Bottom-Up Construction of Active Sites in a Cu-N4-C Catalyst for Highly Efficient Oxygen Reduction Reaction

Wei Li; Chungang Min; Feng Tan; Zhanping Li; Bingsen Zhang; Rui Si; Mingli Xu; Weiping Liu; Liexing Zhou; Qingmao Wei; Yuzhen Zhang; Xikun Yang

doi:10.1021/acsnano.8b08692

Bottom-Up Construction of Active Sites in a Cu-N₄-C Catalyst for Highly Efficient Oxygen Reduction Reaction

ACS Nano. 2019 Mar 26;13(3):3177-3187. doi: 10.1021/acsnano.8b08692. Epub 2019 Mar 6.

Authors

Wei Li^{1

2}, Chungang Min², Feng Tan^{1

2}, Zhanping Li³, Bingsen Zhang⁴, Rui Si⁵, Mingli Xu⁶, Weiping Liu¹, Liexing Zhou², Qingmao Wei^{1

2}, Yuzhen Zhang^{1

2}, Xikun Yang^{1

2}

Affiliations

¹ Faculty of Materials Science and Engineering , Kunming University of Science and Technology , Kunming 650093 , China.
² Research Center for Analysis and Measurement , Kunming University of Science and Technology , Kunming 650093 , China.
³ Analysis Center Tsinghua University , Tsinghua University, Beijing 100080 , China.
⁴ Shenyang National Laboratory for Materials Science , Institute of Metal Research Chinese Academy of Sciences , Shenyang 110016 , China.
⁵ Shanghai Synchrotron Radiation Facility , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201204 , China.
⁶ Faculty of Metallurgical and Energy Engineering , Kunming University of Science and Technology , Kunming 650093 , China.

PMID: 30821960
DOI: 10.1021/acsnano.8b08692

Abstract

Bottom-up construction of efficient active sites in transition metal-nitrogen-carbon (M-N-C) catalysts for oxygen reduction reaction (ORR) from single molecular building blocks remains one of the most difficult challenges. Herein, we report a bottom-up approach to produce a highly active Cu-N₄-C catalyst with well-defined Cu-N₄ coordination sites derived from a small molecular copper complex containing Cu-N₄ moieties. The Cu-N₄ moieties were found to be covalently integrated into graphene sheets to create the Cu-N₄ active sites for ORR. Furthermore, the activity was boosted by tuning the structure of active sites. We find that the high ORR activity of the Cu-N₄-C catalyst is related to the Cu-N₄ center linked to edges of the graphene sheets, where the electronic structure of the Cu center has the right symmetry for the degenerate π* orbital of the O₂ molecule. These findings point out the direction for the synthesis of the M-N-C catalysts at the molecular level.

Keywords: Cu−N4 active sites; ORR; bottom-up fabrication; orbital symmetry; single molecular building blocks.