Atomically dispersed dual frustrated Lewis pairs for efficient relay conversion of nitrate into ammonia

Electrocatalytic nitrate reduction holds great promise for ammonia synthesis. However, the unbalanced adsorption and activation behaviors of intermediates as well as the slow conversion kinetics significantly limit the efficiency. Herein, we design the unusual atomically-dispersed dual frustrated Lewis pairs (AD-FLPs) on the Cu-Co diatomic catalyst (Cu/Co-CN). In Cu/Co-CN, atomically dispersed electron-deficient Cu and adjacent electron-rich N atom serve as Lewis acid and Lewis base site to form N···Cu_SA frustrated Lewis pairs (FLPs), respectively, while Co and N atoms form N···Co_SA FLPs. Noteworthily, N···Cu_SA FLPs preferentially adsorb NO₃^- while N···Co_SA FLPs preferentially adsorb NO₂^-, forming the unique Cu−O−N-O−N and Co−O−N-O−N structures with strong d-p interactions, respectively. These structures induce a push-pull electronic effect for the complementary activation of NO₃^- and NO₂^-. Moreover, AD-FLPs enable the balanced relay reaction kinetics (K₁/K₂=0.95) for conversion of NO₃^- to NO₂^- (K₁) and NO₂^- to NH₃ (K₂), exceeding the single N···Cu_SA FLPs (K₁/K₂=7.1) or single N···Co_SA FLPs (K₁/K₂=0.6), accelerating key intermediates conversion kinetics and achieving rapid relay conversion. As a result, Cu/Co-CN exhibits an ultrahigh NH₃ evolution rate of 482.56 mmol·g⁻¹·h⁻¹ with a Faradaic efficiency of 96 %. This work opens a new chapter for designing high-efficiency FLPs catalysts and exploring structure-activity relationships at the single-atom scale.