MoC nanocrystals confined in N-doped carbon nanosheets toward highly selective electrocatalytic nitric oxide reduction to ammonia
Ge Meng, Mengmeng Jin, Tianran Wei, Qian Liu, Shusheng Zhang, Xianyun Peng, Jun Luo, Xijun Liu
Abstract
Electrochemical nitric oxide reduction reaction (NORR) to produce ammonia (NH3) under ambient conditions is a promising alternative to the energy and carbon-intensive Haber-Bosch approach, but its performance is still improved. Herein, molybdenum carbides (MoC) nanocrystals confined by nitrogen-doped carbon nanosheets are first designed as an efficient and durable electrocatalyst for catalyzing the reduction of NO to NH3 with maximal Faradaic efficiency of 89% ± 2% and a yield rate of 1,350 ± 15 µg·h−1·cm−2 at the applied potential of −0.8 V vs. reversible hydrogen electrode (RHE) as well as high stable activity with negligible current density and NH3 yield rate decays over a 30 h continue the test. Moreover, as a proof-of-concept of Zn−NO battery, it achieves a peak power density of 1.8 mW·cm−2 and a large NH3 yield rate of 782 ± 10 µg·h−1·cm−2, which are comparable to the best-reported results. Theoretical calculations reveal that the MoC(111) has a strong electronic interaction with NO molecules and thus lowering the energy barrier of the potential-determining step and suppressing hydrogen evolution kinetics. This work suggests that Mo-based materials are a powerful platform providing great opportunities to explore highly selective and active catalysts for NH3 production.