Defect Engineering for Photocatalysis: From Ternary to Perovskite Oxynitrides

Exploiting defects and specific anion non-stoichiometry in mixed-anion semiconductors is a challenge that remains at the forefront of photocatalytic and photoelectrochemical water splitting research. The interplay between of oxygen and nitrogen defects in perovskite oxynitrides specifically creates exciting, yet complex, opportunities for optimizing phase stability, ionic conduction and anion order in these materials. In this Minireview we highlight the recent advances in defect engineering in oxynitride semiconductors, such as anion content/non-stoichiometry, surface modification, cation doping and formation of anisotropic layered structures, on photocatalytic and photoelectrochemical water splitting. Avenues warranting further investigation are discussed.