Unraveling the Mechanism of Coordination Engineering in Ni‐N ₂ O ₂ Heterogeneous Molecular Catalysts for H ₂ O ₂ Electrosynthesis

ABSTRACT Sustainable electrosynthesis of H 2 O 2 via two‐electron oxygen reduction reaction on Ni single atom catalysts (SACs) offers a promising alternative to the traditional anthraquinone technology. However, the limited understanding of the structure‐activity relationship of Ni SAC in the oxygen reduction reaction hinders the rational design of high‐performance catalysts for industrially relevant H 2 O 2 production. Herein, we report a series of heterogeneous molecular Ni‐N 2 O 2 catalysts (Ni‐N 2 O 2 HMCs) with precisely modulated electronic structure through non‐first coordination shell engineering. This strategy systematically reveals the intrinsic correlation among electronic configuration (oxidation/spin state), electrochemical stability, and catalytic performance. The optimized low‐spin Ni‐DPP HMC with extended conjugation achieves >90% selectivity for H 2 O 2 across a wide potential range (0.7–0.2 V vs RHE), reaching 97% at 0.5 V, and delivers a record‐high production rate of 52.13 mol g cat −1 h −1 at an industrially relevant current density of 800 mA cm −2 in a flow cell. In situ spectroscopy and DFT calculations reveal that Ni‐DPP modulates the *OOH adsorption, optimizing the balance between activity and selectivity. These findings provide key insights for the rational design of SACs for efficient H 2 O 2 electrosynthesis.