Facile synthesis of self-support vanadium-doped Ni2P nanosheet arrays for highly efficient overall water splitting

It is urgent to explore non-noble metal electrocatalysts with high efficiency and durability for oxygen evolution reaction (OER), which is key to a spectrum of sustainable energy technologies. The electronic regulation via foreign ion/atom doping presents a valid route to improve the intrinsic activity of earth-abundant electrocatalysts. In this research, a facile and cost-effective self-assembly strategy is developed to fabricate the vanadium-doped nickel phosphide electrocatalysts (V-Ni2P) with a three-dimensional nanosheets structure. Then the effect of initial vanadium concentration on the morphology and properties of the target catalyst is investigated. It is found that the V-Ni2P electrocatalyst obtained at the NH4VO3 concentration of 1 mg mL−1 only requires a low overpotential of 228 mV to afford an OER current density of 80 mA cm−2, with a Tafel slope of 76 mV dec–1 and excellent electrocatalytic stability. On the other hand, enhanced hydrogen evolution reaction (HER) performance can also be acquired based on this unique structure under alkaline conditions. Finally, a water electrolysis device is assembled using V-Ni2P as the cathode and anode materials. To afford a current density of 50 mA cm−2, this device only needs a small voltage of 1.65 V, suggesting the potential of V-Ni2P as a bifunctional electrocatalyst for overall water splitting. This study provides a reference for the preparation of a highly active electrocatalyst with controllable composition and microstructure.