| Popis: |
X-ray photoelectron spectra were obtained for a series of M–TiO2 samples in which transition metal ions are directly attached to the surface of anatase TiO2 nanocrystals. The samples were prepared using CrCl3·nH2O, MnCl2·nH2O, FeCl2·nH2O, CoCl2·nH2O, NiCl2·nH2O, and CuCl2·nH2O as metal sources. We observed spontaneous air oxidation of the metal for the Mn–TiO2 and Fe–TiO2 samples as indicated by rapid color changes. X-ray photoelectron spectroscopy (XPS) data confirms the oxidation states of the metals Cr, Co, and Ni are unchanged from the precursor, Mn and Fe are oxidized, and Cu is in a more reduced state. The reduction of Cu likely arises during the XPS experiment – a phenomenon well-documented in the literature; whereas UV–Vis data of the Cu–TiO2 dispersions are consistent with Cu2+. |
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