A new method of preparation of AgBr/TiO₂ composites and investigation of their photocatalytic activity

Silver bromide/titanium dioxide composites were first prepared using titanic acid nanobelts (TAN) as the TiO₂ source. First, TAN reacted with AgNO₃ to prepare Ag-incorporated TAN by the ion-exchange method, and then AgBr/TAN was obtained after adding NaBr. Finally, AgBr/TAN was transformed to AgBr/TiO₂ composites by calcination. The post-treated calcination would not only convert TAN to TiO₂ (H₂Ti₂O₄(OH)₂ → 2H₂O + 2TiO₂), but also increase the effective contact between AgBr and TiO₂, further to improve the separation of photo-generated electron-holes. The advantage of this preparation method is the small particle size (ca. 10–20 nm) and well dispersion of AgBr on the surface of TiO₂, and close contact between AgBr and TiO₂. The effect of the different calcination temperature on the morphology, structure, and properties of AgBr/TiO₂ composites was investigated in detail. The AgBr/TiO₂ composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and ultraviolet–visible diffuse reflectance spectra (UV–Vis DRS). Comparing with pure TAN, AgBr, and AgBr/P25 mixture, the AgBr/TiO₂ composites exhibited enhanced photocatalytic activity in decomposition of methyl orange (MO) under visible light irradiation.