Inclusion of Gold Nanoparticles within Mesoporous TiO2

EUGENIO OTAL; SARA A. BILMES; PAULA C. ANGELOMÉ; GALO J. A. A. SOLER-ILLIA

Conferencia; 11th International Conference on Surface and Colloid Science; 2003

Miniaturization of electronic and mechanic devices to be employed in the emerging nanotechnologies is based on tunable, size dependent, properties of metal nanoparticles and nanowires. However, the use of such miniaturized materials will only be possible if nanoparticles (or nanowires) are organized in a proper configuration, and can be supported, isolated and insulted. In addition an inclusion of metal nanoparticles within a semiconductor template should give tunable electrical controlled by the particlem size and by the distribution of localized states at the metal/semiconductor junction. In the present work we report two approaches for the synthesis of mesostructured Au@TiO2 from mesoporous TiO2 films obtained with a template triblock copolymer F127. The first approach is based on the electrodeposition of gold within the pores of the TiO2 filmformed by dip coating onto a conduction substrate (ITO). The second approach is the inclusion of tailored nanoparticles from au colloids into the film previously functionalized with R-SH molecules, such as cysteine or thioglycolic acid. The presence of gold within the pores is confirmed by TEM. The voltammgram of the Au@TiO2 assembly in 0.1M NaClO4 has the typical profile of gold electrodes confirming the electrical continuity between metallic particles. From in situ UV-vis spectroelectrochemistry measurements the location of surface plasmon band of gold can be easily determined, and coincides with the calculated for a collection of spherical Au particles embedded ina TiO2 dielectric. In addition, this experiments show that there is a decrease in the absorbance associated to localized states in the semiconductor that is tentatively associated to Au --> TiO2 electron transfer accompanying the formation of Au@TiO2.