Abstract
The electrocatalytic carbon dioxide (CO2) reduction reaction (CO2RR) 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 CO2RR 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 CO2RR 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.
Highlights
Copper (Cu) is a unique metal due to its outstanding ability to produce ethylene and other C2+ products in the electrocatalytic CO2 reduction reaction (CO2RR).[1]
A weak Raman signal of surface oxide can be observed with steady-state Raman spectroscopy of pristine Cu-MP before reduction, evidenced by two broad bands at 524 cmÀ1 and 614 cmÀ1 (Figure 1 b).[13c,6] These bands, assigned to Cu oxide (CuOx) surface species, disappear within one second after the onset of À0.4 V reducing potential, in accordance with the cyclic voltammetry (CV) results (Figure S3), evidencing the stripping of surface oxide species,[17] thereby exposing reduced and activated Cu surface for CO2RR
We have successfully performed in situ time-resolved surface-enhanced Raman spectroscopy (TR-SERS) during CO2 electrochemical reduction on Cu electrodes with subsecond time resolution
Summary
Copper (Cu) is a unique metal due to its outstanding ability to produce ethylene and other C2+ products in the electrocatalytic CO2 reduction reaction (CO2RR).[1]. Angewandte Chemie International Edition published by Wiley-VCH GmbH. We take advantage of these two characteristics of Cu, which acts both as an active CO2RR electrocatalyst and SERS-active substrate in our experiments, to achieve sub-second in situ time-resolved SERS (TR-SERS) under CO2RR conditions. This unique combination enabled us to investigate the dynamic surface reconstruction of Cu, as well as chemical processes of adsorbed CO species on polycrystalline Cu electrodes during CO2RR. Our results display that CO2RR and their intermediates are dynamic, and showcase the need for improved time-resolved in situ spectroscopic investigations down to milliseconds in order to investigate the reaction kinetics in great detail
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
