Long-Range Plasmon Field and Plasmoelectric Effect on Catalysis Revealed by Shell-Thickness-Tunable Pinhole-Free Au@SiO₂ Core–Shell Nanoparticles: A Case Study of p-Nitrophenol Reduction

Plasmon-enhanced photocatalysis is an emerging hot field, but the underlying mechanisms are not very clear. The lack of fundamental understanding of the localized surface plasmon resonance (LSPR) induced electromagnetic field enhancement effects on catalysis is an obstacle to the development of general design rules for engineering efficient plasmonic photocatalysts. Herein, we reveal a long-range plasmon field and plasmoelectric effect on catalysis by using p -nitrophenol (also called 4-nitrophenol, 4-NP) as a model reactant and shell-thickness-tunable and pinhole-free Au@SiO 2 core–shell nanoparticles (pf-Au@SiO 2 NPs) as photocatalysts and sensing probes. The influence of long-range plasmon field and plasmoelectric effect on catalysis was evidenced by both the illumination-wavelength- and shell-thickness-dependent catalytic activities of pf-Au@SiO 2 NPs. Impressively, catalytic 4-NP reduction occurs with AuNPs as catalysts, even if the AuNP surfaces were completely isolated and spaced by the insulating and pinhole-free silica shells of thickness less than 2.5 times that of the AuNP radius, due to the long-range plasmon field and plasmoelectric effect. This study and finding provide avenues to have a better understanding of plasmonic effects on catalysis and will benefit the design of plasmonic nanocatalysts for various applications.