Anode Reactants Research Articles

Modelling of the Water Mass Transport through the Membrane of Direct Toluene Electro-Hydrogenation Electrolyzers

The organic hydride toluene/methylcyclohexane (MCH) is an attractive carrier for the bulk and long-distance transport of green hydrogen. On the other hand, the direct toluene electro-hydrogenation in a proton exchange membrane electrolyzer exhibits advantages concerning the conventional two-step toluene hydrogenation process, such as the lower theoretical voltage by avoiding thermal losses [1]. Figure 1 (a) shows the internal structure and illustrates the basic working principle of this electrochemical device.However, the effective toluene supply to the cathode catalyst is a central issue. It is assumed that the accumulation of water dragged from the anode side inhibits the toluene mass transport to the reaction site [2]. Therefore, in practice, a fraction of the toluene stream entering the cathode fails to convert to MCH; instead, hydrogen bubbles are generated. According to the theoretical approach illustrated in Fig. 1 (a), protons transported across the membrane and can be the carrier of associated water. Nevertheless, the water transfer mechanism inside a cell is complex, diverse, and unclear (e.g., as mist, small droplet) [3].According to most conventional modelling approaches, electro-osmosis and back diffusion mainly govern the total water flux through electrolytic membranes. The open literature dealing with PEM fuel cells agrees that the water content of the membrane (correlated with the water activity by earlier studies) is a central factor concerning not only these mass transport mechanisms inside the membrane, but also concerning the mass transfer resistance on its surface. Indeed, to calculate both the electro-osmotic drag and the diffusion coefficients, authors have developed numerous correlations based on a relationship with the membrane water content. However, the experimental data available in the open literature dealing with PEM fuel cells devices largely disagree. Complex factors such as the Schroeder’s Paradox in Nafion® membranes [4] can explain those discrepancies. This leads into a huge uncertainty in the parametrization of those parameters involved in the numerical modelling and simulation of the water transport in electrochemical devices based on PEM technology [5].The objective of this work is to qualitatively study, through numerical simulation, the influence of the main parameters involved in the transport of water through the electrolytic membrane of a direct toluene electro-hydrogenation electrolyzer. To accomplish this aim, a sensitivity analysis was conducted, and the probability distributions set for each modelling parameter (i.e., potential variation range) are consistent with the state-of-the-art. The anode reactants considered were pure water and also diluted solutions of sulfuric acid with concentrations between 0.1-1.5 L/mol. Figure 1 (b) shows the preliminary results obtained when supplying pure water as anode reactant and under the assumption of null water mass transport by back diffusion mechanism. The experimental data gathered from the monitoring of an in-house toluene electro-hydrogenation cell are used as reference to discuss the results obtained from the simulations and to tighten the modelling parameters. Acknowledgements Antonio Atienza-Márquez acknowledges the Ministerio de Universidades of Spain and the Recovery, Transformation and Resilience Plan for financially supporting the postdoctoral contract 2021URV-MS-01.

Visualization of dragged water and generated hydrogen bubbles in a direct toluene electro-hydrogenation electrolyzer

Methylcyclohexane is an appealing liquid organic hydrogen carrier produced from toluene hydrogenation. The direct toluene electro-hydrogenation technique in proton exchange membrane electrolyzers avoids heat losses and reduces the electricity consumption concerning the conventional methods. However, this technology faces a critical issue. The water dragged by electro-osmosis from the anode side blocks the toluene supply to the cathode reaction site. This paper presents the experimental visualization, for the first time, of water droplets and generated hydrogen bubbles inside the cathode porous transport layer of a direct toluene electro-hydrogenation cell. Experiments were conducted under different current densities and using not only pure water but also dilute sulfuric acid as anode reactant. The visualizations revealed that the bubbling grew sharply as the electric current increased between 20 and 100 mA/cm2. It was also observed that water droplets got stuck inside the cell. As for hydrogen, small bubbles left the cell rapidly while larger ones stayed inside for longer. Finally, the experimental visualizations confirmed that the water dragging phenomenon was mitigated by using dilute sulfuric acid as anode reactant instead of pure water. Indeed, the hydrogen generation was halved at 200 mA/cm2 and the methylcyclohexane Faraday efficiency was boosted by 15%–22% points.

Intensification of proton conductivity through polymer electrolytic membrane using novel electrode pattern

The performance of a polymer electrolyte membrane fuel cell is contingent on the focal property of the protonic conductivity to accelerate the electrochemical reaction based on the membrane activity or on the uniform and even distribution of the reactants. For the even distribution, novel Flow Fields (FF) of the electrode pattern are obligatory to maintain the distribution for a long period for the conversion of protons from the anode reactant. In this study, a novel X Flow Field (XFF) electrode pattern is developed and compared with the conventional serpentine Flow Field (SFF) electrode pattern numerically and experimentally. The performance of the cell through the XFF electrode pattern has shown an improvement of 14.89% numerically and 14.61% experimentally as it distributes the reactants evenly to accelerate the electrochemical reaction, and induce a lower pressure drop and lower water saturation. The effect of pressure and Mass Flow Rate (MFR) of the reactants on the cell performance is discussed and it is found that the increment in Power Density (PD) of the cell is proportional to the increment of the MFR and the pressure because of the even distribution of the reactants, better membrane protonic conductivity, enhancement of the electrode kinetics and improvement in the mass transfer.

The effect of non-spherical platinum nanoparticle sizes on the performance and durability of proton exchange membrane fuel cells

• Developed and implemented a novel one-pot synthesis technique. • Synthesized non-spherical carbon-supported platinum nanoparticle catalysts. • Carried out physical, half- and full cell electrochemical characterizations. • Catalyst with 2 nm Pt size has excellent performance (> 1.1 W/cm 2 peak power density). • Catalyst with larger Pt size (5 nm) has excellent durability under AST. Platinum (Pt) nanoparticles with different sizes of 2 nm and 5 nm supported on functionalized high surface area carbon (HSC) have been successfully synthesized with a one-pot synthesis technique in large scale. Of the interest for the proton exchange membrane fuel cell applications, the synthesized supported catalysts are evaluated by physical characterizations, half-cell and scaled up single cell tests to study the impact of the catalyst sizes on cell performance and durability. Physical characterizations clearly demonstrate the sizes, shapes, crystallinity phases, and the total loading of the Pt nanoparticles on HSC. Half cell characterizations demonstrate higher electrochemical surface area, higher mass activity, and less durability for the working electrode prepared by the smaller Pt nanoparticle sizes (2 nm) than the larger Pt nanoparticles (5 nm). Scaled up single cell tests using air and hydrogen as the cathode and anode reactants demonstrate the membrane electrode assembly (MEA) prepared by smaller Pt nanoparticle sizes (2 nm) shows the maximum power density of 1.1 W/cm 2 , which is 7% higher than the maximum power density of MEA prepared by larger Pt nanoparticles (5 nm) under similar operational conditions. The 30,000 cycles of accelerated stress test on the membrane electrode assembly prepared by larger Pt nanoparticles (5 nm) demonstrates 13% drop at maximum power density, illustrating the excellent performance against degradation (ageing).

Enhanced cross-flow split serpentine flow field design for square cross-sectional polymer electrolyte membrane fuel cell

Enhanced Cross-flow split serpentine flow field (ECSSFF) for a rectangular cross sectional polymer electrolyte membrane fuel cells (PEMFCs) has been shown to be an effective layout compared to parallel serpentine designs. The concept of ECSSFF channel layout is extended to a square cross-sectional cell in this work. This is carried out with a detailed 3D and two-phase flow coupled with electrochemistry analysis in a computational environment using ANSYS®17.2. A detailed parametric study for fuel cell having square ECSSFF channel design is presented in this work. In addition, this layout is also evaluated for its efficacy at higher active areas up to 200 cm2. The study on different channel to rib width ratios has indicated that the ratio of 1:1 results in peak performance at cell operating pressure and temperatures of 200 kPa and 70 °C for fully humidified anode reactants and 50% humidified cathode reactants. The performance of the square PEMFC with 4-channel ECSSFF design on cathode side is found to be superior to that with five parallel serpentine design and the proposed design is also found to be effective for higher active areas.

Impact of OER Catalyst Activity and Stability on PEMFC Fuel Starvation Caused Cell Reversal Tolerance

Polymer electrolyte membrane fuel cells (PEMFCs) are considered as one of the most promising alternatives to internal combustion engines (ICEs). In a fuel cell electric vehicle (FCEV), the technology provides high energy conversion efficiency and power density at relatively low operating temperatures, with zero or low greenhouse gases emissions. Materials and systems research and development over the last decade have significantly improved the output power and lifetime of the PEMFC stacks. For wide adoption of PEMFCs to replace ICEs, continuing improvements in durability and cost are required. Cell voltage polarity reversal can result in irreversible damage of materials in the PEMFC membrane electrode assembly (MEA), gas diffusion layer (GDL), and even the bipolar plates [1], especially in fuel starvation caused cell reversal events. A number of circumstances can lead to fuel starvation, such as ice formation and severe water flooding which block the anode reactant channels, a sudden change in reactant demand due to load change, and improper reactant control during fuel cell start-up [2]. In fuel starvation caused cell reversal events, carbon oxidation (MEA material degradation) or oxygen evolution reaction (OER, i.e., water electrolysis) will take place to sustain the current generated from unaffected neighbor cells in the fuel cell stack. To avoid the detrimental oxidation of MEA materials, the water electrolysis process is preferred to be promoted by incorporating OER catalysts into the anode catalyst layer. Ruthenium and iridium based oxides are state-of-art PEM water electrolyzer (PEMWE) catalysts. In spite of their different anode layer design and operating conditions, the OER activity and stability of these catalysts have been investigated as the reversal tolerant catalyst (RTC) in PEMFCs [3]. Ru based catalysts provide high OER catalytic activity and increase the fuel cell reversal tolerance. However, they are prone to degradation due to insufficient stability in the PEMFC environment and operating condition. In PEMWE, the catalyst is expected to be stable at potentials higher than 1.4V, on the other hand, in PEMFC, the OER catalyst in the anode is required to be robust to potential swings between 0V to 1V (vs. SHE), because of the fuel cell start-up and shutdown processes. Considering the structure of the anode compartment, the OER catalyst is in direct contact with the electrode substrate in PEMWE, whereas in PEMFC, carbon supported platinum (Pt/C) catalyst of the hydrogen oxidation reaction (HOR) is also incorporated in the anode layer. The presence of Pt/C catalyst adds further complication toward the development of reversal tolerant anode since the carbon corrosion resistance is also required to be considered. Figure 1.a reveals an example in which using the same OER catalyst with similar loading, the cell reversal tolerance for two anode HOR catalyst designs can be significantly different. In this study, the impact of OER catalyst activity and stability on fuel cell reversal tolerance and durability is explored. Also, the strategic pathways to improve both the reversal tolerance and durability of OER catalysts in PEMFC are discussed. It has been demonstrated that these approaches can provide remarkable reversal tolerance without a significant trade-off in the performance and durability of the fuel cell. Figure 1.b shows that by catalyst treatment, both cell reversal tolerance and durability of the anode layer have been improved.

Three-dimensional non-isothermal model development of high temperature PEM Fuel Cells

A three-dimensional non-isothermal mathematical model is developed in a triple mixed serpentine flow multichannel domain for a high temperature PEM Fuel Cell having a phosphoric acid doped PBI membrane as electrolyte and an active area of 25 cm2 within Comsol Multiphysics. The inlet temperatures of cathode and anode reactants are taken as 438 K. Model predicts pressure, and temperature distribution along the channels and membrane current density distribution over the membrane electrodes. The model results are obtained at two different operation voltages, 0.45 V and 0.60 V. Resulting average current densities are respectively 0.313 A cm−2 and 0.224 A cm−2. The non-isothermal model results are compared to isothermal model results from a previous study and various other single channel non-isothermal model results available in the literature. The pressure drop at cathode compartment is predicted to be 6500 Pa, whereas it is found to be 6400 Pa for the isothermal model. The temperature difference within the system is found to be 0.18 K for the operation voltage of 0.6 V, whereas this value increases to 0.31 K for the operation voltage of 0.45 V. The temperature difference isocontours are illustrated for the whole cell. Considering changes in temperature, one can employ isothermal operation assumption for this system as an approximation and simplification for the governing equations, since the variation in the temperature within the cell is less than 1 K. It should be emphasized that multichannel model predictions are more realistic compared to single channel models. The model developed here can be extended to larger electrode active area and different multichannel configurations.

Performance analysis of a transparent PEM fuel cell at theoptimized clamping pressure applied on its bolts

Experiments were carried out on a single transparent proton exchange membrane (PEM) fuel cell with titanium gas distributor plates. Effect of the clamping pressure due to torque applied on each bolt, anode and cathode humidification temperatures, fuel cell temperature and cathode flow rate on the performance of the fuel cell are discussed in this work. Results show that the performance of fuel cell increases first to a maximum and then decreases with further increase in bolt torque. The cell performance decreases with increase in cathode humidification temperature and increases with the cell temperature. Also, humidification of anode reactant is important to improve the performance of the fuel cell. The effect of cathode flow rate is less at activation and ohmic overpotential region but it is significant at concentration overpotential region.

Electrochemical De-Hydrogenation of Liquid MCH at Room Temperature

Hydrogen is a potential candidate for energy carrier role with high gravimetric energy density of 33kWh/kg. However, owing to its low volumetric energy density, 0.003kWh/l at STP, which is very small compared to common fuels, it poses logistical barriers in its widespread use. Conventional methods of hydrogen storage and transportation include compression up to pressures near ~80MPa or liquefaction by cooling down to temperatures below -253˚C. Another promising method of hydrogen storage is to chemically store in the form of organic hydrides. One such organic hydride is methyl-cyclo hexane (MCH), which is liquid at standard temperature and pressure and can be reversibly hydrogenated and de-hydrogenated for storage and extraction of hydrogen, respectively. Extraction of hydrogen from MCH through dehydrogenation is an endothermic process (ΔH=204.8kJ/mol), so to favor hydrogen production the reaction is carried out at high temperatures. Conventionally, this is carried out in chemical plant sized reactors at temperatures near ~350˚C [1]. Maintaining such a high temperature in small scale energy devices increases the cost and complexity. Hence it is difficult to carry out dehydrogenation locally within the energy devices which utilize the thus extracted hydrogen. A low temperature (<120˚C) and low pressure (~1atm) dehydrogenation process able to be carried out in small scale devices can herald widespread use of MCH as a hydrogen carrier. This will promote hydrogen as a viable option to conventional fuels. In this study, we have demonstrated the dehydrogenation of MCH at room temperature and pressure using polymer electrolyte membrane (PEM) based electrochemical cell. By applying a potential across the membrane electrode assembly (MEA), consisting of carbon supported catalyst electrode as anode and cathode, hydrogen evolution was observed at cathode side with the supply of MCH at the anode. Quinones have been used as reaction mediator to lower the electrode potential required for the dehydrogenation of liquid MCH to below the water electrolysis potential (1.23V). Formation of toluene as a dehydrogenation by-product at anode was also confirmed using gas chromatography mass spectrometry (GC-MS) analysis. Effect of temperature variation and anode reactant flow rate has been investigated. References F. Buonomo, D. Sanfilippo, F. Trifirò, in: G. Ertl, H. Knözinger, J. Weitkamp (Eds.), Handbook of Heterogeneous Catalysis, vol. 5, VCH, Weinheim, 1997, p. 2140

Three Dimensional Numerical Analysis of 1kW Class Anode Supported Flat Tubular Solid Oxide Fuel Cell Stack

Three dimensional numerical analysis of 1 kW flat tubular solid oxide fuel cell (FT-SOFC) stack that embedded in RPG is conducted. In this present analysis, steady state heat and mass transfer, species concentration and electrochemical reactions along with their losses are analyzed for FT-SOFC stack using two types of fuels; humidified hydrogen and reformed natural gas. However, the final objective of this numerical study is to design a complete 1 kW fuel cell stack system, which will be comprised of FT-SOFC stack, heat exchangers, after burner and integrated reformer. It is interesting to note that fuel cell operate best when they are fed with pure hydrogen which is quite clear from the result mentioned below. The reason is that inert gases are built up at higher current density causing concentration polarization in case of reformed gas. But the problem with pure hydrogen is its storage. An important feature of solid oxide fuel cell is its fuel flexibility. To take advantage, reformed natural gas is employed as alternative fuel as it contains more than 70 % hydrogen & more than 10% CO which act as a fuel. In the numerical computation process, governing equations for continuity, momentum, mass and energy conservation are solved simultaneously. The distribution of the reaction fields in Anode-supported FT-SOFC are found similar to those in the planar SOFC. However, the concentration and activation polarizations in FT-SOFC can be reduced by additional reactant diffusion through the porous ribs of the fuel channel. The present 1kW class stack consists of 80 anodes supported flat tubular (FT) SOFC’s, arranged parallel in a group of 40 cells each. The FT cells are positioned in vertical direction and placed in a preheated air enclosure whereas as fuel gas is supplied through the bottom manifold. To effectively conduct a three-dimensional (3-D) computational analysis of the flat-tubular stack, a commercial ANSYS Fluent 13.0 code is used. The User defined function (UDF an in house code) is also utilized for the simulation of electrochemical reactions, losses in cell voltage due to activation, ohmic and concentration. The changes on the voltage and power of the SOFC stack, current density distribution, temperature distribution, and species concentrations in relation to varying amounts of reaction gas flow are analyzed. To calculate activation loss during electrochemical reactions in cells, the different experimental formulas of exchange current density presented by Achenbach et al., Costamagna et al., Campanari et al. and Aguiar et al. were used. The formula of Achenbach indicates that only partial pressure of H2, an anode reactant, influences the determination of activation loss. By contrast, the formula of Costamagna et al. shows that both reactant H2 and product H2O affect the determination of activation loss. Although the reaction orders of the reactants and products observed by the two authors are different. Both Achenbach and Costamagna show a reaction order close to stoichiometry of electrochemical reaction in the anode. In this selected part of project, numerical study of FT-SOFC stack is done with both pure hydrogen and reformed natural gas. The I-V-P curves of the experimental and calculation results conducted on the basis of the different formulas were compared to identify a most suitable model for the SOFC stack in this current work. The electrical powers of stack system obtained from experiment using pure hydrogen and reformed natural gas are 1203 W, 1123 W respectively. Whereas, electrical powers of stack system obtained from numerical simulation are 1220 W, 1168 W respectively. The error between the calculated and experimental I-V-P curves of SOFC stack is around 4 %. The analysis is envisioned to facilitate advancements in design for Flat Tubular SOFC stacks as well as system operation for practical applications. Figure 1

Investigation of degradation effects in polymer electrolyte fuel cells under automotive-related operating conditions

The influence of artificial starvation effects during automotive-related operating conditions is investigated within a polymer electrolyte fuel cell (PEFC) using non-dispersive infrared sensors and a current scan shunt. Driving cycles (DC) and single load change experiments are performed with specific fuel and oxidant starvation conditions.Within the DC experiments, a maximal CO2 amount of 4.67 μmol per cycle is detected in the cathode and 0.97 μmol per cycle in the anode exhaust without reaching fuel starvation conditions during the DC.Massive cell reversal conditions occur within the single load change experiments as a result of anodic fuel starvation. As soon as a fuel starvation appears, the emitted CO2 increases exponentially in the anode and cathode exhaust. A maximal CO2 amount of 143.8 μmol CO2 on the anode side and 5.8 μmol CO2 on the cathode side is detected in the exhaust gases. The critical cell reversal conditions only occur by using hydrogen reformate as anode reactant. The influence of the starvation effects on the PEFC performance is investigated via polarization curves, cyclic and linear sweep voltammetry as well as electrochemical impedance spectroscopy. The PEFC performance is reduced by 47% as a consequence of the dynamic operation.

Effects of temperature, triazole and hot-pressing on the performance of TiO2 photoanode in a solid-state photoelectrochemical cell

The photocurrent of hydrogen generating solid-state photoelectrochemical cell utilising a polybenzimidazole proton-conducting membrane and gaseous anode reactants has been enhanced by operation at higher temperatures. With a bias of 0V for example, photocurrent increased from 15 to 30μA/cm2 on moving from 25°C to 45°C. The increase in photocurrent, which was limited by the dehydration of the cell, was shown to have contribution from improved electrode kinetics. Modification of TiO2 surface with triazole, a conjugated heterocyclic compound, led to significant increase in photocurrent up to 4 fold increase at 0V and 25°C. This was attributed to improved separation of photogenerated charge carriers, as confirmed by correspondingly increased carrier lifetimes from 50ns to 90ns for triazole-modified TiO2. Assembly of the photoelectrochemical cell by hot-pressing induced a ̴0.3eV red shift in optical absorption edge of TiO2, in agreement with a shift of its valence band maximum to higher binding energy.

A New Paradigm for PEMFC Ultra-Thin Electrode Water Management at Low Temperatures

In this paper, we provide initial results of a novel method which dramatically improved the performance of ultra-thin electrode polymer electrolyte membrane fuel cells under highly water-condensing operating conditions, realized via modification of the anode gas diffusion layer and utilization of reduced anode reactant pressures, including sub-atmospheric pressure down to 20kPa. Measurements indicated that the sub-atmospheric anode reactant acted to greatly reduce the water flux exiting out the cathode, likely reducing cathode water flooding and oxygen transport limitations.

Nanostructured Co3O4 Materials: Synthesis, Characterization, and Electrochemical Behaviors as Anode Reactants in Rechargeable Lithium Ion Batteries

Three distinct Co3O4 nanostructures of nanoparticles, nanocubes, and hierarchical pompon-like microspheres were prepared through facile solution routes. These materials were characterized by XRD, SEM and FE-SEM, and nitrogen adsorption, and their formation mechanisms were briefly discussed. Their electrochemical behaviors as electrode reactants for lithium ion batteries were evaluated by cyclic voltammograms, electrochemical impedance spectroscopy, and static charge−discharge cycles. Among the three, pompon-like microspheres exhibit the best electrochemistry, revealed by the perfect combination of high discharge capacities and excellent cycling retention. A direct comparison of electrochemical behaviors between these three nanostructures reflects interesting “nanostructure effect”, which is reasonably discussed in terms of how particle sizes, nanostructures, and crystallinity of Co3O4 materials function in tuning their electrochemistry. Observations from this research are expected to extend to other trans...

Harvesting energy from the marine sediment–water interface: III. Kinetic activity of quinone- and antimony-based anode materials

Benthic microbial fuel cells (BMFCs) consist of an anode imbedded in marine sediment, connected by an external circuit to a cathode in overlying water. Long-term power density of BMFCs is limited by mass transport of the anode reactants, the transport being attributed to natural processes, including diffusion, convention, and tidal pumping. In order to increase short-term power density of BMFCs and long-term power density of a more recently reported BMFC, which artificially augments mass transport of the anode reactants, new anode materials are reported here with faster kinetics for microbial reduction as compared to commonly used G10 graphite. Results indicate that the kinetic activities (KAs) of glassy carbon graphite with surface-confined anthraquinone-1,6-disulfonic acid (AQDS), graphite paste with an incorporated Sb(V) complex, and oxidized graphite, and oxidized graphite subsequently modified with AQDS is 1.9–218 times greater than the KA of plain G10 graphite.

Microbial fuel cell using Enterobacter aerogenes

A microbial fuel cell whose anode was steeped directly in a cultivating liquid was demonstrated to work long term by adding nutrients periodically. A fairly large current density (ca. 60 μA/cm 2) was obtained by using a stainless-steel net electrode plated with platinum black. The electroactivities of glucose and metabolites produced by Enterobacter aerogenes were analysed by the single scan voltammogram method. From the analysis, it was found that the main anode reactant was hydrogen which was biochemically produced from glucose by the bacteria.

Microbial fuel cell using Enterobacter aerogenes

A microbial fuel cell whose anode was steeped directly in a cultivating liquid was demonstrated to work long term by adding nutrients periodically. A fairly large current density (ca. 60 μA/cm 2) was obtained by using a stainless-steel net electrode plated with platinum black. The electroactivities of glucose and metabolites produced by Enterobacter aerogenes were analysed by the single scan voltammogram method. From the analysis, it was found that the main anode reactant was hydrogen which was biochemically produced from glucose by the bacteria.

Applications of the gas diffusion electrode to a backward feed and exhaust (BFE) type methanol anode

A new application of the gas diffusion electrode as a BFE-type anode to direct methanol oxidation is proposed. This was prepared using the same concept as that proposed by us in the preparation of an electrode for hydrogen—air fuel cells working under the contribution of whole catalyst clusters. The electrode consists of two layers: a catalysed, semi-hydrophobic reaction layer, and a hydrophobic gas-supplying layer. Methanol is supplied to the catalyst layer in the vapour phase via the hydrophobic layer by circulating methanol dissolved in water to the backside of the electrode, and the carbon dioxide produced can be evolved from the surface of the hydrophobic layer. The use of the anode is extremely effective for a high contribution of catalyst clusters and for eliminating the decrease in this contribution caused by covering the clusters with carbon dioxide bubbles. The electrode-loaded Pt+Ru catalyst on the optimized reaction layer exhibits very high performances, especially when it is heat-treated at 250°C in air, e.g. 100 mA cm −2 at 0.4 V and a limiting current of more than 1 A cm −2. Many other advantages are gained by the BFE anode, as demonstrated in applications to the direct methanol fuel cell and to the anode reactant for zinc-electrowinning.