Preparation And Characteristics Of Carbon Nanotubes/Chalcogenide Semiconductor Composites

Carbon nanotubes/ ZnS composite, Carbon nanotubes/ CdS composite and Carbon nanotubes/ PbS composite with different shape were successfully synthesized in water bath or by hydrothermal reaction. Study was made on their photoluminescence and influence on the shape of the composites were also systematically researched under different prodecessors, pH values, surfactants and react time.For the carbon nanotubes/ZnS composite, after covalent functionalization of carbon nanotubes with Ethylene diamine tetraacetic acid (EDTA) groupes grafted, carbon nanotubes/ZnS nanowires with core-shell structure were prepared in water bath under ultrasonic. ZnS nanoparticles densely spread on the surface of carbon nanotubes which formed a shell and could not be seen at other places. Compared with ZnS synthesized in the same way, trap states emission of the composite has 6 nm blue shift, and band edge emission has 16 nm blue shift. It was found that carbon nanotubes/ZnS nanowires were synthesized when adding sodium dodecyl benzene sulfonate (SDBS) or Sodium deoxycholate (SDC) as surfactants. However, except for deposited or coated on the surface of carbon nanotubes, ZnS grew into a lot of micro-spheres. Carbon nanotubes/ ZnS nanowires with core-shell structure can also be synthesized through hydrothermal reaction with SDC. While many nano-spheres of ZnS were string on carbon nanotubes with SDBS as surfactants. When Zn(CH₃COO)₂ were replaced by Zn(NO₃)₂, the size of ZnS nanoparticles became much smaller and they were piled up on the surface of carbon nanotubes. When Sodium subsulfite or Thiourea were used as sulfur source, or Hexadecyl trimethyl ammonium bromide (CTAB) as surfactants, many ZnS micro-spheres formed and ZnS were not coated or deposited on the surface of carbon nanotubes.For the carbon nanotubes/CdS composite, carbon nanotubes/ CdS nanowires with core-shell structure were prepared in water bath under ultrasonic. With SDBS as surfactant and pH value is 1, carbon nanotubes/ "starfish" shaped CdS composite were synthesized. It was found that the "starfish" shaped CdS with size of about 50 nm densely spread on the surface of carbon nanotubes. There were many protuberances on the surface of "starfish" shaped CdS. pH played an important role in the formation of "starfish" shaped CdS, and the sensitive value was at about 1. When pH=l or lower, the "starfish" shaped CdS formed; when pH value were improved to 2 or higher, the size of CdS became remarkably smaller, and agglomeration became obvious. The shape of CdS became disorder and the coating ratio reduced. It was also found that SDBS played an important role in control of particle size of CdS and acted as a dispersant.For the carbon nanotubes/PbS composite, cubic shaped PbS densely spread on the surface of carbon nanotubes treated by covalent functionalization. The composite show good photoluminescence and has remarkably blue shift.