A Copper(I) oxide-zinc oxide nano-catalyst hybrid: Brief characterization and study of the kinetic of its photodegradation and photomineralization activities toward methylene blue

Abstract

In this study, as-prepared coupled copper(I) oxide-zinc oxide (Cu2O–ZnO) nanoparticles were briefly characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), diffuse reflectance spectroscopy (DRS), and scanning electron microscope/energy-dispersive X-ray methods, followed by testing their photocatalytic activity toward the photodegradation and photomineralization of methylene blue (MB). The cubic phase of Cu2O and the hexagonal wurtzite ZnO crystallite phases were detected in the XRD pattern of the nano-composite. In addition, the average crystallite sizes of 22.15, 11.11, and 17.85 nm, as well as 46, 35, and 61 nm were estimated for the as-prepared ZnO, Cu2O, and Cu2O–ZnO samples by the Scherrer and the Williamson-Hall equations, respectively. Further, the bandgap energy (Eg) values of 3.12, 2.23, and 2.29 eV were obtained for the above-mentioned samples corresponding to their absorption-edge wavelengths of 398, 555, and 541 nm, respectively. Based on the findings, FTIR confirmed the synthesis of cubic Cu2O crystals during the synthesis procedure. Furthermore, direct photolysis and surface adsorption processes removed 1.7 and 2% of MB while the photodegradation process by ZnO, Cu2O, and Cu2O–ZnO simultaneously removed 35.1, 50.1, and 78.0% of MB molecules, respectively. The coupled system with the Cu2O:ZnO mole ratio of 1:2 showed the highest activity. Finally, the rate constant values of 0.0198 and 0.0192 min-1 corresponding to the t1/2 values of 35 and 36.1 min were obtained for MB photodegradation and photomineralization, respectively.