Phase stability and band-gap engineering of pure TiO2 for visible light photocatalyst via photon-induced method

This study compares undoped TiO₂ nanoparticles made using two wet-chemical methods: sol-gel(SG) and photon-induced methods (PIM). The focus is on phase stability and bandgap control for visible-light photocatalysis. TiO₂ synthesized using the PIM method retained the anatase phase even after heating to 750 °C. In contrast, the SG method primarily produced the rutile phase. X-ray diffraction(XRD) confirmed this phase stability. The PIM process helps prevent the transformation from anatase to rutile by controlling heat through light exposure. Morphological studies showed that PIM-made particles were more uniform and better dispersed. This reduced clumping and increased surface area. Optical analysis revealed a reduced bandgap of 2.96 eV for the PIM-synthesized TiO₂ samples, likely resulting from defect states, oxygen-rich conditions, or other non-stoichiometric features introduced during the synthesis process. Photocatalytic tests showed that PIM-TiO₂ degraded methylene blue(MB) by 96.5%, which was much better than the 56% achieved by SG-TiO₂. This is likely due to better separation of charge carriers and improved structure from photon-assisted synthesis. Overall, the photon-induced method is more energy-efficient and produces better-performing TiO₂ photocatalysts. These materials have potential uses in pollution control, solar energy, and advanced materials.

Graphical Abstract