Structural, optical, morphological and oxygen vacancies induced visible-light-driven photocatalytic activity of graphene oxide conjugated Fe-doped CuO nanocomposite

Efficient removal of organic pollutants from water is vital for environmental protection. This work reports a novel environmental friendly, cost-effective, easy production, fast collection and good recyclable photocatalyst viz. graphene oxide based iron doped copper oxide nanocomposite (GO/Cu_0.9Fe_0.1O) against methylene blue (MB). Moreover, it explores the structural, optical, morphological, electronic, and enhanced photocatalytic properties of pristine CuO, 10 % Fe-doped CuO (Cu_0.9Fe_0.1O) nanoparticles (NPs), GO/Cu_0.9Fe_0.1O nanocomposite. The sol-gel auto-combustion method was used to prepare pure CuO and 10 % Fe-doped CuO (Cu_0.9Fe_0.1O) nanoparticles, while the sonication method was applied to prepare GO/Cu_0.9Fe_0.1O nanocomposite. The average crystallite sizes were determined from Rietveld-refined XRD patterns and found to be 29 nm, 22 nm, and 21 nm for pure CuO, Cu_0.9Fe_0.1O, and the GO/Cu_0.9Fe_0.1O nanocomposite, respectively. SEM images confirmed good crystal quality and defect-free surfaces of the sample. Tauc plots reflect a reduction in the optical band gap from 2.71 eV to 1.87 eV due to the effect of Fe doping and GO content. The presence of considerable oxygen vacancies and Fe^2+/Fe⁺³ mixed ionic states in the GO/Cu_0.90Fe_0.10O is verified using XPS which played a significant role in the photocatalytic degradation of methylene blue (MB). Scavenger tests were conducted using 1,4-benzoquinone (BQ) and isopropyl alcohol (IPA) to identify the reactive species responsible for the photocatalytic activity. The photocatalytic activity was verified by degrading MB, a well-known organic dye, under 50 W LED light (reduced the reliance on expensive UV source), suggesting that GO/Cu_0.9Fe_0.1O nanocomposite could be a promising material for wastewater treatment.