▎ 摘　　要

Herein, a strategy for one-step fabrication of cobalt sulfide/graphene (Co1-xS/G) nanocomposite as bifunctional catalyst for oxygen catalysis is demonstrated. The one-step fabrication method involves annealing the mixture of cobalt salt, thioacetamide, and graphene oxide with the assistance of small amount of glycol without any further purification steps. The Co1-xS/G shows a morphology with small-sized Co1-xS nanocrystals strongly and uniformly anchored on the graphene surface. Systematically electrochemical studies demonstrate that the Co1-xS/G with optimized components shows superior catalytic activities toward oxygen reduction and oxygen evolution, which are comparable or even superior to commercial Pt/C and Ir/C catalysts. As a result, the potential hysteresis of Co1-xS/G is the lowest among all the samples. The facile operability of the fabrication method and the high bifunctional activity of Co1-xS/G may pave one practical way for broad applications including fuel cell, metal-O-2 battery, and water electrolysis.