Ru atom-modified Co4N-CoF2 heterojunction catalyst for high-performance alkaline hydrogen evolution

D-band-center control engineering, particularly combining both cation and anion intercalations towards heterostructure formation with simultaneous usage of Ru, N as well as F species, for optimal electronic structure as efficient hydrogen evolution reaction (HER) catalysts remains a daunting challenge but critical for renewableenergy technologies. Herein, we lay emphasis on the design of active-site electronic structure based on dband-center shift through the construction of Co4N-CoF2 heterostructure coupled with Ru doping (Ru/Co4NCoF2). Solvothermal coordination reaction followed by annealing course causes cooccurrence of F, N, Ru in Co neighborhood. As-obtained Ru/Co4N-CoF2 exhibits superior HER activity in alkaline electrolyte with overpotential as low as 53 mV to yield a current density of 10 mA cm(-2) which is close to that of commercial Pt/C, outperforming many transition-metal-based catalysts recent-reported. Moreover, it still presents good durability with continuous operation of 22 h in 1.0 M KOH. Such excellent performance is ascribed to appropriate electron structure of Ru/Co4N-CoF2 for optimized hydrogen binding abilities on Co/Ru sites as confirmed by synchrotronbased X-ray adsorption near-edge structure and X-ray photoelectron spectroscopies. This study not only establishes highly active electrocatalysts by impacting d-band center of active sites but also provides valuable insights into the synergistic-effect protocol of doping and heterostructure strategies for d-band-center shifting.