Activating in-plane dead zones of anode catalyst layers in proton exchange membrane water electrolyzers.
basic_science · Level V
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- Record sourced from PubMed, PMID 42386725.
- Also identified by DOI 10.1038/s41467-026-75223-1.
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Abstract
The utilization of iridium-based anode catalysts in proton exchange membrane water electrolyzers is largely limited by the presence of electrochemically inactive "dead zones" within the catalyst layer. Here, by combining in-situ visualization of gas bubble evolution with quantitative conductivity measurements and electrochemical analysis, we establish that the limited in-plane electronic conductivity, dictated by the ionomer disrupting the conductive network of IrO<sub>2</sub> nanocatalysts, is the dominant factor. A sequential spray-coating strategy is further developed, which decouples the deposition of a pristine conductive catalyst layer from the ionomer and thereby preserves continuous electron transport pathways. This approach effectively activates the in-plane dead zones, resulting in membrane electrode assemblies that exhibit over 30% higher activity (4.2 A cm<sup>-2</sup>@2.0 V@80 °C; membrane: Nafion 115) than those prepared by the conventional one-step method based on IrO<sub>2</sub>/ionomer mixed inks. Crucially, this approach achieves both low iridium loading (0.25 mg cm<sup>-2</sup>) with standard catalysts and demonstrates extended stability over 8300 hours under practical current densities.