Engineering oxygen vacancy-rich Co3O4 nanowire as high-efficiency and durable bifunctional electrocatalyst for overall alkaline water splitting

A novel kind of vacancy-rich nanowire arrays were prepared by reducing rough Co₃O₄ nanowires with NaBH₄ solution on 3D nickel foam at room temperature for overall water splitting. Co₃O₄/NF treated by NaBH₄ for 10 min was highly active for oxygen evolution reaction (OER) and simultaneously efficient for hydrogen evolution reaction (HER) with the need of the overpotentials of 240 and 132 mV to drive 10 mA·cm^-2 in alkaline media, respectively. Furthermore, the electrocatalysts as both cathode and anode in a two-electrode system presented excellent durability for over 60 h at 10 mA·cm^-2, maintaining the cell voltage of merely 1.63 V. This work provides new methods and ideas for the preparation of transition metal oxide bifunctional electrocatalysts rich in oxygen vacancies.