LAUSR

Electrocatalytic nitrogen reduction (NRR) to produce ammonia (NH3 ) at ambient conditions is a promising alternative for the Haber-Bosch process. However, developing highly active and stable NRR catalysts to replace precious metals remains challenging. Herein, we report an unusual NRR electrocatalyst with a single Zn(I) site supported on hollow porous N-doped carbon nanofibers (Zn1 N-C). The Zn1 N-C nanofibers exhibit an outstanding NRR activity with a high NH3 yield rate of ∼16.1 μg NH3 h-1 mgcat -1 at -0.3 V and Faradaic efficiency (FE) of 11.8% in alkaline media, surpassing other previously reported carbon-based NRR electrocatalysts in which the transition metal is dispersed atomically and anchored at nitrogen (TM-Nx ) sites. 15 N2 isotope labeling experiments confirm that the feeding gas is the only nitrogen source in the production of NH3 . Structural characterizations reveal that atomically dispersed Zn(I) sites with Zn-N4 moieties serve as real active sites, and nearby graphitic N site synergistically facilitates the NRR activity. In situ attenuated total reflectance-Fourier transform infrared measurement and theoretical calculation demonstrate that the formation of initial *NNH intermediate is the rate-limiting step toward NH3 generation. It also indicates the graphitic N atom adjacent to the tetracoordinate Zn-N4 center significantly lowers the energy barrier for this process to accelerate hydrogenation kinetics. This article is protected by copyright. All rights reserved.