▎ 摘　　要

NO3- is a prominent waste byproduct in ammunition industries, and valorization of NO3- into NH3 is desired. NH3 synthesized from waste using renewable energy could be used as an energy storage medium. For such a process, higher selectivity, stability, and enhanced activity per unit mass of catalyst is required. This work reports CoO nanoclusters functionalized on graphene as an efficient catalyst for electrochemical NO3- reduction to NH3 with >98% NH3 Faradaic efficiency and an NH3 current density (geometric) of approximate to 400 mA cm(-2). A highest NH3 yield of 25.63 mol g(-1) h(-1) is obtained. The developed catalyst prevents the N-N coupling step which is required for promoting the selectivity of NH3 over N-2. Density functional theory calculations reveal that CoO NC/graphene has similar selectivity to that of polycrystalline Co and that higher activity can be obtained with lower catalyst loading.