Substrate-dependent interfacial stability of nanostructured Ni electrodes under dynamic on-off operation for...

Achieving robust interfacial stability between nanostructured catalysts and conductive substrates is critical for alkaline anion exchange membrane water electrolysis (AEMWE). Here, we elucidate the substrate-dependent electro-chemo-mechanical stability of 3D porous Ni electrodes rapidly electrodeposited (-1 A cm^-2) on four distinct industrial meshes (Inconel, stainless steel, Ni, and Ti). This high-current deposition successfully normalized macroscopic geometric effects, isolating the intrinsic substrate chemistry. While the hydrogen evolution kinetics remained comparable across all meshes, oxygen evolution reaction (OER) activity was profoundly dictated by the substrate. The SS@Ni electrode exhibited exceptional OER performance, originating from the spontaneous anodic dissolution and incorporation of substrate-derived Fe (∼32 at%), which generates highly active Ni-Fe oxyhydroxide sites. Crucially, under rigorous dynamic AEMWE single-cell operations, SS@Ni and Inc@Ni maintained pristine nanostructural integrity, whereas pure Ni and Ti suffered severe delamination. With quantitative tape tests confirming identical initial mechanical adhesion across the primary meshes, we demonstrate that this durability gap is driven by intrinsic structural stability, not physical bonding. Substrate-derived Fe/Cr species act as indispensable structural stabilizers; by restricting deep, volume-expanding Ni(OH)₂/NiOOH phase transitions, they protect the porous framework from chemo-mechanical collapse. Leveraging this interfacial synergy, the SS@Ni cell achieved outstanding practical performance, requiring only 1.91 V at 1 A cm^-2 at 80 °C. These findings establish strategic substrate alloying as a fundamental design principle for robust, high-current AEMWE.