When gold is not noble: Nanoscale gold catalysts

While inert as bulk material, nanoscale gold particles dispersed on oxide s upports exhibit a remarkable catalytic activity. Temperature-programmed rea ction studies of the catalyzed combustion of CO on size-selected small mono dispersed Au-n (n less than or equal to 20) gold clusters supported on magn esia, and first-principle simulations, reveal the microscopic origins of th e observed unusual catalytic activity, with Aus found to be the smallest ca talytically active size. Partial electron transfer from the surface to the gold cluster and oxygen-vacancy F-center defects are shown to play an essen tial role in the activation of nanosize gold clusters as catalysts for the combustion reaction.