Further information

Synthesis of colloidal PbS nanosheets in a three-neck flask as it has been performed e.g. in T. Bielewicz et al. "Tailoring the height of ultrathin PbS nanosheets and their application as field-effect transistors", Small 11 (2015) 826. First, lead acetate was dissolved in diphenyl ether and oleic acid and heated to 75 °C until the solution turned clear. Then a vacuum was applied for to transform the lead acetate into lead oleate and to remove the acetic acid in the same step. The solution was heated under nitrogen flow to the desired reaction temperature while a chloroalkane was added under reflux. In the video at time 00:05, the sulfur source was injected and the reaction started. At 00:14 the solution starts to turn reddish - this is the nucleation of PbS clusters. At 00:24 the solutions becomes turbid - a sign for two-dimensional oriented attachment to nanosheets. At 00:30 the solution starts shows a silverish shimmer - the nanosheets grow in the third direction, the confinement is lifted and the nanosheets reflect light, almost like a metal.

Further reading

T. Bielewicz et al. "Tailoring the height of ultrathin PbS nanosheets and their application as field-effect transistors", Small 11 (2015) 826.