A comprehensive review of cobalt-based electrocatalysts synthesized via new microwave-assisted methodology

Electrochemical water splitting is a promising method for the production of clean hydrogen and oxygen, but the high cost and low efficiency of the catalytic materials for electrodes in water electrolyzers remain the main obstacle. The optimal electrocatalyst can reduce the energy cost of water splitting by lowering the overpotential (OP). Therefore, it is highly necessary to develop an efficient and non-precious electrocatalyst to drive the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) during water splitting. Researchers often concentrate only on reducing the experimental values such as OP and Tafel slope while neglecting the expensive synthesis process of the electrocatalysts. Therefore, it is crucial to develop less expensive methods for synthesizing catalysts. The microwave synthesis method is the most economic, fast and energy efficient method. Additionally, cobalt (Co)-based electrocatalysts have shown great potential in HER and OER and have been widely utilized in water splitting. This review provides an overview of the mechanisms of OER and HER and summarizes the electrochemical performances of multiple Co-based electrocatalysts, such as Co oxides, selenides, and phosphides, based on the advanced rapid microwave-assisted synthesis methodology. Finally, it concludes by discussing future perspectives and potential challenges.