Effect of calcination time on the physicochemical properties and photocatalytic performance of carbon and nitrogen co-doped tio2 nanoparticles

The application of highly active nano catalysts in advanced oxidation processes (AOPs) improves the production of non-selective hydroxyl radicals and co-oxidants for complete remediation of polluted water. This study focused on the synthesis and characterisation of a highly active visible light C–N-co-doped TiO₂ nano catalyst that we prepared via the sol-gel method and pyrolysed at 350 °C for 105 min in an inert atmosphere to prevent combustion of carbon moieties. Then we prolonged the pyrolysis holding time to 120 and 135 min and studied the effect of these changes on the crystal structure, particle size and morphology, electronic properties and photocatalytic performance. The physico-chemical characterisation proved that alteration of pyrolysis holding time allows control of the amount of carbon in the TiO₂ catalyst causing variations in the band gap, particle size and morphology and induced changes in electronic properties. The C–N–TiO₂ nano composites were active under both visible and UV light. Their improved activity was ascribed to a low electron–hole pair recombination rate that enhanced the generation of OH^. and related oxidants for total deactivation of O.II dye. This study shows that subtle differences in catalyst preparation conditions affect its physico-chemical properties and catalytic efficiency under solar and UV light.