Passivation Engineering Via Dynamic Construction of Amorphous Oxides on a Topologically Close-Packed Phase for Sustainable Hydrogen Production.

The pursuit of earth-abundant electrocatalysts for acidic water electrolysis is fundamentally limited by a material-design paradox: high activity necessitates reactive sites, yet these sites are inherently vulnerable to corrosion. Here, we present a paradigm shift that transforms corrosion from a destructive process into a useful synthesis tool. We demonstrate that a topologically close-packed (TCP) intermetallic phase, when electrochemically activated in acid, naturally forms a self-passivating, corrosion-resistant amorphous oxide layer that establishes a durable and catalytically active interface. This corrosion-built oxide layer enables exceptional hydrogen evolution reaction (HER) performance (90 mV at 10 mA/cm2) coupled with extended stability (>200 h at 100 mA/cm2). Our work establishes "passivation engineering" as a general design principle, leveraging guided corrosion to construct stable, active phases, offering a universal route to bridge the activity-stability divide in non-precious electrocatalysis.