Iron-doped ruthenium with a good interfacial environment achieving superior hydrogen evolution activity under alkaline conditions†

Electrocatalytic water splitting, a promising alternative to fossil fuels, has substantial potential for hydrogen generation. However, developing efficient electrocatalysts for the hydrogen evolution reaction (HER) faces challenges, especially in alkaline environments due to slow kinetics. Herein, we report supported ruthenium particles with iron alloying (RuFe/FeNC) as an effective HER catalyst under alkaline conditions. RuFe/FeNC demonstrates an ultralow overpotential of 9.3 mV and a high turnover frequency (TOF) of 1.35 H₂ s⁻¹ at −0.025 V_RHE, obviously surpassing the benchmark 20% Pt/C. Our analysis, employing techniques such as electrochemistry, in situ spectroscopic techniques, density functional theory, and ab initio molecular dynamics, shows that Fe sites modulate the electrode–electrolyte interface microstructure effectively. This modulation increases the population of H-down interfacial water molecules, weakening hydrogen-bond interactions over the catalyst surface and enhancing water dissociation at Ru sites. Additionally, it creates electron-rich Ru sites and electron-deficient Fe sites. Ru sites optimize hydrogen adsorption Gibbs free energy, acting as proton aggregators, while Fe sites collect hydroxides, mitigating adverse site blocking effects on Ru sites. Integrating these factors is crucial for the high HER activity of RuFe/FeNC, offering a new perspective on enhancing HER performance by controlling interfacial structure through doping.