Electrochemical Oxidation of Chlorine-Doped Co(OH)₂ Nanosheet Arrays on Carbon Cloth as a Bifunctional Oxygen Electrode

The primary challenge of developing clean energy conversion/storage systems is to exploit an efficient bifunctional electrocatalyst both for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with low cost and good durability. Here, we synthesized chlorine-doped Co(OH) 2 in situ grown on carbon cloth (Cl-doped Co(OH) 2 ) as an integrated electrode by a facial electrodeposition method. The anodic potential was then applied to the Cl-doped Co(OH) 2 in an alkaline solution to remove chlorine atoms (electro-oxidation (EO)/Cl-doped Co(OH) 2 ), which can further enhance the electrocatalytic activity without any thermal treatment. EO/Cl-doped Co(OH) 2 exhibits a better performance both for ORR and OER in terms of activity and durability because of the formation of a defective structure with a larger electrochemically active surface area after the electrochemical oxidation. This approach provides a new idea for introducing defects and developing active electrocatalyst.