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

The electrochemical conversion of carbon dioxide (CO<inf>2</inf>) 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 O<inf>2</inf> as a byproduct. This study introduces a dual-alkali electrolyzer that combines carbon dioxide reduction (CO<inf>2</inf>RR) 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 CO<inf>2</inf> reduction reaction and MOR. Additionally, the hybrid MOR–CO<inf>2</inf>RR 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 CO<inf>2</inf> electrolysis systems. This research emphasizes innovative strategies for enhancing electron utilization and minimizing energy consumption in CO<inf>2</inf> electrolysis while fostering the advancement of highly effective electrocatalysts.