Band gap engineering of titanium dioxide (TiO2) nanoparticles prepared via green route and its visible light driven for environmental remediation

The present study investigates the green synthesis and characterization of Calcium-doped titanium dioxide nanoparticles (Ca-TiO₂ NPs) for their potential application in the degradation of organic pollutants under visible light. The nanoparticles were prepared using a simple phytosynthesis method and characterized by various spectroscopic and microanalytical techniques for structural and optical properties. From UV spectroscopic result it is observed that the energy band gap of pure titanium dioxide (TiO₂) is decreased from 3.1 eV to 2.52 eV, 2.45 eV and 2.35 eV for 2 %, 5 % and 9 % Ca-doped which shows the transformation from UV to Visible light absorbance. The results obtained suggested that, the introduction of calcium significantly enhanced visible light absorption, thereby extending the photocatalytic activity into the visible spectrum. In this study, the degradation potential of Ca-TiO₂ NPs was assessed through the degradation of 4-Nitro phenol and Congo red organic pollutant dyes under visible light spectrum. Results show a substantial improvement in visible light degradation compared to undoped TiO₂, indicating the phenomena of calcium-doped titanium dioxide nanoparticles as efficient visible light-responsive photocatalysts for environmental remediation.