Interfacial electronic metal-support interaction and hydroxyl spillover synergy in Ru/MoC heterojunctions for accelerated alkaline hydrogen evolution

The hydrogen evolution reaction (HER) in alkaline media is hindered by sluggish water dissociation and strong hydroxyl (*OH) poisoning, requiring catalysts that deliver both high activity and long-term stability. Here we design 3% Ru/MoC heterojunctions that operate via a causally coupled interfacial mechanism, in which electronic metal-support interaction (EMSI) reshapes the interfacial thermodynamic landscape that governs the feasibility and directionality of hydroxyl spillover. Uniform Ru nanoclusters anchored on MoC nanorods establish EMSI, leading to a downshift of the Ru d-band center and moderated *OH binding. Meanwhile, the MoC support accommodates hydroxyl species and facilitates their spillover away from Ru sites, mitigating surface poisoning. As a result, 3% Ru/MoC delivers an overpotential of 35 mV at 10 mA cm −2 and a Tafel slope of 35 mV dec −1 in 1 M KOH, while retaining nearly unchanged activity over 1800 min. As the cathode in anion exchange membrane water electrolyzers (AEMWE), it sustains stable hydrogen production for 120 h at current densities up to 500 mA cm −2 at 80 °C. In situ spectroscopy and density functional theory (DFT) confirm that interfacial thermodynamic modulation correlates with spontaneous hydroxyl spillover and sustained surface regeneration during alkaline HER. This study establishes a quantitative interfacial design principle for spillover-enabled catalysis, linking atomic-scale thermodynamics with device-level durability. 3% Ru/MoC heterojunctions integrate electronic metal-support interaction (EMSI) and hydroxyl spillover, enabling interfacial charge redistribution and *OH spillover. EMSI weakens Ru-*OH binding while spillover directs *OH to MoC, preserving active Ru sites. Download: Download high-res image (184KB) Download: Download full-size image