Ternary ordered L10-Pt-Co-Fe intermetallics for efficient ORR catalysis through dissociation pathway

Developing efficient and durable Pt-based electrocatalysts for oxygen reduction reaction (ORR) is critical for the practical application of fuel cells but still remains challenge at present. Here we successfully synthesized a series of ternary L1-PtCoFe (x=0.33, 0.50 and 0.67) intermetallic nanoparticles (NPs) supported on reduced graphene oxide for ORR catalysis. L1-PtCoFe exhibits the highest mass activity (MA) of 0.93 A mg at 0.9 V (1.82 times the corresponding binary L1-PtCo intermetallics) and minimal activity loss (24.73 % loss in MA) after 30,000 potential cycles. By Density Functional Theory calculations, the excellent performance of ternary L1-PtCoFe can be ascribed to: (1) more efficient electronic structure regulation caused by dual-element driven electron transfer, which leads to more electron accumulation on Pt and weakens the over-binding of oxygen-containing species, (2) the unique two-center bridge pattern of O adsorption over Pt-Fe site leads to ORR proceeding the dissociative mechanism, avoiding the formation of OOH*.