Doping-induced structural evolution from rutile to anatase: formation of Nb-doped anatase TiO2 nanosheets with high photocatalytic activity

Semiconductor nanostructures with specially exposed reactive crystal facets are promising to promote photocatalytic/photoelectrochemical reactions. Here, we demonstrate that the introduction of niobium into TiO2 can modify TiO2 surface chemistry, which in turn influences the growth of TiO2 nanostructures from one-dimensional rutile nanorods at a low niobium doping concentration to two-dimensional anatase nanosheets at a high niobium doping concentration. Additionally, the electronic structure, optical properties, and surface activity for O-2 adsorption are substantially influenced for Nb-doped TiO2 by electron donation from the niobium dopant, which significantly enhances the light-induced generation of super oxide radicals (O-2(-center dot)), and thus improves the photocatalytic activity of Nb-doped TiO2.