A Co 3 O 4 /CuO composite nanowire array as low-cost and efficient bifunctional electrocatalyst for water splitting

Development of high-performance and economic electrocatalysts for full water splitting which plays an important role in clean energy conversion is of considerable practical significance. Herein, a three-dimensional hierarchical Co3O4/CuO composite nanowire array was prepared by one-step hydrothermal treatment and annealing treatment on the surface of nickel foam. As a bifunctional electrocatalyst, the efficiency of both two parts of water splitting reaction, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can be effectively improved. The special structure of Co3O4/CuO composite nanowire array provides a great many effective reactive sites on the surface of electrode for water splitting and the existence of Co3O4 improves the overall conductivity of electrode, accelerates the charge transfer process. Specifically, the nickel foam electrode modified by Co3O4/CuO composite nanowire array only need the overpotentials of 61.4 and 150 mV to achieve the current density of 10 mA/cm2 for the HER and OER in 1.0 M KOH, respectively, and the Tafel slope of 66 and 160 mV/dec. The self-assembled two-electrode electrolyzer, with the electrode as the anode and cathode, was used for the full water splitting experiment, and it was found that the current density of 10 mA/cm2 is driven by only 1.53 V voltage and exhibit long-term stability. Here, a simple method is provided to obtain an efficient bifunctional electrocatalyst of water splitting, which has a practical reference for realizing clean energy conversion.