Abstract:

While H₂ features high energy density, environmental friendliness, and renewability, its efficient production is limited by the sluggish kinetics of the oxygen evolution reaction (OER). Here, we report a Pt@PtNi₃ core@shell alloy electrocatalyst that, through Ni incorporation, modulates the occupancy of Pt 5d antibonding orbitals and simultaneously enhances both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) activities. The optimized Pt@PtNi₃-500 delivers an ultralow overpotential of 21 mV at 10 mA cm^-2 for HER under acidic conditions and a low onset potential of 1.27 V for UOR under alkaline conditions, surpassing monometallic Pt and Ni counterparts. When employed in an asymmetric acid-alkaline electrolyzer (HER/UOR), Pt@PtNi₃-500 achieves a 68.3% reduction in electrical energy consumption for H₂ production compared to traditional alkaline water splitting (HER/OER). Mechanistic investigations reveal that appropriate Ni incorporation in Pt@PtNi₃ increases the occupancy of Pt 5d–H 1s antibonding orbitals, which not only reinforces H⁺ adsorption but also weakens the overly strong H^* binding. Simultaneously, it reduces the energy barrier for ^*NH₂ dehydrogenation, thereby synergistically accelerating both H₂ generation and urea decomposition. This work provides new insights into the design of alloy electrocatalysts for high-efficiency H₂ production.

Key words: Hydrogen evolution reaction, Urea oxidation reaction, Pt@PtNi₃ core@shell alloy, Asymmetric acid-alkaline catalysis, Antibonding orbital occupancy