Structure–Activity Correlations for Au Nanoclusters Supported on TiO2

The catalytic performance of reducible metal‐oxide‐supported Au nanoclusters displays striking dependencies on several factors such as dispersion, support, pretreatment, and preparation methods. Planar model Au/TiO2 catalysts have been prepared in ultrahigh vacuum in order to investigate the strong size dependence of low‐temperature CO oxidation. It is demonstrated that the experimentally observed structure sensitivity of CO oxidation on Au/TiO2 may be rationalized by a quantum size effect. Via scanning tunneling microscopy and spectroscopy (STM/STS) and elevated pressure reaction kinetics measurements, we show that a clear correlation exists between the structural, electronic, and reactivity properties of supported Au nanoclusters.