Studies on surface functionalized single wall carbon nanotube for electrochemical double layer capacitor application

Surface functionalization of single wall carbon nanotubes (SWCNTs) is carried out by chemical and electrochemical oxidation in aqueous medium. Treatment of SWCNT in acid mixtures results oxygenated surface with mainly micro porous texture which shows a pseudocapacitance of 209 Fg(-1) in 1 M H2SO4 solution at a current rate of 50 mAg(-1). The SWCNT surface become slightly non-polar when treated with fuming HNO3 even in the presence of oxygenated species. Under a current rate of 50 mAg(-1), a maximum capacitance of 202 Fg(-1) is observed in 1 M Et3MeNBF4 in polycarbonate due to presence of mesopores. Electrochemical oxidation in KNO2 functionalizes the SWCNT surface with NO2 species which shows intermediate pseudocapacitance facilitating probably organization of only smaller ions along the walls of mesopores of SWCNT. The mixed acid treated SWCNTs exhibit sensibly larger capacitance of 160 Fg(-1) even at higher current rate of 5000 mAg(-1).