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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: Talk
Thursday, March 21, 2024, 11:00–11:15, H 0106
Hydration layer ordering effects at gold - electrolyte interfaces confined by an atomic force microscope tip — •Martin Munz1, 2, Wiebke Frandsen2, Beatriz Roldan Cuenya2, and Christopher Kley1, 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