Achieving 78.2 % Faraday Efficiency for Electrochemical Ammonia Production Via Covalent Modification of CNTs with B4C

Abstract Electrochemical reduction of N 2 to NH 3 provides an alternative to the Haber‐Bosch process for sustainable NH 3 production driven by renewable electricity. Here, we reported carbon nanotubes (CNTs) covalently modified with boron carbide (B 4 C) as a nonmetallic catalyst for efficient electrochemical nitrogen reduction reaction (NRR) under ambient conditions. The structure of the catalyst was characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), elemental mapping, X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The catalyst held a superior selectivity for NRR with high Faraday efficiency of 78.2 % accompanying with NH 3 yield rate of 14.0 μg mg −1 cat. h −1 under the condition of 0.1 M Na 2 SO 4 and −0.6 V vs. RHE. Electrochemical experiments including cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization curves were performed to explain the best electrochemical properties of B 4 C/CNTs among the samples. This work demonstrates that the strategy of covalent modification plays an important role to improve the selectivity of electrochemical NRR catalyst, thus allowing the reactions to proceed more efficiently.