Boosting Nitrogen Reduction Reaction via Electronic Coupling of Atomically Dispersed Bismuth with Titanium Nitride Nanorods

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) is a promising alternative to the traditional Haber-Bosch process. However, the sluggish kinetics and competitive hydrogen evolution reaction result in poor NH₃ yield and low Faradaic efficiency (FE). Herein, single bismuth atoms incorporated hollow titanium nitride nanorods encapsulated in nitrogen-doped carbon layer (NC) supported on carbon cloth (NC/Bi SAs/TiN/CC) is constructed for electrocatalytic NRR. Impressively, as an integrated electrode, it exhibits a superior ammonia yield rate of 76.15 µg mg_cat ^-1 h^-1 (9859 µg μmol_Bi ^-1 h^-1 ) at -0.8 V versus RHE and a high FE of 24.60% at -0.5 V versus RHE in 0.1 m Na₂ SO₄ solution, which can retain stable performance in 10 h continuous operation, surpassing the overwhelming majority of reported Bi-based NRR catalysts. Coupling various characterizations with theory calculations, it is disclosed that the unique monolithic core-shell configuration with porous structure endows abundant accessible active sites, outstanding charge-transfer property, and good stability, while the cooperation effect of Bi SAs and TiN can simultaneously promote the hydrogenation of N₂ into NH₃ * on the TiN surface and the desorption of NH₃ ^* to release NH₃ on the Bi SA sites. These features result in the significant promotion of NRR performance.