Investigating active site of gold nanoparticle Au_(55)(PPh _3)_(12)Cl_6 in selective oxidation

摘要

We present an ab initio investigation of structural, electronic, catalytic, and selective properties of the ligand-covered gold nanoparticle Au _(55)(PPh_3)_(12)Cl_6 and associated model clusters. The catalytic activity of the Au_(55)(PPh_3) _(12)Cl_6 nanoparticle in the presence of O_2 stems from a combined effect of triphenylphosphine ligands and surface structure of the "magic-number" quasi-icosahedral Au_(55) core, which entails numerous ligand-encompassed triangle Au_6 faces as the active sites. Under the Eley-Rideal mechanism, the "triangle-socket" active site not only can accommodate one pre-adsorbed O_2 (which is subsequently activated to the superoxo species) with one styrene molecule at a time but also can provide spatial confinement which favors the formation of an oxametallacycle intermediate that leads to unique selectivity in styrene oxidation.