Electron buffer effect in Cr–Pt3Ni catalysts for robust oxygen reduction electrocatalysis

Bimetallic platinum-nickel alloy nanostructures (PtNi/C) have garnered significant attention due to their potential to catalyze the oxygen reduction reaction (ORR), yet their practical applications are hindered by challenges in catalytic activity and durability. Here, we present a strategy that entails introducing the electron buffer Cr into Pt₃Ni alloy nanoparticle catalysts with the aim of lessening the surface polarization of Pt shells. The as-prepared Cr–Pt₃Ni/C catalyst demonstrates strong interatomic interactions, thereby augmenting both the catalytic activity and durability of fuel cells. The Cr–Pt₃Ni/C catalyst exhibits remarkable ORR performance, attaining a half-wave potential (E_1/2) of 0.934 V, which is 37 mV greater than Pt/C (0.897 V). After 30,000 ADT cycles, Cr–Pt₃Ni/C exhibits negligible loss in E_1/2, with the ECSA and MA retained as high as 99.2 % and 92.7 % of their initial values, respectively. Furthermore, the PEMFC tests revealed outstanding performance with peak power densities of 2.90 W cm⁻²@H₂–O₂ and 1.85 W cm⁻²@H₂-air under low Pt loadings, underscoring the potential of Cr–Pt₃Ni/C for practical fuel cell applications. DFT computations signify that the ORR activity is enhanced by the introduction of Cr into Pt₃Ni/C to optimize the surface strain, and the enhancement of durability is attributable to Cr's contribution to charge transfer in the Pt shell and the increase of the dissolution energy barrier of Ni.