3D CuCo2S4/NiCo2S4 core-shell composites as efficient bifunctional electrocatalyst electrodes for overall water splitting

Water splitting is a vital reaction for the storage of renewable energy, which requires highly active and steady catalysts to produce hydrogen and oxygen. While the development of efficiently stable bifunctional electrocatalysts for the simultaneous production of hydrogen and oxygen remains challenge. Herein, we show a simple multi-step process to prepare porous CuCo2S4/NiCo2S4 core-shell materials directly as bifunctional electrocatalyst electrodes for water splitting. The porous NiCo2S4-sheets combined with CuCo2S4-rods on nickel foam not only can provide for more active sites and higher specific surface area, but also maintain their structural integrity. At a current density of 10 mA cm−2, the CuCo2S4/NiCo2S4 core-shell electrodes deliver lower overpotentials of 271 mV and 206 mV for the oxygen and hydrogen evolution reaction, respectively. The CuCo2S4/NiCo2S4 core-shell electrodes are successfully used as bifunctional electrocatalyst towards overall water splitting and showed overpotential of 1.66 V at the current density of 10 mA cm−2. A ≈97% current density retention for 50 h is represented which illustrates the superior stability of this electrode material and water splitting device. Subsequently, a water splitting process is demonstrated using electrochemical cell based on CuCo2S4/NiCo2S4 core-shell electrodes driven by a perovskite solar cell module. H2 and O2 are generated. Our work here demonstrates the possibility of wide application of catalytic material to produce clean energy driven by perovskite solar cell. The work also illustrates the potential applications of CuCo2S4/NiCo2S4 core-shell nanometer materials for clean energy generation.