Anomalous photodegradation response of Ga, N codoped TiO2 under visible light irradiations: An interplay between simulations and experiments

Ga and/or N doped TiO2 nanoparticles synthesized by one pot hydrothermal method possess pure anatase phase with spherical morphology. Calculations based on density functional theory (DFT) explained the band gap narrowing, origin of optical absorption and the possible changes in the photocatalytic activity of synthesized nano-photocatalysts. Analysis of band structure and density of states revealed that N and Ga, N codoping introduced some partially occupied states above the valance band maximum which might influence the electron hole pair recombination. Calculations as well as experiments confirmed the shifting of absorption edge towards visible regime due to doping. Spectroscopic investigations confirmed the existence of dopant atoms in the doped samples. Ga doped TiO2 samples provided the best photocatalytic activity compared to the synthesized samples attributed to the suitable band structure, enhanced optical absorption and effective separation between photoexcited carriers.