The effect of the graphene oxide quantum dot (GOQD) synthesis method on the photocatalytic and antibacterial activities of GOQD/ZnO

Abstract

Graphene Oxide Quantum Dots (GOQD) have attracted considerable research interest owing to their use in photocatalysis and antibacterial applications. In this study, pyrolysis and hydrothermal methods were used to prepare GOQD (p-GOQD and h-GOQD) sheets with different characteristics that affect the photocatalytic and antibacterial activities of GOQD/ZnO. The synthesized p-GOQD/ZnO and h-GOQD/ZnO were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy. As a result, we found that p-GOQD/ZnO (18–20 nm) exhibited better photocatalytic activity than h-GOQD/ZnO (20–22 nm), with degradation percentages of 97.6 % and 93.04 %, respectively, at 60 min. The degradation rate constants are found to be 0.0498 min−1 for p-GOQD/ZnO and 0.0335 min−1 for h-GOQD/ZnO. In addition, the antibacterial activity of p-GOQD/ZnO was better than that of h-GOQD/ZnO against Escherichia coli and Staphylococcus aureus, with inhibition zone diameters of 10.40 mm and 9.75 mm, respectively. The outstanding photocatalytic and antibacterial performance of p-GOQD/ZnO suggests that p-GOQDs provide better characteristics and applications for ZnO semiconductor composites. The advantages of p-GOQD/ZnO are synergistic effects, low dislocation density, large surface area, and defects, which demonstrate its potential for practical applications in environmental remediation.