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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 34: Emerging Topics in Chemical and Polymer Physics, New Instruments and Methods I

CPP 34.6: Vortrag

Donnerstag, 21. März 2024, 11:00–11:15, H 0106

Hydration layer ordering effects at gold - electrolyte interfaces confined by an atomic force microscope tip — •Martin Munz^{1, 2}, Wiebke Frandsen², Beatriz Roldan Cuenya², and Christopher Kley^{1, 2} — ¹Helmholtz Young Investigator Group Nanoscale Operando CO2 Photo-Electrocatalysis, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany — ²Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany

We introduce a correlative microscopy approach, combining in situ conductive atomic force microscopy (c-AFM) with simultaneous friction force and morphology imaging, thus enabling nanoscale physical-chemical interrogation of the catalyst - electrode interface. For the class of bimetallic electrocatalysts, the electric conductivity variations across nanopatterned CuOx islands on Au electrodes can be resolved in air, water and potassium bicarbonate aqueous electrolytes. In line with current contrasts between catalyst surface areas of different composition and oxidation state, I-V curves showed highly resistive CuOx islands. Simultaneously measured friction force images suggested a qualitative contrast variation upon transitioning from water to bicarbonate electrolyte, thus indicating that friction forces respond to hydration layer ordering effects. Complementary in situ AFM friction force measurements, using cantilevers with a high force sensitivity, revealed a decrease in the friction coefficient with increasing ionic concentration, for the low-concentration regime of a potassium perchlorate aqueous electrolyte, thus suggesting a chaotropic effect.

Keywords: Hydration layer; Friction; Viscosity; Chaotropic/kosmotropic; Lateral force microscopy