The electrocatalytic characterization and mechanism of carbon nanotubes with different numbers of walls for the VO 2 + /VO 2+ redox couple

• Published in: Physical chemistry chemical physics : PCCP 2018-03, Vol.20 (11), p.7791-7797
• Main Authors: Lv, Zhaoqian, Zhang, Jin, Lv, Yang, Cheng, Yi, Jiang, San Ping, Xiang, Yan, Lu, Shanfu
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/C7CP08683K

Carbon nanotubes (CNTs) have been applied as catalysts in the VO /VO redox, whereas the mechanism of CNTs for the redox reaction is still unclear. In this work, the mechanism of the VO /VO redox is investigated by comparing the electrocatalytic performance of CNTs with different distributions. For different CNTs, the peak current density of the VO /VO redox increases with increasing content of oxygen-functional groups on the surface of CNTs, especially the carboxyl group which is proved as active sites for the redox reaction. Moreover, the reversibility of the VO /VO redox decreases with increasing defects of CNTs, as the defects affect the charge transfer of the catalytic reaction. Nevertheless, when a multi-walled CNT sample is oxidized to achieve a high content of oxygen functional groups and defects, the peak current density of the redox reaction increases from 38.5 mA mg to 45.4 mA mg whilst the peak potential separation (ΔE ) also increases from 0.176 V to 0.209 V. Overall, a balance between the oxygen functional groups and the defects of CNTs affects the peak current and the reversibility for the VO /VO redox.