Synergistic CoN-Decorated Pt Catalyst on Two-Dimensional Porous Co-N-Doped Carbon Nanosheet for Enhanced Oxygen Reduction Activity and Durability

Abstract

Herein, an oxygen reduction reaction (ORR) catalyst consisting of CoN-decorated Pt nanoparticles (NPs) on thin two-dimensional (2D) nanosheet-structured Co-N-doped porous carbon is prepared by utilizing the pyrolyzed nanosheet-shaped Co-based metal-organic framework as a template for Pt deposition. After Pt deposition and acid leaching, the remaining Co species on the Pt surface are converted to CoN species by ammonia heat treatment, which are also attached on the Pt surface. The as-synthesized CoN-decorated Pt on the Co-N-functionalized 2D carbon (CoN-Pt/CoNC-2D) displays an excellent ORR activity, better than a commercial Pt/C in half-cell and single-cell tests, and also exhibits remarkable long-term durability with only a ∼17 mV shift in half-wave potential after 30 000 potential cycles. Such excellent ORR catalytic performance is attributed to strong cooperative synergistic interactions between the CoN-Pt and CoNC-2D in the catalyst. The CoN species formed on the Pt surface not only change the Pt electronic structure by down-shifting the Pt d-band center but also passivate the Pt surface to prevent Pt oxidation and dissolution during the ORR. On the other hand, the thin porous CoNC-2D nanoflake support significantly improves the accessibility of reactants to enhance mass transfer and prevents segregation and agglomeration of CoN-Pt NPs during the ORR through strong metal-support interaction, further enhancing ORR activity and durability of the CoN-Pt/CoNC-2D catalyst. © 2020 American Chemical Society.