Tri-phase interface regulation of ionomer-encapsulated Ag/C catalyst for industrial CO ₂ electrolyzer: A DOE-based analysis

Carbon monoxide (CO) stands as one of the most valuable and economically viable products in the electrochemical reduction of CO₂. In this study, we introduced high-surface-area porous carbon and anion-exchange ionomer to silver nanoparticles, rapidly constructing a tri-phase interface that enhances CO₂ transport and proton conduction. The ionomer-encapsulated tri-phase interface further improves reaction selectivity by increasing HCO₃⁻ concentration. Flow cell tests revealed that the 80% Ag/C catalyst double the partial current density of CO as compared to commercial Ag nanoparticles. To integrate the synthesized 80% Ag/C into industrial-scale membrane electrode assembly (MEA) electrolyzers (10 cm × 10 cm), we developed a comprehensive evaluation system incorporating CO selectivity, cell voltage, and actual gas conversion ratio (λact) with only one piece of MEA. This approach allowed systematic evaluation of current density and gas flow rate effects, followed by operational parameter optimization to 300 mA·cm⁻² and 1000 sccm. Under optimal conditions, the 80% Ag/C catalyst demonstrated stable operation for over 60 hours with a cell voltage of 3 V. The observed CO Faradaic efficiency decay rate suggests a projected operational lifetime exceeding 500 hours. This work not only presents an efficient modification strategy to enhance the CO₂ reduction performance of silver-based catalysts, but also establishes a design-of-experiment (DOE) methodology for industrial-scale testing conditions optimization, thereby facilitating the advancement of CO₂RR toward practical industrial applications.