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

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 m(2) 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.