Modulating Urea Oxidation by Iron-Accelerated Reconstruction and Tailoring Anionic Microenvironment

Anodic small-molecule electro-oxidation offers a promising route to couple low-energy hydrogen production with value-added chemical transformations. Nevertheless, Ni-based anodes for urea oxidation (UOR) are constrained by sluggish reconstruction, interfacial poisoning, and mass-transport limitations. Here we engineer self-supported Fe-doped Ni₃S₂ nanosheet arrays and advance a cooperative bimetallic active-site-anionic microenvironment regulation strategy. Operando spectroscopy and electrochemical analyses reveal that Fe dopants act as an electronic pump, accelerating the formation of a Ni(Fe)OOH surface skin and weakening Ni-S bonds to trigger anion-derived reconstruction. Under operating potentials, an operando-generated interfacial SO₄^2- layer mediates proton-coupled electron transfer while electrostatically suppressing carbonate adsorption, thereby alleviating the single-site Sabatier constraint via multisite synergy and enhancing activity and selectivity. The optimized electrode delivers 200 mA cm^-2 at 1.355 V (vs RHE) for UOR and exhibits bifunctional capability with a hydrogen-evolution overpotential of 59 mV at 10 mA cm^-2. This mechanism-driven paradigm of interfacial gating and coreconstruction provides a transferable blueprint for UOR and, more broadly, anodic small-molecule electro-oxidations.