Electronic synergism of pyridinic- and graphitic-nitrogen on N-doped carbons for the oxygen reduction reaction

Xiaomei Ning; Yuhang Li; Jingyan Ming; Qiang Wang; Hongjuan Wang; Yonghai Cao; Feng Peng; Yanhui Yang; Hao Yu

doi:10.1039/c8sc04596h

Electronic synergism of pyridinic- and graphitic-nitrogen on N-doped carbons for the oxygen reduction reaction

Chem Sci. 2018 Dec 13;10(6):1589-1596. doi: 10.1039/c8sc04596h. eCollection 2019 Feb 14.

Authors

Xiaomei Ning^{1

2}, Yuhang Li¹, Jingyan Ming¹, Qiang Wang³, Hongjuan Wang¹, Yonghai Cao¹, Feng Peng⁴, Yanhui Yang³, Hao Yu¹

Affiliations

¹ School of Chemistry and Chemical Engineering , Guangdong Provincial Key Lab of Green Chemical Product Technology , South China University of Technology , Guangzhou 510640 , China . Email: yuhao@scut.edu.cn ; ; Tel: +86 20 8711 4916.
² School of Chemistry and Chemical Engineering , Lingnan Normal University , Zhanjiang 524048 , China.
³ Institute of Advanced Synthesis , School of Chemistry and Molecular Engineering , Jiangsu National Synergetic Innovation Center for Advanced Materials , Nanjing Tech University , Nanjing 211816 , China.
⁴ School of Chemistry and Chemical Engineering , Guangzhou University , Guangzhou , 510006 , China.

Abstract

Nitrogen-doped carbon materials (NCs) are extensively studied for the oxygen reduction reaction (ORR). However, the nature of active sites of pyridinic nitrogen (N_P) or graphitic nitrogen (N_G) on NCs is still under debate. Herein, we demonstrated that the ORR activity of NCs in alkaline media depended on the electronic synergism between N_P and N_G, rather than any single type of N. We measured the transferable electrons of NCs by absorption spectroscopy using 7'7'8'8-tetracyanoquinodimethane as an electron acceptor. The transferable electron amount of NCs is relevant to either N_P or N_G, leading to the [N_P] : [N_G] ratio as an electron transfer descriptor of NCs in a reverse volcano curve manner across nineteen NCs. The similar dependence of ORR activity on the [N_P] : [N_G] ratio of NCs was also discovered, demonstrating the synergistic effect of N_P and N_G. These results provide a new angle to understand the nature of ORR activity of NCs and optimize the ORR catalyst.