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

Abstract

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 TiO2 was 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 -TiO2 showed 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 TiO2 lattice 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 TiO2 improved the anatase stability the antimicrobial activity is not significantly enhanced compared to pure anatase TiO2 under visible light illumination. Te-TiO2 attained 100% disinfection within 70 min of visible light irradiation and maintained equal antibacterial efficiency as pure TiO2 at 750 °C.