Scalable Production of Disordered Nickel‐Iron‐Aluminum Oxides as Stable Anodes for Water Electrolysis: The Role of Aluminum

ABSTRACT The production of anode electrocatalysts for water electrolysis typically involves energy‐intensive synthesis protocols. Here, we employ solution precursor plasma spraying to produce nanostructured nickel‐iron‐aluminum oxide anodes. The as‐produced coatings exhibit a highly porous morphology characterized by structural disorder with Ni(II) and Fe(III) occupying distorted octahedral sites. Aluminum plays a critical role in inhibiting crystal growth, benefiting amorphization and porosity, while simultaneously modifying the solid‐electrolyte interface and improving the ionic and electronic transport and overall reaction kinetics. This leads to enhanced adsorption energy of oxygen intermediates and a favorable change in the rate‐determining step of the oxygen evolution reaction (OER). As a result, the as‐produced anodes exhibit excellent OER activity (0.5 A cm −2 at 1.74 V RHE ) and operational stability (160 h at 0.5 A cm −2 in 1 M KOH). Applying a mild thermal annealing (300°C) initially leads to reduced OER activity but improves coating adhesion and prevents material detachment. The high OER activity is recovered after prolonged operation, resulting in a degradation rate of only 150 µV h −1 . Our work reports a robust and scalable method for the fabrication of platinum group metal‐free anodes, bridging the gap between fundamental catalyst design and industrial applications for green hydrogen production.