Non‐Local Electronic Perturbation at Low‐Coordinated Ru Sites Boosts N ₂ Photoreduction

Atomic‐level regulation of the coordination environment in single‐atom catalysts (SACs) remains a significant challenge in heterogeneous photocatalysis. This study presents a second‐shell engineering strategy through the insertion of oxygen into the secondary coordination sphere of low‐coordinated Ru‐N 2 sites, creating a non‐local electronic perturbation distinct from conventional first‐shell modification. The distal oxygen atom functions as a remote electron pump through the C─O─N bridging network, increasing the electron density at the Ru site and enhancing Ru d π‐N p π back‐donation interactions. This strengthened π‐back‐donation induces an asymmetric charge distribution between the proximal and distal nitrogen atoms of adsorbed N 2 , weakening the N≡N bond and reducing the rate‐determining step barrier from 1.034 to 0.822 eV while maintaining optimal product desorption. Consequently, Ru─O─CN achieves an ammonia evolution rate of 767.52 µmol ·g − 1 ·h − 1 under visible light irradiation, representing a 2.64‐fold enhancement over Ru─CN and approximately 150‐fold improvement compared to pristine g‐C 3 N 4 . This work demonstrates that non‐local coordination engineering through second‐shell heteroatom doping provides an effective approach for fine‐tuning the electronic structure of SACs.