SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 43: Poster: Plasmonics and Nanooptics I

O 43.7: Poster

Dienstag, 28. März 2023, 18:00–20:00, P2/EG

Electrochemistry of the surface of electrically contacted plasmonic resonators — •Paul Mörk, Luka Zurak, Jessica Meier, Bert Hecht, and Thorsten Feichtner — Nano-Optics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany

Catalytic processes on gold surfaces are well known to enhance electrochemical processes. When the gold is showing geometric features on the nanometer scale, plasmonic resonances in the visible wavelength range can occur. This establishes addidional degrees of freedom (photon routing, heating, hot electron generation) to tailor an efficient material for photo-electrochemical processes interesting for energy applications like water splitting or CO₂ reduction.

Here we show the results of experiments with directly electrically connected plasmonic resonantors made via focused ion beam milling from monocrystalline gold flakes. Under ambient conditions without any further chemical added we observe a resonance shift by several ten of nanometers on a time scale of seconds when applying a electrical potential as high as 20 Volts to the gold surface. The effect reverses when the bias voltage is switched of on the time scale of hours. We present evidence that we observe the electrochemical oxidation and reduction of gold mediated by the omnipresent waterlayer covering every surface with nanometer thickness and deliver an outlook to the application within electrochemical cells.