Characterization of Au/TiO2 nanocomposites by XPS

Au/TiO2 nanocomposites were prepared by a hybrid route consisting in the rf sputtering of gold on porous titania xerogels [TiOx(OH)y(OR)z] obtained by means of the sol-gel route. In particular, titania substrates were prepared on silica slides by dip-coating starting from ethanolic solutions of Ti(OPri)4 (OPri=iso-propoxy) and Hacac (2,4-pentanedione). Subsequently, Au depositions were performed on the as-prepared xerogels in Ar plasmas at temperatures as low as 60 °C. The resulting systems were finally annealed in air for 1 h at 200, 400, and 600 °C, with the aim of tailoring gold distribution in the titania matrix. Their structure, composition and morphology were studied by glancing incidence x-ray diffraction (GIXRD), optical absorption spectroscopy, and x-ray photoelectron spectroscopy (XPS). This work is dedicated to the XPS characterization of a representative Au/TiO2 sample analyzed after annealing in air at 600 °C. In particular, detailed scans for the Au 4f, Ti 2p, O 1s, and C 1s regions and related data are presented and discussed. The obtained results point to the presence of metallic gold and TiO2 , with carbon contamination limited only to the outermost layers.