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Fine tuning of the size of CdS nanoparticles synthesized by a photochemical method

Marandi, M ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. DOI: 10.1088/0957-4484/17/5/011
  3. Publisher: 2006
  4. Abstract:
  5. In this work, we propose a combined photochemical-chemical method that enables us to grow CdS nanoparticles with ångström precision. CdS nanoparticles were formed through a photo-induced reaction between CdSO 4 and Na2S2O3. Thioglycerol (C 3H8O2S) was used as the capping agent. Fine tuning of the size was subsequently carried out by controlling the pH of the solution. Optical absorption spectroscopy was mainly used to monitor the process of particle formation, and to measure the bandgap and size. X-ray diffraction spectra confirmed the optical sizes and demonstrated crystalline nanoparticles. In the presence of the capping agent there was a dark growth that was completely dependent on the pH of the solution. The rate of dark growth decreased when the pH of the solution increased to 7.0. In pHs of 7.5 and 8, we observed a boundary situation where the number of particles was constant and only the existing particles grew in size. We proposed a model to explain this effect. The model is based on the formation of a local higher H+ concentration near the nanoparticle's surface. Finally, in pHs higher than 8.3 there was no dark growth. In a typical procedure, we showed that fine tuning of the size with ångström precision is possible, i.e. a 1.6 Å change in size was obtained in 45 min reaction time. © 2006 IOP Publishing Ltd
  6. Keywords:
  7. Absorption spectroscopy ; Cadmium sulfide ; Crystalline materials ; Mathematical models ; Photochemical reactions ; X ray diffraction analysis ; Fine tuning ; Particle formation ; Photochemical-chemical method ; Thioglycerol ; Nanostructured materials
  8. Source: Nanotechnology ; Volume 17, Issue 5 , 2006 , Pages 1230-1235 ; 09574484 (ISSN)
  9. URL: https://iopscience.iop.org/article/10.1088/0957-4484/17/5/011