Cadmium nanoparticles

RAFT polymerization lends itself to the synthesis of polymers with thiol end groups. Several groups have utilized the property of thiols and dilhioesLers to bind heavy metals such as gold or cadmium in preparing brushes based on gold film or nanoparticles1 8 761 763 and cadmium selenide nanoparticles.763 76 1... 

The synthetic approach is very simple and does not require any special set up. In a typical room temperature reaction, 1.0 mL aqueous solution of cadmium chloride was added to 20 mL aqueous solution of soluble starch in a 50 mL one-necked round-bottom flask with constant stirring at room temperature. The pH of the solution was adjusted from 6 to 11 using 0.1 M ammonia solution. This was followed by a slow addition of 1.0 mL colourless selenide ion stock solution. The mixture was further stirred for 2 h and aged for 18 h. The resultant solution was filtered and extracted with acetone to obtain a red precipitate of CdSe nanoaprticles. The precipitate was washed several times and dried at room temperature to give a material which readily dispersed in water. The same procedure was repeated for the synthesis of PVA and PVP - capped CdSe nanoparticles by replacing the starch solution with the PVA and PVP polymers while the synthesis of elongated nanoparticles was achieved by changing the Cd Se precursor ratio from 1 1 to 1 2. The synthesis of polymer capped ZnSe nanoparticles also follows the same procedure except that ZnCb solution was used instead of CdCb solution. 

Badr, Y. and Mahmoud, M. A. (2005). Optimization and photophysics of cadmium selenide nanoparticles. Physica B condensed matter., 369, 278-286. 

Carrot, G. Scholz, S. M. Plummer, C. J. G. Hilbron, J. G. and Hedrick, L. J. (1999). Synthesis and Characterization of Nanoscopic Entitles Based on Poly(Caprolactone)-Grafted Cadmium Sulfide Nanoparticles. Chem. Mater., 11, 3571-3577. 

Oluwatobi, S. O. and Revaprasadu, N. (2007). A Novel Method to Prepare Cysteine Capped Cadmium Selenide Nanoparticles. Mater. Res. Soc. Symp. Proc. 0951, E03-12. 

Oluwafemi, O. S. and Revaprasadu, N. (2008). A new synthetic route to organically cayyed cadmium selenide Nanoparticles. New J. Chem., 32,1432-1437. 

The formation of semiconductor nanoparticles and related stmctures exhibiting quantum confinement within LB films has been pmsued vigorously. In 1986, the use of the metal ions in LB films as reactants for the synthesis of nanoscale phases of materials was described [167]. Silver particles, 1-2 mn in size, were produced by the treatment of silver be-henate LB films with hydrazine vapor. The reaction of LB films of metal salts (Cd, Ag, Cu, Zn, Ni, and Pb ) of behenic acid with H2S was mentioned. The use of HCl, HBr, or HI was noted as a route to metal halide particles. In 1988, nanoparticles of CdS in the Q-state size range (below 5 mn) were prepared inside LB films of cadmium arachi-... 

The photoelectrochemical properties of CdS nanoparticles formed in LB films of cadmium arachidate on ITO glass (indium tin oxide-coated glass) were investigated [188]. The CdS particles were formed by exposure to H2S gas, and then the cadmium arachidate structure was regenerated by exposing the gas-treated films with aqueous solutions of CdCL. Gassing/immersion cycling increased the particle size from 2.3 0.7 nm after one cycle to 9.8 2.4 nm after five cycles. The 9.8-nm particles showed UV-visible ab-... 

FIG. 16 Current versus bias voltage for a CdS nanoparticle on the end of an STM tip. The CdS particles were formed by exposing a bilayer of cadmium arachidate on the STM tip to H2S gas. The other conducting surface is a highly oriented pyrolytic graphite electrode. The inset is a plot of differential conductance versus the bias voltage. (Reproduced with permission from Ref. 202. Copyright 1996 National Academy of Sciences, U. S. A.)... 

Scanning tunnel microscopy (STM) was chosen as a tool for realization of this task (Wilkins et al. 1989). CdS nanoparticles were formed in a bilayer of cadmium arachidate deposited onto the surface of freshly cleaved graphite (Erokhin et al. 1995a). The graphite was used as the first electrode. Initially, STM was used for locahzing the position of the particles. Eigure 28 shows the images of different areas of the sample. The particles are vis-... 

Rabchynski SM, Ivanou DK, Streltsov EA (2004) Photoelectrochemical formation of indium and cadmium selenide nanoparticles through Se electrode precursor. Electrochem Commun 6 1051-1056... 

Choi S-J, Woo D-H, Myung N, Kang H, Park S-M (2001) Electrochemical preparation of cadmium selenide nanoparticles by the use of molecular templates. J Electrochem Soc 148 C569-C573... 

Pal B, Torimoto T, Iwasaki K, Shibayama T, Takahashi H, Ohtani B (2004) Size and structure-dependent photocatalytic activity of jingle-beU-shaped silica-coated cadmium sulfide nanoparticles for methanol dehydrogenation. J Phys Chem B 108 18670-18674... 

DNA hybridization based on cadmium sulfide nanoparticle tags. Electrochem Commun 4 ... 

Mastai Y, Polsky R, Koltypin Y et al (1999) Pulsed sonoelectrochemical of cadmium selenide nanoparticles. J Am Chem Soc 121 10047-10052... 

Brus and co-workers produced nanoparticles of CdSe from the pyrolysis of the single-molecular cadmium selenate precursor [Cd(SePh)2].392 The similar metal(benzylthiolate) compounds [M(SCH2C6i Is)2] (M = Zn, Cd) were also used in the solid-state preparation of ZnS and CdS particles and produced mixtures of the hexagonal and cubic phases of the crystallites, with sizes of 5nm, on thermolysis between 200 °C and 400 °C under nitrogen.393 The bis(trialkylsilyl)chalco-genides [(Me3SiE)2Cd] (E = S, Se), prepared by heterocumulene metathesis as in Equation (11), were used to produce nanoparticles. If the reactions are carried out in TOPO, TOPO-passivated CdE nanoparticles can be obtained although there was little control over particle size 394... 

---