TiO₂-SnS₂ nanocomposites: solar-active photocatalytic materials for water treatment

The study is aimed at evaluating TiO₂-SnS₂ composites as effective solar-active photocatalysts for water treatment. Two strategies for the preparation of TiO₂-SnS₂ composites were examined: (i) in-situ chemical synthesis followed by immobilization on glass plates and (ii) binding of two components (TiO₂ and SnS₂) within the immobilization step. The as-prepared TiO₂-SnS₂ composites and their sole components (TiO₂ or SnS₂) were inspected for composition, crystallinity, and morphology using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Diffuse reflectance spectroscopy (DRS) was used to determine band gaps of immobilized TiO₂-SnS₂ and to establish the changes in comparison to respective sole components. The activity of immobilized TiO₂-SnS₂ composites was tested for the removal of diclofenac (DCF) in aqueous solution under simulated solar irradiation and compared with that of single component photocatalysts. In situ chemical synthesis yielded materials of high crystallinity, while their morphology and composition strongly depended on synthesis conditions applied. TiO₂-SnS₂ composites exhibited higher activity toward DCF removal and conversion in comparison to their sole components at acidic pH, while only in situ synthesized TiO₂-SnS₂ composites showed higher activity at neutral pH.