Supercapacitor performance of binder‐free buckypapers from multiwall carbon nanotubes synthesized at different temperatures

Abstract

Multiwall carbon nanotubes (MWCNTs) have been synthesized by aerosol‐assisted catalytic chemical vapor deposition method from a 2% ferrocene solution in toluene at temperatures of 720 and 800 °C. After an oxidation by a HNO3/H2SO4 mixture, MWCNTs were dispersed in water and deposited in form of buckypapers with a thickness of ∼150 μm. The obtained materials were used as working electrodes of supercapacitors without adding of binder. The electrode from MWCNTs synthesized at lower temperature showed the larger capacitance in 1 M H2SO4 and 6 M KOH electrolytes, especially at low scan rates. An increase of double‐layer capacitance was due to larger specific surface and microporosity of the material; a gain in pseudocapacitance was attributed to larger quantity of oxygenated groups developed on the defective surface of nanotubes. The electrode showed a good cyclic performance during a repetitive charge/discharge test.A larger specific capacitance of MWCNTs synthesized at 720 °C is related with etching of nanotube tips and higher oxygenation of nanotube surface as the result of binder‐free buckypaper electrode preparation.