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research article

Local pH-controlled reactivity investigations by thin-layer scanning tunneling microscopy

Ammann, E.
•
Beuret, C.
•
Indermühle, P.-F.
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2001
Electrochimica Acta

A newly designed thin-layer STM (TLSTM) technique is presented based on a microfabricated probe combining an electrolytic STM probe with an annular iridium oxide microelectrode operating as a potential-controlled generator or scavenger of H+. This TLSTM configuration can be used to combine in situ STM studies of electrode processes with the simultaneous investigation of H+ flux integrals associated with the electrode reaction. In this paper, the technique is applied to investigate the H+ exchange behaviour of electropolymerised polyaniline films and associated STM-relevant properties in 0.5 M NaClO4 + 10-2 M HClO4. For a polyaniline film kept in the intermediate (emeraldine) oxidation state at 0 mV versus MSE it is shown that its thickness increases due to H+ insertion if the pH is lowered from pH 2 to ca. 1.6, and that its conductivity decreases significantly if the pH is increased from 2 to ca. 12. In a second experiment, where the exchange of H+ at pH 2 is monitored during film oxidation and reduction within the potential range of both redox transfer steps, it is shown that significant exchange of H+ occurs only in the interval of the second (emeraldine/pernigraniline) redox transfer. © 2001 Elsevier Science Ltd. All rights reserved.

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Type
research article
DOI
10.1016/S0013-4686(01)00579-5
Author(s)
Ammann, E.
•
Beuret, C.
•
Indermühle, P.-F.
•
Kötz, R.
•
de Rooij, N. F.  
•
Siegenthaler, H.
Date Issued

2001

Published in
Electrochimica Acta
Volume

47

Issue

1

Start page

327

End page

334

Note

250

Peer reviewed

REVIEWED

Written at

OTHER

EPFL units
SAMLAB  
Available on Infoscience
May 12, 2009
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/38939
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