Interface charge engineering in Pd₃Sn/Ru heterostructures for ultra-efficient wide-pH hydrogen evolution

Noble metal catalysts (e.g., Pt, Pd) are crucial for efficient water-splitting hydrogen production, yet their pH-dependent performance and stability hinder large-scale use. Although they exhibit excellent hydrogen evolution reaction (HER) activity in acidic conditions, their slow hydrolysis kinetics in alkaline environments-due to limited free protons (H⁺)-restrict practical applications. To address these challenges, this work designs a Pd₃Sn/Ru heterostructure catalyst exhibiting wide-pH HER activity, particularly exhibiting almost identical HER activity in acidic and alkaline electrolytes. Density functional theory calculations reveal that interfacial charge redistribution (Δq = 0.51 e^-/Pd₃Sn) induces modulation of the d-band center, optimizing the hydrogen adsorption free energy (ΔG_H = -0.06 eV) and thereby significantly enhancing HER kinetics. Electrocatalytic experiments validate that the Pd₃Sn/Ru heterostructure achieves ultralow overpotentials of 20 mV in 0.5 M H₂SO₄ and 22 mV in 1.0 M KOH at 10 mA cm^-2, substantially surpassing the performance of Pd₃Sn (36 mV) and Ru (73 mV), while exceeding commercial platinum. The heterostructure maintains exceptional stability with minor performance degradation after 100 h of continuous operation in both acidic and alkaline conditions, achieving Faradaic efficiency of 99 %. These results establish a heterointerface engineering strategy to overcome noble metals' pH limitations, enabling practical water-splitting applications.