(160d) Interfacial Perimeter Sites in Au-TiO2 Systems

The interfacial perimeter sites formed by small TiO₂ clusters on Au particles have been implicated to be active for reactions such as selective oxidation of propane to acetone and 2-propanol decomposition to acetone. Until now, there is practically no structural information on these sites. We found that it is possible to generate catalytic active interfacial perimeter sites on large Au particles (~20 nm) by decorating them with TiO₂ clusters derived from anionic, hydrolytically stable titanium (IV) complexes. Attractive interactions between charged Ti precursors and Au particle surface facilitated application of the Ti complex, which was subsequently converted to TiO₂ at 150⁰C using O₃ to destroy the organic ligands. Au particles of this size exhibit Surface Enhanced Raman Scattering Resonance, resulting in substantial amplification of vibrational signals attributable to TiO₂ clusters. In combination with DFT calculations, this allowed estimating the upper limit of the size of TiO₂ clusters. Subsequently, catalytic activity of the resulting assemblies was correlated to availability of Au-TiO₂ interfacial sites. This methodology holds promise for application of small clusters of other metal oxides on metal nanoparticles in solution.