Remarkable photocatalytic performance and recyclable pathway of cleansing wastewater using ZnO–rGO nanocomposite

This research presents the development and analysis of reduced graphene oxide (rGO), zinc oxide (ZnO) nanoparticles, and ZnO–rGO nanocomposites to assess their degradation capacity against toxic dye molecules in wastewater treatment. We used rGO, surface modified with ZnO, for photocatalytic degradation of methyl orange driven by visible light. The necessary characteristics of the ZnO, rGO, and their nanocomposite ZnO–rGO in a 5:1 ratio have been investigated by x-ray diffraction, Fourier transform infrared, field emission scanning electron microscopy, and UV–vis spectroscopy. Furthermore, the energy bandgap of ZnO nanoparticles and rGO–ZnO nanocomposites was determined using the diffuse reflectance spectroscopy method. Adding rGO to ZnO nanoparticles contributes to bandgap reduction, expanding their absorbance into the visible light spectrum—a promising attribute for photocatalytic applications. The outstanding degradation performance was obtained up to ∼99% using the ZnO–rGO composite, compared to ∼67% using pure ZnO with the same dosage amount after 90 min. Recyclability of the material was assessed for five consecutive cycles, confirming that it could potentially be reused several times with notable removal efficiency.