Non-Pt Cathode Electrocatalysts for Anion-Exchange-Membrane Fuel Cells

This chapter provides an overview of the recent advancement in the development of non-Pt electrocatalysts for oxygen reduction reactions (ORRs) in alkaline media; catalyst materials discussed include carbon-supported transition metals (Pt/C, Pd/C, Ag/C), transition-metal macrocycles (M–N–C), and multifunctional materials (e.g., metallic alloys, metallic MnO2, macrocycle-treated metals). The important factors affecting ORR kinetics are identified through combined theoretical simulations and experimental measurements. The inconsistencies between the ORR activities observed in fuel cell tests and those observed in rotating disk electrodes, as reported by several research groups, were analyzed in details, and plausible theoretical explanations were proposed. Several promising bifunctional catalysts and their potentials as replacements for Pt in anion-exchange-membrane fuel cell (AEMFC) applications are discussed. For the AEMFC technology to mature as a low-cost high-performance energy device, further improvement of the performance and durability of the catalysts is essential; we believe that the necessary improvements can be achieved through intelligent design of multifunctional catalysts.