Adsorption and Activation of O 2 on Small Gold Oxide Clusters: the Reactivity Dominated by Site-Specific Factors

作者：Lulu Huang, Wen Liu, Jin Hu, Xiaopeng Xing · 发表于：The Journal of Physical Chemistry A · 年份：2022 · DOI：10.1021/acs.jpca.2c04438 · 被引用次数：7 · 研究领域：Catalytic Processes in Materials Science、Nanocluster Synthesis and Applications、Catalysis and Oxidation Reactions

We experimentally explored adsorption and activation of O 2 on small anionic clusters Au x O y – containing one to five gold atoms and between one and three oxygen atoms using an instrument including a magnetron sputtering cluster source, a micro flow reactor running at low temperature, and a time-of-flight mass spectrometer. Some species, including AuO –, one isomer of Au 2 O 2 –, Au 3 O –, one isomer of Au 3 O 3 –, and Au 5 O 2 –, can adsorb an O 2 molecule. We theoretically explored the structures of these active species and the inert ones appearing in the experiment by combining a structure search strategy based on the genetic algorithm and the density functional theory (DFT) calculations. Impressively, all active species observed in the experiment have a −O-Au site, in which the gold atom is a dangling or a vertex atom. Each −O-Au site can strongly adsorb one O 2 with its Au atom to form a straight-line structure −O-Au-O–, and the adsorbed O 2 is significantly activated by accepting one electron with one of its π 2p * orbitals. With no exception, all oxygen sites and the −O-Au-Au sites in Au x O y – are inert. Analyses on the density of states (DOS) of representative species well interpret the physical origins of the activity of −O-Au and the inertness of −O-Au-Au. The observations that site-specific factors dominate the reactivity of gold oxide clusters with O 2 are in contrast to what happens in the reactions of Au n – with O 2, where clusters’ reactivity is completely...