Bifunctional Non-precious Metal Electrocatalysts of Porous WO2 Hexahedral Networks for Full Water Splitting
The demand for sustainable hydrogen production in full water splitting is to hunt for non-precious metal bifunctional electrocatalysts with excellent activity and stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a simple two-step way to synthesize porous WO2 hexahedral networks supported on nickel foam (WO2 HN/NF) is reported. In this strategy, WO2 HN/NF catalysts were prepared by hydrothermal synthesis and annealing treatment. The porous WO2 HN/NF composite shows the current density of -10 mA cm−2 at an overpotential of 48 mV for HER and 10 mA cm−2 at an overpotential of 300 mV for OER in alkaline electrolyte (1.0 M KOH). Additionally, density functional theory (DFT) calculations further proved the high performance of HER, which showed the electronic effect of the WO2. Based on remarkable electrochemical performance for both the HER and OER, we made a symmetric electrochemical water-splitting device. To afford a 10 mA cm−2 water-splitting current density, the alkaline water electrolyzer made from WO2 HN/NF needs a cell voltage of 1.59 V and keeps stable over 48 h under continuous electrolysis operation, which is not inferior to commercial Pt/C integrated performance.