Effect of Ga and Gd as Catalyst in ZnO/Reduced Graphene Oxide Composites upon Photodegradation Process

Abstract

Photocatalytic degradation was improved by addition of gallium (Ga) and gadolinium (Gd) as catalysts for zinc oxide/reduced graphene oxide (ZnO/rGO) composites. Preparation, physical characterisation, dye degradation, photocatalytic activity and kinetic mechanisms of Ga-ZnO/rGO and Gd-ZnO/rGO composites were investigated. Physical characteristics of the composites were studied using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Photocatalytic activity of the composites was investigated by degradation of reactive blue dye solution as a function of contact time, catalyst type and catalyst concentration. Results indicated that Ga-ZnO/rGO (2 wt%Ga) and Gd-ZnO/rGO (0.6 wt%Gd) were capable of dye degradation at 62.76% and 54.43% respectively under UV irradiation for 3 h with the photocatalytic process described by pseudo first order kinetics as 0.0059 and 0.0058 min-1. Findings confirmed that addition of Ga and Gd in composite systems enhanced removal of reactive blue dye solution. Optimum conditions were recorded for Ga 2 wt% and Gd 0.6 wt% in ZnO/rGO composite. Results indicated that Ga-ZnO/rGO (2 wt%Ga) and Gd-ZnO/rGO (0.6 wt%Gd) showed promise for removal of reactive blue dye.