Chloride Ion Adsorption Enables Ampere-Level CO₂ Electroreduction over Silver Hollow Fiber

Electrochemical conversion of CO₂ into valuable feedstocks is a promising strategy for carbon neutrality. However, it remains a challenge to possess a large current density, a high faradaic efficiency and excellent stability for practical applications of CO₂ utilization. Herein, we report a facile tactic that enables exceedingly efficient CO₂ electroreduction to CO by virtue of low-coordination chloride ion (Cl^- ) adsorption on a silver hollow fiber (Ag HF) electrode. A CO faradaic efficiency of 92.3 % at a current density of one ampere per square centimeter (1 A cm^-2 ) in 3.0 M KCl with a sustained performance observed during a 150-hour test was achieved, which is better than state-of-the-art electrocatalysts. The electrochemical results and density functional theory (DFT) calculations suggested a low-coordination Cl^- adsorption on surface of Ag HF, which not only suppressed the competitive hydrogen evolution reaction (HER), but also facilitated the CO₂ reduction kinetics.