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 Co 3 O 4 /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 Co 3 O 4 /CuO composite nanowire array provides a great many effective reactive sites on the surface of electrode for water splitting and the existence of Co 3 O 4 improves the overall conductivity of electrode, accelerates the charge transfer process. Specifically, the nickel foam electrode modified by Co 3 O 4 /CuO composite nanowire array only need the overpotentials of 61.4 and 150 mV to achieve the current density of 10 mA/cm 2 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/cm 2 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.