Customizing CO 2 Electroreduction by Pulse-Induced Anion Enrichment.

Electrochemically converting CO into specified high-value products is critical for carbon neutral economics. However, governing the product distribution of the CO electroreduction on Cu-based catalysts remains challenging. Herein, we put forward an anion enrichment strategy to efficiently dictate the route of *CO reduction by a pulsed electrolysis strategy. Upon periodically applying a positive potential on the cathode, the anion concentration in the vicinity of the electrode increases apparently. By adopting KF, KCl, and KHCO as electrolytes, the dominant CO electroreduction product on commercial Cu foil can be tuned into CO (53% ± 2.5), C2+ (76.6 ± 2.1%), and CH (42.6 ± 2.1%) under pulsed electrolysis. Notably, one can delicately tailor the ratios of CO/CH, CH/C2+, and C2+/CO by simply changing the composition of the electrolyte. Density functional theory calculations demonstrate that locally enriched anions can affect the key CORR intermediates in different ways owing to their specific electronegativity and volume, which leads to the distinct selectivity. The present study highlights the importance of tuning ionic species at the electrode-electrolyte interface for customizing the CO electroreduction products.