Molecularly Imprinted TiO2/WO3-Coated Magnetic Nanocomposite for Photocatalytic Degradation of 4-Nitrophenol Under Visible Light

Abstract

In this paper, a molecularly imprinted TiO2/WO3-coated magnetic Fe3O4@SiO2 nanocomposite was developed for photocatalytic degradation. Fe3O4 nanoparticles were first prepared by a traditional co-precipitation method, and then a SiO2 shell was grown on the surface of the Fe3O4 nanoparticles. Finally, a 4-nitrophenol imprinted TiO2/WO3 coating was obtained on the surface of the Fe3O4@SiO2 nanocomposite via a sol-gel method and subsequent calcination. The new composite was characterised by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution TEM (HRTEM) and vibrating sample magnetometry (VSM). In addition, the adsorption ability and photocatalytic activity of the composite were investigated. Results showed that the imprinted composite had higher adsorption ability for the template than the non-imprinted composite. The imprinted catalyst could degrade 4-nitrophenol under visible light with a first-order reaction rate of 0.1039 h–1, which was ~2.5 times that of the non-imprinted catalyst. The new imprinted catalyst showed good catalytic selectivity, an ease of being recycled by an external magnetic field, good reusability, no need for additional chemicals, and allows the possibility of utilising solar light as energy resource. Therefore, the catalyst can be potentially applied for ‘green’, low-cost and effective degradation of 4-nitrophenol in real wastewater.