Preparation and Properties of N-Doped Carbon Microtubes as the Electrode Material in Electrochemical Capacitor

A series of N-doped carbon microtubes was prepared by using Reed catkins as the precursor and with both direct carbonization and chemical activation methods at different temperatures. The chemical activation method is more efficient, simpler and cost less compared to the traditional preparation method of N-doped carbon microtubes. The chemical activation material JJCZH-750(JJ stands for Reed catkins, Z stands for Zinc chloride, C stands for carbonization and 750 the optimized temperature) was optimized. The carbon microtubes were characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis(TGA), X-ray photoelectron spectroscopy, N2 adsorption-desorption analysis, and electrochemical measurements. The results show that carbon accounts for 94.36%(mass fraction) and nitrogen accounts for 1.24%(mass fraction) of the sample, which shows a tendency to exist as graphite. TGA analysis of the samples indicates a high thermal stability with a mass loss lower than 5% below 400 degrees C. N-2 sorption isotherms show that the samples is predominantly microporous(peak 1.2 nm) and occasionally mesoporous. Electrochemical measurements suggest that Reed catkins-based JJCZH-750 carbon microtubes have a specific capacitance up to 170 F/g, which remains at 153 F/g after 5000 cycles in a voltammetry test, showing a potential as electrode material in electrochemical capacitors.