Lecture
Van Marum Colloquium: Visualizing electrified solid-liquid interfaces
- Date
- Wednesday 24 April 2024
- Time
- Location
-
Gorlaeus Building
Einsteinweg 55
2333 CC Leiden - Room
- CE.0.18
Abstract
To design efficient electrochemical interfaces for sustainable energy conversion, it is crucial to resolve the molecular structures of the electric double layer, where inevitably all electrocatalytic reactions take place. While most current electrochemical scanning probe microscopy approaches are successfully employed to study the structural evolution of an electrode surface even under reaction conditions [1], they are largely insensitive to the solvent structure formed at the liquid side. In contrast, high-resolution atomic force microscopy (AFM) has been shown to be able to visualize the vertical arrangement of water molecules in the direction normal to the surface, see e.g., [2]. However, only very few reports exist with potential control in an operating electrochemical cell. We recently developed an electrochemical frequency-modulation AFM that can be simultaneously performed with scanning tunneling microscopy (STM) using stiff self-sensing quartz cantilevers (qPlus sensors) [3,4]. This allows us to locally image both the vertical layering of the interfacial solvent and the lateral structure of the electrochemical double layer in great detail.
In this talk, I will briefly introduce the state-of-the-art of electrochemical scanning probe microscopy including the possibilities given by qPlus force sensors and discuss a couple of examples from our recent work on well-defined single crystals. These include investigations of a Au(111) electrode in various aqueous electrolytes that reveal a distinct potential-dependent, oscillatory frequency shift modulation in z-direction. Depending on the applied potential, the charge of the electrode and the type of ions, we attribute these oscillations to water and/or ion layering close to the electrode, which we can correlate with atomistic molecular dynamics simulations.
References
- A. Auer, M. Andersen, E.-M. Wernig, N.G. Hörmann, N. Buller, K. Reuter and J. Kunze-Liebhäuser, Nat. Catal. 3, 797–803 (2020)
- T. Fukuma and R. Garcia., ACS Nano. 12, 11785–11797 (2018)
- F.J. Giessibl, Rev. Sci. Instrum. 90, 011101 (2019)
- A. Auer, B. Eder and F.J. Giessibl, J. Chem. Phys. 159, 174201 (2023)