Ultrasound-assisted synthesis of PbS quantum dots stabilized by 1,2-benzenedimethanethiol and attachment to single-walled carbon nanotubes

• Ultrasound assisted synthesis of PbS QDs stabilized by 1,2-benzenedimethanethiol.
• Sizes 2.7 and 3.6 nm diameter that absorbs and emit in NIR (1000–1350 nm) region.
• In-situ growth of PbS-QD (size 4.9 nm) on single-walled carbon nanotube achieved.
• Sol–gel method to encapsulate PbS-QD in silica composites that retain fluorescence.
• Important for solar cells, sensor applications and telecommunications research.

Lead sulfide (PbS) quantum dots stabilized by 1,2-benzenedimethanethiol can be synthesized by mixing Pb(NO3)2 and Na2S solutions in ethanol under ultrasound irradiation. The PbS quantum dots (2.7 and 3.6 nm in diameter) are characterized by their absorption and fluorescence spectra in the near infrared region and by other surface analytical techniques. With addition of single-walled carbon nanotubes (SWNT) to the system, this ultrasound-assisted procedure allows attachment of PbS nanoparticles to SWNT surface via π–π stacking, thus providing a simple one-pot method for preparation of SWNT–PbS nanoparticle composite materials. Using the ultrasound-assisted method for synthesizing silica composites containing PbS nanoparticles by a sol–gel process is also described.