Synthesis and photocatalytic evaluation of visible Light-Activated Ni-S codoped TiO₂ in Metanil yellow degradation
摘要
This research describes the synthesis, characterization, and photocatalytic performance of nickel-sulfur (Ni-S) codoped titanium dioxide (TiO2) nanoparticles to degrade metanil yellow dye under visible light. The large bandgap of pristine TiO2 (3.2 eV) limits its photocatalytic activity to the visible range and, therefore, requires changes to enhance its performance. Non-metal and metal doping, in particular, codoping with elements such as nitrogen, fluoride, and sulfur, potentially narrows the bandgap. Here, Ni-S codoping effectively lowers the bandgap to 2.75 eV, thereby increasing the absorption of visible light. X-ray diffraction is used to confirm the anatase phase, and UV–Vis diffuse reflectance spectroscopy indicated a red shift, which is a direct indication of increased light-harvesting capability. The incorporation of Ni and S dopants is confirmed by Fourier transform infrared spectroscopy. Energy-dispersive X-ray spectroscopy combined with scanning electron microscopy is used to confirm elemental distribution, and transmission electron microscopy shows that the nanoparticles are well-dispersed and the sizes are between 15 and 25 nm. Ni-S codoped TiO2 achieves a significantly enhanced photocatalytic efficiency; thus, the metanil yellow concentration of 10 ppm is degraded up to 92% in 120 min under visible light. Improved photocatalytic activity is attributed to improved UV-visible absorption, surface acidity, and oxygen vacancy formation. These results suggest that Ni-S codoped TiO₂ is a highly effective photocatalyst for visible light-driven environmental applications.