Photocatalytic degradation of methyl orange under ultraviolet–visible light irradiation using WO3-ZnO nanocomposites synthesized via Saffron petal extract

Abstract

The elimination of organic dyes through photocatalysis is an effective approach for achieving pollution-free environments. WO3-ZnO nanocomposites with ZnO:WO₃ weight ratios of 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100, labeled as 100Z, 20WZ, 40WZ, 60WZ, 80WZ, and 100W, respectively, were synthesized through an environmentally green synthesis method. Subsequently, the WO3-ZnO nanocomposites were utilized for the photocatalytic degradation of methyl orange (MO) under the irradiation of ultraviolet -visible light. The resultant products were characterized using a comprehensive suite of characterization techniques, including X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance spectroscopy (DRS). The XRD patterns indicated the formation of crystal structures of ZnO, WO3, and the WO3-ZnO nanocomposites. Based on optical investigations, the direct optical band gaps of 100Z, 20WZ, 40WZ, 60WZ, 80WZ, and 100W were measured to be 3.29, 3.27, 3.09, 3.26, 3.05, and 2.99 eV, respectively. The photocatalytic efficacy of the synthesized nanocomposites was evaluated through the degradation of MO. The obtained results demonstrated that the synergistic effect between WO3 and ZnO contributes to the enhancement of charge separation and reduction in the recombination rates of charge carriers, thereby significantly augmenting the photocatalytic efficiency. Notably, the 40WZ nanocomposite exhibited the highest photocatalytic degradation efficiency of MO under UV -vis light irradiation. It was observed that 100% removal of the MO dye could be achieved by the 40WZ nanocomposite within 15 min of light irradiation.