Silica-supported Ag-Au bimetallic nanosystems by XPS

Bimetallic Ag-Au/SiO2 nanosystems were synthesized by sequential deposition of Au and Ag on silica substrates via rf-sputtering. Sample preparation was accomplished at 60 °C from Ar plasmas, using a constant sputtering time for gold (10 min), followed by silver deposition at different times (5-20 min) in order to vary the Ag/Au ratio as well as the total metal content. A proper choice of the synthesis conditions allowed us to obtain a controlled dispersion of silica-supported bimetallic nanoparticles with tailored size and shape, as evidenced by X-ray Photoelectron Spectroscopy (XPS), X-ray Excited Auger Electron Spectroscopy (XE-AES), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), and optical absorption spectroscopy. This work is devoted to the XPS and XE-AES characterization of a representative Ag-Au/SiO2 specimen with an average nanoparticle size of 9 +/- 5 nm. In particular, detailed scans for the C 1s, O 1s, Si 2s, Au 4 f, Ag 3d, and Ag MNN regions and related data are presented and discussed.