Simple Construction of Amorphous Monometallic Cobalt‐Based Selenite Nanoparticles using Ball Milling for Highly Efficient Oxygen Evolution Reaction

Abstract Amorphous transition‐metal based materials with disordered structure are very desirable in the field of sustainable energy devices and technologies such as water‐splitting and secondary batteries due to their inherent properties of anisotropy and defects. To date, it is very urgent to explore new methods to prepare amorphous electrocatalysts. Herein, we use a simple approach to construct amorphous Co‐based selenite electrocatalyst by mechanical ball milling for oxygen evolution reaction (OER). Due to its amorphous structure as well as more active species, the obtained amorphous cobalt selenite C 4 S‐12 h material on the glassy carbon electrode shows superior electrochemical performance with a low overpotential of 255 mV to drive 10 mA cm −2 in 1.0 M KOH electrolyte. In addition, this catalyst also has an excellent intrinsic activity (high mass activity of 162.0 A g −1 and TOF of 0.063 s −1 at the overpotential of 350 mV) and remarkable long‐term stability (at least 32 h at a current density of 10 mA cm −2 ). This study offers a simple and environmentally friendly method to construct highly efficient electrocatalysts for water oxidation.