Rich P vacancies modulate Ni2P/Cu3P interfaced nanosheets for electrocatalytic alkaline water splitting

[Display omitted] •A two-step strategy is developed to construct Ni2P/Cu3P with rich P vacancies.•The synergistic effects of interfaces and P vacancies have been investigated.•Ni2P/Cu3P with rich P vacancies exhibits superior activities in HER and OER.•A low voltage of 1.60 V is achieved at 10 mA cm−2 for the constructed full-cell. Constructing well-defined interfaces is vital to improve the electrocatalytic properties, but the studies on transition-metal-interface electrocatalysts with rich vacancies are rarely reported. Here, rich P vacancies to modulate Ni2P/Cu3P interfaced nanosheets for overall water splitting is demonstrated. We conduct a series of experimental parameters to adjust the nanostructures of Ni2P/Cu3P, and to get insight into the synergistic effects of interfaces and P vacancies on the catalytic activities. Notably, Ni2P/Cu3P with rich P vacancies shows the lowest overpotential requirements of 88 and 262 mV at 10 mA cm−2 towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The good activity is ascribed to abundant electroactive sites, electric field effect at the interfaces and tuning the electron structure by P vacancies. In addition, as bifunctional electrode, Ni2P/Cu3P with rich P vacancies allows for a low water-splitting voltage of 1.60 V at 10 mA cm−2. This work may open up a new route for efficient electrocatalysts through the synergistic effects of interfaces and vacancies.