Monolithic Nickel Catalyst Featured with High‐Density Crystalline Steps for Stable Hydrogen Evolution at Large Current Density

Abstract Producing hydrogen via electrochemical water splitting with minimum environmental harm can help resolve the energy crisis in a sustainable way. Here, this work fabricates the pure nickel nanopyramid arrays (NNAs) with dense high‐index crystalline steps as the cata electrode via a screw dislocation‐dominated growth kinetic for long‐term durable and large current density hydrogen evolution reaction. Such a monolithic NNAs electrode offers an ultralow overpotential of 469 mV at a current density of 5000 mA cm −2 in 1.0 m KOH electrolyte and shows a high stability up to 7000 h at a current density of 1000 mA cm −2 , which outperforms the reported catas and even the commercial platinum cata for long‐term services under high current densities. Its unique structure can substantially stabilize the high‐density surface crystalline steps on the catalytic electrode, which significantly elevates the catalytic activity and durability of nickel in an alkaline medium. In a typical commercial hydrogen gas generator, the total energy conversion rate of NNAs reaches 84.5% of that of a commercial Pt/Ti cata during a 60‐day test of hydrogen production. This work approach can provide insights into the development of industry‐compatible long‐term durable, and high‐performance non‐noble metal catas for various applications.