Toward Shape-Controlled Metal Oxynitride and Nitride Particles for Solar Energy Applications

Photocatalytic water splitting is a promising platform for clean and renewable energy. Photocatalysts that absorb visible light are critically needed to efficiently harness solar energy, and metal oxynitrides and nitrides have the potential to address this need owing to their narrower band gaps compared to oxides. The catalytic activity of these materials could be enhanced through the synthesis of structurally defined particles with reduced recombination sites and the preferential expression of catalytically active sites. This Perspective highlights recent progress and current challenges associated with the design and synthesis of metal (d 0 /d 10 ) oxynitride and nitride particles with defined structural features for photocatalytic applications. Nitriding oxide templates with defined morphology and topotactic transformations of structurally defined templates are promising routes to metal oxynitrides and nitrides with shape control. Case studies show that such synthetic advances are often coupled with enhanced photocatalytic activity; however, greater synthetic control is still required to understand the structure–function relationships of these promising materials.