The direct electroreduction of CO₂ to pure CO streams has attracted much attention for both academic research and industrial polymer synthesis development. Here, we explore catalytically very active, coral-structured Ag catalyst for the generation of pure CO from CO₂-feeds in lab-bench scale zero-gap CO₂ electrolyzer. Coral-shaped Ag electrodes achieved CO partial current densities of up to 312 mA cm⁻², EE_CO of 38%, and FE_CO clearly above 90%. In-situ/operando X-ray Absorption Spectroscopy revealed the sustained presence of Ag⁺ subsurface species, whose local electronic field effects constitute likely molecular origins of the favorable experimental kinetics and selectivity. In addition, we show how electrode flooding in zero-gap CO₂ electrolyzer compromises efficient CO₂ mass transfer. Our studies highlight the need for a concomitant consideration of factors related to intrinsic catalytic activity of the active phase, its porous structure and its hydrophilicity/phobicity to achieve a sustained high product yield in AEM zero-gap electrolyzer.

将CO ₂直接电还原为纯CO物流已引起学术研究和工业聚合物合成开发的广泛关注。在这里，我们探索了具有催化活性的珊瑚结构银催化剂，用于在实验室工作台规模的零间隙CO ₂电解槽中从CO _2进料生成纯CO 。珊瑚形的Ag电极的CO分流密度高达312 mA cm ^-2，EE _CO为38％，FE _CO明显高于90％。原位/操作X射线吸收光谱显示Ag ⁺持续存在地下物种，其局部电场效应可能是有利的实验动力学和选择性的分子起源。此外，我们展示了零间隙CO ₂电解槽中的电极溢流如何损害有效的CO ₂传质。我们的研究强调需要同时考虑与活性相的固有催化活性，其多孔结构及其亲水性/疏水性相关的因素，以在AEM零间隙电解槽中实现持续的高产量。