Proton-filtering covalent organic frameworks with superior nitrogen penetration flux promote ambient ammonia synthesis

The simultaneous achievement of both high ammonia yield and Faradaic efficiency in electrochemical nitrogen reduction is a long-sought-after goal. However, due to the strong competing hydrogen evolution and extremely low solubility of N-2 in aqueous systems, thermodynamic modulation at the catalyst level is insufficient, leaving the current performance still far from practical application. Here, we rationally control the diffusion of the reactants to obtain suppressed proton supply and greatly enhanced nitrogen flux using proton-filtering covalent organic frameworks, forcing a highly selective and active nitrogen reduction. In this proof-of-concept system, we achieved a high performance in the electrochemical ammonia synthesis (ammonia yield rate 287.2 +/- 10.0 mu g h(-1) mg(cat)(-1)Faradaic efficiency 54.5 +/- 1.1%) using a traditional carbon-based catalyst. The proposed strategy successfully optimizes the mass transfer that greatly facilitates nitrogen reduction, providing powerful guidelines for achieving green ammonia production at a more practical level.

Automated summary

By controlling the diffusion of reactants and using proton-filtering covalent organic frameworks, a highly selective and active nitrogen reduction was achieved in electrochemical ammonia synthesis. This strategy optimizes mass transfer and provides guidelines for practical green ammonia production.