Investigation of long-range plasmonic field effects in Au@SiO2 nanostructures using p-nitrophenol reduction

As an emerging field, plasmonic photocatalysis has gradually garnered attention from researchers. It is generally accepted that localized surface plasmonic resonance (LSPR) in noble metallic nanostructures enhances photocatalysis through the induction of a long-range plasmonic field. Furthermore, nanostructures in close proximity can enhance the electromagnetic (EM) field via plasmonic coupling, which also contributes to improved photocatalytic activity. In this study, core-shell nanostructures composed of Au nanorods (AuNRs) with pinhole-free SiO2 shells (pf-AuNRs@SiO2) are synthesized as non-contact, long-range photocatalysts. By tuning the aspect ratios (ARs) of the AuNRs to match the LSPR peaks with the wavelength of the irradiation light source, an optimized photocatalytic effect was achieved in the reduction of p-nitrophenol (p-NP). Additionally, by comparing shell thicknesses of 5 nm and 10 nm, it was observed that the 5 nm thickness exhibited superior catalytic efficiency. This enhancement is attributed to the thinner shell allowing reactants to be placed within a stronger plasmonic field. •Photocatalysts composed of Au nanorods and pinhole-free SiO2 shells are prepared.•The plasmonic effect is evaluated by the photocatalytic reduction of p-nitrophenol.•ARs of AuNRs and shell thickness on the plasmonic field effect is investigated.•Nanorods exhibit greater photocatalytic activity compared to nanospheres.•Nanorods with the AR of 2.5 and shell thickness of 5 nm show stronger plasmonic field.