Correlating Single‐Atomic Ruthenium Interdistance with Long‐Range Interaction Boosts Hydrogen Evolution Reaction Kinetics

Abstract Correlated single‐atom catalysts (c‐SACs) with tailored intersite metal–metal interactions are superior to conventional catalysts with isolated metal sites. However, precise quantification of the single‐atomic interdistance (SAD) in c‐SACs is not yet achieved, which is essential for a crucial understanding and remarkable improvement of the correlated metal‐site‐governed catalytic reaction kinetics. Here, three Ru c‐SACs are fabricated with precise SAD using a planar organometallic molecular design and π–π molecule–carbon nanotube confinement. This strategy results in graded SAD from 2.4 to 9.3 Å in the Ru c‐SACs, wherein tailoring the Ru SAD into 7.0 Å generates an exceptionally high turnover frequency of 17.92 H₂ s⁻¹ and a remarkable mass activity of 100.4 A mg⁻¹ under 50 and 100 mV overpotentials, respectively, which is superior to all the Ru‐based catalysts reported previously. Furthermore, density functional theory calculations confirm that Ru SAD has a negative correlation with its d‐band center owing to the long‐range interactions induced by distinct local atomic geometries, resulting in an appropriate electrostatic potential and the highest catalytic activity on c‐SACs with 7.0 Å Ru SAD. The present study promises an attractive methodology for experimentally quantifying the metal SAD to provide valuable insights into the catalytic mechanism of c‐SACs.