One Pot, Rapid and Green Photo-Chemical Synthesis of Ag2S and Ag2S-ZnS Core–Shells

Water soluble Ag 2 S and Ag 2 S-ZnS core–shells were prepared using a photochemical approach by means of 12 W UV lamp with 250–400 nm wavelengths. Energy dispersive x-ray spectrometry and elemental mapping confirmed the uniform formation of quantum dots (QDs). X-ray Diffraction and Transmission Electron Microscope characterizations were employed to confirm the formation of Ag 2 S and Ag 2 S-ZnS core-shells with sizes about 3 nm and 10 nm, respectively. Fourier transform infrared spectroscopy indicated that UV illumination results in good attachment of 3-mercaptopropionic acid (MPA) to the surface of Ag 2 S QDs. Photoluminescence measurements showed a strong emission around 870 nm with photoluminescence quantum yields of about 3.8% and 4.6% for Ag 2 S and Ag 2 S-ZnS core-shells, respectively. This green method of synthesis using MPA together with their rather high emission yield is promising for the application for in vivo bio-imaging.