Integrating Plasmonic Nanoparticles with TiO2 Photonic Crystal for Enhancement of Visible-Light-Driven Photocatalysis

Aimed at enhancing photocatalysis through intensifying light harvesting, a new photocatalyst was fabricated by infiltrating Au nanopartides into TiO2 photonic crystals (TiO2 PC/Au NPs). Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed that the Au NPs with average diameter around 15 nm were dispersed uniformly into the porous TiO2 material. The results of the transmittance spectra demonstrated that the light absorption by Au NPs was amplified after they were infiltrated into TiO2 240, which was fabricated from 240 nm polystyrene spheres. In the photocatalytic experiments of 2,4-dichlorophenol degradation under visible light (lambda > 420 nm) irradiation, the kinetic constant using TiO2 240/Au NPs was 2.3 fold larger than that using TiO2 nanocrystalline/Au NPs (TiO2 NC/Au NPs). The excellent photocatalysis benefited from the cooperatively enhanced light harvesting owing to the localized surface plasmon resonance of Au NPs, which extended the light response spectra and the photonic effect of the TiO2 240 which intensified the plasmonic absorption by Au NPs. The hydroxyl radicals originated from the electroreduction of dissolved oxygen with photogenerated electrons via chain reactions were the main reactive oxygen species responsible for the pollutant degradation.