Ag-TiO2 thin films were prepared with a sol-gel route, using titanium isopropoxide and silver nitrate as precursors, at 0, 0.03 and 0.06 Ag/Ti nominal atomic ratios. After drying at 80°C, the films were fired at 300°C, 500°C, and 600°C for 30 min and 5 h. Glancing angle X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS), with depth profiling of the concentration, were used to study the films. XPS analysis showed the presence of C and N as impurities in the nanocomposite films. Their concentration decreased with increasing the firing temperature. Chemical state analysis showed that Ag was present in metallic state, except for the outer layer where it was present as Ag+. For the films prepared with aAg/Ti concentration of 0.06, depth profiling measurements of the film fired at 300°C showed a strong Ag enrichment at the outer surface, while composition remained almost constant within the rest of the film, at Ag/Ti atomic ratio of 0.02. Two layers were found for the films heated to 500°C, where the Ag/Ti ratios were 0.015 near the surface and 0.03 near the substrate. The photoelectrochemical properties of Ag-TiO2 were studied for thin films deposited on ITO substrates. Photocurrents of Ag-TiO2 nanocomposite electrodes fired at 300°C were observed even at visible light, for wavelengths longer than 400 nm.
Bibliographical noteFunding Information:
The authors wish to thank Dr. Alessandro Mar-tucci and Dr. Plinio Innocenzi of the University of Padova for useful discussions and criticisms. This work was partially performed during stays in Tsukuba of E. Traversa, supported by COE Fellowships, and a stay in Rome of N. Koshizaki, supported by the Science and Technology Agency (STA) of Japan.
- Photoelectrochemical properties
- Thin films
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- General Chemistry
- Condensed Matter Physics
- Materials Chemistry