Single-Atom Intercalation-Driven Topological Ferroelectric Metal for High-Performance Hydrogen Evolution Reaction

Intercalation engineering has become an effective strategy for tailoring the electronic and structural properties of layered materials, enabling functionalities that are absent in their pristine counterparts. In this work, we propose that intercalation engineering can be used to realize multifunctional catalysts that combine metallic and topological electronic structures with switchable polarization and catalytic activity-an outstanding challenge in materials science. Specifically, inserting an isolated Cu atom into monolayer AB₃ (A = Bi, Sb, As; B = Cl, Br, I) converts the parent nonpolar semiconductors into ferroelectric (FE) metallic systems with switchable FE polarization. This intercalation simultaneously reconstructs the electronic band structures and induces Weyl points near the Fermi level. Remarkably, the presence of an intercalated Cu atom substantially enhances the intrinsic hydrogen evolution reaction (HER) activity of monolayer AB₃, leading to a significantly reduced hydrogen adsorption free energy. Furthermore, the switchable FE polarization enables effective modulation of the catalytic activity, allowing the HER performance to be tuned by FE polarization reversal. Our results establish single-atom intercalation as a powerful route to couple ferroelectricity, topological metals, and electrocatalysis, opening a pathway toward electrically controllable topological FE catalysts for sustainable hydrogen production.