Interfacial water regulation on Ru single atoms doped Co₃O₄ toward efficient electrochemical hydrogenation of quinoxaline.

Abstract

Electrochemical hydrogenation of quinoxaline presents a promising alternative to traditional methods, yet is suffering from low current density and Faradaic efficiency due to the hampered hydrogenation process. Herein, we develop a cocatalytic system of Ru single atoms doped Co₃O₄ nanosheet (Ru_SA/ns-Co₃O₄) to optimize the interfacial H₂O behavior by tuning the Ru single atoms concentration for accelerating the electrochemical hydrogenation of quinoxaline, which enables remarkable Faradaic efficiency of 82% toward 1,2,3,4-tetrahydroquinoxaline at high current density of 200 mA cm^-2. Detailed experimental and theoretical studies reveal that Ru single atoms trigger interfacial charge redistribution, inducing an asymmetric local electric field that reconstructs interfacial H₂O molecules into an H-down configuration. This reorientation remodels the hydrogen-bonded water network, shortens the distance between hydrogen atoms and the Co₃O₄ surface, regulates K•H₂O availability, and enhances H₂O dissociation to supply H*. Consequently, the membrane electrode assembly electrolyser exhibits a long-term stability of >100 h at 200 mA cm^-2. Our findings highlight the prospect of interfacial water microenvironment for electrochemical hydrogenation of unsaturated N-heterocyclic compounds, with promising applications for the electrosynthesis of other valuable chemicals.