교육

세미나

Alkaline-Membrane Electrolysis: Catalyst Fundamentals to Performance, Durability, and Interface Design

날짜
2023-12-05 10:30:00
학과
탄소중립대학원
장소
ZOOM Webinar
연사
Shannon W. Boettcher (University of Oregon)

Commercialized membrane electrolyzers use acidic proton exchange membranes (PEMs). These systems offer high performance but require the use of expensive precious-metal catalysts such as IrO2 and Pt that are nominally stable under locally acidic conditions. Alkaline-exchange-membrane (AEM) electrolyzers in principle offer the performance of PEM electrolyzers with the ability to use earth-abundant catalysts and inexpensive bipolar plate materials. I will highlight our fundamental work in understanding the chemical and electrochemical processes in earth-abundant water-oxidation catalysts over the past decade and we are using that understanding to drive progress in high-performance AEM electrolyzers.

Baseline systems operate at 1 A·cm-2 in pure water feed at < 1.9 V at a moderate temperature of ~70 °C using either IrO2 or Co3O4 anode catalyst layers, PiperION alkaline ionomers, and stainless-steel porous transport layers. These devices, however, degrade rapidly compared to PEM electrolyzers which we link to chemical and structural changes in the ionomer-catalyst reactive zone using a combination of integrated reference-electrode device architectures, impedance, and cross-sectional and post-mortem materials analysis. We further discover that dynamic Fe-based OER catalysts – that have world-record performance in traditional liquid alkaline electrolyzer systems – perform poorly with enhanced degradation rates in alkaline membrane electrolysis, illustrating fundamentally different chemical design principles for OER catalysts.

Given this baseline understanding, I will end with new chemical strategies we have developed to mitigate degradation and enhance performance using novel ionomers, passivated electrolyte-catalyst interfacial architectures, and specifically designed multicomponent anode oxygen catalysts.