ZnO/TiO2 photocatalysts for degradation of methyl orange by low-power irradiation.

Abstract

Photocatalysts are the most essential in photocatalytic degradation of dyes in wastewater. Here, ZnO/TiO₂ composite photocatalysts with variable proportions were prepared by chemical deposition method in order to meet the realistic requirements of low-cost synthesis, high stability, and environmental friendliness. The as-prepared photocatalyst was characterized by the technologies of scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, UV-vis diffuse reflection, photoluminescence spectroscopy, electrochemistry, nitrogen adsorption and X-ray diffraction. The degradation of methyl orange (MO) was applied to evaluate the photocatalytic activity of ZnO/TiO₂ under low-power irradiation. At the same time, the effects of the chemical composition of photocatalyst, pH and MO concentration of solution on the photocatalytic degradation performance were mainly investigated. The results demonstrated an excellent synergistic effect between ZnO and TiO₂ for improving the photocatalytic efficiency of the composite catalyst. The highest degradation rate of MO reaches to 98.6% for the photocatalyst with a mass proportion of ZnO:TiO₂ being 0.131:1 under the condition of 10 mg/L for MO concentration and 6.7 for pH via the light of ultraviolet radiation A band. This study brings a new way for the production of low-cost and efficient catalysts with low-power light sources to mitigate azo dyes, e.g. MO.