Co-adsorption of p-mercaptobenzoic acid on silver nanoparticles enhances the plasmon-mediated coupling reaction of p-ethynylaniline

The enhancement of the electromagnetic field elicited by localized surface plasmon resonance (LSPR) is conducive to the generation of charge carriers, which have an important effect in driving many kinds of chemical reactions. Nonetheless, the short lifespan of charge carriers generated by plasmon (typically femtoseconds to nanoseconds) limits their effectiveness in promoting chemical reactions. Here, we have applied surface-enhanced Raman scattering (SERS) spectroscopy to probe the plasmon-mediated coupling reaction of p-ethynylaniline (PEAN) on silver nanoparticles (Ag NPs). The use of p-mercaptobenzoic acid (PMBA) as a co-catalyst facilitated the transfer and separation of hot electrons produced by the plasmon at its interface with the Ag NPs. This process accelerated the PEAN coupling reaction by extending the lifespan of hot carriers, which was achieved by matching hot electrons produced by the plasmon with the lowest unoccupied molecular orbital (LUMO) energy distribution of co-adsorbed PMBA molecules. These survey results indicate the potential for effective acceleration or inhibition of plasmon-mediated chemical reactions (PMCR) through the introduction of molecular co-catalysts, offering a simple, cost-effective, and efficient strategy for preparing plasmon catalysts.