Intrinsic Ni⁰-Ni^δ+ Pairs in Anti-Perovskite NiNNi₃ Act as Hydrogen Radical Emitters for Cu Enabling Promoted...

Electrocatalytic nitrate reduction (NO₃RR) enables ambient-condition ammonia production, while ampere-level application is still limited by the unsatisfactory efficiency due to the insufficient *H supply for rapid *NO hydrogenation. Herein, we tackled this challenge by constructing the NiNNi₃/Cu heterostructure catalyst that utilizes the substantial electrostatic potential differences derived from the intrinsic Ni⁰-Ni^δ+ pairs in anti-perovskite NiNNi₃ to accelerate the O─H bond cleavage for *H generation, enhancing NO₃RR. Consequently, the NiNNi₃/Cu delivers 1.2 A cm^-2 with 100 ± 0.7% Faradaic efficiency (FE) at ultralow +0.05 V_RHE. The paired electrosynthesis by coupling NO₃RR with formaldehyde oxidation yields 500 mA cm^-2 at a low cell voltage of 0.8 V, with 95% NH₃-FE and 90% formate-FE. Importantly, industrial-level application is further demonstrated by a flow cell with 25 cm² electrode that delivers 20 A, and produces 64 g NH₄Cl for 20 h. This work provides a novel rationale for catalyst design that can boost *H density to accelerate hydrogenation kinetics for advanced electrosynthesis applications.