Evaluation of the Photocatalytic Performance of Nanocomposite Material of TiO₂ and Nanoporous Gold Prepared by Simple Processing Method

Abstract

Nano-scale noble metallic materials exhibit catalytic activity and can serve as photocatalytic cocatalysts. The effectiveness of nanoporous gold (NPG) as a cocatalyst on TiO₂ depends on NPG pore size and composition. Suitably sized pores ensure that NPG can exhibit surface plasmon resonance, which enhances the photocatalytic activity of TiO₂ for hydroxyl (OH) radical generation. Moreover, Ag on NPG serves as generation sites for reactive oxygen species, because O₂ can be decomposed to atomic oxygen. Owing to these factors, NPG could serve as a high-performance cocatalyst for TiO₂. In this study, we utilized the porous property of NPG to fabricate a nanocomposite material of TiO₂ and NPG (TiO₂/NPG) without annealing or complicated processing. Moreover, we evaluated the photocatalytic activity of the TiO₂/NPG composite by measuring the amount of generated OH radicals. Our results suggest that NPG promoted the generation of OH radicals and that the amount of OH radicals increased with particular pore sizes of NPG and amounts of Ag.

Fig. 1 Plane-view SEM images of the NPG surface with pore sizes of (a) 10 nm, (b) 20 nm, (c) 30 nm, (d) 40 nm, and (e) 50 nm, and (f) NPG with TiO₂.