Pt‑based Intermetallic Compound Catalysts for the Oxygen Reduction Reaction: from Problems to Recent Developments

Proton exchange membrane fuel cells (PEMFCs) are promising next-generation energy conversion devices with advantages including high energy conversion efficiency, low noise, and environmental friendliness. On the PEMFC cathode, the oxygen reduction reaction (ORR) relies heavily on Pt-based catalysts, where PtMx (M stands for transition metal) intermetallic compounds (IMCs) are considered the best choice to enhance the catalytic activity. However, problems such as inadequate catalytic activity, high cost, and insufficient durability, etc. still hamper its commercialization. The optimizations of the catalyst structure, the improvements in the preparation process, and the understanding of the reaction mechanism are of great value. The developments of cathodic oxygen reduction catalysts for PEMFCs will also focus on improving the catalytic activity of intermetallic compound nanoparticles, the utilization rate, and the durability of Pt. Controlling the particle size and particle/carrier interaction remain key issues for future research. The catalyst reaction mechanism, the surface changes of the nanoparticles of Pt (111) face before and after the catalytic reaction, and the targeted regulation of the adsorption strength between the IMCs and oxygen-containing intermediates adjusted by transition metals need to be investigated more specifically and directly. At the application level, the expression of catalyst properties in the catalyst membrane electrode and reactor are the keys to the performance of PEMFCs. Therefore, researches on PEMFCs are still systematic works. This paper summarized the recent process toward the optimization of catalyst preparation, the exploration of new catalysts, and the new understanding of the mechanism. Given the reference to the development of PEMFCs, future research can start from the existing problems, solve the shortcomings of the catalyst, and promote the practical application of PEMFCs.