Halogen adsorbates on polymer-stabilized gold clusters: Mass spectrometric detection and effects on catalysis

The mass spectrometry of gold clusters stabilized by poly(N-vinyl-2-pyrrolidone) (Au:PVP) revealed the presence of Cl adsorbates derived from synthetic precursors, mainly on the Au-34 and Au-43 clusters. Changes in the amount of Cl adsorbates on the Au clusters did not affect the catalytic properties for the aerobic oxidation of benzyl alcohol, suggesting that the Cl atoms were only weakly bound to the Au clusters. In contrast, the replacement of Cl with Br on the Au-34 and Au-43 clusters significantly suppressed activity, without any influence on the electronic structure. This result indicated that the Br atoms were strongly bound to the Au clusters and sterically blocked their active sites. The substantial reduction of the catalytic activity by the Br adsorbates suggested that the Au-34 and Au-43 clusters made a major contribution to the catalytic activity of the Au:PVP. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.