Improved photocatalytic activity of ZnO coupled CuO nanocomposites synthesized by reflux condensation method

Abstract

Nanostructured CuO-ZnO nanocomposites were successfully synthesized for different Zn2+ concentrations by reflux condensation method without using any surfactant, and their photocatalytic activity was evaluated using methyl orange and methylene blue dyes under UV light irradiation. XRD revealed the formation of CuO-ZnO nanocomposites, composing of monoclinic CuO and hexagonal ZnO. XPS analysis revealed that CuO-ZnO nanocomposites are made up of Cu( II), Zn( II) and O. FESEM and TEM images showed that pure CuO exhibit 3D flower-like microstructure, while the CuO-ZnO nanocomposites prepared for different Zn2+ concentrations have 3D flower-like CuO, microstructure adorned with rod-like ZnO particles. UV-Vis DRS showed absorption bands corresponding to CuO and ZnO around 960 nm and 395 nm, respectively. PL spectra of CuO-ZnO nanocomposites exhibited reduced PL emissions compared to pure CuO, indicating the low recombination rate of photogenerated electrons and holes. Photodegradation assay revealed that catalytic activity of CuO-ZnO nanocomposites increased with Zn2+ concentration, and also effectively degrade methyl orange and methylene blue dyes when compared to pure CuO. The enhanced photocatalytic activity of CuO-ZnO nanocomposites were mainly ascribed to the reduced recombination and efficient separation of photogenerated charge carriers. The possible mechanism for the improved photocatalytic activity of CuO-ZnO nanocomposites was proposed.