Interface-mediated electronic modulation of ruthenium@ruthenium phosphide heterojunction on hollow mesoporous carbon spheres for efficient hydrogen evolution in alkaline and acidic media

The advancement of hydrogen energy technologies depends on the development of stable and effective electrocatalysts for the hydrogen evolution reaction (HER) in both acidic and alkaline conditions. Ru-based materials show promise as substitutes for platinum, yet performance optimization is hindered by challenges in rational active-site design and heterostructure construction. Herein, a Ruthenium@Ruthenium Phosphide (Ru@Ru₂P) heterojunction supported on hollow mesoporous carbon spheres (HMCS) was successfully fabricated through a template-assisted pyrolysis-in situ phosphination strategy. This architecture integrates well-dispersed heterojunction nanoparticles with a conductive carbon framework. The catalyst exhibits exceptional activity and stability, achieving low overpotentials of 18.0 mV in 1.0 M KOH and 47.0 mV in 0.5 M H₂SO₄ at 10 mA cm⁻², along with stable operation for 45 h at 50 mA cm⁻². Combined experimental and theoretical analyses show that interfacial charge transfer from Ru to Ru₂P effectively modulates the electronic structure of Ru₂P active sites, favoring H-O bond cleavage and optimizing hydrogen adsorption free energy to −0.18 eV. This study demonstrates that interfacial electronic engineering is a feasible strategy for rational catalyst design by developing a highly active and durable Ru-based heterojunction electrocatalyst.