Monomeric (VO2+) and dimeric mixed valence (V2O33+) vanadium species at the surface of shape controlled TiO2 anatase nano crystals

Metal atoms and ions at well-defined anatase TiO2 crystals with exposed (1 0 1) and (0 0 1) facets represent a promising platform for fundamental studies in catalysis using model systems of high complexity for the development of novel catalytic systems exhibiting higher than usual activities. Herein, we report the geometric and electronic structures of supported paramagnetic vanadium catalysts obtained by reaction of VCl4 vapours with shape controlled anatase TiO2 supports with preferential (1 0 1) and (0 0 1) facets. Electron Paramagnetic Resonance (EPR) spectroscopy and Density Functional theory (DFT) calculations reveal the presence specific monomeric (VO2+) and dimeric mixed valence (V2O33+) species with molecular structures dependent on the TiO2 surface termination.