Potential-Dependent Morphology of Copper Catalysts During CO2 Electroreduction Revealed by In Situ Atomic Force Microscopy

Electrochemical AFM is a powerful tool for the real-space characterization of catalysts under realistic electrochemical CO2 reduction (CO2RR) conditions. The evolution of structural features ranging from the micrometer to the atomic scale could be resolved during CO2RR. Using Cu(100) as model surface, distinct nanoscale surface morphologies and their potential-dependent transformations from granular to smoothly curved mound-pit surfaces or structures with rectangular terraces are revealed during CO2RR in 0.1 m KHCO3. The density of undercoordinated copper sites during CO2RR is shown to increase with decreasing potential. In situ atomic-scale imaging reveals specific adsorption occurring at distinct cathodic potentials impacting the observed catalyst structure. These results show the complex interrelation of the morphology, structure, defect density, applied potential, and electrolyte in copper CO2RR catalysts.

Automated summary

Electrochemical AFM is an effective tool for real-space characterization of catalysts under CO2RR conditions, revealing the complex interplay between morphology, structure, defect density, applied potential, and electrolyte in copper CO2RR catalysts. The study showed distinct nanoscale surface morphologies and their potential-dependent transformations during CO2RR on a Cu(100) model surface in 0.1 m KHCO3. In situ atomic-scale imaging identified specific adsorption at different cathodic potentials impacting the catalyst structure.