CuCo Hybrid Oxides as Bifunctional Electrocatalyst for Efficient Water Splitting

Solar-driven water splitting is a promising approach for renewable energy, where the development of efficient and stable bifunctional electrocatalysts for simultaneously producing hydrogen and oxygen is still challenging. Herein, combined with the hydrogen evolution reaction (HER) activity of a copper(I) complex and oxygen evolution reaction (OER) activity of cobalt-based oxides, a type of 1D copper-cobalt hybrid oxide nanowires (CuCoO-NWs) is developed via a facile two-step growth-conversion process toward a bifunctional water splitting catalyst. The CuCoO-NWs exhibit excellent catalytic performances for both HER and OER in the same basic electrolyte, with optimized low onset overpotentials and high current densities. The efficient HER activity is ascribed to the formation of Cu2O, while the activity for OER is primarily enabled by Co-based oxides and abundant oxygen vacancies. The CuCoO-NWs allow for the assembly of a water electrolyzer with strong alkaline media, with a current density of 10 mA cm(-2) at 1.61 V. Further combination with a commercial silicon photovoltaic allows the direct use of solar energy for spontaneous water splitting with excellent stability for over 72 h, suggesting the potential as a promising bifunctional electrocatalyst for efficient solar-driven water splitting.