Photocatalytic degradation of low-concentration gaseous benzene in air via bifunctional tin-doped titanium dioxide catalyst

Benzene, a common volatile organic compound (VOC) detected in indoor environments, poses challenges for its removal because of its stable molecular structure and low-concentration. In this study, we successfully synthesized tin-doped titanium dioxide (Sn-TiO₂) using a simple hydrothermal method. Various characterization techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunner–Emmet–Teller (BET) and molecular probes were employed to analyze the phase composition, structure and morphology, as well as photocatalytic properties of TiO₂ and Sn-TiO₂. The characterization results showed that moderate addition of tin doping not only effectively enhanced the capture ability of benzene molecules but also promoted hydroxyl radicals (·OH) generation, which was further validated by in-situ diffuse reflectance infrared Fourier transform (DRIFT) spectra and density function theory (DFT) calculations. Degradation experiments on gaseous benzene revealed that under 15 W ultraviolet (UV) light irradiation in humid and closed conditions for 60 min, 1 % Sn-TiO₂ achieved a benzene degradation efficiency of 93.14 %, with almost complete mineralization. Furthermore, flow system experiments demonstrated efficient decomposition of trace amounts of benzene (∼10 mg/m³) in the air to satisfy emission standards when employing 1 % Sn-TiO₂ at a flow rate of 100 L/min.