Water’s place in Au catalysisby Gregory M. Mullen and C. Buddie Mullins
The discovery of highly active gold catalysts for CO oxidation (CO + ½O2 → CO2) about 25 years ago (1) ignited substantial interest in the use of gold as a catalyst. Yet, this seemingly simple reaction has proven to be quite complicated. No consensus exists regarding the mechanism by which gold catalyzes CO oxidation. Confounding the understanding of this process was the discovery that incorporation of minute quantities of water in the reactant feed stream can increase catalytic activity by up to several orders of magnitude (2). Many conflicting reports have been proposed for the role of water in the CO oxidation reaction. On page 1599 of this issue, Saavedra et al. (3) present a compelling mechanism that ties together the conclusions of many of these reports.