L-cysteine-assisted synthesis and optical properties of Ag2S nanospheres

Ag2S 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 alpha-Ag2S. The optical absorption spectra of the Ag2S nanospheres showed very broad absorption peaks centered at about 515 nm in wavelength. Photoluminescence spectra exhibited emission peaks centered at similar to 637 nm in wavelength accompanied by weaker shoulder peaks at similar to 590 nm in wavelength when the sample was excited with a wavelength of 490 nm. In addition, the formation mechanism of the Ag2S nanospheres was also determined. The 1-cysteine-assisted hydrothermal route using L-cysteine as the sulfur source and chelating reagent provides an alternative approach to generate sulfide nanocrystals.