Molecular Cocatalyst-Induced Enhancement of the Plasmon-Mediated Coupling of p-Nitrothiophenols at the Silver Nanoparticle–Graphene Oxide Interface

The plasmon-mediated coupling reaction of nitroaromatic compounds is an effective strategy to synthesize the aromatic azo compounds that are widely applied in material science, pharmacy, and agricultural chemistry. Nonetheless, the reaction rate can be further improved since the lifetime of the plasmon-generated hot carriers is limited to femtoseconds or picoseconds. Herein, using in situ plasmon-enhanced Raman spectroscopy, we reveal that the adsorbed positively charged methyl violet molecules on the silver nanoparticle (Ag NP)–graphene oxide (GO) composite structure act as simple and cost-effective molecular cocatalysts, largely boosting the coupling of p-nitrothiophenol to p,p′-dimercaptoazobenzene. This boosting is attributed to the promoted separation of the plasmon-generated hot carriers at the Ag NP–GO interface. In addition, the reduction of laser power will help to promote the efficiency of the MV-induced acceleration. This work provides a highly simple, efficient, and cost-effective strategy to accelerate the coupling reaction of nitroaromatic compounds, and this strategy can be extended to the acceleration of many other plasmon-mediated chemical reactions.