Impact of Intermittent Operation on Zero-gap CO₂ Electrolyzers

Electrochemical carbon dioxide reduction (CO 2 RR) driven by renewable electricity, such as solar power, presents a promising pathway for sustainable energy conversion. However, system performance and stability are challenged by intermittent operation due to renewable energy supply or industrial process halts. Herein, we investigate the impact of intermittent operation on zero-gap CO 2 electrolyzers. We reveal that intermittent operation induces flooding in the microporous layer (MPL) of the gas diffusion electrode (GDE), driven by pressure differentials and hydrophobicity degradation. This flooding impedes CO 2 transport and promotes the hydrogen evolution reaction (HER). To mitigate this effect, we propose the use of electrowetting-resistant and nonconductive GDEs, with polytetrafluoroethylene (PTFE) as a proof of concept, which effectively mitigates flooding and maintains CO 2 RR selectivity under intermittent conditions. Our findings provide critical insights into the design of resilient CO 2 RR systems capable of stable operation under the dynamic conditions of renewable energy integration.