Recent advances in cobalt-based electrocatalysts for hydrogen and oxygen evolution reactions

Electrochemical water splitting has proven to be the most promising way to generate hydrogen. However, the high cost and low efficiency of the catalysts for cathode and anode in water splitting device remain the most knotty obstacle that needs to be stepped over. The optimal electrocatalysts can lower the energy costs required for water splitting via the reduced overpotential. Therefore, developing efficient and nonprecious electrocatalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) is highly critical and challenging. Cobalt (Co)-based electrocatalysts have been widely applied as electrocatalysts for HER and OER in water splitting. In this review, the mechanisms of HER and OER, was first illustrated, the preparation and electrochemical performance of various Co-based electrocatalysts, including cobalt oxides, hydroxides, sulfides, phosphides, nitrides and selenides for HER or OER are then summarized. Finally, the potential challenges and the future perspective of Co-based electrocatalysts are proposed.