The surface chemistry of hybrid nanometer-sized particles I. Photochemical deposition of gold on ultrafine TiO2 particles

Hybrid colloidal particles consisting of a gold shell and an ultrafine TiO2 particle core were formed by irradiation of an HAuCl4 solution with light at a wavelength λ>330 nm in the presence of TiO2 colloid. Absorption maxima attributed to gold surface plasmons were observed at 525–555 nm. The size of the AuTiO2 particles, determined by TEM, was about 10 nm. The catalytic properties of the coupled particles were tested in parallel experiments of the photocatalytic reduction of methylene blue both on TiO2 and the AuTiO2 particles.