Synthesis of a stable colloidal solution of PbS nanoparticles

A method has been proposed for the synthesis of stable colloidal solutions of lead sulfide nanoparticles from aqueous lead acetate and sodium sulfide solutions. The citrate ion and ethylenediaminetetraacetic acid were used as complexing agents to stabilize the solution. The solutions obtained were shown to remain stable at room temperature for at least 30 days from the instant of synthesis, depending on the initial reactant concentration. According to X-ray diffraction and dynamic light scattering data, the stability and coagulation of the nanoparticles in solution were influenced by the lead and sulfur concentration, the presence of complexing agents, and the quantitative relation between the lead and complexing agent ions in solution. Optical absorption measurements for the colloidal PbS nanoparticle solutions showed that their absorbance was a nonlinear function of reactant concentration.