Electric-Field-Treated Ni/Co3O4 Film as High-Performance Bifunctional Electrocatalysts for Efficient Overall Water Splitting

Rational design of bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with excellent activity and stability is of great significance, since overall water splitting is a promising technology for sustainable conversion of clean energy. However, most electrocatalysts do not simultaneously possess optimal HER/OER activities and their electrical conductivities are intrinsically low, which limit the development of overall water splitting. In this paper, a strategy of electric field treatment is proposed and applied to Ni/Co3O4 film to develop a novel bifunctional electrocatalyst. After treated by electric field, the conductive channels consisting of oxygen vacancies are formed in the Co3O4 film, which remarkably reduces the resistance of the system by almost 2 × 104 times. Meanwhile, the surface Ni metal electrode is partially oxidized to nickel oxide, which enhances the catalytic activity. The electric-field-treated Ni/Co3O4 material exhibits super outstanding performance of HER, OER, and overall water splitting, and the catalytic activity is significantly superior to the state-of-the-art noble metal catalysts (Pt/C, RuO2, and RuO2 ǁ Pt/C couple). This work provides an effective and feasible method for the development of novel and efficient bifunctional electrocatalyst, which is also promising for wide use in the field of catalysis.