Tunable Production of Syngas via Pulsed-Potential Electrolysis of CO2 over Single-Crystal Cu(100)

Obtaining syngas from the electrochemical reduction of CO₂ has been considered an economical and promising solution for energy and environmental sustainability. Cu-based catalysts have been attracting great attention due to their low cost and easy accessibility, while tuning the selectivity toward specific products is a critical issue. In this work, a pulsed-potential strategy coupled with a low-reduction overpotential is applied to (100) single-crystal Cu foils. Only H₂ and CO are observed under the bias of a low-reduction potential. By tuning the pulse width and anodic potential, controllable syngas with a broad range from ∼97:5 to ∼5:14 can be obtained with the same low cathodic potential. Based on various characterization results before and after pulse electrolysis, the enhanced CO production is attributed to the in situ-generated Cu⁺ species and roughened surface, as well as the modulation of local pH and CO₂ concentration near the electrode.