Synthesize Large-Diameter and Porous Carbon Nanotubes with Nickel Nanowires as the Template.

We report a method to synthesize Large-diameter and porous carbon nanotubes (LPCNTs) by carbon segregation with nickel nanowires (Ni-NWs) as the template. Unlike carbon nanotubes synthesized via conventional routes, the wall thickness is determined by the carburization time and the tube diameter and length are followed the template. The surface and structure of the LPCNTs were characterized by scanning and transmission electron microscopy (SEM and TEM), the LPCNTs retained their original tube shape, the thickness of the wall of the tube could be controlled, and a great amount of pores formed in the tube wall, the capacitance of the LPCNTs with the unique porous structure tube were increased compared with the Large-diameter CNTs (LCNTs), and the capacitance of the LPCNTs and LCNTs were 61 F/g and 78 F/g, respectively. We also performed further heat treatment at high temperature to improve the quality of the tube, resulting in a substantial changed of its morphology, the tubes exhibit relatively straight, smooth of its morphology, and the larger diameter was substantially shrink.