Hierarchical Electrode Design for Highly Efficient and Stable Anion Exchange Membrane Water Electrolyzers

Anion exchange membrane water electrolyzer (AEMWE) is a promising technology for green hydrogen production to reduce carbon emissions in industrial and heavy-duty transportation sectors. AEMWE has the advantage of using nonplatinum group metal oxides for the anode oxygen evolution reaction (OER) and therefore lower the capital expenditure comparing to proton exchange membrane water electrolyzers (PEMWE). However, the commercialization and deployment of AEMWE in large scale is still limited by its durability. Herein, we study how electrode structure and the cell operating conditions affect the cell stability and performance. Catalyst layer structures, including porosity and tortuosity, were investigated and correlated with cell performance for better understanding and designing AEMWE. Durability of different catalyst layers were investigated and correlated with catalyst layer structure and ionomer stability. Electrode fabrication methods were found to have significant impact on the catalyst layer structure and therefore catalyst utilization. With a doctor blading method to fabricate the catalyst layer, electrodes were scaled up from 5 cm-2 to >25cm-2 with negligible voltage loss. With these findings, cell performance was improved towards <1.8V at 2A cm-2 and durability of >500h was achieved at 2A cm-2 for a 25 cm-2 cell in 0.5M KOH.