Paired flow-cell electrolysis for formate production from CO2 and methanol feedstocks with cell faradaic efficiency exceeding 180%

Abstract

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.