Probing the Interactions of O-2 with Small Gold Cluster Au-n(Q) (n=2-10, Q=0,-1): A Neutral Chemisorbed Complex Au5O2 Cluster Predicted

摘要

Enormous progress has been made in catalytic oxidation reactions involving nanosized gold particles. However, the reaction mechanism of O-2 with neutral gold clusters remains complicated. Here, we have performed an unbiased structure search for Au-n(Q) and AunO2Q (n = 2-10, Q = 0, -1) clusters by means of CALYPSO structure searching method. Subsequently, the lowest-energy candidate structures were fully optimized at the B3PW91/Au/LANL2DZ/O/6-311+G(d) level of theory to determine the global minimum structures. Based on the ground-state structures of Au-n(-) and AunO2- (n = 2-10), we have simulated the photoelectron spectra (PES) using time-dependent density functional theory. The good agreement between simulated PES and the corresponding experimental data suggest that the current ground-state structures are the true minima. The locally maximized value of the adsorption energy in Au5O2, where the unpaired electron of Au-5 can transfer to O-2, makes it the most promising candidate of the chemisorbed complex. A comprehensive analysis of molecular orbitals and chemical bonding of the Au5O2 cluster reveals that O-2 can be chemisorbed onto the neutral Au-5 cluster.