Design of an elevated pressure electrochemical flow cell for CO2 reduction

Abstract

The electrochemical CO2 reduction reaction (CO2RR) has been proposed as a sustainable way of closing the carbon cycle while synthesizing useful commodity chemicals. One of the possible routes to scale up the process is the elevated pressure CO2RR, as this increases the concentration of the poorly soluble CO2 in aqueous systems. Yet, there are not many studies that focus on this route owing to the inherent challenges with high pressure systems. In this study, a novel high pressure flow cell setup has been designed and validated. The modular design uses a clamp system, which facilitates simple stacking of multiple cell parts while being capable of handling pressures up to 50 bar. The effects of CO2 pressure on the reaction were investigated on a gold (Au) foil cathode in a 0.1 M KHCO3 electrolyte. We successfully measured gaseous products produced during high pressure operation using an inline gas chromatograph. We find that the selectivity toward CO2 reduction products is enhanced while that of H2 evolution is suppressed as the pressure is increased from 2 to 30 bar. The reported setup provides a robust means to conduct high pressure electrolysis experiments in an easy and safe manner, making this technology more accessible to the electrochemical CO2RR community. Graphical abstract