Local Spin-State Tuning of Iron Single-Atom Electrocatalyst by S-Coordinated Doping for Kinetics-Boosted Ammonia Synthesis

Yan Li; Yaxin Ji; Yingjie Zhao; Junxiang Chen; Sixing Zheng; Xiahan Sang; Bin Yang; Zhongjian Li; Lecheng Lei; Zhenhai Wen; Xinliang Feng; Yang Hou

doi:10.1002/adma.202202240

Local Spin-State Tuning of Iron Single-Atom Electrocatalyst by S-Coordinated Doping for Kinetics-Boosted Ammonia Synthesis

Adv Mater. 2022 Jul;34(28):e2202240. doi: 10.1002/adma.202202240. Epub 2022 Jun 6.

Authors

Yan Li¹, Yaxin Ji², Yingjie Zhao¹, Junxiang Chen², Sixing Zheng¹, Xiahan Sang³, Bin Yang¹, Zhongjian Li¹, Lecheng Lei¹, Zhenhai Wen², Xinliang Feng⁴, Yang Hou^{1

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Affiliations

¹ Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, China.
² CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.
³ Research and Testing Centre of Material School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, 430070, China.
⁴ Center for Advancing Electronics Dresden (cfaed) and Department of Chemistry and Food Chemistry, Technische Universitaet Dresden, 01062, Dresden, Germany.
⁵ Institute of Zhejiang University - Quzhou, Quzhou, 324000, China.
⁶ School of Biological and Chemical Engineering, NingboTech University, No.1 South Qianhu Road, Ningbo, 315100, China.

PMID: 35522454
DOI: 10.1002/adma.202202240

Abstract

The electrochemical nitrogen reduction reaction (e-NRR) is envisaged as alternative technique to the Haber-Bosch process for NH₃ synthesis. However, how to develop highly active e-NRR catalysts faces daunting challenges. Herein, a viable strategy to manipulate local spin state of isolated iron sites through S-coordinated doping (Fe_SA -NSC) is reported. Incorporation of S in the coordination of Fe_SA -NSC can induce the transition of spin-polarization configuration with the formation of a medium-spin-state of Fe (t_2g 6 e_g 1), which is beneficial for facilitating e_g electrons to penetrate the antibonding π-orbital of nitrogen. As a consequence, a record-high current density up to 10 mA cm^-2 can be achieved, together with a high NH₃ selectivity of ≈10% in a flow cell reactor. Both experimental and theoretical analyses indicate that the monovalent Fe(I) atomic center in the Fe_SA -NSC after the S doping accelerates the N₂ activation and protonation in the rate-determining step of *N₂ to *NNH.

Keywords: S-coordinated doping; iron single atoms; kinetics-boosted catalysis; nitrogen reduction reaction; tunable spin states.

Abstract

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