Development of EC-TERS : towards to characterization of electroactive molecular architectures
Résumé
The growing interest in nanofunctionalized surfaces, for their application as (bio-)molecular sensors, catalysts, or else energy-storing devices, pushes the research towards two main objectives. On one side, it is essential to elaborate precise strategies for the surface nanostructuration, while on the other side more accurate analytical methods need to be developed for operating at the working conditions of the device and therefore probing their reactivity in real time.
The second objective specifically was at the center of the presented experimental work, which focused on the optimization of electrochemical tip-enhanced Raman spectroscopy (EC-TERS). Electrochemical cell-like setups were designed to work both in a scanning tunneling microscope (STM) [1] and in an atomic force microscope (AFM), either in an upright or in an inverted configuration. Despite the issues due to the presence of liquid (as tip-sample polarization constraints in STM [2] or laser refraction issue in side-illumination AFM), the new developments allowed performing dynamic electrochemical measurements in quite a wide potential range simultaneously to TERS time mapping [3,4].
The performances of the upgraded setups were therefore tested on gold-immobilized layers carrying a nitrobenzene functional group, whose complex electrochemical reaction mechanism has been extensively studied and debated. Based on the results obtained by the spectroelectrochemical analysis, hypothesis on the reaction path followed by the nitrobenzene in the employed measurement conditions could be drawn.