Liquid-Phase Synthesis of Silver Sulfide Nanoparticles in Supersaturated Aqueous Solutions

Silver sulfide powders and colloidal solutions were synthesized by chemical deposition from aqueous solutions of silver nitrate and sodium sulfide in the presence of sodium citrate as a stabilizing agent. X-ray diffraction, electronic microscopy, the Brunauer-Emmett-Teller method, and dynamic light scattering were used to determine nanoparticle sizes in the deposited powders and colloidal solutions. The varying reagent concentrations in the reaction mixture provided nanopowders with average particle sizes ranging from similar to 1000 to similar to 40-50 nm. Silver sulfide nanoparticles in colloidal solutions have sizes of 15-20 nm. A qualitative correlation is found between the silver sulfide particle size and the supersaturation of the solutions used in the synthesis.