Regulating the metal-support interactions of Ru on hollow nitrogen-doped carbon to enhance the hydrogen evolution reaction activity

• • Ru/H-NC annealed at 300 °C achieves an overpotential of 35.45 mV at 10 mA/cm² with an ultralow Ru loading of 24.03 μg/cm² on glassy carbon, outperforming commercial Pt/C under alkaline conditions and reducing precious metal usage by over 90%. • • XPS analysis confirms that increasing annealing temperature from 200 to 400 °C progressively strengthens MSIs, with electron transfer from Ru to H-NC support, enabling precise tuning of Ru valence state for optimized HER activity. • • Electrochemical impedance spectroscopy reveals that HER kinetics (charge-transfer resistance) first decrease then increase with MSI enhancement, with the optimal MSI at 300 °C yielding the lowest Rct, directly correlating with the volcano-type activity trend. • • DFT calculations demonstrate that MSIs modulate the adsorption free energies of H* and HO* intermediates on Ru clusters, achieving near-thermoneutral ΔG_H* (≈0 eV) and reduced water dissociation barriers, which is critical for alkaline HER where water dissociation is rate-limiting.