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Nitrogen-doped carbon monolith for alkaline supercapacitors and understanding nitrogen-induced redox transitions

By Da-Wei Wang, Feng Li, Li-Chang Yin, Xu Lu, Zhi-Gang Chen, Ian R. Gentle, Gao Qing (Max) Lu and Hui-Ming Cheng

Abstract

A nitrogen-doped porous carbon monolith was synthesized as a pseudo-capacitive electrode for use in alkaline supercapacitors. Ammonia-assisted carbonization was used to dope the surface with nitrogen heteroatoms in a way that replaced carbon atoms but kept the oxygen content constant. Ammonia treatment expanded the micropore size-distributions and increased the specific surface area from 383 m 2 g -1 to 679 m 2 g -1. The nitrogen-containing porous carbon material showed a higher capacitance (246 F g -1) in comparison with the nitrogen-free one (186 F g -1). Ex situ electrochemical spectroscopy was used to investigate the evolution of the nitrogen-containing functional groups on the surface of the N-doped carbon electrodes in a three-electrode cell. In addition, first-principles calculations were explored regarding the electronic structures of different nitrogen groups to determine their relative redox potentials. We proposed possible redox reaction pathways based on the calculated redox affinity of different groups and surface analysis, which involved the reversible attachment/detachment of hydroxy groups between pyridone and pyridine. The oxidation of nitrogen atoms in pyridine was also suggested as a possible reaction pathway

Publisher: 'Wiley'
Year: 2012
DOI identifier: 10.1002/chem.201102806/epdf
OAI identifier: oai:eprints.usq.edu.au:31722
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