Effect of chalcogens (S, Se, and Te) on the anatase phase stability and photocatalytic antimicrobial activity of TiO₂

The effect of chalcogens such as sulphur (S), selenium (Se), and tellurium (Te) on the anatase to rutile phase transition (ART) of titanium dioxide (TiO₂) was investigated. 2※mol % of chalcogen doped TiO₂was synthesised via a sol-gel technique. The as-synthesised samples were calcined at different temperatures from 500※°C to 800※°C for 2※h. X-ray diffraction (XRD) and Raman spectroscopy were used to study the ART of TiO₂. Te-TiO₂showed the highest anatase phase (44%) at 750※°C as compared to other samples. X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectroscopy (UV-DRS) was further utilised to investigate the oxidation state and optical properties. UV-DRS results showed that the substitutional doping of chalcogens in the TiO₂lattice enhanced visible light absorption. The photocatalytic efficiency was tested for the disinfection of Escherichia coli (E.coli) under visible light irradiation. It is noted that while the chalcogen modified TiO₂improved the anatase stability the antimicrobial activity is not significantly enhanced compared to pure anatase TiO₂under visible light illumination. Te-TiO₂attained 100% disinfection within 70※min of visible light irradiation and maintained equal antibacterial efficiency as pure TiO₂at 750※°C.