Fabrication of novel Tin-doped TiO2/Ti3C2 MXene photocatalyst for enhanced visible light-driven degradation of Rhodamine B and Dinoseb: Response surface methodology optimization

Abstract

Transition metal carbides (MXenes) have emerged as promising 2D materials for photocatalysis due to their exceptional conductivity and high surface area. In this study, we synthesized a novel Sn-doped TiO₂/Ti₃C₂ MXene nanocomposite via a hydrothermal method and characterized it using various structural, optical, and electrochemical techniques, including Mott–Schottky analysis, Tafel plots, and photocurrent measurements. The incorporation of Sn effectively narrowed the bandgap of TiO₂ from 3.40 eV to 3.26 eV, while integration with Ti₃C₂ MXene further reduced it to 2.76 eV and facilitated efficient charge separation through Schottky junction formation. Under visible light irradiation, the photocatalyst achieved high degradation efficiencies of 95.64 % for Rhodamine B and 91.38 % for Dinoseb, corresponding rate constants of 0.0576 min⁻¹ and 0.0175 min⁻¹. The investigation found that hydroxyl radicals (^•OH) and superoxide radicals (^•O₂⁻) are the main reactive species responsible for pollutant degradation, and TOC analysis confirmed the photocatalyst’s ability to mineralize over 80 % of organic pollutants into inorganic compounds. Response surface methodology (RSM) was employed for multivariate optimization of operational parameters. The material also demonstrated excellent reusability over seven cycles. This nanocomposite is the first report on combining Sn-doped TiO₂ with Ti₃C₂ MXene for synergistic enhancement in visible-light-driven photocatalysis, providing a highly efficient and stable platform for removing hazardous organic pollutants from wastewater.