Ruthenium Ion‐Complexed Graphitic Carbon Nitride Nanosheets Supported on Reduced Graphene Oxide as High‐Performance Catalysts for Electrochemical Hydrogen Evolution

Carbon‐based materials are promising, low‐cost electrocatalysts toward hydrogen evolution reaction (HER), although the catalytic performance needs to be further improved before commercialization. In this study, ruthenium ions are incorporated into graphitic carbon nitride/reduced graphene oxide (rGO) hybrids to form Ru−C 3 N 4 /rGO composites through Ru−N coordination bonds. The incorporation of Ru ions, at a loading of 1.93 at. %, leads to electron redistribution within the materials and dramatically enhances the HER performance over those of C 3 N 4 , C 3 N 4 /rGO, and Ru−C 3 N 4 , with an overpotential of only −80 mV to reach a current density of 10 mA cm −2 , a Tafel slope of 55 mV dec −1 , and an exchange current density of 0.462 mA cm −2 . This performance is comparable to that of Pt/C, and ascribed to the positive shift of the conduction band of the composite, where the charge carrier density increases by a factor of about 250 over that of C 3 N 4 , leading to a lower energy barrier for hydrogen evolution. The results suggest a new strategy in the design and engineering of functional nanocomposites for effective HER electrocatalysis by embedding select metal ions into carbon‐based molecular skeletons.