Robust oxygen electrocatalysis enabled by bulk nitrogen-doped hierarchical structure cobalt carbide

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 1; no. 39; pp. 2924 - 2933
• Main Authors: He, Caimei, Zhang, Danling, Cai, Yezheng, Hou, Cheng, Wu, Xiangsi, Ma, Zhaoling, Huang, Youguo, Wang, Hongqiang, Li, Qingyu
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 11.10.2022
• Subjects: Black carbon; Carbon black; Catalysis; Catalysts; Chemical reduction; Cobalt; Doping; Electrocatalysis; Electrocatalysts; Electronic structure; Energy conversion; Metal air batteries; Metal carbides; Metal compounds; Nitrogen; Oxygen; Oxygen evolution reactions; Oxygen reduction reactions; Rechargeable batteries; Renewable energy; Robustness; Ruthenium oxide; Specific capacity; Structural hierarchy; Zinc-oxygen batteries
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d2ta05585f

The search for earth abundant, highly active, and robust electrocatalysts is central to the wide spread application of renewable energy conversion technologies. Herein, bulk nitrogen-doped hierarchical structure cobalt carbide, which was composed of nano/micro-particles and coupled with carbon black (denoted as N-Co 2 C HS/EC), was developed as a bifunctional oxygen electrocatalyst. N-Co 2 C HS/EC exhibited a high half-wave potential of 0.825 V for the oxygen reduction reaction and a low overpotential of 287 mV for the oxygen evolution reaction, both of which were superior to those of precious Pt/C and RuO 2 catalysts. Impressively, a rechargeable zinc-air battery driven by bifunctional N-Co 2 C HS/EC delivered a larger peak power density (205 mW cm −2 ), a higher specific capacity (793.08 mW h g Zn −1 ), and better rate performance than the one driven by Pt/C + RuO 2 mixture catalysts. Systematic characterization studies and theoretical calculations revealed that the enhanced oxygen electrocatalysis of N-Co 2 C HS/EC was attributed to the increased amount of active Co-N x moieties and the tailored electronic structure due to nitrogen doping. Moreover, the integrated microrod/sheet array benefited the electrocatalytic stability and electron/mass transmission. This work proposed an in situ nitrogen-doping strategy to substantially boost the electrocatalytic performance of metal carbides, which may inspire more effort for developing efficient metal compound electrocatalysts for energy conversion. The search for earth abundant, highly active, and robust electrocatalysts is central to the wide spread application of renewable energy conversion technologies.