Electrochemically Deposited Zinc Oxide-Reduced Graphene Oxide as Bifunctional Composite for Photocatalyst and Photoelectrochemical Applications

In this work, we report a hybrid nanocomposite material composed of reduced graphene oxide/zinc oxide (RGO/ZnO), which has gained attention for photocatalytic wastewater treatment and photoelectrochemical applications. We synthesized RGO/ZnO thin films using modified Hummer’s method and electrochemical deposition. Initially, RGO was coated onto indium tin oxide (ITO) via drop-casting, followed by ZnO electrodeposition. The surface morphology of ZnO was adjusted using additives to enhance porosity and surface area. This RGO/ZnO composite was employed for photodegradation of methylene blue (MB) dye under visible light. The combination of RGO and ZnO improved catalytic properties due to ZnO electronic, optical, and catalytic characteristics, with RGO serving as an excellent electron conductor with high mobility. Characterization of the nanocomposite was conducted using X-ray diffraction, scanning electron microscopy, and UV–Visible diffuse reflectance spectroscopy. The UV–visible spectrum showed significant MB absorption over time, and photocatalytic activity was evaluated by degradation kinetics of MB dye under solar illumination. The RGO/ZnO composite demonstrated 95.4% photodegradation of MB compared to 63.4% by pure ZnO. Additionally, the RGO/ZnO showed an enhanced photocurrent response of 5.5 mA/cm² with lower overpotential. Our work suggests a pathway for the fast synthesis of RGO-semiconductor nanocomposites with superior photocatalytic properties for modern applications.