Optimizing Nickel-Based catalysts for UOR: The role of W interface in nickel-selective oxidation reaction (NSOR) enhancement

Abstract

The urea oxidation reaction (UOR) presents a promising alternative to the oxygen evolution reaction (OER) for hydrogen production, offering a lower theoretical potential and capacity for wastewater treatment. However, the sluggish kinetics of UOR demand advanced catalyst development. Here, we report a tungsten-doped nickel catalyst (Ni₁₀₀-W₁-NF) synthesized via electrochemical deposition on nickel foam, which demonstrates exceptional catalytic performance. The Ni₁₀₀-W₁-NF catalyst achieves a current density of 100 mA cm^–2 at 1.35 V vs. RHE during UOR, significantly surpassing undoped Ni-based catalysts. When integrated into a two-electrode system coupling UOR with the hydrogen evolution reaction (HER), the system operates at 1.56 V to reach 100 mA cm⁻², a notable voltage reduction compared to OER-coupled systems. Phase characterization and density functional theory (DFT) calculations reveal that the optimized W doping induces electron transfer from Ni to W, reducing the adsorption-free energies of OH^– to − 4.23 eV and Ni (III)-urea to − 2.88 eV. This electronic modulation enhances UOR kinetics by accelerating the nickel-selective oxidation reaction (NSOR) and stabilizing high-valence nickel species. Compared to existing strategies, this work demonstrated the unique effectiveness of W doping in precisely tailoring electronic structures and reaction pathways, offering a sustainable and energy-efficient route for hydrogen production through urea electrolysis.