Enriching Surface-Accessible CO in the Zero-Gap Anion-Exchange-Membrane-Based CO Electrolyzer.

Zero-gap anion exchange membrane (AEM)-based CO electrolysis is a promising technology for CO production, however, their performance at elevated current densities still suffers from the low local CO concentration due to heavy CO neutralization. Herein, via modulating the CO feed mode and quantitative analyzing CO utilization with the aid of mass transport modeling, we develop a descriptor denoted as the surface-accessible CO concentration ([CO ] ), which enables us to indicate the transient state of the local [CO ]/[OH ] ratio and helps define the limits of CO -to-CO conversion. To enrich the [CO ] , we developed three general strategies: (1) increasing catalyst layer thickness, (2) elevating CO pressure, and (3) applying a pulsed electrochemical (PE) method. Notably, an optimized PE method allows to keep the [CO ] at a high level by utilizing the dynamic balance period of CO neutralization. A maximum j of 368±28 mA cm was achieved using a commercial silver catalyst.