Chlorine-mediated construction of monometallic Ru–RuO2 with abundant interfaces for efficient pH-universal hydrogen evolution catalysis

Abstract

The precise construction of highly dispersed monometallic composites with abundant grain boundaries, beyond conventional gradient or core–shell structures, remains a key challenge. Herein, we report a chlorine-mediated strategy to achieve monometallic Ru–RuO₂ featuring a high density of well-defined heterointerfaces. By leveraging the distinct binding energies of Ru–O and Ru–Cl, a controlled in situ reduction process selectively converts Cl-occupied regions in a RuOCl precursor into metallic Ru domains, yielding an intimately interwoven Ru/RuO₂ heterostructure. This unique architecture provides a high density of interfacial active sites, leading to exceptional pH-universal hydrogen evolution reaction (HER) performance. The optimized Ru/RuO₂ catalyst achieves remarkably low overpotentials of 22, 54, and 26 mV at 10 mA cm⁻² in 1 M KOH, 1 M phosphate buffer solution (PBS), and 0.5 M H₂SO₄, respectively, surpassing commercial Pt/C. Density-functional-theory (DFT) calculations illustrated that the remarkable HER activity stems from synergistic metal–oxide interactions: RuO₂ promotes efficient water dissociation, while adjacent metallic Ru sites optimize hydrogen adsorption, collectively accelerating the HER kinetics. This work provides a general design strategy for constructing high-performance heterointerface-enriched electrocatalysts.