Interaction of gold with co-condensed and grafted HMS-SH silica: study by 29Si(1H) CP-MAS-NMR,XRD,XPS and Au LIII EXAFS

Hexagonal mesoporous silica (HMS) is functionalised with mercaptopropyl groups by adopting two different pro-cedures; co-condensation and grafting. In both cases tetra-ethylorthosilicate (TEOS) and 3-mercaptopropyltriethoxysil-ane (3-MPTES) are used as the silicon and sulfur precursors, respectively. The obtained materials are analysed by several techniques such as N2sorption, TG-DTA, XRD, SAXS and-solid state 29Si {1H} CP-MAS NMR spectroscopy. By taking advantage of the chemical interaction between gold and the -SH groups, the effect of the thiol addition procedure on the supporting capability of the functionalised silica is evalu-ated by depositing gold through the incipient wet impregna-tion technique. The influence of the functionalisation method on the electronic structure of gold and on its surface distribu-tion is determined by extended X-ray fine absorption spectra (EXAFS) of Au at the LIII edge and by X-ray photoelectron spectroscopy (XPS).