Space-confined iron nanoparticles in a 3D nitrogen-doped rGO-CNT framework as efficient bifunctional electrocatalysts for rechargeable Zinc–Air batteries

• Published in: Microporous and mesoporous materials 2020-05, Vol.298, p.110100, Article 110100
• Main Authors: Guo, Chunhui, Li, Lei, Zhang, Ting, Xu, Yixiang, Huo, Yunhao, Li, Shengjuan
• Format: Article
• Language: English
• Subjects: Bifunctional electrocatalysts; Iron nanoparticles; Nitrogen-doped rGO-CNT framework; Rechargeable zinc-air battery
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2020.110100

Transitional metal nitrogen-doped carbon catalysts are increasingly attractive due to their high bifunctional activities in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of rechargeable zinc-air batteries. In the present work, space-confined iron nanoparticles in a 3D nitrogen-doped reduced graphene oxide-carbon nanotube (rGO-CNT) framework (Fe-NCNTs/NG) were synthesized by pyrolysis of a compound comprising urea, anhydrous ferric chloride (FeCl3) and ammonium chloride (NH4Cl) in the presence of graphene oxide (GO). Carbon nanotubes (CNTs) were grown from urea under the catalysis of iron before the pyrolysis to obtain Fe-NCNTs/NG. Nitrogen was introduced into the rGO-CNT framework from urea and NH4Cl in the pyrolysis process at a temperature of 700/800/900/1000 °C. XRD, SEM, HRTEM and XPS techniques were employed to characterize Fe-NCNTs/NG and showed iron and/or Fe3O4 nanoparticles are confined in the 3D nitrogen-doped rGO-CNT framework. The electrochemical test results demonstrate that as-prepared Fe-NCNTs/NG can conduct better catalytic performances than Pt/C and IrO2 in the aspects of a higher half-wave potential and a lower overpotential. Specifically, the best catalytic performance of Fe-NCNTs/NG was achieved when it was prepared by a 30:1 mass ratio of urea to FeCl3 and pyrolyzed at a temperature of 900 °C. Furthermore, a home-made zinc-air battery loading a Fe-NCNTs/NG electrode showed better charge-discharge stability and higher power density than a Pt/C loaded zinc-air battery. The present work demonstrates that the Fe-NCNTs/NG framework is promising to be an alternative to Pt/C and/or IrO2 in the rechargeable zinc-air battery industry. Space-confined iron nanoparticles in a 3D nitrogen-doped graphene-CNT framework were prepared as efficient bifunctional electrocatalysts for rechargeable zinc-air batteries. [Display omitted] •Iron nanoparticles were confined in a 3D graphene-CNT framework.•ORR activities are effected by the calcination temperature and urea/FeCl3 ratio.•As-prepared battery performed better than a Pt/C zinc-air battery.