Abstract
TiO
2
has a wide range of applications since it has the best photocatalytic activity. Its photocatalytic activity can be enhanced by doping with suitable elements. Hydrothermal method and sol–gel synthesis are mainly considered for the preparation of doped TiO
2
nanoparticles. Modern characterization techniques are used to study the doped material. The main contribution of doping is enhanced photocatalytic activity by shifting the absorption edge towards the visible region. Here we had made a review on the synthesis procedure, characterization and photocatalytic activity of the Sc, Hf doped, and co-doped TiO
2
nanocrystals.