ABSTRACT
An interconnected Au nanoparticle arrangement is obtained by electrodeposition from Au(III) soluble complexes within the pore system of block-copolymer templated mesoporous titania films. The resulting Au@TiO2 nanocomposites (5 nm Au particles, 5.5 nm amorphous titania walls) have the electrochemical behavior of a gold electrode of high surface area. The attenuation of Au surface plasmon due to -OH electroadsorption and the existence of mixed localized states in these Au@TiO2 nanocomposites are observed by in situ spectroelectrochemistry.
ABSTRACT
In this paper, we report the complete synthesis and characterization procedures to generate highly organized and oriented mesoporous titania thin films, using poly(ethylene oxide) (PEO)-based templates. Controlled conditions in the deposition, postsynthesis, and thermal treatment steps allow one to tailor the final mesostructure (2D hexagonal, p6m, or 3D cubic, Im3m). Various techniques were used to determine the time evolution of the mesostructure. Spectroscopic techniques (UV/vis, (17)O NMR) and EXAFS/XANES have been used to follow the chemical changes in the Ti(IV) environment. Crossing these techniques spanning all ranges permits a complete description of the chemistry all the way from solution to the mesostructured metal oxide. A critical discussion on all important chemical and processing parameters is provided; the understanding of these features is essential for a rational design and the reproducible construction of mesoporous materials.
