Photocatalytic studies of copper oxide nanostructures for the degradation of methylene blue under visible light

Abstract

As a well-known global fact, the presence of toxic, non-biodegradable and harmful organic pollutants in soils, wastewater, and atmosphere has become an indisputable significant environmental problem. The present study reports the photocatalytic properties of the cubic-shaped Cu/Cu2O/CuO and bud-shaped CuO nanoparticles for methylene blue (MB) removal from the synthetic dye solution. Nanocrystalline copper oxide particles are synthesized by a simple solvothermal method followed by an annealing process at 400 °C in an open atmosphere. The crystalline structure and morphology of the nanoparticles are characterized by X-ray diffraction and field emission-scanning electron microscopy. The optical band gap energies of the prepared powders are estimated using the UV–vis spectrometer. Interestingly, cubic shaped Cu/Cu2O/CuO nanoparticles shows a photo-degradation efficiency of about 78% after 120 mins whereas bud-shaped CuO shows 61% in the presence of H2O2. Further, Cu/Cu2O/CuO nanoparticles show good recyclability of up to three cycles. The excellent photocatalytic performance and reusability properties of Cu/Cu2O/CuO heterojunctions also synergistically lowers the electron–hole recombination rate, promotes the utilization of light and photo-generation of charge carriers. All these combined effects result in the enhanced photocatalytic degradation and mineralization of the MB dye.