One-step copper-catalyzed synthesis of porous carbon nanotubes for high-performance supercapacitors

Abstract

The supercapacitor with high power density, long cycling life, security and reliability is a kind of energy storage device that attracts currently much attention. Porous carbon nanotubes with large specific surface area and excellent electrical conductivity are a promising electrode material for supercapacitors. A simple bottom-up synthesis strategy is proposed for porous carbon nanotubes. The carbon dioxide as a carbon source is converted to carbon and then deposited on the surface of the copper powder that plays a catalytic role, and the carbon atoms are arranged in an orderly manner at high temperature to form porous carbon nanotubes. The factors that affect the growth of porous carbon nanotubes are found. The relationships between these factors and the morphology and structure of porous carbon nanotubes are discussed to reveal the growth of porous carbon nanotubes. In addition, the as-prepared porous carbon nanotubes exhibit a high specific surface area and excellent electrochemical performances, which can maintain a high specific capacitance under a large current density and a high sweep rate. The assembled symmetric supercapacitor successfully provides energy for small devices. • Copper was first discovered to catalyze the synthesis of porous carbon nanotubes. • Carbon dioxide serves as the carbon source to prepare porous carbon nanotubes by a bottom-up strategy. • The factors that affect the growth of carbon nanotubes are found and discussed in detail. • The porous carbon nanotubes exhibit high special capacitance (300.1 F g −1 ) and outstanding cycling stability.