Exploration of catalytically active materials for efficient electrochemical hydrogen and oxygen evolution reactions

Hydrogen, an efficient and clean energy source has the potential to power our energy systems of the future. Electrochemical water splitting as a hydrogen evolution source has acquired great interest in related research and technology. Noble metal-based electrode materials were previously utilized for water decomposition, but their low abundance and high cost have limited their practical applications. Recently, earth-abundant transition metal sulfides and phosphides/phosphates are employed as an electrode material in water electrolysis. These materials are emerging as promising electrode materials and are preferably integrated into electrochemical water splitting owing to their extremely stronger redox chemistry, permanence and incredible electronic conductivity. Therefore, a comprehensive report is highly desired to provide an overview of the current state of the field. Herein, we report the thermodynamics of both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) mechanisms that helps us to understand the water electrolysis in detail. Furthermore, the attractive transition metal sulfides, phosphates and phosphides-based electrode materials are discussed and presented in a detailed manner to summarize their performance for hydrogen and oxygen evolution water electrolysis.