Achieving selectivity in TiO2-based photocatalysis

Nanocrystalline titanium dioxide (NTO) mediated photocatalysis is a powerful tool for the total mineralization of a wide range of organic compounds caused by the in situ generation of hydroxyl radicals upon ultraviolet/visible light irradiation. NTO is well known for its non-selective catalysis, especially in aqueous media. However, making NTO into a selective photocatalyst enables selective degradation of compounds as well as selective formation of valuable organic products. Both selective degradation and selective formation using NTO are based on the same principles of photocatalysis. Selectivity in degradation is achieved in the attraction, adsorption, and mineralization stages of photocatalysis whereas desorption of the oxygenated products, moderate crystallinity of NTO and doping are responsible for selective formation. Recent reports on NTO selective photocatalysis are reviewed in this article according to the chemistry used to achieve selectivity.