Recent advances in making nano-sized TiO2 visible-light active through rare-earth metal doping

Doping with metals and non-metals is a popular technique that facilitates visible light activity of titanium dioxide. More recently, rare-earth metals have shown tremendous potential as dopants not only in red-shifting the absorption but also in improving the photocatalysis of TiO₂. This feature article discusses recent developments in making TiO₂ visible-light active through single and co-doping with rare earth metals. An emphasis is placed on wet chemical techniques and their associated effects on the phase, adsorption, surface area, and photocatalytic activity of TiO ₂. New techniques, such as electrospinning, magnetron sputtering, co-precipitation, and complexation, as well as the use of nanotubes and physical support are also discussed. © The Royal Society of Chemistry.