Work‐function‐induced Interfacial Built‐in Electric Fields in Os‐OsSe2Heterostructures for Active Acidic and Alkaline Hydrogen Evolution

Abstract Theoretical calculations unveil that the formation of Os‐OsSe 2 heterostructures with neutralized work function (WF) perfectly balances the electronic state between strong (Os) and weak (OsSe 2 ) adsorbents and bidirectionally optimizes the hydrogen evolution reaction (HER) activity of Os sites, significantly reducing thermodynamic energy barrier and accelerating kinetics process. Then, heterostructural Os‐OsSe 2 is constructed for the first time by a molten salt method and confirmed by in‐depth structural characterization. Impressively, due to highly active sites endowed by the charge balance effect, Os‐OsSe 2 exhibits ultra‐low overpotentials for HER in both acidic (26 mV @ 10 mA cm −2 ) and alkaline (23 mV @ 10 mA cm −2 ) media, surpassing commercial Pt catalysts. Moreover, the solar‐to‐hydrogen device assembled with Os‐OsSe 2 further highlights its potential application prospects. Profoundly, this special heterostructure provides a new model for rational selection of heterocomponents.