Structure-activity correlations for Au nanoclusters supported on TiO2

The catalytic performance of reducible metal-oxide-supported Au nanocluster s displays striking dependencies on several factors such as dispersion, sup port, 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 th e experimentally observed structure sensitivity of CO oxidation on Au/TiO2 may be rationalized by a quantum size effect. Via scanning tunneling micros copy and spectroscopy (STM/STS) and elevated pressure reaction kinetics mea surements, we show that a clear correlation exists between the structural, electronic, and reactivity properties of supported Au nanoclusters.