Deflagration synthesis of nitrogen/fluorine co-doped hollow carbon nanoparticles with excellent oxygen reduction performance
Yousong Liu, Bing Huang, Shengjie Peng, Tao Wang, Guangbin Ji, Guangcheng Yang, Seeram Ramakrishna
Index: 10.1039/C8QI00200B
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Abstract
Critical factors such as doping content, electronic conductivity and porosity need to be addressed to obtain excellent oxygen reduction reaction (ORR) performance with metal-free carbon-based materials. However, creating a facile approach to obtain carbon materials with a high doping level, high graphitization degree and high surface area still remains a great challenge. In this work, we develop a NaN3/C5F5N deflagration method to synthesize high N/F co-doped carbon hollow nanospheres (N/F-HC) with a high graphitization degree. The deflagration of NaN3 can produce Na nanoclusters, which can not only capture partial F atoms from C5F5N but can also be used as templates for the formation of a hollow structure. The heat liberation from deflagration and the subsequent F-capturing reaction could generate an extremely high temperature for graphitic structure formation. Moreover, the ultra-fast deflagration and F-capturing reaction allow carbon growth to be completed in seconds, which can ensure a high N/F doping content. The optimized N/F-HC catalyst exhibits superior ORR performance with long-term stability compared to a commercial Pt/C electrocatalyst in an alkaline medium. The synthetic strategy described in this work is facile and is expected to underpin future research efforts to develop metal-free electrocatalysts for the ORR and other applications.