SPR effect of Au nanoparticles on the visible photocatalytic RhB degradation and NO oxidation over TiO2 hollow nanoboxes

Abstract Three-dimensional (3D) TiO2 hollow structures have attracted much attention due to their unique properties. However, the large bandgap of (3.2 eV) results in the fact that anatase TiO2 photocatalyst can only be excited by UV light, which only accounts for 3-5% of the solar energy. On considering that nobel metallatic nanomaterials can harvest visible light due to surface plasmon resonance (SPR) effect, in this paper, three kinds of Au nanoparticles with different morphologies, namely Au nanospheres (Au-NSs), Au nanorods (Au-NRs) and Au nanopentogons (Au-NPs) were prepared and used as photosensitizers to modified TiO2 hollow nanoboxes (TiO2-HNBs), aiming to explore high efficient visible-light-responsive photocatalyst. The photoreacitivty of Au/TiO2-HNBs was evaluated by photoctalytic oxidation of Rhodamine B (RhB) and NO under visible irradiation (λ>420 nm). It was found that the visible photoreactivity of TiO2-HNBs was greatly enhanced after modified with Au nanoparticles, and TiO2-HNBs loaded with Au-NRs exhibit the highest visible photocatalytic activity towards both RhB degradation and NO oxidation. Upon visible irradiation, SPR effect induces the production of hot electrons from the Au nanoparticles, which can further transfer to the conduction band of TiO2-HNBs to produce superoxide radicals (•O2-), resulting in an efficient separation of photo-generated electron-hole pairs. The photoreactivity of Au-NRs/TiO2-HNBs towards RhB degradation almost keeps unchanged even after recycling used for 5 times, indicating that it is promising to be use in practical applications.