Study of the photocatalytic activity of nanocrystalline S, N-codoped TiO2 thin films and powders under visible and sun light irradiation

► Homogeneous and transparent S, N-codoped TiO2 thin films were prepared by sol gel dip coating method. ► The equivalent powders were obtained by aging the residual sol of pure and modified TiO2. ► Sol gel method can produce crack-free and homogeneous doped TiO2 thin films with high photocatalytic activity. ► The thin films and powders exhibit excellent photocatalytic activity for degradation of methyl orange under both visible and sun light irradiation.