A parametric study of visible-light sensitive TiO₂ photocatalysts synthesis via a facile sol–gel N-doping method

In the present work, a parametric study of visible-light sensitive TiO₂ via a facile sol–gel N-doping method was carried out. Visible-light activity of as-prepared products was assessed using solutions of methylene blue as model pollutants. Optimal visible-light activity was achieved at equal N-to-Ti precursor molar ratio and 350 °C calcinations. Characterisation of structural, chemical and optical properties of synthesised TiO₂ photocatalysts was also undertaken to elucidate the effects of N-to-Ti precursor molar ratio and calcinations temperature on the resulting photocatalytic activity. The pH value of N-doped TiO₂ sol during the preparation was also found to be an effective indicator of N-doping quality without using any post-synthesis analysis. These findings could be utilised in the successful development of TiO₂ photocatalysts or their nanocomposites for cost effective solar irradiation-driven environmental technology.