Vanadium doped nickel hydroxide nanosheets for efficient overall alkaline water splitting

Abstract

Developing bifunctional electrocatalysts with high efficiency and low cost for overall water splitting at large current densities is of great value for industrial application, yet remains challenge. Herein, hetero-atom doping is adopted as the effective strategy to boost catalysis performances. Vanadium elements are doped into nickel hydroxide via a hydrothermal method to improve oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalysis performance. XPS spectra reveal that vanadium dopants not only tune the chemical state of Ni, but also serve as promotor during the catalysis. SEM and TEM characterizations show the nanosheets assembled architecture, which provides structure advantages of easily accessible active sites and accelerates charge transfer. Electrochemical tests indicate that V-doping results in improved active sites and enhanced kinetics. The as-prepared V doped Ni(OH)2 nanosheets grown on nickel foam (V–Ni(OH)2/NF) display advanced electrocatalysis performances for both OER and HER. To reach high current densities of 100 and 400 mA cm−2, the V–Ni(OH)2/NF only needs low overpotentials of 275 and 476 mV for OER and 254 and 493 mV for HER. A two-electrode electrolyzer using V–Ni(OH)2/NF as bifunctional catalyst exhibits low cell voltages of 1.58 and 1.84 V at current densities of 100 and 400 mA cm−2 for overall water splitting in alkaline solution.