金纳米粒子单层膜表面SPR催化反应的原位SERS研究

摘要

表面增强拉曼散射(SERS)基底的活性和均匀性是其SERS应用研究的关键,通过气-液两相界面自发组装的方式及控制组装的时间可制备致密性不同的金纳米粒子单层膜(Au MLF).由于疏松和致密基底表面的LSPR产生的方式和强度不同导致SERS增强效应和均匀性两者无法同时兼顾,通常得到局域表面等离激元共振(SERS)增强性能及表面等离激元共振(SPR)催化性能优异但均匀性欠佳的疏松基底,或SERS增强性能与SPR催化性能中等但均匀性优越的致密基底.研究表明SERS增强效应的提高与粒子密度增加和“热点”活性增加有关,而SPR催化转化率仅与“热点”活性有关.本文以致密的Au MLF为基底,以对巯基苯胺(PATP)和对巯基苯甲酸(MBA)为探针分子系统研究了激光功率对SPR催化反应效率的影响,研究发现激光功率提高可显著提升PATP偶联反应及MBA脱羧反应的转化率.同时发现后者脱羧反应的速率与激光功率平方的倒数成线性关系,为相关表面过程的动力学参数测定提供了新的途径.%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 ofAu 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 ofpara-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.