Boosting electrocatalytic N2 reduction to NH3 on β-FeOOH by fluorine doping

• Published in: Chemical communications (Cambridge, England) Vol. 55; no. 27; pp. 3987 - 3990
• Main Authors: Zhu, Xiaojuan, Liu, Zaichun, Wang, Huanbo, Zhao, Runbo, Chen, Hongyu, Wang, Ting, Wang, Faxing, Luo, Yonglan, Wu, Yuping, Sun, Xuping
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Ammonia; catalytic activity; Catalytic converters; chemical reactions; Density functional theory; Doping; Electrocatalysts; electrodes; energy; enzymes; Fluorine; hydrogen; Iron; Nanorods; nitrogen; nitrogen fixation; Nitrogenation; Reduction; Transition metals
• ISSN: 1359-7345; 1364-548X; 1364-548X
• DOI: 10.1039/c9cc00647h

As the cheapest and one of the most abundant transition metals, Fe is not only involved in nitrogenases for biological N2 fixation but is also extensively utilized in the Haber–Bosch process for industrial-scale NH3 synthesis. However, the application of Fe-based electrocatalysts for ambient N2-to-NH3 conversion still requires exploration of effective strategies to boost the catalytic performances for simultaneously achieving a large NH3 yield and a high Faradaic efficiency (FE). Here, we report that the ambient electrocatalytic N2 reduction activity of a β-FeOOH nanorod can be greatly improved by fluorine doping. When tested at −0.60 V vs. reversible hydrogen electrode (RHE) in 0.5 M LiClO4, such a β-FeO(OH,F) nanorod obtains an optimal NH3 yield (42.38 μg h−1 mgcat.−1) and FE (9.02%), much higher than those of pristine β-FeOOH (10.01 μg h−1 mgcat.−1, 2.16%). Density functional theory calculations reveal that the enhancement in activity originates from the lower reaction energy barrier (0.24 eV) of the nanorod than that of β-FeOOH (0.59 eV).