Layer-by-layer grown scalable redox-active ruthenium-based molecular multilayer thin films for electrochemical applications and beyond

Kaliginedi, Veera Bhadra Rao; Ozawa, Hiroaki; Kuzume, Akiyoshi; Maharajan, Sivarajakumar; Pobelov, Ilya; Kwon, Nam Hee; Mohos, Miklos; Broekmann, Peter; Fromm, Katharina M.; Haga, Masa-aki; Wandlowski, Thomas (2015). Layer-by-layer grown scalable redox-active ruthenium-based molecular multilayer thin films for electrochemical applications and beyond. Nanoscale, 7(42), pp. 17685-17692. Royal Society of Chemistry 10.1039/C5NR04087F

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Kaliginedi, Veera Bhadra Rao; Kuzume, Akiyoshi; Pobelov, Ilya; Mohos, Miklos; Broekmann, Peter and Wandlowski, Thomas

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

2040-3364

Publisher:

Royal Society of Chemistry

Language:

English

Submitter:

Dr Veera Bhadra Rao Kaliginedi

Date Deposited:

22 Dec 2015 10:24

Last Modified:

02 Feb 2016 14:15

Publisher DOI:

10.1039/C5NR04087F

BORIS DOI:

10.7892/boris.74441

URI:

https://boris.unibe.ch/id/eprint/74441

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