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Sub‐Second Time‐Resolved Surface‐Enhanced Raman Spectroscopy Reveals Dynamic CO Intermediates during Electrochemical CO 2 Reduction on Copper
Author(s) -
An Hongyu,
Wu Longfei,
Mandemaker Laurens D. B.,
Yang Shuang,
Ruiter Jim,
Wijten Jochem H. J.,
Janssens Joris C. L.,
Hartman Thomas,
Stam Ward,
Weckhuysen Bert M.
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202104114
Subject(s) - raman spectroscopy , electrochemistry , ethylene , analytical chemistry (journal) , copper , surface enhanced raman spectroscopy , chemistry , materials science , electrode , inorganic chemistry , catalysis , optics , raman scattering , metallurgy , physics , biochemistry , chromatography
The electrocatalytic carbon dioxide (CO 2 ) reduction reaction (CO 2 RR) into hydrocarbons is a promising approach for greenhouse gas mitigation, but many details of this dynamic reaction remain elusive. Here, time‐resolved surface‐enhanced Raman spectroscopy (TR‐SERS) is employed to successfully monitor the dynamics of CO 2 RR intermediates and Cu surfaces with sub‐second time resolution. Anodic treatment at 1.55 V vs. RHE and subsequent surface oxide reduction (below −0.4 V vs. RHE) induced roughening of the Cu electrode surface, which resulted in hotspots for TR‐SERS, enhanced time resolution (down to ≈0.7 s) and fourfold improved CO 2 RR efficiency toward ethylene. With TR‐SERS, the initial restructuring of the Cu surface was followed (<7 s), after which a stable surface surrounded by increased local alkalinity was formed. Our measurements revealed that a highly dynamic CO intermediate, with a characteristic vibration below 2060 cm −1 , is related to C−C coupling and ethylene production (−0.9 V vs. RHE), whereas lower cathodic bias (−0.7 V vs. RHE) resulted in gaseous CO production from isolated and static CO surface species with a distinct vibration at 2092 cm −1 .