l-Cysteine-Assisted Synthesis and Optical Properties of Ag₂S Nanospheres

Ag 2 S nanospheres were synthesized by a hydrothermal reaction using l -cysteine as the sulfur source and chelating reagent. The X-ray diffraction patterns and X-ray photoelectron spectra confirmed that the products were monoclinic α-Ag 2 S. The optical absorption spectra of the Ag 2 S nanospheres showed very broad absorption peaks centered at about 515 nm in wavelength. Photoluminescence spectra exhibited emission peaks centered at ∼637 nm in wavelength accompanied by weaker shoulder peaks at ∼590 nm in wavelength when the sample was excited with a wavelength of 490 nm. In addition, the formation mechanism of the Ag 2 S nanospheres was also determined. The l-cysteine-assisted hydrothermal route using l -cysteine as the sulfur source and chelating reagent provides an alternative approach to generate sulfide nanocrystals.