Nickel nitride–black phosphorus heterostructure nanosheets for boosting the electrocatalytic activity towards the oxygen evolution reaction

The extraordinary oxygen evolution reaction (OER) in alkaline fuel cells and water-splitting systems demands a high electron transfer rate and catalysts with numerous active sites and massive hydroxyl groups. Herein, we proposed a new heterostructure of nanosheets 〈electron depletion|interfacial reaction center|hydroxyl captor〉, demonstrated as 〈nickel nitride (Ni3N)|nickel phosphide (Ni2P)|black phosphorus (BP)〉. Compared with other catalysts reported for the OER, the 〈Ni3N|Ni2P|BP〉 heterostructure shows superior electrocatalytic performance with an ultralow overpotential of 247 mV at 10 mA cm−2 and high durability in alkaline electrolytes. The high performance of the catalyst results from (i) the superior capability of the hydroxyl groups captured by ultrathin oxide layers on the catalyst surface; (ii) the stable connection between Ni3N and BP via the formation of the Ni2P interface; and (iii) the excellent electron transfer rate due to the metallic nature of Ni3N.