Synergistic\nBimetallic Metallic Organic Framework-Derived\nPt–Co Oxygen Reduction Electrocatalysts

Abstract

The\nrational design of Pt-based electrocatalysts is of paramount\nimportance for the commercialization of proton exchange membrane fuel\ncells (PEMFCs). Pt–Co alloys and nitrogen-doped carbons have\nbeen shown to be effective in enhancing the kinetics of the oxygen\nreduction reaction (ORR). Herein, we reported on two kinds of Pt–Co\nelectrocatalysts, PtCo ordered intermetallic and PtCo₂ disordered\nalloys, supported on bimetallic MOF-derived N-doped carbon. The synergistic\ninteraction between Pt–Co nanoparticles and Co–N–C\nenhanced the overall ORR activity and maintained the integrity of\nboth structures and their electrochemical properties during long-term\nstability testing. The optimal activity for both PtCo and PtCo₂ occurred after 20 000 potential cycles. The enhanced\nperformance of PtCo was ascribed to the formation of a two-atomic-layer\nPt-rich shell and the lattice strain caused by the core–shell\nPtCo@Pt structure. The increased activity of PtCo₂ was\nascribed to the formation of large, spongy, and small solid nanoparticles\nduring electrochemical dealloying and thus the exposure of more Pt\nsites on the surface. The strategy described herein advances our understanding\nof the structure–activity relationship in electrocatalysis\nand sheds light on the future development of more active and durable\nORR electrocatalysts.