Direct Membrane Deposition for CO<sub>2</sub> Electrolysis
Tartela Alkayyali, Ali Shayesteh Zeraati, Harrison Mar, Fatemeh Arabyarmohammadi, Sepehr Saber, Rui Kai Miao, Colin P. O’Brien, Hanshuo Liu, Zhong Xie, Guangyu Wang, Edward H. Sargent, Nana Zhao, David Sinton
Abstract
The use of forward-bias bipolar membranes (f-BPM) in CO 2 electrolyzers offers the advantage of avoiding costly CO 2 reactant loss. However, current f-BPM-based electrolyzers require a high voltage and produce H 2 at the expense of CO 2 reduction products. In this work, we develop a direct membrane deposition (DMD) approach that combines anion and cation exchange membranes (AEM and CEM, respectively) to increase transport and facilitate CO 2 regeneration. The DMD approach provides flexibility to tune the properties of the composite and optimize the AEM:CEM ratio for low resistance and low H 2 evolution. Compared to a standard f-BPM, the DMD approach reduced the H 2 Faradaic efficiency by 2-fold (25% vs 12%, respectively), reduced mass transport resistance by over 50%, decreased full-cell potential by 0.84 V, increased the selectivity toward multicarbon products by over 2-fold (29% vs 65%, respectively), and achieved >17% in multicarbon product energy efficiency at 300 mA cm –2 .