Synthesis of Fe3O4@SiO2@α-Fe2O3/TiO2-rGO nanohybrids for heterogeneous photocatalytic transformation of lignocellulosic biomass

This study explored mild and cost-effective conditions for the valorization of lignocellulosic biomass. Herein, reduced graphene oxide (rGO) supported magnetic core double-shell nanomaterials were successfully synthesized by an innovative four-step approach. Fe3O4 nanoparticles were first produced to act as cores without using any surfactants. The magnetite/silica core–shell structure was then prepared by hydrolysis of tetraethoxysilane in the presence of core particles under alkaline conditions. The outermost shell, the α-Fe2O3/TiO2 layer, was grown over a magnetic core of Fe3O4@SiO2 using a co-precipitation and calcination approach. Furthermore, nanohybrids were fabricated by loading Fe3O4@SiO2@α-Fe2O3/TiO2 nanoparticles on rGO using a hydrothermal method. Nanomaterial characterization by vibrating-sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) showed both nanomaterials with and without rGO support are soft ferromagnetic and the presence of Fe3O4, TiO2, Fe2O3 and SiO2 in both nanomaterials. The nanohybrids exhibited increasing photocurrent as a function of illumination by cool white fluorescent light, and their magnetic property enabled the particles to be magnetically separated for recycling and reuse. The efficient photoactivity of the Fe3O4@SiO2@α-Fe2O3/TiO2-rGO nanohybrids was confirmed for conversion of two lignocellulose model compounds: 83.9