No abstract

Pore structures and electrochemical performances of mass-produced metal-free single-walled carbon nanotubes (mf-SWCNTs) heated in either CO 2 gas or dry air were investigated. Pore structures, defects, and electrochemical performances of mf-SWCNTs were analyzed mainly using the N 2 adsorption method, apparent density measurement, Raman spectroscopy, and cyclic voltammogram. mf-SWCNT sheets heated in CO 2 gas showed a remarkable increase of the specific surface area up to 1900 m 2 g -1 , but sheets heated in air showed an increase of only up to 1400 m 2 g -1 . Propan-2-ol, 4-methyl-1,3-dioxolan-2-one, or ionic liquid was impregnated in the inner space of mf-SWCNTs to confirm whether the inner space of mf-SWCNTs is filled with each liquid. mf-SWCNTs heated in air were completely filled, but mf-SWCNTs heated in CO 2 were partially filled. From these results, it is estimated that holes of the size of 0.56 nm or larger are opened on the side wall of mf-SWCNTs. A combination of two heat treatments maximized the effective specific capacitance of heated mf-SWCNTs up to 100 F g -1 , which is 1.6 times higher than that of as-grown mf-SWCNTs because of the removal of the carboneous component and the creation of defects on the sidewall of mf-SWCNTs, which allow the electrolyte into the inner space of mf-SWCNTs.

No abstract

No abstract

In this study, we investigated the effect of pressure on the formation and decomplexation of [2]pseudorotaxanes. High pressure accelerated the formation of [2]pseudorotaxanes in an aprotic nonpolar solvent (CDCl(3)/CD(3)CN) via the slipping approach when using two crown ether/secondary ammonium salt systems: dibenzo[24]crown-8/bis(cyclohexylmethyl)ammonium salt (1a/2a) and tetrabenzo[24]crown-8/dibenzylammonium salt (1b/2b). The influence of pressure on the rate constants for the formation of the [2]pseudorotaxanes 3a and 3b revealed activation volumes (DeltaV(double dagger)) of -2.5 and -4.6 cm(3) mol(-1), respectively, at 303 K and zero pressure. We also investigated the effect of pressure on the decomplexation of the [2]pseudorotaxanes 3a and 3b in a polar solvent (DMSO-d(6)/CDCl(3)), obtaining activation volumes of -0.9 and -0.4 cm(3) mol(-1), respectively, at 303 K and zero pressure. Moreover, we calculated the activation parameters for the decomplexation processes on the basis of transition state theory at each pressure.