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

Chenjie Zhang, Jing Zhang, Jieru Lin, Qi Jin, Minmin Xu, Jianlin Yao
2017 Huaxue xuebao  
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
more » ... nsity 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 1 引言 币族金属 Fermi 能级附近的自由电子, 在入射光子 作用下发生集体振荡, 形成表面等离激元共振(Surface Plasmon Resonance, SPR) [1] . SPR 中具有较高能量的共振 电子(即热电子), 可通过电子转移的方式进入分子轨道, 从而促使吸附在金属表面的分子发生一系列化学反 应 [2] . SPR 的热效应还可实现表面的局部加热 [3] , 进一步 促进反应的发生. 目前研究发现 SPR 在 N-N 偶联 [4, 5] 、 水的分解 [6] 、 氢气的解离 [7] 及脱羧 [8] 等反应中起关键的作
doi:10.6023/a17050198 fatcat:eqb5y6rnz5ez7gpumtems6a3dm