Single atomic Fe-N4 active sites and neighboring graphitic nitrogen for efficient and stable electrochemical CO2 reduction

Leta Takele Menisa; Ping Cheng; Xueying Qiu; Yonglong Zheng; Xuewei Huang; Yan Gao; Zhiyong Tang

doi:10.1039/d2nh00143h

Single atomic Fe-N₄ active sites and neighboring graphitic nitrogen for efficient and stable electrochemical CO₂ reduction

Nanoscale Horiz. 2022 Jul 25;7(8):916-923. doi: 10.1039/d2nh00143h.

Authors

Leta Takele Menisa^{1

2}, Ping Cheng^{3

4}, Xueying Qiu¹, Yonglong Zheng^{1

5}, Xuewei Huang^{1

6}, Yan Gao¹, Zhiyong Tang¹

Affiliations

¹ CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China. gaoyan@nanoctr.cn.
² College of Science, University of Shanghai for Science and Technology, Shanghai, 200093, China.
³ College of Natural and Computational Sciences, Department of Chemistry, Haramaya University, P.O. Box 138, Dire Dawa, Ethiopia.
⁴ School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150080, China.
⁵ Institute of Advanced Synthesis (IAS), and School of Chemistry and Molecular Engineering, Jiangsu National Syner-getic Innovation Centre for Advanced Materials, Nanjing Tech University, 211816, Nanjing, China.
⁶ Green Catalysis Center, and College of Chemistry, Zhengzhou University, Zhengzhou, Henan, 450001, P. R. China.

PMID: 35730675
DOI: 10.1039/d2nh00143h

Abstract

Single atomic Fe-N_x moieties have shown great performance in CO₂-to-CO conversion. However, understanding the structural descriptors that determine the activity of Fe-N_x remains vague, and promising strategies to enhance their catalytic activity are still not clear. Herein, we used a high-temperature pyrolysis strategy and post-synthesis acid treatment for the direct growth of a single Fe-N_x site adjacent to graphitic nitrogen for the electrochemical CO₂ reduction reaction. This strategy could significantly reduce the amount of pyridinic and pyrrolic N atoms, while graphitic N surrounding the Fe-N_x site predominantly increases. An experimental study combined with density functional theory revealed that the increase in the neighboring graphitic N decreases the number of electrons transferred between CO and the catalyst for FeN₄-2N-3 and FeN₄-4N-3, which results in the decrease of the adsorption strength of CO and the energy barrier for desorbing CO*. The as-synthesized Fe-N_x neighbored by graphitic nitrogen exhibited maximum faradaic efficiency of 91% at a lower overpotential of 390 mV. Due to the increase in the graphitic N, the catalysts perform efficiently for 35 h without any drop in current density.