Controlled synthesis of W–Co3S4@Co3O4 as an environmentally friendly and low cost electrocatalyst for overall water splitting

Electrochemistry splitting of water is considered to be one of the most fascinating methods to replace traditional chemical fuels. Here, we design a new method to exploit W–Co3S4@Co3O4 heterostructures. The W–Co3S4@Co3O4 material was first prepared and grown in situ on nickel foam by a typical hydrothermal and calcination approach. Based on the principle of electronic regulation, the synergistic effect of W and Co metal ions can increase the charge transfer of the electrode, thus significantly prompting the catalytic activity of the electrode. The W–Co3S4@Co3O4 material present superior catalytic performance for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), and the overpotential at 10 mA cm−2 is 260 mV and 140 mV, respectively. Notably, W–Co3S4@Co3O4 catalyst showed excellent water splitting performance under alkaline conditions (cell voltage of 1.63V @10 mA cm−2). Density functional theory calculation shows that the existence of the Co3O4 material accelerates the rate of hydrogen production reaction, and the existence of the W–Co3S4 material promotes the conductivity of the W–Co3S4@Co3O4 electrode. The synergistic effect of W–Co3S4 and Co3O4 materials is beneficial to the improvement of the catalytic activity of the electrode. This study provides a novel view for the development of electrodes synthesis and a novel paradigm for the development of robust, better and relatively non-toxic bifunctional catalysts.