Shouai Feng

The manufacture of carbon nanotubes decorated with ZnS to enhance the ZnS photocatalytic activity

Abstract Carbon nanotubes with attached ZnS nanocrystals were prepared by a reaction between Zn(NO 3 ) 2 and Na 2 S in an aqueous suspension of carbon nanotubes. Post-refluxing treatment and the order in which the reactants were introduced played a crucial role in the improvement of the interaction between ZnS nanocrystals and carbon nanotubes. Studies on methylene blue degradation revealed that carbon nanotubes could effectively increase the photocatalytic activity of the ZnS nanocrystals. Close contact between carbon nanotubes and the ZnS improved the interfacial electron transfer and restrained the electron/hole (e−/h+) pair recombination of ZnS.

Growth of carbon nanotubes by the catalytic decomposition of methane over Fe-Mo/Al2O3 catalyst: effect of temperature on tube structure

Abstract The effects of temperature, reaction time, and flow rate on the structure of carbon nanotubes (CNTs) were studied using catalytic chemical vapor deposition of methane over an Fe-Mo/Al 2 O 3 catalyst. Results show that the temperature is a key parameter to control the wall thickness of the CNTs. Low temperature leads to the formation of multiwalled carbon nanotubes (MWCNTs) with wall thickness of 2–7 nm. Relatively high temperature is in favor of the growth of double-walled carbon nanotubes (DWCNTs), whereas high temperature promotes the generation of single-walled carbon nanotubes (SWCNTs). A further increase of temperature results in the generation of MWCNTs with a wall thickness of 3–15 nm and large carbon particles.

β-SiC nanorods with uniform amorphous SiO2 wrappers on the outside surface

Abstract Large quantities of β-SiC nanorods with uniform amorphous SiO2 wrappers were synthesized by carbothermal reduction of silica xerogel pieces with carbon nanoparticles embedded in the network. Powder X-ray diffraction (XRD) and infrared (IR) results confirmed the formation of β-SiC and SiO2. Low-magnification transmission electron microscopy (TEM) results showed that the nanorods were typically more than 20 μm in length. High-magnification TEM and high-resolution electron microscopy (HREM) indicated that the β-SiC nanorods (with typical diameters of 14 ± 6 nm) were wrapped in amorphous SiO2 layers (with typical outside diameters of 45 ± 25 nm).

Identification and technical accessibility of the carbon self-assembly concept hidden in catalytic carbon nanotube evolution

Multi-wall carbon nanotubes can readily form by the catalysis of lanthanide oxides. The formed tubes are unusually separated from the catalyst particles, which leads to a straightforward identification of the self-assembly of carbon particles that is hidden in the chaotic carbon-catalyst-hybrid system of catalytic carbon nanotube evolution. Following the identified self-assembly concept, conventional bulk activated carbon (AC) has been successfully transformed into CNTs through a detonation-induced cracking of AC and a real-time re-organization.

Ortho effects on the change in electronic absorption spectrum of pyridinium salts of saturated bromohydrocarbon

The quaterisation process of 1,2-dibromoethane and pyridine is in situ traced by electronic absorption spectrum. Two absorption peaks, induced by mono- and bis-pyridinium salt of 1,2-dibromoethane, appear at 429 nm and 313 nm, respectively. To explain the phenomena, several kinds of alkyl bromides with special structures were selected and compared by experimental measurement and theoretical calculation. The results indicate that for mono-pyridinium salt of 1,2-dibromoethane, the electron donor property of ortho-bromine group increases the electron cloud density of the carbon atom associated with pyridinium cation, which induces red-shift of absorption wavelength.