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Electrochemical impedance spectroscopy of single Au nanorods†
Chemical Science ( IF 7.6 ) Pub Date : 2018-04-02 00:00:00 , DOI: 10.1039/c8sc00983j
Tao Liu 1 , Meng Li 1 , Yongjie Wang 1 , Yimin Fang 1 , Wei Wang 1
Affiliation  

We propose monochromatic dark-field imaging microscopy (DFM) to measure the non-faradaic electrochemical impedance spectroscopy (EIS) of single Au nanorods (AuNRs). DFM was utilized to monitor the plasmonic scattering of monochromatic incident light by surface-immobilized individual AuNRs. When modulating the surface potential at a certain frequency, non-faradaic charging and discharging of AuNRs altered their electron density, leading to periodical fluctuations in the scattering intensity. Analysis of the amplitude and phase of the optical intensity fluctuation as a function of modulation frequency resulted in the EIS of single AuNRs. High-frequency (>100 Hz) modulation allowed us to differentiate the intrinsic charging effect from other contributions such as the periodic migration and accumulation of counterions in the surrounding medium, because the latter occurred at a longer timescale. As a result, single nanoparticle EIS led to the surface capacitance of single AuNRs being closer to the theoretical value. Since interfacial capacitance has been proven sensitive to molecular interactions, the present work also offers a new platform for single nanoparticle sensing by measuring the single nanoparticle capacitance.

中文翻译:


单金纳米棒的电化学阻抗谱†



我们提出单色暗场成像显微镜(DFM)来测量单金纳米棒(AuNR)的非法拉第电化学阻抗谱(EIS)。 DFM 用于监测表面固定的单个 AuNR 的单色入射光的等离子体散射。当以一定频率调制表面电位时,AuNR 的非法拉第充电和放电改变了它们的电子密度,导致散射强度的周期性波动。对光强度波动的幅度和相位作为调制频率函数的分析得出了单个 AuNR 的 EIS。高频(>100 Hz)调制使我们能够将固有充电效应与其他贡献区分开来,例如周围介质中抗衡离子的周期性迁移和积累,因为后者发生在较长的时间尺度上。结果,单纳米颗粒 EIS 导致单 AuNR 的表面电容更接近理论值。由于界面电容已被证明对分子相互作用敏感,因此目前的工作还通过测量单个纳米颗粒电容为单纳米颗粒传感提供了一个新平台。
更新日期:2018-04-02
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