In situ SERS Investigation of SPR-driven Catalytic Reactions on Au Nanoparticles Monolayer Film

Abstract

The activity and uniformity of surface-enhanced Raman scattering (SERS) effect has been already become the critical role for fundamental research and practical application. Herein, Au nanoparticle monolayer films (Au MLF) were fabricated based on the self-assembly of nanoparticles at the air/water interface by introduction of polyvinylpyrrolidone (PVP) as additional agent. The change of assembly duration allowed the formation of Au MLFs with different density. Due to the excitation mode and intensity of localized surface plasmon resonance (LSPR) varying with the nanoparticle density, the activity and uniformity of SERS substrate could not be taken into account at the same time. For example, loose Au MLF exhibited excellent SERS and catalytic performance but poor uniformity, while compact Au MLF held excellent uniformity and reasonable SERS and catalytic performance. It demonstrated that the intensity of SERS signal was not only relevant to the activity but also to the number of "hot spots", while the conversion rate of surface plasmon resonance (SPR) induced catalysis was only associated with the activity of "hot spots". By using the compact film with relative standard deviation of SERS intensity and SPR catalytic efficiency less than 5% and 6% as the SERS substrate, the influence of the external environment on the SPR catalytic reaction was clarified. In this paper, the effect of laser power on the efficiency and reaction rate of SPR induced catalytic reaction was investigated according to the coupling reaction of para-aminothiophenol (PATP) and decarboxylation process of 4-mercaptobenzoic acid (MBA). It was found that the increase of laser power not only improved the efficiency of SPR catalytic reaction, but also accelerated the reaction rate from the perspective of reaction kinetics due to the heat effect and hot electrons generated by SPR. The results indicated that the rate of the SPR catalytic reaction was linear with the reciprocal of the square of the laser power. It provided a new approach for the determination of the kinetic parameters of the related surface processes. Keywords surface-enhanced Raman scattering (SERS); Au monolayer film; plasmon catalyzed surface reaction; laser power; decarboxylation reaction

SERS Studies on the Electrochemical and SPR Synergistic Catalytic Interfacial Reaction of 4-Chlorothiophenol

“…4.1 Au MLF 的制备 参照文献 [34] 方法制备 15 nm Au 溶胶: 取 100 mL 0.01%(质量分数)HAuCl Au 纳米粒子单层膜的制备: 参照文献 [36] 方法, 取 3 mL 30 nm Au 溶胶置于自制的挥发装置(见支持信息, 图 S1)中, 在 40 ℃下真空干燥 16 h. 在气液界面逐渐形成 一层均匀且致密的 Au 纳米粒子单层膜(Au MLF).…”