Effectiveness of photodecomposition of rhodamine B and malachite green upon coupled tricomponent TiO₂(Anatase-Rutile)/ZnO nanocomposite

In this study, mixed phase ZnO-TiO₂ nanocomposite consisting of hexagonal ZnO and anatase/rutile TiO₂ has been synthesized via sol-gel process.The physical and photochemical properties of samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminscience spectra (PL) and and photocurrent action spectra techniques. In the case of minerlization of rhodamine B (RhB) and malachite green (MG) dyes, the coupled ZnO-TiO₂ nanocomposite with the suitable band structure and the lowest photoluminescence intensity showed the best photodecolorization activity. Synergistic effects between the two oxides for photocatalytic decomposition of RhB and MG are proposed to elucidate the decolorization mechanism. The lifetime of electrons and holes was prolonged in the ZnO-anatase/rutile multiple-component system, which can enhance the light harvest and the ability of generating photo-induced electron-hole pairs of active sites, and the favorable electron-transfer properties in the coupled ZnO-TiO₂ nanocomposite. Therefore, the as-prepared ZnO-TiO₂ nanocomposite showed an excellent efficiency towards the removal of aqueous organic dyes and it is of certain significance for environmental photocatalysis.