Center for Electrochemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Welch Hall 2.204, 105 East 24th Street Stop A5300, Austin, Texas 78712-1224, USA.
J Phys Chem B. 2013 Apr 25;117(16):4371-80. doi: 10.1021/jp306934g. Epub 2012 Nov 2.
The individual adsorption events of sub-μm silica and polystyrene spheres (310-530 nm in diam.) were detected by monitoring the blocking of redox mediator diffusion to Pt ultramicroelectrode (UME) substrates by the adsorbing spheres. Under the diffusion limited oxidation of FcMeOH and at low supporting electrolyte concentrations, the negatively charged spheres arrive at the electrode by electrophoretic migration. Sphere adsorption monitoring experiments consisted of long-time (1000-5000 s) chronoamperograms recorded in solutions with fM concentrations of spheres and different concentrations of supporting electrolyte. Trends in the heights of the step features with time reflect changing surface coverage of spheres, and coupled step features in the chronoamperograms suggest dynamic rearrangement of spheres on the surface. Numerical simulations of diffusion blocking at electrodes by adsorbing particles as well as mass transport of particles under migration were also performed, and show good agreement with the experimental data collected.
通过监测氧化还原介质向 Pt 超微电极（UME）基底扩散的受阻情况，检测亚微米级二氧化硅和聚苯乙烯球（直径 310-530nm）的单个吸附事件。在 FcMeOH 的扩散限制氧化和低支持电解质浓度下，带负电荷的球体通过电泳迁移到达电极。球吸附监测实验由在具有 fM 浓度的球体和不同浓度的支持电解质的溶液中记录的长时间（1000-5000s）计时电流法组成。随着时间的推移，台阶特征高度的趋势反映了球体表面覆盖率的变化，计时电流图中的耦合台阶特征表明球体在表面上的动态重排。还对吸附颗粒在电极处扩散阻断以及颗粒在迁移下的传质进行了数值模拟，并且与收集的实验数据吻合良好。
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