Integrating photonic bandgaps with surface plasmon resonance for the enhancement of visible-light photocatalytic performance

Abstract

Intensifying the light harvesting and promoting the separation of photoinduced charge carriers are effective strategies to boost photocatalyst performance. Inspired by these insights, a hybrid photocatalyst was fabricated in this work by the deposition of Au nanoparticles (NPs) on a ZnO photonic crystal (ZnO-PC). The photonic band-gap of the ZnO-PC was tuned experimentally by Bragg's law to couple the slow photon (SP) effect of the ZnO-PC with the surface plasmon resonance (SPR) of Au NPs. Transmission spectra results indicated that, when the SP effect of the ZnO-PC matched well with the SPR of Au NPs, the visible light absorption of Au NPs could be substantially amplified. The hybrid Au/ZnO-PC showed high photocatalytic activity for the degradation of RhB under visible light irradiation, and the degradation kinetic constant (1.42 h⁻¹) is ca. 5.6-fold higher than that of the famous N doped TiO₂ (TiO_2−xN_x, 0.22 h⁻¹) and 24.8-fold higher than that of the commercial ZnO NPs (0.05 h⁻¹). The synergistic effects of the SPR of Au, the SP effect of the ZnO-PC, and the heterostructures between ZnO and Au NPs account for the high photocatalytic performance, which can enhance the harvesting of visible light and promote the separation of charge carriers. A possible reaction mechanism was tentatively proposed based on the active species analysis result. The work not only provides an effective route to enhance photocatalytic efficiency, but also contributes to a better understanding of the role of PCs in the photocatalytic reaction.