Cation Enrichment Promotes High-rate CO Electroreduction to C₂₊ Liquid Products

Electrochemical reduction of CO into valuable multicarbon (C₂₊) liquids is crucial for reducing CO₂ emissions and advancing clean energy, yet mastering efficiency and selectivity in this process remains a tough challenge. Herein, we employ a surface-modification strategy using electrochemically active polymeric 1,4,5,8-naphthalenete-tracarboxylic dianhydride (PNTCDA)-modified copper nanosheets (PM-Cu) to rearrange reactive species in the electric double layer, where the PNTCDA triggers a distinctive enolization that anchor potassium ions (K⁺) onto the cathode surface under reduction condition. Electrochemical analysis and computational simulations revealed that this approach fine-tunes K⁺ distribution in the double layer, making the dehydration of hydrated K⁺ more efficient and reducing active water molecules at the interface, thus inhibiting the hydrogen evolution reaction while concurrently promoting CO reduction via enhanced C-C coupling. For the first time, the PM-Cu catalyst demonstrates ampere-scale current densities with the exclusive selectivity of a C₂₊ liquid product yield exceeding 90 %. Thus, by tailoring the local microenvironment with electrochemically active organics, it is possible to modulate CO reduction, improve sustainable energy storage, and increase industrial carbon utilization.