Bridging activity gaps between batch and flow reactor configurations in the electroreduction of carbon dioxide

To date, the understanding of various modes of CO ₂ mass transport remains incomplete, impeding the transfer of catalysts identified in the more accessible electrochemical batch cells to high-performance flow cells. In this work, we demonstrate that the meniscus region formed between the electrode and the convex liquid level due to the electrowetting of the catalyst plays a vital role in the CO ₂ RR in batch cells. CO ₂ RR in the meniscus region in batch cells exhibits similar performance with that in flow cells, and the performance disparity between these two configurations largely disappears when conducting CO ₂ RR primarily in the meniscus region. An assembled double-sided gas diffusion electrode with a gas channel is developed to maximize the meniscus-like region, achieving a CO ₂ RR partial current density of 640 mA/cm ² _geo on commercial Cu in the KHCO ₃ electrolyte. This performance represents the highest CO ₂ RR activity in neutral buffered media.