Correlating Single-atomic Ruthenium Inter-distance With Long-range Interaction Boosts Hydrogen Evolution Reaction Kinetics.

Correlated single-atom catalysts (c-SACs) with tailored inter-site metal-metal interactions are superior to conventional catalysts with isolated metal sites. However, precise quantification of the single-atomic inter-distance (SAD) in c-SACs has not yet been achieved, which is essential for a crucial understanding and remarkable improvement of the correlated metal site-governed catalytic reaction kinetics. In this study, we fabricated three Ru c-SACs with precise SAD using a planar organometallic molecular design and π-π molecule-carbon nanotube confinement. This strategy results in graded SAD from 2.4-9.3 Å in the Ru c-SACs, wherein tailoring the Ru SAD into 7.0 Å generates an exceptionally high turnover frequency of 17.92 H 2 per second and a remarkable mass activity of 100.4 A mg -1 under 50 and 100 mV overpotential, 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. This article is protected by copyright. All rights reserved.