Controlling Product Distribution of CO<sub>2</sub> Reduction on CuO‐Based Gas Diffusion Electrodes by Manipulating Back Pressure
Baran Sahin, Jane J. Leung, Erhard Mágori, Steffen Laumen, A. Tawil, Elfriede Simon, Olaf Hinrichsen
Abstract
The electrochemical reduction reaction of CO 2 (CO 2 RR) is a promising avenue toward the renewable energy‐driven transformation of a greenhouse gas toward fuels and value‐added chemicals. While copper uniquely can catalyze this reaction to longer carbon chains, Cu‐based electrodes continue to face numerous challenges, including low selectivity toward desired products and poor stability. To unlock its potential for large‐scale industrial implementation, great interest is shown in tackling these challenges, primarily focusing on catalyst and electrode modifications and thereby leaving a research gap in the effects of operation conditions. Herein, back pressure application is introduced in CO 2 electrolyzers at industrially relevant current densities (200 mA cm −2 ) in order to steer selectivity toward C 2+ products. The back pressure adjusts CO 2 availability at the electrode surface, with a high CO 2 surface coverage achieved at Δ P = 130 mbar suppressing the competing hydrogen evolving reaction for 72 h and doubling of stable ethylene production duration. Faradaic efficiency of 60% for C 2+ products and overall C 2+ conversion efficiency of 19.8% are achieved with the easily implementable back pressure operation mode presented in this study. It is proven to be a promising tool for product selectivity control in future upscaled Cu‐based CO 2 electrolysis cells.