Efficient Electrochemical N2 Fixation over Donor-Acceptor FeEu─N4 Active Site.

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) represents a promising approach to sustainable ammonia production, but the low Faradaic efficiency (FE) and poor ammonia yield rate limit its practical application. This work demonstrates an innovative FeEu─NC catalyst that leverages distinct donor-acceptor electron pairs between Fe and Eu atoms to significantly enhance the electrocatalytic NRR. The FeEu─NC catalyst demonstrates an outstanding ammonia yield of 221.6 µg h^-1 mg_cat ^-1 and a Faradaic efficiency of 61.1%, surpassing most previously reported NRR catalysts. Comprehensive experimental characterization indicates that electron transfer from Eu to Fe atoms weakens the N≡N bond, enhances N₂ activation, and reduces the energy barrier of the potential-determining step, compared to Fe─NC. Furthermore, the difference in limiting potentials between the hydrogen evolution reaction (HER) and NRR suggests that the FeEu─NC catalyst prioritizes NRR over HER, enhancing its efficiency for ammonia synthesis. This work provides a blueprint for constructing highly active and selective electrocatalysts by exploiting intermetallic electron transfer, offering significant insights into the design of efficient electrochemical nitrogen fixation systems.