Oxygen vacancies engineered CoMoO4 nanosheet arrays as efficient bifunctional electrocatalysts for overall water splitting

The development of highly efficient, stable and earth-abundant bifunctional electrocatalysts for water splitting is of great significance for confronting the environmental and energy crisis. In this work, we reported the design and synthesis of oxygen vacancies engineered CoMoO4 nanosheet arrays grown on three-dimension (3D) porous Ni foam (NF) support by hydrothermal synthesis followed by reducing gas heat treatment used H2 or NH3, and explored their practical application as bifunctional electrocatalysts for water splitting. The unique 3D nanosheet array can facilitate the interfacial electron transfer and ion transport, as well as promote hydrogen and oxygen gas diffusion, and the formation of oxygen vacancies in CoMoO4 nanosheets can significantly improve efficiency of both hydrogen evolution reaction and oxygen evolution reaction. When using as self-supported bifunctional electrocatalyst to make an electrolyzer, NF/H-CoMoO4 approached 10 mA cm−2 under the cell voltages of 1.56 V, along with excellent durability in an alkaline water electrolyzer, which hold great promise in energy conversion application.