Understanding the competing factors that control the selectivity of alcohol oxidation on Au catalysts

摘要

Ever since the pioneering work of Horuta on the use of supported gold nanoparticles for CO oxidation [1,2], catalysis researchers have been fascinated by the unique properties of these materials as both complete and selective oxidation catalysts. The initial reports of Au nanoparticle activity were quite surprising in light of both theoretical and experimental studies that demonstrate that bulk forms of Au have low activity for activation of di-oxygen, a critical step in any oxidation reaction. Haruta and more recently others, however, have shown that when in the form of supported nanoparticles, Au is much less noble than its bulk counterpart and is active for oxygen dissociation, thereby making it a good oxidation catalyst [3-5]. In the ensuing years much has been learned about the mechanism and site requirements for this reaction on gold nanoparticles [6-9], although a complete understanding is still lacking. While elucidating the mechanism of oxygen activation on Au is an important scientific challenge, understanding what controls the selectivity of the reaction of adsorbed oxygen atoms with organic species on gold surfaces is equally important, since selective oxidation of alcohols is one of the most challenging reactions in the emerging field of green chemistry [10,11].