Grevillea robusta leaf extract-assisted fabrication of ZnO/CuO nanocomposites for enhanced degradation of methylene blue dye

Methylene blue (MB) highly toxic dye that poses significant risks to living beings. Therefore, designing a method to remove this pollutant from industrial effluents is a significant task. As such, mixed metal oxide nanocomposites have become a prominent area of research for the photodegradation of dyes. In this work, zinc oxide nanoparticles (ZnO NPs), copper oxide nanoparticles (CuO NPs), and ZnO/CuO nanocomposites (ZnO/CuO NCs) were synthesized through a green synthesis approach utilizing Grevillea robusta leaf extract. The synthesized nanoparticles were analyzed through different techniques. The band gaps (Eg) were calculated via UV–vis spectra, revealing change in Eg upon compositing. The X-ray diffraction (XRD) specified that the average crystalline sizes ranged from 15.56 to 24.8 nm. Similarly, the SEM revealed variations in particle size after compositing, while the EDX confirmed the consistency of the theoretical ratio with the analytical results. Finally, the efficacy of the nanomaterials was performed for the degradation of MB under sunlight. Photocatalysts against MB follows: ZnO (76%) < CuO (79.3%) < 2:1 ZnO/CuO (89.1%) < 1:1 ZnO/CuO (91.4%) < 1:2 ZnO/CuO (93.94%) in 30 min. The results indicated that the green-synthesized binary NCs are even more effective than those produced by physical and chemical methods, showing promise for reducing organic pollutants.