Formation of Au Nanoclusters on TiO₂ Surfaces by a Two-Step Method Consisting of Au(III)-Complex Chemisorption and Its Photoreduction

Abstract

The aim of this study is to prepare Au clusters with a mean size (d) of less than 3.0 nm, at which nonmetallic properties can be expected to appear. Au clusters (d < 3.0 nm) have been formed rapidly (<2 min) on TiO2 surfaces by a two-step method consisting of Au(III)-complex chemisorption and subsequent photoreduction (λex > 300 nm) at temperatures below 25 °C. In the photoreduction of the Au(III) complex to Au0, chemisorbed and physisorbed H2O on the TiO2 surface acts as a reductant. This method also enables us to produce Au clusters selectively at the UV-irradiated TiO2 surfaces.