d‐Band Optimized Hydrogen Adsorption and Dynamic Reconstruction‐Accelerated Oxygen Evolution on RuS ₂ /(FeNi)S _1.03 Heterointerfaces for Water/Seawater Splitting

Designing efficient bifunctional electrocatalysts for the kinetically divergent hydrogen and oxygen evolution reactions (HER/OER) is challenging due to their conflicting interfacial requirements. Herein, precisely engineered RuS₂/(FeNi)S_1.03 heterointerfaces are constructed via homogeneous chelation-coupled in situ sulfidation, enabling distinct interfacial mechanisms that independently enhance HER and OER. For HER, the RuS₂ component exclusively optimizes HER through static electronic modulation, where interfacial electron transfer at RuS₂/(FeNi)S_1.03 interface downshifts the Ru d-band center to -1.99 eV and weakens hydrogen adsorption ( 0.51 eV). This yields superior HER activity with an overpotential of 270 mV@ at 50 mA cm^-2. Conversely, for OER, the (FeNi)S_1.03 phase undergoes dynamic reconstruction, transforming into an OER-catalytically active Fe-NiO oxide with stable RuS₂ (RuS₂/Fe-NiO interfaces) that reduce intermediate energy barriers and delivers an overpotential of 300 mV at 50 mA cm^-2. This dual-interface synergy enables outstanding bifunctional performance with low cell voltages (1.68 V alkaline water; 1.76 V seawater) and industrial stability (>250 h at 1000 mA cm^- ²), resolving the mechanistic conflict in bifunctional catalyst design.