Regulative Electronic States around Ruthenium/Ruthenium Disulphide Heterointerfaces for Efficient Water Splitting in Acidic Media

Abstract Theoretical calculations unveil the charge redistribution over abundant interfaces and the enhanced electronic states of Ru/RuS 2 heterostructure. The resulting surface electron‐deficient Ru sites display optimized adsorption behavior toward diverse reaction intermediates, thereby reducing the thermodynamic energy barriers. Experimentally, for the first time the laminar Ru/RuS 2 heterostructure is rationally engineered by virtue of the synchronous reduction and sulfurization under eutectic salt system. Impressively, it exhibits extremely high catalytic activity for both OER (201 mV @ 10 mA cm −2 ) and HER (45 mV @ 10 mA cm −2 ) in acidic media due to favorable kinetics and excellent specific activity, consequently leading to a terrific performance in acidic overall water splitting devices (1.501 V @ 10 mA cm −2 ). The in‐depth insight into the internal activity origin of interfacial effect could offer precise guidance for the rational establishment of hybrid interfaces.