Modification of indium-tin oxide electrodes with thiophene copolymer thin films: optimizing electron transfer to solution probe molecules.
Modification of indium-tin oxide electrodes with thiophene copolymer thin films: optimizing electron transfer to solution probe molecules.
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DOI：
10.1021/la061840f.s001
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
F. Marrikar;M. Brumbach;Dennis H Evans;Ariel Lebrón-Paler;J. Pemberton;Ronald J. Wysocki;Neal R. Armstrong
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文献类型：
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作者：
F. Marrikar;M. Brumbach;Dennis H Evans;Ariel Lebrón-Paler;J. Pemberton;Ronald J. Wysocki;Neal R. Armstrong
我们描述了通过 6-{2,3-二氢噻吩并[3,4-b]-1.4-二氧基-2-基甲氧基}己酸 (EDOTCA) 的化学吸附和电聚合以及 3,4-乙撑二氧噻吩 (EDOT) 和 EDOTCA 的电化学共聚对氧化铟锡 (ITO) 电极进行改性，形成超薄膜，从而优化溶液探针分子的电子转移速率。首先通过短暂暴露于强卤酸来激活 ITO 电极，以去除电极表面约 8 nm 的顶部，然后立即浸入 50:50 EDOT/EDOTCA 共聚单体溶液中。使用短暂沉积时间的电势阶梯电沉积来生长厚度为10-100 nm的共聚物薄膜。这些共聚物薄膜的组成通过单体的溶液消耗研究和产品薄膜的原子力显微镜（AFM）、X射线光电子能谱和傅里叶变换红外光谱（反射吸收红外光谱（RAIRS））进行表征。光谱数据表明，当浓溶液（10 mM）发生电聚合时，共聚物的组成接近 80% EDOTCA。 AFM 表征表明电沉积聚（EDOT）/聚（EDOTCA）（PEDOT/PEDOTCA）薄膜非常光滑，具有纳米尺度的纹理。 RAIRS 研究表明，这些薄膜由 EDOTCA 单元与非相互作用的 -COOH 基团和相邻的氢键 -COOH 基团的组合组成。含有 EDOTCA 的聚合物链似乎从特定区域以柱状簇的形式生长，几乎垂直于基底平面。随着它们的生长，这些柱状簇重叠形成几乎连续的氧化还原活性聚合物膜。相对于未活化、未改性的“封闭”ITO电极，ITO活化和这些共聚物膜的形成增强了电极表面的电活性部分。外球溶液氧化还原探针（二甲基二茂铁）在 10 nm 厚的 PEDOT/PEDOTCA 共聚物薄膜上给出标准速率系数 kS > 或 = 0.4 cm.s-1，比未改性的 ITO 表面上的速率系数大 3 个数量级，并且接近在干净的金表面上看到的 kS 值。
We describe the modification of indium-tin oxide (ITO) electrodes via the chemisorption and electropolymerization of 6-{2,3-dihydrothieno[3,4-b]-1.4-dioxyn-2-yl methoxy}hexanoic acid (EDOTCA) and the electrochemical co-polymerization of 3,4-ethylenedioxythiophene (EDOT) and EDOTCA to form ultrathin films that optimize electron-transfer rates to solution probe molecules. ITO electrodes were first activated using brief exposure to strong haloacids, to remove the top approximately 8 nm of the electrode surface, followed by immediate immersion into a 50:50 EDOT/EDOTCA co-monomer solution. Potential step electrodeposition for brief deposition times was used to grow copolymer films of thickness 10-100 nm. The composition of these copolymer films was characterized by solution depletion studies of the monomers and atomic force microscopy (AFM), X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy (reflection-absorption infrared spectroscopy (RAIRS)) of the product films. The spectroscopic data suggest that the composition of the copolymer approaches 80% EDOTCA when electropolymerization occurs from concentrated (10 mM) solutions. AFM characterization shows that electrodeposited poly(EDOT)/poly(EDOTCA) (PEDOT/PEDOTCA) films are quite smooth, with texturing on the nanometer scale. RAIRS studies indicate that these films consist of a combination of EDOTCA units with noninteracting -COOH groups and adjacent hydrogen-bonded -COOH groups. The EDOTCA-containing polymer chains appear to grow as columnar clusters from specific regions, oriented nearly vertically to the substrate plane. As they grow, these columnar clusters overlap to form a nearly continuous redox active polymer film. ITO activation and formation of these copolymer films enhances the electroactive fraction of the electrode surface relative to a nonactivated, unmodified "blocked" ITO electrode. Outer-sphere solution redox probes (dimethylferrocene) give standard rate coefficients, kS > or = 0.4 cm.s-1, at 10 nm thick copolymer films of PEDOT/PEDOTCA, which is 3 orders of magnitude greater than that on the unmodified ITO surface and approaches the values for kS seen on clean gold surfaces.