Nitrogen-coordinated metallic cobalt disulfide self-encapsulated in graphitic carbon for electrochemical water oxidation

Oxygen evolution reaction (OER) is a key process in electrochemical conversion technologies. The rational design of efficient catalyst and understanding of structure-property relationship in catalysis still remain grand challenge. Herein, nitrogen-coordinated CoS2 ultrafine nanoparticles (NPs) self-encapsulated in graphene (N-CoS2@graphene) are obtained through employing zeolitic imidazolate frameworks (ZIFs) as precursors. An insitu N-coordinated and graphene self-encapsulated strategy is developed to improve the catalytic activity and stability. As expected, the N-CoS2@graphene achieved an extremely low overpotentials of only 205 and 292 mV at the current density of 10 and 100 mA cm(-2) for OER, respectively, showing superior activities as compared with state-of-the-art transition-metal-based catalysts. Mechanism explorations reveal that the N-CoS2@graphene offers unique graphene self-encapsulated structure and modulated electron structure of the catalytic sites, which synergistically promotes intrinsic activity and stablility of catalyst. It is expected that the strategy presented here provides prospects for the design of other highly active electrocatalysts for energy conversion.