Electrochemical cyclic voltammetric(CV) scan was applied to inducing the partial oxidation and defects of carbon nanotubes(CNTs).The electrochemically induced functional groups and physical defects were demonstrated to show positive effects on the nanotube capacitance,as exemplified by super-long CNT arrays as model for the easy fabrication of CNT electrodes.Specifically,the initial hydrophobic nanotube surface becomes hydrophilic and a ten-time enhancement in capacitance is observed with respect to the pristine CNT sample.Thus,the electrochemical CV pretreatment can be used as an effective approach to activate the CNT surface for an enhanced electrochemical performance in capacitors,and many other advanced devices beyond capacitors,such as electrochemical sensors and batteries.
HU YueZHAO YangLI YanXIE Xue-junLI HuiDAI Li-mingQU Liang-ti
Clusters Al2P2n-(n = 1―4) were theoretically investigated using density functional theory (DFT) methods at the B3LYP/6-311+G* and B3PW91/6-311+G* levels of theory. The calculated results showed that the planar structure (D2h symmetry) of Al2P2n-(n = 1―4) species was the global minimum. And the negative nucleus-independent chemical shift (NICS) value of Al2P2n-(n = 1―4) species indicated the existence of a ring current in the planar structure (D2h symmetry). A detailed molecular orbital (MO) analysis revealed that the planar structures (D2h symmetry) had π aromaticity,which further exhibited the strongly aromatic character for Al2P2n-(n = 1―4) species.
XU WenGuo,ZHANG YuanChun & ZHAI Lei Institute of Chemical Physics,Beijing Institute of Technology,Beijing 100081,China
