High performance CO reduction at electrolyzer stack level through system optimization

Abstract This study demonstrates the electrochemical reduction of carbon monoxide (COR) at high current densities in a zero‐gap electrolyzer cell and cell stack. By systematically optimizing both the commercially available membrane electrode assembly components (including binder content and gas diffusion layer) and the operating conditions, we could perform COR at current densities up to 1.4 A cm −2 with a maximum C 2+ selectivity of 90%. We demonstrated the scale‐up to a 3 × 100 cm 2 electrolyzer stack that can sustain stable operation at 1 A cm −2 for several hours without significant performance decay and with a total C 2+ selectivity of ~80% and an ethylene selectivity of ~40%. We provide critical insights into the holistic optimization of key system parameters, without using special catalysts or surface additives, which can pave the way for scalable and industrially viable COR processes.