Engineering structural variations in oxynitrides to boost photocatalytic hydrogen evolution: current advances and future directions

Abstract

Utilizing solar energy for conversion and chemical transformation is among the most promising strategies for achieving a “carbon net-zero” future. One of the cleanest approaches to this goal is particle-based photocatalytic water splitting. To enhance photocatalytic efficiency, oxynitrides have been developed as a promising material owing to their strong absorption in the visible range of solar irradiation and their well-suited energy levels for water splitting. Their low band gap, appropriate band edges, and theoretical solar-to-hydrogen efficiencies (STH) exceeding 10%, position oxynitrides as compelling candidates for industrial-scale H₂ production. The properties of oxynitrides are engineered for efficient H₂ production through various techniques, including co-catalyst loading, doping, size and shape tuning, heterojunction formation, and solid solution development. Structural modifications not only augment light absorption but also improve charge separation. This discussion covers different types of metal oxynitrides, the latest synthesis methods, structural modifications, the current advancements in quantitative H₂ production, and charge separation mechanisms for enhanced efficiency. Additionally, we highlight the potential for rapid and straightforward optimization using advanced computational techniques in the future.