Synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes

Abstract

A method for synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes (CNT) by the precipitation of CdS nanoparticles on the CNT surface from an aqueous solution containing the Cd II salt, thiourea, and ammonia was developed. The dependences of the size of particles formed on the CNT on the temperature of the solution and the duration of precipita tion were observed. The degree of imperfection of the CNT surface exerts a substantial effect on the density of the precipitated CdS particles.The development and use of nanoparticles of semicon ductors is of interest for the preparation of photoabsorbing and photoemitting cells. The range of absorption and lu minescence frequencies depends on the nanoparticle size. Hybrid nanosystems combining the properties of one di mensional carbon nanotubes (CNT) and quantum dots of semiconducting materials are being actively developed presently. It is expected that the interaction of semicon ducting nanoparticles with light would result in the elec tron photocurrent through the nanotube and localization of the hole on the nanoparticle. This would allow one to desigh new types of photogalvanic devices. 1 Recently it was repeatedly reported the precipitation of various types of nanoparticles of metal sulfides and selenides, such as CdSe (see Ref.2), Cu 2 S (see Ref.3), and CdS (see Refs 4-6) on the CNT. In particular, modified CdS nano particles were pre prepared and then precipitated from solution on the CNT surface, which made it possible to use such systems as biosensors. 7 During the electrochemical precipitation of CdS nanoparticles ∼15 nm in diameter on bamboo like nanotubes 100 nm in diameter, the CNT were pre oxidized with nitric acid for better precipitation. 8 The photoconductivity of the hybrid CdS/CNT materials was enhanced. The precipitation of CdSe nanoparticles on bundles of double wall CNT was described. 9 The CNT were pre fluorinated to provide a more uniform distribu tion of nanoparticles on the surface. A more complicated multistep approach to the formation of CdS nanoparticles on the nanotube surface is known. 6 By oxidizing the CNT surface with a mixture of acids the surface was firstly func tionalized with carboxyl groups and then Cd 2+ ions were "cross linked" to these groups. As a result of the interac tion with Na 2 S, CdS nanoparticles ∼8 nm in size were formed on the CNT surface.Hydrogen sulfide is often used for the synthesis of CdS. Hydrogen sulfide should be replaced by less toxic organic sulfur containing compounds capable of acting as a sup plier of sulfur atoms. One of the most available sulfur containing reagents of this type is thiourea (NH 2 ) 2 CS (Thio). For example, CdS films were obtained 10,11 from aqueous solutions containing Thio, Cd II salts, ammonia, and NaOH. A possibility to prepare CdS nanoparticles by this reaction was described. 12 The purpose of the present work is to study the forma tion of CdS nanoparticles on the surface of an array of multiwalled CNT aligned perpendicularly to the silicon support using the thio...

Photoluminescence of CdS nanoparticles grown on carbon nanotubes covered by a dielectric polymer layer

“…Oppositely, the growth conditions in sample 4 were controlled by solely the polystyrene film. Before, self‐assembling of CdS nanoparticles in nanowires was detected for such dielectric substrates as oxidized silicon and glass . Probably, this self‐assembling of CdS nanoparticles in an oriented fashion is governed by electrostatic interactions between the substrate and semiconductor clusters.…”

Crystallinity and electroluminescence efficiency of CdS nanoparticles grown on the aligned carbon nanotube array

“…Growth of CdS nanoparticles was conducted from a water solution of CdCl 2 , thiourea SC(NH 2 ) 2 , and ammonia NH 3 8. Thiourea and CdCl 2 were dissolved in an aqueous solution of NH 3 in two different glasses.…”

“…Before the CdS/CNT hybrid synthesis, the surface of CNTs is functionalized with chemically active species, which help in nucleation and growth of CdS 4, 5 or attachment of previously created CdS nanoparticles 6, 7. Recently, we showed that CdS nanoparticles can grow on as‐prepared CNTs 8, which likely contain intrinsic defects formed during catalytic chemical vapor deposition (CCVD) process at relatively low temperatures. Elimination of the step of functionalization of CNT surface is important when the array of CNTs vertically grown on a substrate is used as a template.…”

Synthesis and Electrophoretic Concentration of Cadmium Sulfide Nanoparticles in Reverse Microemulsions of Tergitol NP-4 in n-Decane

“…CdS nanoparticles (NPs)quantum dots­(QDs)are widely used in the development of composite materials with unique properties, − in photocatalytic processes, and in the production of devices with semiconductor coatings, for example, solar cells. , Stable hydrosols and organosols of NPs are most useful for the introduction and uniform distribution of QDs in the composite bulk or film …”