Core‐Periphery Fullerene Architectures Engineer Catalytic Interfaces for Efficient Neutral Hydrogen Evolution

Neutral hydrogen evolution is governed by coupled active‐site and solvent processes, posing a great challenge for catalyst design. Here, ultrasmall Ru nanoclusters are anchored on a sulfonated fullerene scaffold (Ru/C 60 ‐S), exploiting its core‐periphery architecture to couple active‐site energetics with interfacial hydration. Electronic interaction with the fullerene cage polarizes Ru sites, facilitating water activation and moderating H/OH binding, while the sulfonated periphery establishes a less ordered and more field‐responsive interfacial hydrogen‐bond network. Ru/C 60 ‐S requires only 10 mV to reach 10 mA cm −2 , sustains 100 mA cm −2 for over 1000 h in phosphate‐buffered solution, and exhibits minimal activity loss from alkaline to neutral media. Molecular dynamics simulations, operando Raman, in situ FTIR and local pH measurements corroborate this interfacial restructuring under neutral HER conditions. Targeted perturbation of the fullerene periphery rigidifies the hydrogen‐bond network and is accompanied by increased isotope sensitivity, slower interfacial kinetics, and diminished HER activity. These results identify interfacial hydration as a kinetically important component of neutral HER and demonstrate a core‐periphery molecular strategy for cooperatively regulating active‐site energetics and solvent organization.