Design of interfaces and phase interfaces on cathode catalysts for polymer electrolyte fuel cells

Development of heterogeneous catalysts for energy conversion has been required to solve environmental issues arising from the combustion of fossil fuels. Polymer electrolyte fuel cells (PEFC) are promising power generation devices alternative to the internal combustion engine. PEFC performance is strongly dependent on the catalytic activity for the oxygen reduction reaction at the cathode because of sluggish kinetics. Thus, highly active and durable Pt-based cathode catalysts with tailored geometrical and electronic structures have been widely developed. The Pt-based catalysts have been used in membrane-electrode-assembly (MEA) of the PEFC, where the catalyst particles are integrated as the catalyst layers a few micrometers thick. Porous structure and morphology in the catalyst layers with nanometer to micrometer scale should be designed for the facile diffusion of oxygen, proton and water. In this highlight review, we provide an overview for the development of catalysts and catalyst layers with high activity and durability for the PEFC.