Cu-doped TiO₂ hollow nanostructures for the enhanced photocatalysis under visible light conditions

We report a synthetic strategy for fabricating Cu-doped TiO2 hollow nanostructure for visible light responsive photocatalysis. Hollow Cu-doped TiO2 photocatalysts were prepared by sol-gel coating of TiO2 on the surface of SiO2, removal of sacrificial core, Cu2+ ion exchange, and calcination followed by acid leaching. The ion exchanged Cu species allows TiO2 shell to be preferentially crystallized rutile phase, even at low calcination temperature. The acid leaching allows the excess bulk CuO to be dissolved out and Cu-doped TiO2 to expose more reactive TiO2 surface. No measurable CuO composites were observed while uniformly distributed Cu species is detected in acid treated CT-X-HCl samples indicating the Cu2+ ions were homogeneously doped into crystalline TiO2 frameworks. In particular, the CT-650-HCl catalyst that was prepared by calcination at 650 degrees C, followed by HCl leaching, showed beneficial physio-chemical properties, such as narrow bandgap, mixed anatase-rutile crystalline phase, and more reactive TiO2 surface with high surface area, resulting in the best photocatalytic performance towards phenol degradation under visible light conditions. (C) 2021 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.