Paired Flow-Cell Electrolysis for Formate Production from CO₂ and Methanol Feedstocks with Cell Faradaic Efficiency Exceeding 180%

The electrochemical conversion of carbon dioxide (CO₂) into valuable chemicals presents a promising avenue for achieving carbon neutrality. Nonetheless, this process faces significant challenges stemming from the slow kinetics of the anodic oxygen evolution reaction and the formation of low-value O₂ as a byproduct. This study introduces a dual-alkali electrolyzer that combines carbon dioxide reduction (CO₂RR) at the cathode with alkaline methanol oxidation (MOR) at the anode. Utilizing bismuth and nickel-based metal–organic frameworks as catalysts for the cathode and anode, respectively, this dual-electrosynthesis system achieves improved electron efficiency for formate production, demonstrating over 180% selectivity for both electrocatalytic CO₂ reduction reaction and MOR. Additionally, the hybrid MOR–CO₂RR system demonstrates impressive long-term durability, maintaining operation for over 24 h. It provides a formate partial current density of 65 mA cm⁻² at a mere 2.4 V, significantly lowering energy consumption in comparison to traditional CO₂ electrolysis systems. This research emphasizes innovative strategies for enhancing electron utilization and minimizing energy consumption in CO₂ electrolysis while fostering the advancement of highly effective electrocatalysts.