Surface Plasmon Resonance, Formation Mechanism, and Surface Enhanced Raman Spectroscopy of Ag+-Stained Gold Nanoparticles
Surface Plasmon Resonance, Formation Mechanism, and Surface Enhanced Raman Spectroscopy of Ag+-Stained Gold Nanoparticles
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DOI：
10.3389/fchem.2019.00027
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发表时间：
2019-02-14
影响因子：
5.5
通讯作者：
Zhang, Dongmao
中科院分区：
文献类型：
--
作者：
Athukorale, Sumudu;Leng, Xue;Zhang, Dongmao
最近的一系列工作证明了Ag+在金表面的自发吸附。然而，对Ag+与金相互作用的机械理解一直存在争议。本文报道了使用几种原位和非原位测量技术对Ag+与AuNP结合的系统研究。AuNP表面等离子体共振的时间分辨UV-vis测量显示，银吸附通过两个平行的伪一级过程进行，时间常数分别为16（+/- 2）和1，000（+/- 35）s。约95%的Ag+吸附通过快速吸附过程进行。原位zeta电位数据表明，这种快速的Ag+吸附主要是由长程静电力驱动的，导致AuNP电荷中和，而随时间变化的pH值数据表明，缓慢的Ag+结合过程涉及质子释放反应，必须由近距离相互作用驱动。这些实验数据，连同非原位XPS测量表明，吸附的银保持阳离子，但不是作为一个带电的中性银原子提出的反电流反应机制。Ag+染色的AuNPs的表面增强拉曼活性略高于AuNPs，但显著低于银纳米颗粒（AgNPs）。Ag+染色的AuNP上的配体的Sers特征可以不同于AuNP和AgNP上的配体的SERS特征。除了对Ag+染色的AuNPs的形成机制、性质和应用的新见解之外，本工作中提出的实验方法对于研究纳米颗粒界面相互作用也很重要。
A series of recent works have demonstrated the spontaneous Ag+ adsorption onto gold surfaces. However, a mechanistic understanding of the Ag+ interactions with gold has been controversial. Reported herein is a systematic study of the Ag+ binding to AuNPs using several in-situ and ex-situ measurement techniques. The time-resolved UV-vis measurements of the AuNP surface plasmonic resonance revealed that the silver adsorption proceeds through two parallel pseudo-first order processes with a time constant of 16(+/- 2) and 1,000(+/- 35) s, respectively. About 95% of the Ag+ adsorption proceeds through the fast adsorption process. The in-situ zeta potential data indicated that this fast Ag+ adsorption is driven primarily by the long-range electrostatic forces that lead to AuNP charge neutralization, while the time-dependent pH data shows that the slow Ag+ binding process involves proton-releasing reactions that must be driven by near-range interactions. These experimental data, together with the ex-situ XPS measurement indicates that adsorbed silver remains cationic, but not as a charged-neutral silver atom proposed by the anti-galvanic reaction mechanism. The surface-enhanced Raman activities of the Ag+-stained AuNPs are slightly higher than that for AuNPs, but significantly lower than that for the silver nanoparticles (AgNPs). The SERS feature of the ligands on the Ag+-stained AuNPs can differ from that on both AuNPs and AgNPs. Besides the new insights to formation mechanism, properties, and applications of the Ag+-stained AuNPs, the experimental methodology presented in this work can also be important for studying nanoparticle interfacial interactions.