Method Development: Interface Sensing

Nanostructured (meta-)surfaces consisting of metal nanoparticles in contact with a dielectric exhibit absorbance spectra that sensitively depend on the properties of the electrified metal/electrolyte interfaces. We develop and refine methods that exploit this sensitivity to measure in situ minor changes of the interface properties (charge, adsorbed species, etc.) during electrochemical experiments. 

Currently, we pursue two approaches. So called (differential) cyclic plasmo-voltammetry, (d)CPV, employs nanostructured electrodes that exhibit local surface plasmon resonances (LSPRs). The resonance position of the LSPs depends sensitively on the surface charge, adsorbate coverage and the morphology of the plasmonically active nanostructures. (d)CPV tracks the resonance over time and reveals information about changes of surface charge, adsorbate coverage and morphology of the nanoparticle (Figure 1). Under many conditions, (d)CPV offers information that is complementary to the ones obtained in cyclic voltammograms. (d)CPV is particularly powerful for the study of interfacial properties under large faradaic currents, including the morphological stability of the electrode [1,2].

Metasurface-driven Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS) is a technique that exploits the electric near field of a metasurface to enhance vibrational modes of adsorbed molecules. Together with the groups of Stefan Maier (Monash University, Australia) and Andreas Tittl (LMU, Munich) we have been developing single- and multi-band nanophotonic electrochemical platforms that allow for a sensitive detection of reaction intermediates on electrode surfaces. First applications can be found in [3,4].

[1] Characterization of Different Au/Electrolyte Interfaces via In Situ Differential Cyclic Plasmo-Voltammetry M.J. Feil, T.M. Maier, M. Golibrzuch, A.C. Sterr, M. Becherer, and K. Krischer, J. Phys. Chem. C 127, 20137 (2023); https://doi.org/10.1021/acs.jpcc.3c04727

[2] Stability of the Au/electrolyte interface during hydrogen evolution: A Cyclic Plasmo-Voltammetry study M.J. Feil, S. Leisibach, M. Becherer, and K. Krischer, Electrochimica Acta 513, 145509 (2025); https://doi.org/10.1016/j.electacta.2024.145509

[3] Improved in-situ characterization of electrochemical interfaces using metasurface-driven surface-enhanced infrared absorption spectroscopy L. M. Berger, M. Duportal, L. de Souza Menezes, E. Cortés, S. A. Maier, A. Tittl, and K. Krischer, Adv. Functional Materials, 33, 2300422 (2023); https://doi.org/10.1002/adfm.202300411

[4] Multi-band Metasurface-Driven Surface-Enhanced Infrared Absorption Spectroscopy for Improved Characterization of in-Situ Electrochemical Reaction M. Duportal, L. M. Berger, L. de Souza Menezes, E. Cortés, S. A. Maier, A. Tittl, and K. Krischer, ACS Photonics, 11, 714 (2024); https://doi.org/ 10.1021/acsphotonics.3c01592