Leveraging Spatial Distribution of CO Intermediates for Boosting Methanol Formation via Electrochemical CO 2 Reduction

Efficient electrosynthesis of methanol from CO 2 is hindered by the competitive adsorption of CO 2 over CO on cobalt phthalocyanine-based catalysts, which prevents the CO intermediate from further reducing to CH 3 OH. In this work, we show that tuning the electrode architecture, specifically by extending the electrode area and increasing the catalyst layer thickness in the inlet region, can overcome this challenge by controlling the spatial distribution of CO. A 5-fold extension of the electrode area (from 1 to 5 cm 2 ) and subsequently the serpentine flow channel allows CO 2 to be progressively converted to CO along the electrode, enriching CO in the downstream region and facilitating its further conversion to methanol. Likewise, a thicker catalyst layer upstream boosts CO generation upstream, which then drives higher CH 3 OH formation in downstream regions. This approach yields over 10 times enhancement in methanol current density (>30 mA/cm 2 ) and increases methanol Faradaic efficiency by over 30%, without altering the catalyst molecules or operating potential. Multiphysics modeling confirms that the extended channel increases local CO partial pressure and residence time within the catalyst layer, directly correlating with the observed rise in methanol output. Beyond simply increasing gas residence time, the segment-resolved electrode reveals how CO generation and CO utilization evolve spatially along the enlarged GDE. The S1-thickened architecture further demonstrates that methanol formation can be enhanced by redistributing CO-generation capacity along a fixed channel length, highlighting spatial intermediate management as a scale-up-oriented electrode design principle. Our results highlight a strategy for CO 2 -to-methanol conversion by spatially managing CO abundance via electrode design, which can be a powerful complement to catalyst material innovations.