Fernández José L, Wijesinghe Manjula, Zoski Cynthia G
Department of Chemistry and Biochemistry, New Mexico State University , Las Cruces, New Mexico 88003, United States.
Anal Chem. 2015 Jan 20;87(2):1066-74. doi: 10.1021/ac5039187. Epub 2014 Dec 24.
Theoretical and experimental approaches to characterizing nanoelectrode (NE) ensembles of ultramicroelectrode dimensions (UME-NEEs) as a function of fraction of active area and random NE distribution are described. UME-NEEs were fabricated by addressing microregions of a gold-filled polycarbonate membrane through the UMEs of an underlying microfabricated addressable array. Results of Comsol Multiphysics 3D simulations based on randomly spaced NEs of 15 nm radius on a UME disk geometry of radii up to 5 μm are shown for steady-state voltammetry (SSV) and scanning electrochemical microscopy (SECM) experiments. Analytical equations were developed to describe the diffusion-limited steady-state current and steady-state voltammogram at an UME-NEE. These equations are shown to be in good agreement with the simulations and enabled evaluation of experimental SSVs. Comparison of experimental and simulated SECM approach curves, images, and tip voltammograms enabled the fraction of active area and distribution of NEs to be visualized and determined for individual UME-NEEs. Gold UME-NEEs are shown to be unique platforms for electrodeposition in forming nanoparticle electrodes (UME-NPEs). Electrocatalysis results for the oxygen reduction reaction (ORR) on Pt UME-NPEs in 0.1 M H2SO4 are also shown.
本文描述了将超微电极尺寸的纳米电极（NE）阵列（UME-NEEs）表征为活性面积分数和随机NE分布函数的理论和实验方法。UME-NEEs是通过底层微加工可寻址阵列的超微电极对填充金的聚碳酸酯膜的微区进行寻址而制备的。展示了基于半径高达5μm的UME圆盘几何形状上半径为15nm的随机间隔NE的Comsol Multiphysics 3D模拟结果，用于稳态伏安法（SSV）和扫描电化学显微镜（SECM）实验。推导了分析方程来描述UME-NEE处的扩散限制稳态电流和稳态伏安图。这些方程与模拟结果吻合良好，并能够评估实验SSV。实验和模拟的SECM方法曲线、图像和尖端伏安图的比较使得能够可视化并确定单个UME-NEE的活性面积分数和NE分布。金UME-NEEs被证明是用于形成纳米颗粒电极（UME-NPEs）的电沉积的独特平台。还展示了在0.1 M H2SO4中Pt UME-NPEs上氧还原反应（ORR）的电催化结果。
