Synthesis and characterization of rGO/Gd2WO6 nanocomposite for efficient photocatalytic degradation of organic pollutant's and antioxidant's activity

Abstract

Graphene derivatives and metal oxide-based nanocomposites are being researched for their applications in gas sensing, environmental clean-up, and biomedicine. This study aimed to assess the impact of combining reduced graphene oxide (rGO) with Gd₂WO₆ on photocatalytic and antioxidant activities. A novel rGO/Gd₂WO₆ nanocomposite was successfully synthesized using the sol–gel method. The optical, compositional, morphological, and structural characteristics of the rGO, WO₃, Gd₂WO_6, and rGO/Gd₂WO₆ nanocomposites were studied. The as-prepared samples were characterized by XRD, FT-IR, FE-SEM with EDX, UV-DRS, TEM, BET, and XPS to reveal the band gap, crystalline structure, and element composition information. XRD results indicated that the as-prepared catalysts comprised the tetragonal phase of WO₃ and the monoclinic phase of Gd₂WO₆. FT-IR spectral analysis further confirmed the metal–oxygen stretching vibrations. The morphology studies denoted the shapes of synthesized materials. Specifically, the rGO was seen as a sheet-like structure, the WO₃ as an agglomeration, the Gd₂WO₆ as an irregularly shaped agglomeration, and in the rGO/Gd₂WO_6, the Gd₂WO₆ particles are spread over the surface of the rGO which was confirmed by FE-SEM. EDX spectra provide additional evidence for the presence of C, O, Ti, and W elements within the nanocomposite. The UV-diffuse reflectance spectroscopy was used to determine the band gap values by utilizing the Kubelka–Munk function, and the band gap values of rGO, WO₃, Gd₂WO_6, and rGO/Gd₂WO₆ are 3.00, 3.11, 2.99, and 2.94 eV, respectively. TEM analysis reveals that rGO/Gd₂WO₆ has a sheet-like structure. The BET analysis is carried to find the surface area (~ 8.57 m²/g) and pore volume (~ 0.047 cm³/g). The observed surface area and pore volume is favourable for more light absorption and effect the adsorption of dye molecules on the surface of the catalyst. The oxidation state and elemental composition of Gd, W, carbon, and oxygen were determined by X-ray photoelectron spectroscopy (XPS) analysis. The enhanced electron–hole pair separation rate is responsible for the effectiveness of photocatalytic degradation and antioxidant activity of the rGO/Gd₂WO₆ nanocomposite. The visible light photocatalytic degradation of Congo red & methylene blue shows that the rGO/Gd₂WO₆ composite exhibits superior photocatalytic performance (67% and 92%) with maximum degradation rate achieved under visible sunlight exposure to radiation. The antioxidant activity of rGO/Gd₂WO₆ was assessed DPPH radical cation decolourization assay, and the results indicate that rGO/Gd₂WO₆ has potential antioxidant activity. The results of this work showed that Gd₂WO₆ particles decorated on rGO sheets may utilize the lead molecule for improved photocatalytic and antioxidant activities.