Integration of the straightforward and environmentally friendly sol–gel/solvothermal and photodeposition methods as a way to prepare highly photoactive Au/S-TiO₂ and Cu/S-TiO₂ materials

Au/S-TiO₂ and Cu/S-TiO₂ materials were prepared by integrating the sol–gel/solvothermal and photodeposition methods, which constituted a straightforward and environmentally friendly synthesis route with a low time requirement and without heat treatments at high temperatures. The sol–gel/solvothermal method was used to synthesize the base material (S-TiO₂) from TiOSO₄ as the only S and Ti precursor, developed in a previous study. The photodeposition method was used to incorporate Au and Cu metals from chloroauric acid and copper nitrate onto S-TiO₂. The materials were prepared by varying the metal load and the photodeposition time. The photocatalysts were characterized by X-ray diffraction, Raman spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray fluorescence. Formic acid was used to evaluate the photoactivity of the photodeposited materials. The results showed that the materials achieved a higher photoactivity than S-TiO₂ under ultraviolet light and most of the materials, especially Cu/S-TiO₂, achieved slightly higher activity under visible light. The material photodeposited with 0.5% wt of copper for 90 min had the highest photoactivity under visible light. Graphical abstract: [Figure not available: see fulltext.].