Pathways Toward Efficient and Durable Anion Exchange Membrane Water Electrolyzers Enabled By Electro‐Active Porous Transport Layers

Abstract

Green hydrogen, produced via water electrolysis using renewable electricity, will play a crucial role in decarbonizing industrial and heavy‐duty transportation sectors. Anion exchange membrane water electrolyzers (AEMWEs) can overcome many of the performance and cost limitations of incumbent technologies, however, still suffer from durability challenges due to oxidative instability of anion‐exchange ionomers. Herein, the use of an electro‐active porous transport layer as anode (PTL‐electrode) is demonstrated to enable efficient and durable AEMWEs. The stainless‐steel PTL‐electrodes are shown to have superior performance and durability compared to traditional catalyst layers containing ionomer and nanoparticle catalysts. An AEMWE cell operating at 2 A cm−2 for over 600 h exhibited a degradation rate of just 5 µV h−1. During operation, the surface composition of the stainless steel transforms into a mixture of iron and nickel oxyhydroxides, contributing to enhanced oxygen‐evolution reaction activity. The combination of experimental work and modeling elucidates how the bulk structure of the PTL‐electrode offers an additional design dimension to further improve electrolyzer performance. Lastly, a surface modification strategy is applied to a PTL‐electrode to achieve an even higher performing AEMWE (2.3 vs 2.0 A cm−2 at 1.8 V). Overall, this work lays out pathways toward more efficient, durable, and affordable AEMWEs.

Pure-Water-Fed Forward-Bias Bipolar Membrane CO2 Electrolyzer

“… 49 In addition, X-ray photoelectron spectroscopy (XPS) of the EOL cathode catalyst layer shows severe loss of nitrogen from the cationic functional headgroup ( Figure S14 ). AEIs are more prone to oxidative decay under anodic potential; 50 however, degradation could also occur if exceeding the electrochemical stability window even under reductive potential. The performance metrics of this work is compared to that of previously reported BPM CO 2 electrolyzers for CO production ( Table S1 ), 29 , 31 , 51 which indicates enhanced efficiency and durability, although differences in the testing condition and the material should be noted.…”

Ni,Fe,Co-LDH Coated Porous Transport Layers for Zero-Gap Alkaline Water Electrolyzers

“…These results are in agreement with the literature, where the crucial role of Fe in enhancing Ni and Co-based hydroxide activity is reported [ 44 , 45 , 46 ]. Moreover, a substrate of LDH-based electrocatalytic layer is SS, and it has been demonstrated that stainless steel can represent a good electrocatalyst for OER due to its capacity of forming active (oxy)hydroxides under oxidizing conditions [ 2 , 13 ].…”

“…Zero-gap configuration leads to higher efficiency, and it foresees the usage of a so-called porous transport layer (PTL), which ensures electrical continuity between the catalytic layer and the current collector, and that is crucial to remove bubbles from the catalytic layer [ 10 , 11 ]. Functionalizing PTLs with a catalytic layer can be a way to further increase the cell efficiency [ 12 , 13 ].…”

Aryl ether-free polymer electrolytes for electrochemical and energy devices

“…This study suggests that future research should focus on developing active and stable materials for catalysts, catalyst layers, and the integration of catalyst layers into MEAs, particularly as the anode components are highly susceptible to oxidative conditions. Also, more recent results by Peng et al 605 and Lee et al 606 demonstrated a relatively low degradation rate (5–50 μV h −1 ) of 1 M KOH-fed AEMWEs employing aryl ether-free AEMs at 1.5 and 2 A cm −2 , achieving a practical level of hydrogen generation.…”