Aqueous synthesis and characterization of CdTe@Co(OH)2 (core–shell) composite nanoparticles

Multi-functional CdTe@Co(OH)2 core–shell nanoparticles were synthesized in aqueous solution by a seed-mediated growth approach. Initially, CdTe nanocrystals were synthesized with bi-functional molecule mercaptoacetic acid as a stabilizer. The Co2+ in the form of Co(NO3)2 was added to CdTe nanocrystals in aqueous solution and slowly hydrolyzed to deposit a layer of hydroxide (Co(OH)2) onto the luminescent CdTe nanocrystals as a core in the presence of stabilizer at pH ≈ 11.2. The synthesized CdTe@Co(OH)2 core–shell composite nanoparticles were characterized with XRD, EDAX, TEM, FT-IR, Raman, EPR, and thermal analysis (TG/DTG curves). The effect of refluxing time and the concentration of Co2+ on the optical properties of these samples were evaluated using UV–Visible absorption and photoluminescence analysis. The emission peak of the (CdTe@Co(OH)2) composite nanoparticles shifted to 626 nm from 605 nm (CdTe seed). The sizes of CdTe and CdTe@Co(OH)2 composite nanoparticles averaged about 3.43 nm and 6.12 nm, respectively.