Interfacial engineering passivation-resistant NiMoO₄-Ru heterointerface with modulated electronic structure for...

The practical implementation of the sulfide oxidation reaction (SOR) for energy-saving hydrogen production is severely hindered by the rapid sulfur passivation of electrocatalysts, which originates from the over-binding of sulfur intermediates. Herein, we report a rational interface engineering strategy to tackle this challenge by constructing a three-dimensional Ru/NiMoO₄ heterostructure on nickel foam (Ru/NiMoO₄-R/NF). Comprehensive investigations through X-ray photoelectron spectroscopy and X-ray absorption fine structure analyses reveal a strong electronic coupling at the heterointerface, which induces a spontaneous charge transfer from Ru to NiMoO₄. This interfacial electronic modulation successfully generates electron-deficient Ru^δ+ sites with a downshifted d-band center, as verified by density functional theory (DFT) calculations. The optimized electronic structure effectively weakens the adsorption energy of sulfur species, thereby fundamentally mitigating surface passivation. As a result, the Ru/NiMoO₄-R/NF electrode exhibits exceptional SOR activity, requiring an ultralow potential of only 0.338 ± 0.005 V to achieve 100 mA cm^-2, and remarkable long-term stability for over 360 h. In-situ Raman spectroscopy provides direct evidence of the rapid consumption of polysulfide intermediates without observable surface poisoning. When integrated as a bifunctional catalyst in a two-electrode flow cell for overall sulfide electrolysis, the system achieves 720 mA cm^-2 at a cell voltage of only 0.94 ± 0.01 V (70 °C) with robust 160-h stability. This work establishes a heterointerface-driven electronic modulation strategy to overcome the intrinsic passivation challenge in noble-metal SOR catalysis.