Atomic engineering of stability-kinetics Ce-Fe dyads in Ni3S2 for efficient urea-assisted hydrogen production

Atomic Ce-Fe dyad in Ni 3 S 2 enables kinetic-stability synergy for urea electrolysis. • Low cell voltage of 1.37 V at 100 mA·cm −2 with over 510 h durability. • Operando Raman, XAFS and DFT reveal optimized Ni-S bond and d -band center. Replacing the energy-intensive oxygen evolution reaction (OER) with the urea oxidation reaction (UOR) presents a promising route for energy-saving hydrogen production coupled with wastewater remediation. However, developing electrocatalysts that simultaneously achieve high activity and long-term stability remains a formidable challenge. Herein, we propose and validate a novel “kinetic-structural synergy” design principle by constructing atomic-scale Ce-Fe binary catalytic unit within Ni 3 S 2 nanoarrays. Unlike random doping, this defined architecture enables a functional division of labor. The Fe site acts as a kinetic promoter to dramatically lower the potential for active NiOOH phase formation, while the adjacent Ce site functions as a structural and electronic stabilizer, securing the high-valent Ni intermediates. The resulting catalyst achieves an ultra-low UOR potential. When configured in a two-electrode urea electrolyzer, it requires only 1.37 V to deliver 100 mA·cm −2 current density and maintains remarkable stability for over 510 h. In situ Raman spectroscopy directly evidences the earliest formation and exceptional persistence of the NiOOH phase on this catalyst. Combined X-ray absorption fine structure (XAFS) analysis and density functional theory (DFT) calculations elucidate from the atomic-level principle that the Fe-Ce unit cooperatively tunes the local coordination and electronic structure of Ni, leading to an optimal Ni-S bond length and a favorable d -band center of Ni site, collectively facilitating the reaction pathway. This work demonstrates that targeted lanthanide-transition metal pairing can create integrated catalytic units where activity and stability are inherently coupled, providing a new design strategy for advanced energy conversion systems. Download: Download high-res image (166KB) Download: Download full-size image The successful doping of Ce and Fe asymmetric metals to form the Fe-S-Ni-S-Ce catalytic chain alters the bond length/strength of the original Ni-S bond, promoting the formation of high-valent nickel species while enhancing their stability at high oxidation potentials, ultimately achieving a balance between high activity and long-term operation in the urea oxidation process.