Improving coating adhesion of Raney nickel electrodes for alkaline water electrolysis

Raney nickel is a widely used cathode material for alkaline water electrolysis due to its high electrochemically active surface area (ECSA) and strong hydrogen evolution reaction (HER) activity, but its long‑term stability can be limited by poor coating adhesion to the nickel substrate. In this work, the adhesion and durability of NiZn‑based electrodeposited Raney nickel coatings has systematically been investigated using a modified tape test combined with electrochemical tests and surface characterization. Acid pretreatments, sanding, electrochemical etching and post‑heat treatment have been evaluated as strategies to improve coating–substrate bonding. Pretreatment with 5 M HNO₃ combined with sanding 400 yields the most stable coatings, showing strongly reduced delamination at a kinetic overpotential of − 115 mV at -1.6 A cm⁻² in 6 M KOH at 75 °C. In contrast, post‑heat treatment leads to zinc loss and partial closure of the porous structure, resulting in substantially lower ECSA and reduced catalytic performance. Overall, optimized substrate pretreatment rather than post-heat treatment is the most effective strategy for producing durable and active Raney nickel electrodes.