Atomically Dispersed Zinc(I) Active Sites to Accelerate Nitrogen Reduction Kinetics for Ammonia Electrosynthesis

Abstract

Abstract Developing highly active and stable nitrogen reduction reaction (NRR) catalysts for NH 3 electrosynthesis remains challenging. Herein, an unusual NRR electrocatalyst is reported with a single Zn(I) site supported on hollow porous N‐doped carbon nanofibers (Zn 1 N–C). The Zn 1 N–C nanofibers exhibit an outstanding NRR activity with a high NH 3 yield rate of ≈16.1 µg NH 3 h −1 mg cat −1 at −0.3 V and Faradaic efficiency (FE) of 11.8% in alkaline media, surpassing other previously reported carbon‐based NRR electrocatalysts with transition metals atomically dispersed and nitrogen coordinated (TM‐N x ) sites. 15 N 2 isotope labeling experiments confirm that the feeding nitrogen gas is the only nitrogen source in the production of NH 3 . Structural characterization reveals that atomically dispersed Zn(I) sites with Zn–N 4 moieties are likely the active sites, and the nearby graphitic N site synergistically facilitates the NRR process. In situ attenuated total reflectance‐Fourier transform infrared measurement and theoretical calculation elucidate that the formation of initial *NNH intermediate is the rate‐limiting step during the NH 3 production. The graphitic N atoms adjacent to the tetracoordinate Zn–N 4 moieties could significantly lower the energy barrier for this step to accelerate hydrogenation kinetics duing the NRR.