OPTICAL AND ELECTRONIC PROPERTY MODULATION OF NITROGEN-DOPED TIO₂ FOR ENHANCED SOLAR-DRIVEN PHOTOCATALYTIC ACTIVITY

The most common photocatalyst is titanium dioxide (TiO₂). However, its usage is hindered by a wide band gap and fast electron-hole recombination. In this work, nitrogen-doped TiO₂ (N-TiO₂) nanoparticles were prepared via a soul-gel technique modified by varying concentrations of nitrogen. Analysis confirmed the existence of the anatase phase in all samples, and spectroscopic analysis indicated that nitrogen doping had been successfully accomplished. Band gap analysis showed a shift in the absorption edge towards lower energies, thus resulting in narrowing of the band gap and better absorption of visible light. Photoluminescence showed less electron-hole recombination rate, especially when the optimal nitrogen content (1%) was applied. Further, analysis of morphologies proved that porous structures were produced with higher surface area, hence the improvement in photo reactivity. Photocatalytic activity of the N-TiO₂ samples was studied by using methylene blue (MB) degradation in simulated sunlight. It was found that the optimum doping rate was 1%, as it degraded more than 95% of MB within one hour, much higher than pristine TiO₂. Furthermore, the reaction dynamics for N-TiO₂ 1% were significantly faster. Based on mechanistic analysis, it was established that •OH and O₂•⁻ radical anions were major pollutants' degradation pathways.