▎ 摘　　要

A novel and promising non-precious metal catalyst containing cobalt sulfide (Co-S) and graphene is synthesized, and recognized as an efficient and durable electro-catalyst for oxygen reduction reaction (ORR) in alkaline medium. The phase formation and morphologies of Co-S and Co-S/G composites are systematically studied and are correlated with electrochemical behaviors with specific emphasis to electro-catalytic reduction of O-2 molecules. It is found that Co-S/G catalyst annealed at 500 degrees C demonstrates excellent ORR activity in O-2 saturated 0.1 M aqueous KOH electrolyte with dominant 4e-transfer process confirmed by both RDE and RRDE measurements. The stability and durability of the optimized catalyst is ascertained by cycling the potential between -0.8 and 0.2 V vs. Ag/AgCl up to 5,000 potential cycles and found better durability in comparison to the state-of-art Pt/C catalyst. To validate in fuel cell application, the composite is used as cathode catalyst while fabricating membrane electrode assembly (MEA) and demonstrated in anion exchange membrane fuel cell (AEMFC). A peak power density of 31 mW cm(-2) at 30 degrees C under ambient pressure is realized in AEMFC which looks as a promising and an alternative non-precious metal catalyst. (C) 2016 The Electrochemical Society. All rights reserved.