Developing efficient noble-metal-free catalysts for the electrochemical N₂ reduction reaction (NRR) under ambient conditions shows promise in fertilizer production and hydrogen storage. However, there is still a grand challenge but blossoming interest to achieve the high-efficiency electrochemical NRR in aqueous media. A team from college of materials science and engineering of Jilin University has designed an Fe-N/C catalysts with built-in Fe-N₃ sites for the high-efficiency electrochemical nitrogen reduction reaction (NRR). Their research has been published on January 3rd, 2019 in ACS Catalysis.

The hierarchical porous architecture, large active surface area, positively charged surface, weak ferromagnetism, and strong nitrogen chemisorption of Fe-N/C-CNTs all facilitate enormous potential for the electrochemical NRR. This catalyst exhibits enhanced NRR activity with NH₃ production (34.83 μgh^-1mg^-1cat.), faradaic efficiency (9.28% at - 0.2 V vs RHE), selectivity, and stability in 0.1 M KOH aqueous media under mild conditions. More importantly, we demonstrated by experimental results and theoretical calculations that built-in Fe-N3 moieties as a valid catalytically active site elevated the NRR activity effectively. This study provides insight into precise construction of more efficient and stable NRR electrocatalysts and further expands the possibilities of transition metal-nitrogen-carbon (M-N-C)-based nanomaterials in NRR fields.

The structure of F-N₃ in the synthesized material was characterized and analyzed in detail by using the 1W1B-XAFS station of Beijing Synchrotron Radiation Facility (BSRF), and the X-ray absorption near-edge structure (XANES) spectra of Fe K-edge was obtained. The structure and coordination environment of Fe in the Fe-N/C-CNTs catalyst and its Fe-ZIF-8-CNTs precursor were further determined. The average valence state of Fe species in the catalyst was between Fe⁰ and Fe³⁺, and the fitting results showed that the mean coordination number of Fe-N /O in the first shell was 3.0.

This work has been cited in the review of Chem. Rev., Joule and other journals by Qiang Xu research group (Japan) and Ning Yan research group (Singapore), which is a highly significant advance that is certain to accelerate and expand research into the specific functions of single atom catalysis and small molecule activation.

Article：

Ying Wang, Xiaoqiang Cui,* Jingxiang Zhao, Guangri Jia, Lin Gu, Qinghua Zhang, Lingkun Meng, Zhan Shi, Lirong Zheng, Chunyu Wang, Ziwei Zhang, and Weitao Zheng*. Rational Design of Fe-N/C Hybrid for Enhanced Nitrogen Reduction Electrocatalysis under Ambient Conditions in Aqueous Solution. ACS Catalysis, 2019, 9, 336-344.