Sub?Second Time?Resolved Surface?Enhanced Raman Spectroscopy Reveals Dynamic CO Intermediates during Electrochemical CO ₂ Reduction on Copper

The electrocatalytic carbon dioxide (CO2) reduction reaction (CO2RR) into hydrocarbons is a promising approach for greenhouse gas mitigation, but many details of this dynamic remain elusive. Here, time-resolved surface-enhanced Raman spectroscopy (TR-SERS) employed to successfully monitor the dynamics CO2RR intermediates and Cu surfaces with sub-second time resolution. Anodic treatment at 1.55 V vs. RHE subsequent surface oxide (below ?0.4 RHE) induced roughening electrode surface, which resulted in hotspots TR-SERS, enhanced resolution (down ?0.7 s) fourfold improved efficiency toward ethylene. With initial restructuring was followed (<7 s), after stable surrounded by increased local alkalinity formed. Our measurements revealed that highly CO intermediate, characteristic vibration below 2060 cm?1, related C?C coupling ethylene production (?0.9 RHE), whereas lower cathodic bias (?0.7 gaseous from isolated static species distinct 2092 cm?1.