Preparation and photocatalytic properties of a visible light responsive and magnetically separated photocatalyst of γ-Fe2O3/SiO2/GSs/TiO2

A graphene sheet (GS) synthetised from natural graphite powder was doped in titanium dioxide (TiO₂) through the sol-gel method to improve the photocatalytic activity and magnetic γ-Fe₂O₃/SiO₂ particles were added subsequently to improve recycling and reduce the waste of the catalyst. The morphology, microstructure, absorption spectrum and magnetic property of the γ-Fe₂O₃/SiO₂/GSs/TiO₂ composites were characterised via X-ray diffraction, transmission electron microscopy, diffuse-reflectance spectra and a vibrating sample magnetometer, respectively. The result revealed that (i) the nanocrystalline structure of γ-Fe₂O₃/SiO₂/GSs/TiO₂ composites is nearly unchanged compared with pure P25 nanoparticles; (ii) there was a redshift in the absorption edge of the photocatalyst composite; (iii) the photocatalyst composites displayed good superparamagnetism which was in favour of the reclamation of the catalyst; (iv) the adsorption and visible light photocatalytic activity of the composite is enhanced greatly on decomposition of methylene blue and (v) the photocatalysts maintained high photocatalytic activity after being reused several times.