Mobile atomic gold as oxidation catalyst

Abstract In a recent study we reported on the catalytic action of gold on the oxidative removal of carbon from carburized W(110) surfaces at high temperatures, shifting the desorption peak of the formed carbon monoxide by roughly 200 K from 1100 to 1150 K down to 900 K. Motivated by this observation we examined the structure/morphology of gold on these surfaces by scanning tunneling microscopy after annealing to various temperatures, both with and without the presence of adsorbed oxygen. With increasing temperature structural rearrangements of the gold clusters/islands are observed which become most pronounced in the temperature range where the catalytic reaction sets in. In the same temperature range gold-induced segregation of carbon to the surface occurs. As the strong structural changes of the gold clusters require the existence of mobile gold species, we suggest that mobile atomic gold is related to both the enhanced carbon segregation and the observed catalytic effect.