The characterization of electrochemical interfaces is crucial to understand and optimize a broad range of redox-based technology and applications like electro- catalysis, energy conversion and storage or corrosion. Understanding the interplay between adsorbate and substrate in the presence of an electrolyte and how it is affected by the geometry of the system (i.e. defect sites, step edges) requires a technique able to provide chemical information with surface sensitivity and high spatial resolution. In tip-enhanced Raman spectroscopy (TERS), the combination of scanning probe micro- scopy with a Raman system results in a powerful tool that simultaneously provides in situ chemical fingerprints with sub-monolayer sensitivity and high-resolution topo- graphic information. However, the extension of the technique, usually working in ambient or UHV conditions, to solidliquid and electrochemical interfaces has only been achieved recently since it entails important technical challenges. [1-3]
In this talk I will present a novel electrochemical tip-enhanced Raman spectroscopy approach which adapts easily to different experimental conditions such as opacity, shape and dimensions of the sample. The most relevant aspects of the setup develop- ment and the advantages it offers for the study of electrochemical interfaces will be discussed. As a showcase system, we have studied the electrochemical response of a monolayer of adenine on a gold substrate in acidic media. The high sensitivity and spatial resolution allow us to obtain EC-TER spectra of less than 100 adenine molecules on a well-defined flat terrace of Au(111). Combining the results with DFT calculations, we can deduce orientational and chemical changes of the adsorbates as a function of applied potential
[1]Zeng Z-C. et al., JACS, 2015, 137,11928-11931.
[2] Kurouski D. et al., Nano Letters, 2015, 15(12), 7956-7962. [3] Martin Sabanes N., Anal. Chem., 2016, 88, 7108-7114