Hydrothermally synthesised ZnFe2O4/ZnO heterojunction nanocomposites for enhanced RB dye degradation via Z-scheme photocatalysis

ZnFe2O4/ZnO nanocomposites with 1:1, 1:2, 1:3 and 1:4 weight ratios synthesised by hydrothermal method are used as a photocatalyst to degrade Rose Bengal (RB) dye. For structural investigation X-ray diffraction (XRD) and Fourier transform Infrared (FTIR) was performed. The presence of both phases corresponding to ZnFe2O4 and ZnO in XRD suggests the successful formation of a nanocomposite. Value of crystallite size varies from 25.01 nm to 18.61 nm for 1:1 to 1:4 nanocomposite. Almost spherical morphology of nanocomposite obtained through High-resolution transmission electron microscopy (HRTEM). FTIR demonstrated Zn-O and Fe-O bonds in as synthesised samples. Also, X-ray photoelectron spectroscopy (XPS) is used to detect the presence of Fe2+, Zn2+ and O2- ions in synthesized nanocomposites. In UV-DRS, values of band gap vary from 1.73 to 1.88 eV in nanocomposite as the weight ratio of ZnO increases. The formation of heterojunction is responsible for enhancing electron hole mobility. Due to this enhancement, degradation efficiency of 88% is achieved in 90 min irradiation of UV light by ZnFe2O4/ZnO (1:4) nanocomposites for RB dye followed Z-scheme mechanism. Also, the magnetization value of different nanocomposites changes from 0.9 to 0.1 emu/g. Magnetization nature is responsible for separating the catalyst from the reaction mixture after use. So, the nanocomposite can be reused which maintains the green protocol in the environment. ZnFe2O4/ZnO nanocomposite with 1:4 weight ratio can be reused upto 5 cycles. The formation of such nanocomposites can offer unique properties and advantages by combining the characteristics of both materials can lead to enhanced functionalities suitable for various applications such as catalysis, sensors, and magnetic devices.