Subsize Pt-based intermetallic compound enables long-term cyclic mass activity for fuel-cell oxygen reduction

Significance Pt-based alloys are regarded as the oxygen-reduction electrocatalysts with the most potential to replace commercial Pt/C in proton exchange membrane fuel cells as long as their durability reaches the required standard. We demonstrated a series of Pt-based intermetallic compounds with ultrathin Pt skin and an average particle size down to about 2.3 nm that bring sustainable cyclic mass activity in fuel cells. Moreover, the subsize scale of Pt-based intermetallic compounds benefits the design of the confined structure for membrane electrode assembly, which further enhanced the stability under humid fuel-cell operations. Our work highlights advanced electrocatalysts for fuel cells and offers insight into the correlation between the structure and performance for membrane cathode electrode structures.