Visible-light photocatalytic activity of N/SiO2–TiO2 thin films on glass

Nanocrystalline N-doped SiO2/TiO2 visible-light photocatalyst thin films were synthesized using the sol-gel method on glass substrates. The synthesized catalysts were then characterized using several analytical techniques like x-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and UV–vis absorption spectroscopy (UV–vis). The experimental results revealed that the maximum optical response of the synthesized SiO2/TiO2 thin films shifted from the ultraviolet (UV) to the visible-light region (λ≥420 nm). The photocatalytic activity of N-doped SiO2–TiO2 photocatalyst was considerably higher than that of SiO2–TiO2, and this result was obtained with an optimal concentration of 40 mol% of N. The enhanced photocatalytic activity was attributed to the increasing surface area and forming more hydroxyl groups in the doped catalyst