Transient Electrochemical Tip Surface-Enhanced Raman Spectroscopy (EC-Tip-SERS) : Concept and applications in electrocatalysis and material science
Abstract
The development of electrochemical techniques combined to Raman spectroscopy such as electrochemical
Tip- or Surface- Enhanced Raman spectroscopy (EC-TERS or EC-SERS) have attracted considerable
attention over the past years by the scientific community. This spectro-electrochemical combination provides
an accurate view over electrochemical processes occurring at an electrode by acquiring simultaneously local
topography, and vibrational fingerprints about the material or molecules under potential control.[1] Based on
the use of an insulated TERS tip, we introduced recently a new approach that we called EC-Tip-SERS (Figure
1). Here, electroactive molecules are adsorbed directly onto the tip that acts both as working microelectrode
and single hotspot for SERS.[3] Although the spatial resolution is lost in this configuration, interesting
transient mechanistic information can be obtained. In this communication, we will present first the use of this
technique on a redox- and Raman- active model molecule, the Nile blue, in which a temporal resolution in
the order of millisecond can be easily attained. Then, we will consider the use of Tip-SERS in probing
molecular motion within rotaxane-based giant assemblies containing porphyrins derivatives. Finally, we will
demonstrate the use of transient EC-Tip-SERS in scrutinizing electrocatalytic transient mechanisms, such as
those associated to the oxygen reduction reaction towards hydrogen peroxide in water using viologen SAMs
as electrocatalyts
References :
[1] Ding, S. Y., Yi, J., Li, J. F., Ren, B., Wu, D. Y., Panneerselvam, R., & Tian, Z. Q. Nature Reviews
Materials, 1, (2016) 1-16.
[2] Touzalin, T., Joiret, S., Maisonhaute, E., & Lucas, I. T. Analytical chemistry, 89 (2017) 8974-8980.