In Situ Atomic Force Microscopy for Current, Friction and Morphology Imaging of Electrocatalysts
Martin Munz a b, Jeffrey Poon b, Wiebke Frandsen b, Beatriz Roldan Cuenya b, Christopher S. Kley a b
a Helmholtz Young Investigator Group Nanoscale Operando CO2 Photo-Electrocatalysis, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
b Department of Interface Science, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
Proceedings of International Conference on Frontiers in Electrocatalytic Transformations (INTERECT22)
València, Spain, 2022 November 21st - 22nd
Organizers: Sara Barja, Nongnuch Artrith and Matthew Mayer
Oral, Martin Munz, presentation 016
Publication date: 11th October 2022

In catalysis and energy conversion, fundamentals behind poor charge transfer, electrode corrosion or moderate catalytic activity and selectivity remain elusive. Conventional techniques cannot spatially resolve performance-determining properties of electrode-electrolyte interfaces, particularly local electric conductance in liquids, thus hindering rational innovation of key catalytic reactions.

We introduce in situ correlative atomic force microscopy for simultaneously imaging an electrode’s conductivity, chemical-frictional and morphological properties. We visualize conductivity variations across electrocatalyst surfaces, which were chosen with a view to CO2 electroreduction. For bimetallic copper(oxide) - gold electrocatalysts in air, water and bicarbonate electrolyte, current-voltage curves show highly resistive copper(oxide) islands, in agreement with current contrasts. For nanocrystalline gold, we observe current contrasts that indicate resistive grain boundaries, electrocatalytically passive adlayer regions and hydration layer heterogeneities. The combined measurement of the friction force with the current provides the opportunity to interrogate the hydration layer and analyse its effect on the interfacial electron transfer, as the hydration layer molecular ordering may modulate both the mechanical resistance to the tip sliding motion and the electric resistance. In the light of the implemented in situ microscopy method, we outline prospects for establishing structure-property relationships but also for fundamental studies beyond (photo)electrocatalysis, e.g. to investigate solid-liquid interfaces in electrochemical energy storage systems.

J.P. thanks the Croucher Foundation, Hong Kong, for his fellowship funding. Funding by the Helmholtz Association’s Initiative and Networking Fund is greatly appreciated. The authors acknowledge support from the Federal Ministry of Education and Research in the framework of the project CatLab (03EW0015A).

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