In situ XANES studies of TiO2/Fe3O4@C during photocatalytic degradation of trichloroethylene

Mainly anatase and Fe3O4 in the magnetic photocatalysts (TiO2 on Fe3O4@C core–shell nanoparticles (TiO2/Fe3O4@C)) are observed by X-ray powder diffraction (XRD) spectroscopy. The Ti K-edge least-square fitted XANES spectra of the TiO2/Fe3O4@C photocatalyst indicate that the main titanium species are nanosize TiO2 (9 nm) (77%) and bulky TiO2 (23%). Speciation of titanium in the TiO2/Fe3O4@C during photocatalytic degradation of 100 ppm of trichloroethylene (TCE) has also been studied by in situ X-ray absorption near-edge structural (XANES) spectroscopy. TiO2 is not perturbed during the course of photocatalysis. However, it is worth to note that during photocatalytic degradation of TCE, about 33% of FeO and 67% of Fe3O4 are observed in the photocatalyst. It seems that the carbon layer on the TiO2/Fe3O4@C photocatalysts can reduce the possibility for photoexcited electron–hole recombination as usually found on the relatively narrow bandgap of ferric oxide during photocatalysis.