Modulating Local Interfacial Bonding Environment of Heterostructures for Energy‐Saving Hydrogen Production at High Current Densities

Abstract Coupling urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) is an effective energy‐saving technique for hydrogen generation. However, exploring efficient bifunctional electrocatalysts under high current density is still challenging. Herein, hierarchical Fe doped cobalt selenide coupled with FeCo layered double hydroxide (Fe‐Co 0.85 Se/FeCo LDH) array as a self‐supported superior bifunctional heterojunction electrode is rationally designed for both UOR and HER. The unique heterostructure facilitates electron transfer and interface interactions through local interfacial Co‐Se/O‐Fe bonding environment modulation, improving reaction kinetics and intrinsic activity. As a result, the heterostructured electrocatalyst exhibits ultralow potentials of −0.274 and 1.48 V to reach 500 mA cm −2 for catalyzing the HER and UOR, respectively. Particularly, the full urea electrolysis system driven by Fe‐Co 0.85 Se/FeCo LDH delivers 300 mA cm −2 at a relatively low potential of 1.57 V, which is 150 mV lower than the conventional water electrolysis. The combination of in situ characterization and theoretical analysis reveal that the active sites with the adjustable electronic environment are induced by the interfacial bonding of the heterojunction, facilitating the water decomposition of HER and the stabilization of intermediates in UOR. This work inspires the interfacial environment modulation to optimize advanced electrocatalysts for energy‐saving H 2 production.