A scalable membrane electrode assembly architecture for efficient electrochemical conversion of CO2 to formic acid

Abstract

The electrochemical reduction of carbon dioxide to formic acid is a promising pathway to improve CO₂ utilization and has potential applications as a hydrogen storage medium. In this work, a zero-gap membrane electrode assembly architecture is developed for the direct electrochemical synthesis of formic acid from carbon dioxide. The key technological advancement is a perforated cation exchange membrane, which, when utilized in a forward bias bipolar membrane configuration, allows formic acid generated at the membrane interface to exit through the anode flow field at concentrations up to 0.25 M. Having no additional interlayer components between the anode and cathode this concept is positioned to leverage currently available materials and stack designs ubiquitous in fuel cell and H₂ electrolysis, enabling a more rapid transition to scale and commercialization. The perforated cation exchange membrane configuration can achieve >75% Faradaic efficiency to formic acid at <2 V and 300 mA/cm² in a 25 cm² cell. More critically, a 55-hour stability test at 200 mA/cm² shows stable Faradaic efficiency and cell voltage. Technoeconomic analysis is utilized to illustrate a path towards achieving cost parity with current formic acid production methods.

Electrochemical reduction of CO2 to formic acid is a promising and sustainable pathway for valuable chemical generation. However, direct production of formic acid rather than formate is challenging. Herein the authors report a zero-gap membrane electrode assembly architecture with perforated cation exchange membrane for the direct electrochemical synthesis of formic acid from CO2.