Visible light photocatalytic activity of reduced graphene oxide synergistically enhanced by successive inclusion of γ-Fe2O3, TiO2, and Ag nanoparticles

Novel magnetic nanocomposites are synthesized by loading reduced graphene oxide (r-GO) with three brands of nanoparticles consisting of titanium dioxide (TiO2), gamma-iron(III) oxide (gamma-Fe2O3), and silver (Ag) with varying amounts. The resulting Ag/TiO2/gamma-Fe2O3@r-GO demonstrates synergistically enhanced visible light photocatalytic activity, on degradation of wastewater's toxic crystal violet (CV). Specifically, it exhibits higher photoactivity than those of neat graphene oxide (GO), TiO2@GO, gamma-Fe2O3@GO, and TiO2/gamma-Fe2O3@GO, possibly because of effective separation of photogenerated carriers via strongly coupled Ag/gamma-Fe2O3@r-GO cocatalyst and the enrichment of organic molecules on the graphene nanosheets. A higher photocatalytic efficiency is observed when 11.5 wt% Ag nanoparticles are incorporated in TiO2/gamma-Fe2O3@GO. After 3 successive cycles, the latter nanocomposite maintains 97% removal efficiency with excellent stability and easy recovery. Considering its facile preparation and high photocatalytic activity, it is hoped that this photocatalyst will find its application in various fields such as air purification and wastewater treatment. The structure and properties of Ag/TiO2/gamma-Fe2O3@r-GO are characterized by Fourier-transform infrared (FOR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet-visible spectrometry (UV-vis) and Raman spectroscopy techniques. (C) 2014 Elsevier Ltd. All rights reserved.