Molecular approaches to catalysis: Naked gold nanoparticles as quasi-molecular catalysts for green processes

Gold nanoparticles smaller than ∼2 nm show interesting catalytic properties arising from their size-determined electronic and geometrical structures. They are able to dissociate molecular O2 with low activation barriers and become oxidized in a reversible way at low temperature. Several oxygen species adsorbed on the nanoparticle surface, as well as different gold sites including low coordinated neutral Au0 atoms and cationic AuI and Auδ+ species, are generated on the oxidized nanoparticles. The implication of these new sites in the mechanism of different gold-catalyzed reactions in which oxygen plays a crucial role is discussed here.

Small gold nanoparticles can dissociate molecular O2 and become reversibly oxidized. Different adsorbed oxygen species and low coordinated neutral and cationic gold sites are generated on the oxidized nanoparticles. The implication of these new sites in the mechanism of several reactions in which oxygen plays a crucial role is discussed.Figure optionsDownload high-quality image (65 K)Download as PowerPoint slideHighlights
► Gold nanoparticles smaller than 2 nm are reversibly oxidized by molecular O2 at low temperature.
► Alcohol oxidation to aldehyde is favored by the presence of chemisorbed oxygen species.
► Oxidized gold nanoparticles are effective in ethane epoxidation but lead to propene combustion.
► Surface oxygen species play a positive role in the homocoupling of phenylboronic acid.