Pt alloy oxygen-reduction electrocatalysts: Synthesis, structure, and property

Proton exchange membrane fuel cells (PEMFCs) are considered a promising power source for electric vehicles and stationary residential applications. However, current PEMFCs have several problems that require solutions, including high cost, insufficient power density, and limited performance durability. A kinetically sluggish oxygen reduction reaction (ORR) is primarily responsible for these issues. The development of advanced Pt-based catalysts is crucial for solving these problems if the large-scale application of PEMFCs is to be realized. In this review, we summarize the recent progress in the development of PtM alloy (M = Fe, Co, Ni, etc.) catalysts with an emphasis on ordered PtM intermetallic catalysts, which exhibit significantly enhanced activity and stability. In addition to exploring the intrinsic catalytic performance in traditional aqueous electrolytes via engineering nanostructures, morphologies, and crystallinity of PtM particles, we highlight recent efforts to study catalysts under real fuel cell environments by the membrane electrode assembly (MEA).