Electronic modulation of CoP nanosheets array by Zn doping as an efficient electrocatalyst for overall water splitting

The rational design of effective bifunctional electrocatalysts with good morphology, structure, and unique electronic properties, is crucial for efficient overall water splitting. Herein, a zinc-doped cobalt phosphide (CoP) nanosheet catalyst (Zn-CoP/CF) with a three-dimensional nanoarray structure in situ grown on a cobalt foam (CF) substrate was synthesized via a hydrothermal and gas-phase phosphatizing two-step route. Benefitting from the large specific surface area, numerous active sites, and the regulation of electron distribution between metals, Zn-CoP/CF requires low overpotentials of 327 mV for the hydrogen evolution reaction and 440 mV for the oxygen evolution reaction at 1000 mA cm-2. Moreover, a small cell voltage of 2.01 V is attained to achieve the current density of 1000 mA cm-2 for overall water splitting. This work provides a new idea for improving the intrinsic activity of electrocatalysts and demonstrates the potential of effectively constructing optimized electronic structures in the synthesis of high-current density electrocatalysts. A zinc-doped CoP nanosheet catalyst (Zn-CoP/CF) grown in situ on a cobalt foam substrate with a three-dimensional array structure, can effectively improve the electrocatalytic overall water splitting performance due to the gradual dissolution of Zn.