A controlled approach for synthesizing CdTe@CrOOH (core-shell) composite nanoparticles

A seed-mediated growth approach was used to synthesize CdTe@CrOOH core-shell composite nanoparticles in aqueous solution. Chromium oxyhydroxide shell was developed around a small quantum dot that can lead to composite particles which is expected to lead to some new properties and applications. The aqueous synthesized CdTe nanoparticles with bi-functional molecules (Mercaptoacetic Acid (MAA)) at pH approximate to 11.2 served as cores, and CrOOH was deposited on them to form core-shell nanoparticles in aqueous solution. The effect of refluxing time and the concentration of Cr3+ on the preparation of these samples were measured using UV-Visible absorption and photoluminescence analysis. The emission peak of the resulted core-shell composite nanoparticles (CdTe@CrOOH) shifted from 605 (CdTe seed) to 630 nm. The sizes of CdTe nanoparticles averaged about 3.22 nm, and the CdTe@CrOOH composite nanoparticles averaged about 6.68 nm. The particles after coating with hydroxide shell were bigger than the uncoated CdTe seeds. The synthesized CdTe@CrOOH core-shell nanoparticles were characterized with XRD, EDAX, FT-IR, EPR, TEM, and thermal analysis (TG/DTG curves). The synthesized core-shell composite nanoparticles were subjected to suitable magnetic field to understand the effect on UV visible absorption and photoluminescence spectra. The results show that as-prepared nanoparticles with core/shell structure exhibit interesting optical properties. (C) 2011 Elsevier B.V. All rights reserved.