Solar-Light-Driven Efficient ZnO–Single-Walled Carbon Nanotube Photocatalyst for the Degradation of a Persistent Water Pollutant Organic Dye

An efficient photocatalyst, ZnO–single-walled carbon nanotube (ZnO–SWCNT) nanocomposite was successfully fabricated through a straightforward one-pot–two-chemical recrystallization technique followed by thermal decomposition. The photocatalytic efficiency of the prepared ZnO–SWCNT composite was investigated by assessing the degradation of a persistent water-pollutant dye (methylene blue, MB) under visible-light irradiation. We found that the synthesized photocatalyst is an effective and recyclable agent for the decomposition of an MB solution. Its photocatalytic performance was substantially better than that of pristine ZnO nanorods or pristine SWCNTs. The reusability of the photocatalyst was also examined, affirming that it could be used repeatedly for five cycles without conspicuous loss of morphology or catalytic performance.

Electronic structures and spectroscopic regularities of phenylene-modified SWCNTs

The equilibrium geometries and electronic structures for a series of single-wall carbon nanotubes (SWCNTs) modified with phenylene were studied using the density functional theory (DFT) at the B3LYP/6-31G(d) level. Of the four configurations of the phenylene-modified SWCNTs, the v-configuration in which the bond is perpendicular to the main axis of the SWCNT is the most thermodynamically stable. The increase in radii of the modified SWCNTs generally leads to a decrease in the energy gaps. The first absorptions in the electronic spectra of the modified SWCNTs compared with those in the electronic spectra of pristine SWCNTs are basically red-shifted. The chemical shifts of bridged carbon atoms connected with phenylene in the v-configuration are shifted downfield relative to those of the pristine SWCNTs. The aromaticity of the rings in SWCNTs is improved owing to the addition of phenylene.

Characteristic Features of Stone-Wales Defects in Single-Walled Carbon Nanotube; Adsorption, Dispersion, and Field Emission

Adsorption behaviors of dodecanethiol (C12H25SH) molecules are investigated on the surface of single-walled carbon nanotubes (SWCNTs) with vibrational and X-ray photoelectron spectrometers. The active adsorption sites are proved as Stone-Wales (SW) defects (5–7 ring defects). The SW defect-removed SWCNTs formed by reacting nanotubes with allyl acrylate molecules are compared with pristine SWCNTs in dispersion and field emission. The former shows higher dispersion and field emission than the latter.

Purification, Dispersion and Biofunctionalization of Singlewall Carbon Nanotubes

Potential application of Carbon Nanotubes as a drug delivery system is limited by their hydrophobity and their natural tendency to aggregate in the bundles. Dispersion and solubility of Singlewall Carbon Nanotubes (SWCNT) in Phosphate Buffered Saline (PBS) solution via non covalent and covalent interactions was investigated. Galactosyl-β1-Sphyngosine (glycolipid precursor of cerebrosides, structured with a hydrophobic chain, a hydrophilic head and an amine group between them) was used. Pristine SWCNTs were wrapped with Galactosyl-β1-Sphyngosine (Gal-Sphy), whereas the carboxylic groups of the functionalized CNTs were activated in order to interact with amine groups of Galactosylsphyngosine and render the coating stronger. Samples dispersion was characterized by optical absorption spectroscopy (OAS). The comparison and efficiency of the dispersion stability of the functionalized material in respect to the pristine SWCNTs will be presented. We exploited Raman Spectroscopy to evaluate relative purity of the samples, and the Infrared analysis to characterize the presence of the functional groups on the tubes surface. The morphology of the samples was studied using high resolution transmission electron microscopy (HR-TEM).