Mitigating the Pt Dissolution of Pt–Cr Intermetallics during the Oxygen Reduction Reaction in Acid Medium

Platinum-based intermetallic nanostructures are considered promising electrocatalysts for the sluggish oxygen reduction reaction (ORR). Notwithstanding, degradation issues, such as metal dissolution, still hamper the large-scale implementation of these materials. Herein, by using the Pt–Cr intermetallic system as case of study, we have produced carbon-supported nanoparticles (NPs) of ca. 5 nm whose crystalline structure was carefully tuned, obtaining the L1 2 Pt 3 Cr and the L1 0 PtCr phases. The electrochemical stability toward the ORR of both Pt–Cr intermetallics presents a clear benefit relative to the Pt/C benchmark. Our experimental results, supported by theoretical calculations, indicate an enhanced metal dissolution resistance of both Pt–Cr intermetallics, the origin of which stems from a high intrinsic kinetic barrier for oxygen adsorption-induced Cr segregation and a built-in formation of Cr–O that stabilizes the adjacent Pt sites during the cathodic dissolution. This work provides insights and strategies for the rational design of robust Pt-based ORR electrocatalysts.