Direct methanol fuel cell cathode catalyst layer

Liu, R, and Wang, C. Y. Optimization of cathode catalyst layer for direct methanol fuel cells Part II Computational modeling and design. Electrochimica Acta 2006 52 1409-1416. 

Methanol (MeOH) crossover from the anode to the cathode in the direct methanol fuel cell (DMFC) is responsible for significant depolarization of the Pt cathode catalyst. Compared to Pt-based catalysts, NPMCs are poor oxidation catalysts, of methanol oxidation in particular, which makes them highly methanol-tolerant. As shown in Fig. 8.25, the ORR activity of a PANI-Fe-C catalyst in a sulfuric acid solution is virtually independent of the methanol content, up to 5.0 M in MeOH concentration. A significant performance loss is only observed in 17 M MeOH solution ( 1 1 water-to-methanol molar ratio), a solution that can no longer be considered aqueous. The changes to oxygen solubility and diffusivity, as well as to the double-layer dielectric environment, are all likely to impact the ORR mechanism and kinetics, which may not be associated with the electrochemical oxidation of methanol at the catalyst surface. Based on the ORR polarization plots recorded at... 

The thickness of the cathode catalyst layer (CCL) in low-temperature fuel cells varies from ten micrometres in modern PEFCs to hundred of micrometres in direct methanol fuel cells (DMFCs). The CCL in DMFCs operates at a high level of flooding, which reduces ORR efficiency. The considerable thickness of the active layer facilitates electrochemical conversion under these conditions. 

Abstract One of the most critical fuel cell components is the catalyst layer, where electrochemical reduction and oxidation of the reactants and fuels take place kinetics and transport properties influence cell jjerformance. Fundamentals of fuel cell catalysis are explain, concurrent reaction pathways of the methanol oxidation reaction are discussed and a variety of catalysts for applications in low temperature fuel cells is described. The chapter highlights the most common polymer electrolyte membrane fuel cell (PEMFC) anode and cathode catalysts, core shell particles, de-alloyed structures and platinum-free materials, reducing platinum content while ensuring electrochemical activity, concluding with a description of different catalyst supports. The role of direct methanol fuel cell (DMFC) bi-fimctional catalysts is explained and optimization strategies towards a reduction of the overall platinum content are presented. 

Cathode catalyst layer using supported Pt catalyst on ordered mesoporous carbon for direct methanol fuel cell. Journal of Power Sources,... 

The ORR electrochemistry in gas saturated 0.05 mol dm" H SO was investigated at 25 °C using a platinum RDE, with or without organic impurities in the solution. These organic impurities are supposed to come into the cathode catalyst layer through the catalyst ink or MEA binders (2-propanol, Triton-X 100), from decomposition products from MEA binders and membranes (acetone, 1-hexanal, and 1-octanal) or from crossed-over anode fuel (methanol) through the polymer electrolyte in the case of direct methanol fuel cells. 

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