Functionalized ZnOFe3O4 semiconductor oxides, grafted to the epoxy groups of graphene oxide with a narrow band gap and enhanced photocatalytic activities
Christopher Nonso Chukwuati, Richard M. Moutloali, Tien‐Chien Jen
Abstract
Functionalized zinc oxide (fZnOFe 3 O 4 ) was synthesized and grafted to the epoxy (∼C-O) groups of graphene oxide (GO) to develop the fZnOFe 3 O 4 @GO composites. The Fourier transform infrared spectrometer provided initial evidence confirming the successful grafting of fZnOFe 3 O 4 to the ∼C-O groups of GO. To this effect, bands for the ∼C-O groups were not observed on the C1s orbital of the fZnOFe 3 O 4 @GO composites, while they were present in the C1s orbital of GO at 286 eV, as indicated by the X-ray photoelectron spectroscopy. Because of the composite's improved physical and chemical properties, the band gap energy of GO and ZnO was tuned from E g , 2.5 and 3.3 eV, respectively, to 1.75 and 1.08 eV in the fZnOFe 3 O 4 and fZnOFe 3 O 4 @GO composites, respectively; degradation efficiency above 95 % was observed for methylene blue and Congo red dye molecules with the fZnOFe 3 O 4 and fZnOFe 3 O 4 @GO composites. In the case of textile industry wastewater, the fZnOFe 3 O 4 @GO composite exhibited a degradation efficiency of 64 % with a corresponding decay constant (k) of −1.04867 under ultraviolet light irradiation. In contrast, fZnOFe 3 O 4 NPs demonstrated a removal capacity of only 19 % (k: −0.20909). The improved surface area, thermal stability, reduced band gap, and lower photoluminescence intensity render the composites valuable in sustainable applications.