Fe‐based catalysts for nitrogen reduction toward ammonia electrosynthesis under ambient conditions

Abstract

As one of the most important chemicals and carbon‐free energy carriers, ammonia (NH3) has significant energy‐related applications in industry and agriculture. Ninety percent of NH3 is produced by the Haber–Bosch process using high‐purity N2 and H2 at high temperatures and pressures, which consumes about 1% of the total energy production and causes 1.4% of global CO2 emissions. The environmentally friendly electrochemical nitrogen reduction reaction (NRR) with low energy consumption is a promising alternative to the conventional Haber–Bosch process. However, the main issue is the low Faradaic efficiency and NH3 selectivity of electrochemical NRR, caused by inert nitrogen molecules and competitive hydrogen evolution reaction. As one of the cheapest and most abundant transition metals widely utilized in the Haber–Bosch process, the Fe element has presented the potential high performance for the electrochemical NRR. This article summarizes recent advances and research progress in non‐noble Fe‐based catalysts used for NH3 electrosynthesis. Various synthetic protocols, structure/morphology modification, performance improvement, and reaction mechanisms are comprehensively presented. Based on recent experimental and theoretical studies, we aim to illuminate the structure–property relationship and offer an excellent opportunity for engineering advanced Fe‐based catalysts for nitrogen fixation. The most critical challenges and opportunities for Fe‐based catalysts are also provided. This review would open up a promising avenue toward developing platinum‐group‐metal‐free catalysts for electrochemical NRR applications in the future.

Deciphering Electrolyte Selection for Electrochemical Reduction of Carbon Dioxide and Nitrogen to High‐Value‐Added Chemicals

“…Thus, it is of essential significance to develop novel strategies to overcome the drawback of the aqueous electrolytes for their less gas solubility and larger proton concentrations. [ 92 ]…”

“…summarized recent advances and research progress in non‐noble Fe‐based catalysts applied in NRR and found that Fe‐based catalysts are excellent candidates for NH 3 synthesis, particularly for neutral electrolytes with lower potential. [ 92,93 ] Liu et al. reported a Fe single‐atom catalyst (SACs) for NRR and obtained a high FE of 18.6 ± 0.8% and NH 3 yield rate of 62.9 ± 2.7 µg h −1 mg −1 in neutral 0.1 m PBS electrolyte at room temperature and −0.4 V versus RHE.…”

“…[91] Wu et al summarized recent advances and research progress in non-noble Fe-based catalysts applied in NRR and found that Fe-based catalysts are excellent candidates for NH 3 synthesis, particularly for neutral electrolytes with lower potential. [92,93] [90] Copyright 2018, The Authors, Published by Springer Nature. c) NH 3 yields of Ni-Fe-MoS 2 and MoS 2 in 2 h at those potentials.…”

Promoting ZIF-8-Derived Fe–N–C Oxygen Reduction Catalysts via Zr Doping in Proton Exchange Membrane Fuel Cells: Durability and Activity Enhancements

“…The approach may further provide a solution to design dual-metalsite catalysts for other critical electrocatalysis processes such as oxygen reduction to H 2 O 2 , 47 CO 2 reduction, 48 and nitrogen electrochemical reactions. 49,50 ■ ASSOCIATED CONTENT * sı Supporting Information…”

“…This study demonstrated an effective strategy for a carbon catalyst doped with two atomic-scale transition metals (late transition metal Fe and early transition metal Zr) that exhibited improved performance and durability in an actual PEM fuel cell. The approach may further provide a solution to design dual-metal-site catalysts for other critical electrocatalysis processes such as oxygen reduction to H 2 O 2 , CO 2 reduction, and nitrogen electrochemical reactions. , …”