Morphology Control of Nanoscale PbS Particles in a Polyol Process

Nanostructured PbS with different morphologies and particle sizes have been prepared through a polyol process. Narrow size distribution for star-shaped, octahedral, tetradecanehedral, and cubic products were achieved by slowly introducing the source materials using a peristaltic pump in the presence of poly(vinylpyrrolidone) (PVP) as additive. Systematic variation of the kinetic factors, including the additive, the reaction temperature, the duration time, the ratio of source materials, the sulfur sources, and the Pb(Ac) 2 ·3H 2 O concentration, reveals that the morphology depends mainly on the supersaturation degree of the free sulfur ions released from thiourea under elevated temperature. Semiquantitative analysis based on the X-ray diffraction (XRD) patterns of these products gives that the peak area ratio of (200) to (111) increases with the increase of the supersaturation degree within the reaction system. The four types of symmetric morphology showed different oxidation stability toward the 514.5 nm argon ion laser irradiation when the power was set at 12.5 mW.