Toward Control of Gold Cluster Aggregation on TiO2 via Surface Treatments

Abstract

Well-defined Au-TiO2 materials were synthesized by deposition of triphenylphosphine-protected Au9 clusters on TiO2 (Aeroxide P-25), pre-treated in eight different ways and subsequently exposed to two post-treatments. X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy studies showed that in most cases the PPh3 ligand shell was removed upon deposition even before post-treatment, coinciding with some cluster aggregation. However, clusters deposited on TiO2 treated using H2SO4 and H2O2 showed remarkable resistance to aggregation, even after high-temperature calcination, while clusters on H2-treated TiO2 showed the greatest resistance to aggregation under ozonolysis.