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Investigation of Cobalt Phthalocyanine at the Solid/Liquid Interface by Electrochemical Tip-Enhanced Raman Spectroscopy

delete2019-04-01
delete43
PRE
AI
S
Song Jiang
Z
Zhu Chen
C
Chen Xu
D
Duc Nguyen
M
Michael Mattei
G
Guillaume Goubert
R
Richard P. Van Duyne *
DOI:10.1021/acs.jpcc.9b00513delete
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Abstract

Abstract

En 中文
Electrochemical tip-enhanced Raman spectroscopy (EC-TERS) with three excitation wavelengths in combination with in situ electrochemical scanning tunneling microscopy (EC-STM) and absorption measurements has been employed to provide comprehensive insights into the electrochemical processes of cobalt phthalocyanine (CoPc) at the solid/liquid interface supported on a Au(111) substrate. As the substrate potential becomes more negative, CoPc molecules form a highly ordered monolayer on the Au(111) surface (>0.1 V) until the ordered-to-diffusing phase transition is triggered (<0.1 V). CoPc molecules in the ordered phase are reduced during cathodic scanning, which leads to a redshift in the resonance condition and gives rise to distinct EC-TERS behaviors which depend on excitation wavelengths. The ordered-to-diffusing phase transition of CoPc molecules results in the disappearance of the EC-TERS signal. The catalytic activity of CoPc for the oxygen reduction reaction (ORR) was not visible in the EC-STM and has negligible effect on the EC-TERS measurements. The comprehensive evidence from EC-TERS, EC-STM, and absorption spectroelectrochemistry clearly demonstrates that partially reduced CoPc molecules are the dominant species under steady state measurements during the oxygen reduction reaction.
Keywords:
SCANNING-TUNNELING-MICROSCOPY
OXYGEN REDUCTION REACTION
SINGLE-MOLECULE
SELF-ORGANIZATION
PORPHYRIN
SURFACES
AU(111)
RESOLUTION
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Journal

Journal of Physical Chemistry C cover
Journal of Physical Chemistry C
IF:
3.2
Papers:
5.6W
Citations:
15.0W

Organization

N
Northwestern University
Scholars:
6.1W
Papers: 5.2W
Citations: 3.9K