Tailored highly efficient Co-doped TiO2/CoTiO3 heterojunction photocatalyst for methylene blue degradation under visible light

A typical Co-doped TiO2/CoTiO3 heterostructure photocatalyst was synthesized using a facile and cost-effective modified sol-gel route. The as-prepared photocatalysts were further annealed at 400, 600, and 700 degrees C temperatures and termed CT400, CT600, and CT700, respectively. The XRD analysis of the CT600 photocatalyst reveals the presence of anatase-rutile homojunction and the high crystallinity nature of TiO2. The spectral response and the bandgap of the photocatalysts were analyzed using UV-DRS. The decrease in bandgap due to Co ion doping as well as the synergistic effect of both homojunction and heterojunction in Co-TiO2/CoTiO3 significantly enhanced the photocatalytic activity under visible light. The presence of oxygen vacancies, charge carrier migration, and the chemical compositions of the photocatalysts were studied using ESR, PL, and XPS techniques. Under the visible light, Co-TiO2/CoTiO3 (CT600) photocatalyst exhibited 97% degradation of methylene blue in 90 min, which is similar to 42-fold higher than that of pristine TiO2. No sacrificial reagents were applied in this research. Notably, this visible light active Co-TiO2/CoTiO3 photocatalyst has the potential for the application of large-scale solar-induced dye removal.