Abstract
Synthesis of valuable chemicals from CO(2) electroreduction in acidic media is highly desirable to overcome carbonation. However, suppressing the hydrogen evolution reaction in such proton-rich environments remains a considerable challenge. The current study demonstrates the use of a hollow fiber silver penetration electrode with hierarchical micro/nanostructures to enable CO(2) reduction to CO in strong acids via balanced coordination of CO(2) and K(+)/H(+) supplies. Correspondingly, a CO faradaic efficiency of 95% is achieved at a partial current density as high as 4.3 A/cm(2) in a pH = 1 solution of H(2)SO(4) and KCl, sustaining 200 h of continuous electrolysis at a current density of 2 A/cm(2) with over 85% single-pass conversion of CO(2). The experimental results and density functional theory calculations suggest that the controllable CO(2) feeding induced by the hollow fiber penetration configuration primarily coordinate the CO(2)/H(+) balance on Ag active sites in strong acids, favoring CO(2) activation and key intermediate *COOH formation, resulting in enhanced CO formation.