Oxygen reduction on Pt/[TaOPO 4 /VC], Pt/[NbOPO 4 /VC], Pt/[Ta 2 O 5 /VC], and Pt/[Nb 2 O 5 /VC] electrocatalysts in alkaline electrolyte

New opportunities exist for the electrocatalysts in oxygen reduction reaction (ORR) in alkaline fuel cells (AFCs) in terms of electrocatalytic activity and material stability. In alkaline electrolyte, the electrocatalytic process is more facile than in acidic electrolyte due to the weakening of the competitive adsorption by the unreactive anion (1, 2). Compared to acid electrolytes, a much wider range of electrode materials are stable in alkaline electrolyte, including a number of less expensive materials; therefore, less platinum or even some non-noble metals (3-7) can be considered.. Recent studies have shown that platinum supported on metal oxide MO x (M=Ce, Ti, Mo, W, Nb, Ta) gave enhanced electrocatalytic activity for ORR ACKNOWLEDGEMENTS We are grateful to the Office of Naval Research for continued support of our research

Pt/C nanocatalysts for methanol electrooxidation prepared by water-in-oil microemulsion method

Pt nanoparticles supported on Vulcan XC-72R were synthesized by water-in-oil microemulsion method. By incorporating different amounts of HCl as a capping agent in the precursor-containing water phase, nanoparticle shape was varied. Influencing the growth of certain facets leads to the changes of the particle shape depending on the preferential facets. As a result, nanoparticles exhibit some of the electrochemical features typical for single crystals. Commonly employed synthesis procedure for water-in-oil microemulsion method was altered with the addition of catalyst support in the system and changing the catalyst cleaning steps. Prepared catalysts were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and electrochemical methods. Activity and stability for methanol oxidation reaction (MOR), a structure-sensitive reaction, were tested. Electrochemical results reveal the influence of particle size, shape and exposed facets on the electrochemical processes. TEM investigations confirm electrochemical findings, while TGA verifies Pt loading in catalyst powder. Based on the results, optimal HCl concentration for cubic particle formation is determined, and structural effect on MOR activity and stability was tested. Cuboidal NPs show very good reaction activity and fair stability under applied experimental conditions