Construction of Hierarchically One-Dimensional Core-Shell CNT@Microporous Carbon by Covalent Bond-Induced...

A covalent bond-induced surface-confined cross-linking is reported to construct one-dimensional coaxial CNT@microporous carbon composite (CNT@micro-C). Octaphenyl polyhedral oligomeric silsesquioxane (Ph-POSS) composed of eight phenyls and a -Si₈O₁₂ cage was selected as precursor for microporous carbon. The layer-by-layer cross-linking of phenyl anchored Ph-POSS on the surface of CNT; after carbonization and etching of -Si₈O₁₂ cages, CNT@micro-C including CNT core and microporous carbon shell was harvested. The thickness of microporous carbon shell can be well tailored from 6.0 to 20.0 nm, and the surface area of CNT@micro-C can reach 1306 m² g^-1. CNT@micro-C combines the structural advantages of CNT and microporous carbon, presenting large surface area, high electrical conductivity, fast ion transfer speed, and short ion transfer distance. When used as electrode material, CNT@micro-C reveals superior supercapacitive performance; for example, its capacitance can reach 243 F g^-1 at 0.5 A g^-1 and slightly decreases to 209 F g^-1 at 10 A g^-1, indicating a capacitance retention of 86%. Even at a very high scan rate of 50 A g^-1, a high capacitance of 177 F g^-1 is retained, giving a capacitance retention of 73%.