Minimization of defects in Nb-doped TiO 2 photocatalysts by molten salt flux

Abstract Transition metal doping is a popular pathway to improve the photocatalytic performance of TiO 2 . However, most dopants are aliovalent (e.g., Nb 5+ , W 6+ , and Fe 3+ ), where defects are inevitably introduced (e.g., oxygen or Ti 3+ defects). To minimize defects and hence ensure better separation of photogenerated charges, this work incorporates an Nb dopant into TiO 2 in a flux of molten salt. The molten salt flux not only induces recrystallization of TiO 2 nanoparticles into nanowires but also allows a + 4 valence dopant in the TiO 2 lattice to inhibit formation of Ti 3+ or oxygen defects. This minimization of defects enhances the photocatalytic activity in the degradation of gaseous acetaldehyde. This enhancement is mainly attributed to the higher crystallinity of TiO 2 and better separation of charge carriers induced by equivalent Nb-doping.