Development of In Situ Electrochemical Scanning Electron Microscopy with Ionic Liquids as Electrolytes

• Published in: Chemphyschem Vol. 9; no. 5; pp. 763 - 767
• Main Authors: Arimoto , Satoshi, Oyamatsu, Daisuke, Torimoto, Tsukasa, Kuwabata , Susumu
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 04.04.2008; WILEY‐VCH Verlag; Wiley
• Subjects: Chemistry; conducting materials; Electrochemistry; electron microscopy; Exact sciences and technology; General and physical chemistry; ionic liquids; scanning electron microscopy; X-ray fluorescence analysis; Scanning electron microscopy; X-ray fluorescence analysis; Conducting material; Electrolyte; X ray fluorescence; In situ; Electrochemistry; conducting materials; ionic liquids; Electron microscopy; Pyrrole polymer; Ionic liquid
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.200700758

We report that ionic liquids (ILs) can be observed by electron microscopy without any charging of the liquid. Based on this, we present an in situ electrochemical scanning electron microscopy (in situ ECSEM) system. The key technology that enables in situ ECSEM is that charges can be removed from an IL by grounding it with a Pt wire, even if the IL is in an insulating glass cell. As a first demonstration, we describe the redox reaction of a polypyrrole (PPy) film accompanied by changes in its thickness when it is polarized by the film‐deposited Pt electrode in the IL. Furthermore, energy‐dispersive X‐ray fluorescence (EDX) analysis can be employed for the electrode polarized in the IL. The component analysis by EDX of PPy in an IL containing K+ as a marker, reveals doping of electrolyte cations into the PPy film upon the latter′s reduction and dedoping of cations from the film upon oxidation. No charge: Since ionic liquids can be observed by SEM without any charging of the liquid, certain reactions can be observed under polarization conditions. The sequence shows that the oxidation and reduction of a PPy film polarized at various potentials are accompanied by decreases and increases, respectively, in the film thickness.