Comparative Synthesis of N-TiO2 Photocatalysts via Green and Chemical Routes for Enhanced Photocatalytic Performance

Abstract

To improve the visible light-driven photocatalytic activity of TiO₂, nitrogen-doped (N-TiO₂) nanoparticles were prepared through two different methods: a green method using Taraxacum officinale flower extract and a traditional chemical precipitation method. The structural, morphological, elemental, and optical properties of the resultant N-TiO₂ samples were comprehensively examined by X-ray diffraction, Fourier-transform infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, Scanning and Transmission electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). Both preparation methods resulted in anatase-phase TiO₂ with successful nitrogen doping; however, the green-synthesized N-TiO₂ displayed a smaller average crystallite size (~30 nm), greater nitrogen content (3.83 wt.%), and narrower band gap of 2.8eVcompared to its chemically synthesized counterpart. Photocatalytic activity was assessed through the degradation of methyl orange under visible light illumination. The green-synthesized N-TiO₂ attained a degradation efficiency of 86.6% within 120 minutes, outperforming the chemically synthesized sample (73.3%). The superior activity is ascribed to enhanced charge carrier separation and synergistic effects of bio-compound surface functionalities. This study illustrates the efficacy of green synthesis in the production of environmentally friendly and highly active N-TiO₂ photocatalysts, showing great potential for wastewater treatment and organic pollutant degradation under visible light.