Precursor modulated active sites of nitrogen doped graphene-based carbon catalysts via one-step pyrolysis method for the enhanced oxygen reduction reaction

• Published in: Electrochimica acta 2021-02, Vol.370, p.137712, Article 137712
• Main Authors: Zhang, Xiaoran, Zhang, Xiao, Zhao, Shiyong, Wang, Yun Qiu, Lin, Xu, Tian, Zhi Qun, Shen, Pei Kang, Jiang, San Ping
• Format: Article
• Language: English
• Subjects: Active control; Carbon; Catalysts; Catalytic activity; Charge density; Configurations; Density functional theory; Electrochemical analysis; Graphene; Nitrogen; Nitrogen active species; Nitrogen configuration; Oxygen reduction reaction; Oxygen reduction reactions; Precursor modulation; Precursors; Pyridinic N and graphitic N; Pyrolysis
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2021.137712

Tuning active configurations of different nitrogen (N) species and elucidating their influence on the catalytic activity for oxygen reduction reaction (ORR) is important to develop N-doped carbon (N/C) as efficient metal-free catalysts. The challenge is to selectively control the active N sites of N/C. Herein, we approach this challenge by modulating N active species in graphene structured N/C with specific precursors via a one-step pyrolysis process. In this method, 5-aminouracil is selected as the N-containing precursor platform to modulate the pyridinic N (NP), while 2,6-diaminopyridine and 1,3-diaminobenzene are used to modulate graphitic N (NG) and pyrrolic N (NPY), respectively. N/C materials with specific different N configurations such as N/CNP+NG, N/CNP+NP and N/CNP+NPY are successfully synthesized and identified by microstructure and phase characterization. Electrochemical results demonstrate that N/CNP+NG exhibits the best ORR performance, achieving an onset potential (Eonset) of 0.98 V and half-wave potential (E1/2) of 0.86 V vs. RHE, respectively, which is comparable to that obtained on conventional Pt/C. By contrast, N/CNP+NPY exhibits the lowest activity for ORR. Density functional theory (DFT) simulation further validates that the NP+NG configuration produces strong electronic distribution on carbon matrix that leads to high charge and high spin density on surrounding carbon atoms. This work provides a facile approach to design N doped graphene structured carbon materials with active N configurations for ORR. [Display omitted]