Methanol-facilitated surface reconstruction catalysts for near 200% faradaic efficiency in a coupled system

Abstract

The coupling of the carbon dioxide reduction reaction (CO2RR) and methanol oxidation reaction (MOR) holds great promise for the energy-efficient production of HCOO−. However, anode catalysts' limited selectivity (<80%) and stability (<15 h) have impeded electron utilization and HCOO− production rates. To overcome it, copper-copper(I) oxide-copper(II) oxide nanowires (Cu─CuO─Cu2O NWs) catalysts have been developed, which exhibit exceptional performance in promoting the MOR with a faradic efficiency of nearly 100% at commercially viable current densities, and long stability over 100 h at 100 mA cm−2. Interestingly, the unique structure of the catalysts, when exposed to methanol, facilitates a transition from Cu/CuO to Cu2O. This phenomenon promotes the MOR while inhibiting the competitive oxygen evolution reaction (OER). By coupling the anodic reaction with cathodic CO2 reduction, the system demonstrates exceptional performance in HCOO− production, achieving an overall faradic efficiency of nearly 200% at 100 mA cm−2 with a low cell voltage of 2.382 V. Techno-economic analysis indicates that the production costs of HCOOH are ≈US$0.37 and 0.35 kg−1 at 100 and 150 mA cm−2, respectively, significantly lower than those associated with traditional electrochemical methods.