Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
Nanoscale. 2015 Nov 14;7(42):17685-92. doi: 10.1039/c5nr04087f. Epub 2015 Sep 9.
Here we report the first study on the electrochemical energy storage application of a surface-immobilized ruthenium complex multilayer thin film with anion storage capability. We employed a novel dinuclear ruthenium complex with tetrapodal anchoring groups to build well-ordered redox-active multilayer coatings on an indium tin oxide (ITO) surface using a layer-by-layer self-assembly process. Cyclic voltammetry (CV), UV-Visible (UV-Vis) and Raman spectroscopy showed a linear increase of peak current, absorbance and Raman intensities, respectively with the number of layers. These results indicate the formation of well-ordered multilayers of the ruthenium complex on ITO, which is further supported by the X-ray photoelectron spectroscopy analysis. The thickness of the layers can be controlled with nanometer precision. In particular, the thickest layer studied (65 molecular layers and approx. 120 nm thick) demonstrated fast electrochemical oxidation/reduction, indicating a very low attenuation of the charge transfer within the multilayer. In situ-UV-Vis and resonance Raman spectroscopy results demonstrated the reversible electrochromic/redox behavior of the ruthenium complex multilayered films on ITO with respect to the electrode potential, which is an ideal prerequisite for e.g. smart electrochemical energy storage applications. Galvanostatic charge-discharge experiments demonstrated a pseudocapacitor behavior of the multilayer film with a good specific capacitance of 92.2 F g(-1) at a current density of 10 μA cm(-2) and an excellent cycling stability. As demonstrated in our prototypical experiments, the fine control of physicochemical properties at nanometer scale, relatively good stability of layers under ambient conditions makes the multilayer coatings of this type an excellent material for e.g. electrochemical energy storage, as interlayers in inverted bulk heterojunction solar cell applications and as functional components in molecular electronics applications.
在这里，我们报告了首例具有阴离子存储能力的表面固定钌配合物多层薄膜的电化学储能应用研究。我们采用了一种新型双核钌配合物，具有四足锚固基团，通过层层自组装工艺在铟锡氧化物（ITO）表面构建有序的氧化还原活性多层涂层。循环伏安法（CV）、紫外-可见（UV-Vis）和拉曼光谱分别显示出峰电流、吸光度和拉曼强度随层数的线性增加。这些结果表明，在 ITO 上形成了有序的钌配合物多层，X 射线光电子能谱分析进一步证实了这一点。层的厚度可以纳米精度控制。特别是，研究的最厚层（65 个分子层和约 120nm 厚）表现出快速的电化学氧化/还原，表明在多层内电荷转移的衰减非常低。原位 UV-Vis 和共振拉曼光谱结果表明，ITO 上的钌配合物多层薄膜具有相对于电极电势的可逆电致变色/氧化还原行为，这是例如智能电化学储能应用的理想前提。恒电流充放电实验表明，多层膜具有赝电容行为，在 10μA cm(-2)的电流密度下具有 92.2 F g(-1)的良好比电容和优异的循环稳定性。如我们的原型实验所示，在纳米尺度上精细控制物理化学性质，以及在环境条件下相对较好的层稳定性，使得这种类型的多层涂层成为例如电化学储能、倒置体异质结太阳能电池应用中的夹层以及分子电子应用中的功能组件的理想材料。
