A scalable hydrothermal-electrodeposition strategy for Fe-Doped Ni(OOH)/Ni(OH)₂ electrocatalysts enabling 1 A cm⁻² oxygen evolution and solar-driven hydrogen production

In this work, a scalable electrodeposition strategy is described to coat a flat pure metallic nickel sheet by using a hydrothermally treated electrolyte bath and to get nanostructured iron (Fe)-doped nickel oxyhydroxide (NiOOH) / nickel hydroxide (Ni(OH)₂), an earth-abundant electrocatalyst. The optimised electrocatalyst demonstrates competitive performance in terms of high electrocatalytic current densities of approximately 1 A/cm² for the oxygen evolution reaction (OER) with significantly low overpotential, meeting approaches industrially relevant performance metrics for alkaline water electrolysers. The catalysts exhibit unique hierarchical nanostructures and maintain stable operation at 400 mA/cm² for 17 h. The catalyst-coated nickel sheet also shows significant activity with good gas evolution in two-electrode configurations in a PV-coupled demonstration. Due to its high-performing electrocatalysis, it can be further scaled up to apply to higher TRL electrolyser development (alkaline) and to achieve higher hydrogen production at the stack level. The fabrication approach enables direct deposition on practical substrates suitable for scalable electrolyser manufacturing.