System Design Rules for Intensifying the Electrochemical Reduction of CO₂ to CO on Ag Nanoparticles

Electroreduction of CO₂ (eCO₂RR) is a potentially sustainable approach for carbon-based chemical production. Despite significant progress, performing eCO₂RR economically at scale is challenging. Here we report meeting key technoeconomic benchmarks simultaneously through electrolyte engineering and process optimization. A systematic flow electrolysis study - performing eCO₂RR to CO on Ag nanoparticles as a function of electrolyte composition (cations, anions), electrolyte concentration, electrolyte flow rate, cathode catalyst loading, and CO₂ flow rate - resulted in partial current densities of 417 and 866 mA/cm² with faradaic efficiencies of 100 and 98 % at cell potentials of −2.5 and −3.0 V with full cell energy efficiencies of 53 and 43 %, and a conversion per pass of 17 and 36 %, respectively, when using a CsOH-based electrolyte. The cumulative insights of this study led to the formulation of system design rules for high rate, highly selective, and highly energy efficient eCO₂RR to CO.