Dynamics of bulk and surface oxide evolution in copper foams for electrochemical CO₂ reduction

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Yang, Fan ; Jiang, Shan ; Liu, Si ; Beyer, Paul ; Mebs, Stefan ; Haumann, Michael ; Roth, Christina ; Dau, Holger:
Dynamics of bulk and surface oxide evolution in copper foams for electrochemical CO₂ reduction.
In: Communications Chemistry. Bd. 7 (2024) . - 66.
ISSN 2399-3669
DOI: https://doi.org/10.1038/s42004-024-01151-0

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Abstract

Oxide-derived copper (OD-Cu) materials exhibit extraordinary catalytic activities in the electrochemical carbon dioxide reduction reaction (CO2RR), which likely relates to non-metallic material constituents formed in transitions between the oxidized and the reduced material. In time-resolved operando experiment, we track the structural dynamics of copper oxide reduction and its re-formation separately in the bulk of the catalyst material and at its surface using X-ray absorption spectroscopy and surface-enhanced Raman spectroscopy. Surface-species transformations progress within seconds whereas the subsurface (bulk) processes unfold within minutes. Evidence is presented that electroreduction of OD-Cu foams results in kinetic trapping of subsurface (bulk) oxide species, especially for cycling between strongly oxidizing and reducing potentials. Specific reduction-oxidation protocols may optimize formation of bulk-oxide species and thereby catalytic properties. Together with the Raman-detected surface-adsorbed *OH and C-containing species, the oxide species could collectively facilitate *CO adsorption, resulting an enhanced selectivity towards valuable C2+ products during CO2RR.