Simultaneously Incorporating Atomically Dispersed Co‐Nx Sites with Graphitic Carbon Layer‐Wrapped Co9S8 Nanoparticles for Oxygen Reduction in Acidic Electrolyte

Abstract

AbstractA facile yet robust synthesis is reported herein to simultaneously incorporate atomically dispersed Co‐Nx sites with graphitic layer‐protected Co9S8 nanoparticles (denoted as Co SACs+Co9S8) as an efficient electrocatalyst for oxygen reduction in acidic solution. The Co SACs+Co9S8 catalyst shows low H2O2 selectivity (∼5 %) with high half‐wave potential (E1/2) of ∼0.78 VRHE in 0.5 M H2SO4. The atomic sites of the catalyst were quantified by a nitrite stripping method and the corresponding site density of the catalyst is calculated to be 3.2×1018 sites g−1. Besides, we also found the presence of a reasonable amount of Co9S8 nanoparticles is beneficial for the oxygen electrocatalysis. Finally, the catalyst was assembled into a membrane electrode assembly (MEA) for evaluating its performance under more practical conditions in proton exchange membrane fuel cell (PEMFC) system.