Facile fabrication of hierarchical film composed of Co(OH)2@Carbon nanotube core/sheath nanocables and its capacitive performance

• Published in: RSC advances 2018, Vol.8 (67), p.38550-38555
• Main Authors: Fang, Hua, Chen, Gaoyun, Wang, Lixia, Ji, Yan, Zhang, Linsen, Gao, Kezheng, Zhang, Yongxia, Wang, Lizhen
• Format: Article
• Language: English
• Subjects: Capacitance; Carbon nanotubes; Chemistry; Current density; Electrophoretic deposition; Low currents; Nanoparticles; Porosity; Sheaths; Surface area; Synergistic effect
• ISSN: 2046-2069
• DOI: 10.1039/c8ra07031h

A hierarchical film composed of Co(OH)2@carbon nanotube (CNT) core/sheath nanocables (CCNF) was generated via a simple and rapid electrophoretic deposition method. It is found that the Co(OH)2 sheath was uniformly anchored on the surface of conductive CNT core. The Co(OH)2 sheath, with a thickness of ∼20 nm, was composed of numerous very tiny nanoparticles. Such a unique nanostructure endows the CCNF with a high surface area of 126 m2 g−1 and a hierarchical porosity, resulting in a large accessible surface area for redox activity. As expected, the CCNF exhibits high specific capacitance and excellent rate performance. Its specific capacitance reached 1215 F g−1 under a low current density of 1 A g−1 and was maintained at 832 F g−1 when the current density was increased 20 times to 20 A g−1. A high capacitance retention of 99.3% was achieved after 10 000 cycles at 1 A g−1. Such intriguing capacitive behavior is attributed to the synergistic effect of the CNT core and the Co(OH)2 sheath.