [1] V. Allodi, S. Brutti, M. Giarola, M. Sgambetterra, M.A. Navarra, S. Panero, G. Mariotto, Polymers 2016, 8, 68. Acknowledgements: The results of this work have been obtained in the framework of the project titled “Polymer electrolyte membrane water electrolysers: innovative, cost-effective electrocatalysts with enhanced durability”, funded by Sapienza University of Rome (ATENEO 2015, prot. C26A15HE93).

Resume : Irreversible processes on the electrodes severely affect performances and full-scale application of microbial fuel cells (MFCs). Single Chamber MFCs are mainly limited by the cathodic oxygen reduction reaction, which is kinetically hindered, and further obstructed by fouling and deposition phenomena on the cathode. pH increases through the cathode, facilitating salts and inorganic forms precipitation. The study of biofouling and precipitation processes is therefore crucial for a deeper understanding and optimization over long term operation of MFCs. In this work, a carbon-based cathode, consisting of carbon cloth covered with a carbon microporous layer, was investigated. The electrochemical behaviour of the cathode has been analysed over time during the MFC life. X-ray microcomputed tomographies (microCTs) have been carried out at progressive stages of cathode inactivation. The technique provides cross-sectional images and 3D reconstruction of volumes. Lower grayscale values in the image indicate lower X-ray attenuation, (i.e., lower atomic density) thus allowing to distinguish biofilm from inorganic fouling on the basis of the value of the linear attenuation coefficient calculated voxel (3D pixel). MicroCT was combined with SEM and EDX techniques in order to recognise chemical species in each different layer of the cathode’s section. Results correlated the calcium and sodium carbonate deposits, in the inner and outer part of the cathode respectively, with the produced electric current over time. A specific microCT-related software quantified the time-dependent salts deposition, identifying a correlation between the decreasing performances and the increasing quantity of calcium carbonate deposits.

Resume : One of the biggest obstacles to the diffusion of fuel cells is their cost, a large part of which is due to platinum (Pt) electrocatalysts. Complete removal of Pt is a difficult if not impossible task for proton exchange membrane fuel cells (PEM-FCs). The Anion Exchange Membrane Fuel Cell > (AEM-FC) has long been proposed as a solution as non-Pt metals may be employed. Despite this, few examples of Pt free AEM-FCs have been demonstrated with modest power output. The main obstacle preventing the realization of a high power density Pt free AEM-FC is sluggish hydrogen oxidation (HOR) kinetics of the anode catalyst. In this presentation we describe a Pt free AEM-FC that employs a mixed carbon-CeO2 supported palladium (Pd) anode catalyst that exhibits enhanced kinetics for the HOR. AEM-FC tests run on dry H2 and pure air show peak power densities of more than 500 mW cm-2. We have investigated the origin of this remarkable performance using cyclic voltammetry (CV), HR-TEM/STEM as well as XAS. This analysis shows the improvement is due to a strong interaction between Pd and CeO2. This talk describes a careful morphological analysis that attests to a fine dispersion of the Pd nanoparticles accumulated mostly on the ceria part of the catalyst. Such a structure helps to weaken the Pd-H bonds and assists in supplying OHad from oxophilic CeO2 to the Pd-Had (HOR reaction sites), thus accelerating the overall HOR.

Resume : The Solid Oxide Fuel Cells (SOFC) are electrochemical devices that may find application in stationary as well oversize vehicles such as aircraft or ships. Accordingly, the SOFC systems must demonstrate reliability towards the utilization of conventional heavy hydrocarbon fuels such as the diesel especially for on-board applications. The SOFC has already demonstrated a level of maturity as regards the manufacture of cells having Ni-based anode, stack, and systems. Nowadays, this type of technology is quite far from its use in real environmental conditions in which H2 is not available, although the main manufacture companies have forecasted that the global SOFC market is being to grow of 10.3 % over the period 2014-2019 as reported by TechNavio. Therefore, the main possibility for a rapid penetration of such technology into the market of generators for distributed energy is the utilization of a chemical processor coupled to the SOFC. Diesel is a complex mixture of heavy hydrocarbons; therefore, for a good comprehension of the processes occurring during the transformation of a fuel to energy, a pure and single hydrocarbon molecule simulating a complex fuel is necessary. In these terms, the use of n-dodecane for tests concerning the next use of diesel into the SOFC can give significant information. In this work we explored the reliability and feasibility of a coupled system based on a chemical processor and a SOFC operating at 800 °C. Furthermore, we will report on the development of a 500 Wel system based on a SOFC stack coupled with a reformer of n-dodecane.

Resume : Hydrophilic 2D platelike layers in polymeric matrix is of great interest due to significant gains in thermal stability, mechanical and barrier properties of the resulting nanocomposites. Lately, a series of novel nanostructured organo-modified layered materials based on graphene oxide (GO) and on silicates (clays and LDH) were synthesized, to be homogeneously dispersed into Nafion polymer. The membrane preparation procedure, as well as the exploitation of their large surface area, to be properly functionalized and to interact with the polymer, are the key points to prepare advanced nanocomposites for PEMFC applications. For instance, such materials can modulate the nature of water confined in the nanosized ionic channels of Nafion, and, as a result, hybrid membranes have showed high proton mobility and water retention at temperature >100 °C. Furthermore, the barrier properties of these layered materials was valuated to reduce the methanol crossover (critical issue in the DMFCs), through obstruction effect by increasing of the tortuosity of the fuel diffusion path. NMR spectroscopy is crucial for the molecular dynamics investigation, and was widely used to study the proton transport mechanism within the membranes through direct measurement of the self-diffusion coefficients (PFG technique) and the spin-lattice relaxation times (T1). The aim was to provide a general description of the water management (and methanol) inside the systems and of the effects of the fillers.

Resume : One of the critical issues in Direct Methanol Fuel Cells (DMFC) technology is the crossover of liquid methanol from anode to cathode side. Due to its high affinity with water, methanol crosses the Nafion® membrane reaching the cathode, where it oxidizes in presence of oxygen without electron injection in the external circuit causing severe energy loss. One possible solution presented is using palladium barriers, due to its remarkable proton conduction properties. In 2014, Casalegno et.al developed a palladium barrier deposited directly on the Nafion 115® membrane by PLD [Int. J. Hydrogen En. 2014, 39(6), 2801-2811]. Although the protonic resistance was increased, the cell efficiency improved due to a strong decrease in methanol crossover. In this work, we present a compact Pd barrier deposited on a thinner Nafion XL® membrane (25.7µm) by means of DC sputtering. The choice of a 4 times thinner membrane, compared to state of art Nafion 115® is to compensate the decrease in proton conductivity due to the presence of the palladium. Palladium barriers are sandwiched between two commercial DMFC electrodes and tested in fuel cell configuration. Performance curves and spectroscopy analysis are performed, while membrane resistance and methanol crossover are constantly monitored. With an efficient way to block the crossover, it could be possible to improve the cell performances along with the efficiency, filling partially the gap to large-scale commercialization of this technology.

Resume : Hydrogen compression by means of an electrochemical cell (EHC) is a very efficient and innovative technology for high pressure hydrogen storage, meanwhile efficient small size gas compressors able to withstand low power Polymer Electrolyte Fuel Cell (PEFC) stack conditions are hard to find on the market. They are also quite inefficient, noisy, produce undesired vibrations and pulsation. Thanks to its modularity, simplicity and the use of most of the fuel cell technology parts and design, the EHC (Electrochemical Hydrogen Compressor) can be used also for hydrogen recirculation within a Polymer Electrolyte Fuel Cell (PEFC) stack. In such a case, the pressure drop is usually very low (0,5-1 bar) while operative conditions (pressure, flow, temperature and relative humidity) are mostly influenced by the stack. In this work, the behaviour of two different membranes (a reference Nafion NR212 and a in-house manufactured composite Ni-TiOx) has been studied to optimise the operation at low pressure and give design input for an integrated stack-EHC unit. The experimental results show that the composite membrane gives better performance than the thinner Nafion NR212 thanks to its water retention properties, also giving evidence that the largest energy loss is due to the membrane resistance. The best operative conditions are then to operate at low current density, increasing the active area of the MEA (membrane and electrode assembly) and the overall EHC size.

Resume : Chitosan is a naturally abundant, low-cost and renewable polymer, which has excellent properties such as, biodegradability, non-toxicity and excellent stability. This biopolymer has good complexing ability due to the presence of –OH and –NH2 groups on the chain. During the last few years, nitrogen-doped carbon seems to be the most suitable oxygen reduction reaction (ORR) active material in the cathode catalyst for low temperature fuel cells. Recently, our research group have shown that hybrid chitosan derivative–carbon black used as support for Pt nanoparticles can improve the activity toward the ORR [1]. Herein, we describe the preparation and characterization of new bio-nanocomposite formed by chitosan with graphene and heteropolyacids for ORR in alkaline media. Physicochemical characterization of catalyst was performed by FTIRS, TGA, Raman, XRD, XPS, TEM and ICP-OES. Activity toward ORR was carried out in a three-electrode electrochemical cell using a rotating ring-disc electrode (RRDE). Acknowledgements This work was supported by the Spanish Government under the MINECO project ENE2014-52158-C2-1R (co-funded by FEDER), Spanish National Research Council COOPB20202 and MERC project 721394002. M.R.A acknowledges the FPU-2012 program for financial support. References 1. B. Aghabarari M. V. Martinez-Huerta, M. Ghiaci, J. L. G. Fierro and M. A. Peña, RSC Advances, 2013, 3, 5378

Resume : For practical applications of the MFC technology, the design as well as the processes of manufacturing and assembly, should be optimised for the specific target use. Another rising technology, additive manufacturing (3D printing), can contribute significantly to this approach by offering a high degree of design freedom. In this study, we investigated the use of commercially available 3D printable polymer materials as the MFC membrane and anode. The best performing membrane material, Gel-Lay, produced a maximum power of 240 ± 11 µW, which was 1.4 fold higher than the control CEM with PMAX of 177 ± 29 µW. Peak power values of Gel-Lay (133.8 – 184.6 µW) during fed-batch cycles were also higher than the control (133.4 – 160.5 µW). In terms of material cost, the tested membranes were slightly higher than the control CEM, primarily due to the small purchased quantity. Finally, the first 3D printable polymer anode, a conductive PLA material, showed significant potential as a low-cost and easy to build MFC anode, producing a stable level of power output, despite poor conductivity and relatively small surface area per unit volume. These results demonstrate the practicality of monolithic MFC fabrication with individually optimised components at relatively low cost.