Acta Chim. Sinica ›› 2017, Vol. 75 ›› Issue (11): 1082-1086.DOI: 10.6023/A17090402 Previous Articles     Next Articles

Special Issue: 纳米传感分析

Communication

纳米电极稳态电流表征的探讨

马慧a, 马巍a, 杨哲曜a, 丁志峰b, 龙亿涛a   

  1. a 华东理工大学 化学与分子工程学院 结构可控先进功能材料及其制备教育部重点实验室 上海 200237;
    b Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Canada, ON N6A 5B7
  • 收稿日期:2017-09-01 出版日期:2017-11-15 发布日期:2017-10-09
  • 通讯作者: 龙亿涛 E-mail:ytlong@ecust.edu.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.21327807,21775043)和高等学校学科创新引智计划(No.B16017)和加拿大自然科学和工程理事会(No.RGPIN-2013-201697)资助.

Characterization of Steady-State Current at Nanoelectrodes

Ma Huia, Ma Weia, Yang Zheyaoa, Ding Zhifengb, Long Yi-Taoa   

  1. a Key Laboratory for Advanced Materials, School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai 200237;
    b Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Canada, ON N6A 5B7
  • Received:2017-09-01 Online:2017-11-15 Published:2017-10-09
  • Contact: 10.6023/A17090402 E-mail:ytlong@ecust.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21327807, 21775043), the Program of Introducing Talents of Discipline to Uni-versities (No. B16017) and Natural Sciences and Engineering Council of Canada (No. RGPIN-2013-201697).

Steady-state cyclic voltammetry has several advantages that make it extremely useful for characterization of ultramicroelectrodes, such as rapid electrode performance assessment and size determination. However, due to the nanoscale size effect, the slight variations in geometry of the nanoelectrodes can lead to significant perturbations in its performance. In this study, electrochemical experiments and finite-element simulations using COMSOL Multiphysics software were conducted to characterize the steady-state current dependence on electrode radii, geometries and recesses. To study the above characterics, the Pt nanodisk electrodes with different sizes were fabricated using a laser-assisted wire pulling method on a P-2000 laser puller. Sluggish current responses were obtained for electrodes with a radius smaller than 80 nm in a 5 mmol/L ferrocene (Fc) CH3CN electrolyte solution containing 0.2 mol/L Tetra-n-butylammonium hexafluorophosphate (TBAPF6). The experimental results agree very well with the simulations. It was discovered that the sluggish responses are due to the kinetically limited electron transfer resulting from the slow reaction rate relative to diffusion. Moreover, a minimum, constant steady state current value was measured once the RG value (i.e., the ratio of overall electrode radius to active electrode radius) was greater than 3. However, the current increased obviously with the RG value decreased below this value due to the enhanced mass transport. In addition, the steady-state voltammetric responses of recessed nanoelectrodes were investigated. It was found that the steady-state current decreased rapidly as the recess depth increased and a classical sigmoidal shape current response was obtained recovering from a sluggish current response. The unique current responses resulted from the restriction of the diffusion of redox molecules in a deep channel to the electrode. To verify the correlation of recess depth to current response, a model was built based on two-dimensional axial symmetry and the obtained simulation results were consistent well with the experimental data. Our findings offer an understanding on the relationship between the nanoelectrode geometry and steady-state cyclic voltammetry, which can provide insight into their electrochemical behaviors.

Key words: nanoelectrode, steady-state cyclic voltammetry, finite-element simulations, size and geometry