d-Band Optimized Hydrogen Adsorption and Dynamic Reconstruction-Accelerated Oxygen Evolution on RuS2/(FeNi)S1.03 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 RuS 2 /(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 RuS 2 component exclusively optimizes HER through static electronic modulation, where interfacial electron transfer at RuS 2 /(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 RuS 2 (RuS 2 /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.