ZnO-ZnTe hierarchical superstructures as solar-light-activated photocatalysts for azo dye removal

Abstract

The excessive amount of textile effluents disposed into the water streams is a common source of contamination of the hydrosphere. To efficiently remove pollutants in water bodies, there is growing demand for highly efficient, cost effective, and green remediation techniques. In line with such demand, a heterostructured photocatalyst (ZnO-ZnTe) has been prepared through the assembly of zinc oxide (ZnO) and zinc telluride (ZnTe). A synergistic interaction between surface adsorption and photocatalysis was explored for the removal of azo dye using a hierarchical superstructure under solar-light irradiation. Methylene blue (MB) was bleached by about 91% under visible irradiation for 2 h to support the role of the prepared heterostructures as effective photocatalysts (QY is 3.16 x 10⁻⁷ molecules/photon). Moreover, the kinetic reaction rate of ZnO-ZnTe superstructures was 19.0 mu mol g⁻¹ h⁻¹, which was 1.54 and 1.97 times higher than those of pristine ZnO and ZnTe, respectively. These results may be ascribed to the presence of a common cation that may have helped in the diffusion of photogenerated electrons between ZnO and ZnTe, while efficiently suppressing the recombination frequency of photogenerated electrons and holes.