(52b) Direct Seawater Electrolysis Enabled By Robust Ion Transport Control in Membrane Electrolyzers with Asymmetric Electrolyte Conditions
AIChE Annual Meeting
Monday, November 14, 2022 - 8:15am to 8:30am
Herein we evaluate the strategy for generating H2 directly via seawater electrolysis of preventing the transport of anionic constituentsâparticularly Cl- owing to the corrosive nature of its oxidesâacross the membrane electrode assembly from the catholyte to the anolyte. We also quantify the shift in pH conditions for hydrogen evolution and oxygen evolution catalysis away from ideality when this transport is not mitigated, as well generation of particularly corrosive anolyte conditions that destroy overall cell performance. To quantify the degree to which permselective ionomer architectures mitigate the aforementioned failure modes, we 1) performed electrolysis under asymmetric electrolyte conditions that included HER in simulated or real seawater with OER in deionized water, and 2) coupled electrochemical with quantitative compositional analyses of device components and electrolyte conditions over time. Our methodology for screening the performance and stability of seawater electrolyzers highlights the promise of bipolar membrane electrolyzers as incredibly robust against feed contamination, with >19 hours of continuous operation with real seawater. We further implicate the use of BPM electrolyzers in an array of energy-conversion applications involving un-treated water feedstocks.