Metal-Doped Titanium Dioxide for Environmental Remediation, Hydrogen Evolution and Sensing: A Review

Titanium dioxide is an essential photocatalyst for the purification of water and air and energy generation. Titanium dioxide shows relatively high chemical stability and reactivity under ultraviolet light (lambda< 387 nm), the energy of which exceeds the 3.3 eV bandgap in the crystalline anatase phase. TiO2 is active under UV light, and its practical applicability is limited under visible light. Modification techniques like metal doping can enhance its activity under visible light. Metal doping is employed for introducing additional states in the TiO2 bandgap. Fewer energy transitions are required to cause visible light absorption by these impurities. This review focuses on the effects of metal-doping and applications of metal-doped TiO2 in the fields of environmental remediation, hydrogen evolution, and sensing.