synthesis of cds quantum dots and optimization of conditions in conventional and microwave heating...
TRANSCRIPT
![Page 1: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/1.jpg)
Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave
heating methods
S. D. Hettiarachchi and T. G. ChasteenDepartment of Chemistry
![Page 2: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/2.jpg)
Nanoparticles• Particles between 1 nm to 100 nm in size• There are many different nanoparticles in shape
and size.
Nanowires
Nanotubes
2
www.kurzweilai.net (04.02.2014)
![Page 3: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/3.jpg)
Quantum Dots (QDs)• A quantum dot is a tiny particle of a
semiconductor nanocrystal which shows quantum mechanical properties.
• They can range from 2 to 10 nanometers in diameter. (Size of the smallest grain of sand is around 62500 nm)
• Because of their small size, quantum dots display unique optical and electrical properties.
3
![Page 4: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/4.jpg)
• The electronic characteristics of a quantum dot are related to its size.
• It has an ability to produce light as fluorescence
• The color of the light is tunable according to its size.
• Ability to conduct electricity
4
![Page 5: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/5.jpg)
Advantages and uses of CdS QDs
• Light emitting diodes
• Solar cells
• Biofluorescent tagging
• Lasers
• Biomedical imaging
www.nanocluster.mit.edu (04.02.2014)
5
![Page 6: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/6.jpg)
Imaginary sketch of CdS quantum dot
6A. Abdelhay, D. Billaud, M. Abyan, L. Balan, J. Gaumet, G. Medjadhi, J. Ghanbaja, R. Schneider, ACS Appl. Matter. Interfaces. 4 (2012) 2561- 2569.
G
G G
G
G
G
G
G
![Page 7: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/7.jpg)
Glutathione (GSH)
7
Glutathione (GSH) is an important antioxidant in plants, animals, fungi and some bacteria.
It is a tripeptide with a peptide linkage between the carboxyl group of the glutamate side-chain and the amine group of cysteine which is further attached by peptide linkage to a glycine.
Thiol groups are reducing agents, naturally existing in animal cells.
GSSG Figure 2
Figure 1
![Page 8: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/8.jpg)
Glutathione (GSH) capped CdS QDs
• Increase the biocompatibility
• Can be used in mild chemical conditions
• QDs can be synthesized in short time periods.
• GSH is acting as a reducing agent, so there is no need to add any toxic reducing agents.
Pérez-Donoso, J.M.; Monrás, J.P.; Bravo, D.; Aguirre, A.; Quest, A. F.; Osorio-Román, I.O.; Aroca, R.F.; Chasteen, T.G.; Vásquez, C.C. PloS ONE 2012, 7(1), e30741.
8
![Page 9: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/9.jpg)
Objectives
• Synthesize CdS QDs in environmentally greener protocols by using GSH as a capping agent
• Optimize the conditions to synthesize the tunable CdS QDs in the conventional heating method and microwave irradiation
9
![Page 10: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/10.jpg)
10
CdS QDs synthesis in different GSH molar ratios
at various temperatures in conventional heating method
![Page 11: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/11.jpg)
Procedure
CdCl2 (4mM Final concentration) Borax Citrate Buffer (pH 9)
Na2S was added
QD nucleation was initiated by raising the temperature up to 40,50,60,70, and 80 0C one at a time
11
Added to
1. Vortexed
2. After 5 minutes
Pérez-Donoso, J.M.; Monrás, J.P.; Bravo, D.; Aguirre, A.; Quest, A. F.; Osorio-Román, I.O.; Aroca, R.F.; Chasteen, T.G.; Vásquez, C.C. PloS ONE 2012, 7(1), e30741.
Reduced Glutathione (GSH) was added at different concentrations
![Page 12: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/12.jpg)
Results and Discussion
12
![Page 13: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/13.jpg)
Color variations of CdS QDs in 10 mM GSH concentration at 70 0C
1 Hour 2 Hours 3 Hours 4 Hours
5 Hours 6 Hours 24 Hours 48 Hours
13
![Page 14: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/14.jpg)
14
CdS QDs synthesis by the microwave irradiation
![Page 15: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/15.jpg)
Microwave Bomb
15
Side view Upper view
Internal parts
![Page 16: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/16.jpg)
Microwave synthesis of CdS QDs
15 Seconds 30 Seconds20 Seconds 25 Seconds
10 Seconds5 SecondsBefore Microwave
16
![Page 17: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/17.jpg)
Conclusion
• Synthesis of CdS QDs was successful by using GSH as a capping agent
• For the normal heating process, the optimum condition for the tunable QDs is 10 mM GSH concentration at 70 0C
• By the microwave irradiation it could produce blue to red CdS QDs within 30 seconds
17
![Page 18: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/18.jpg)
Acknowledgements• Supervisor Dr. T. G. Chasteen
• Former Members Mr. Tharaka Wansapura and Ms. Desire Lopez
• Dr. José Manuel Pérez Donoso , Universidad de Santiago de Chile, Santiago, Chile
• Mr. Vicente María Durán Toro, Universidad de Santiago de Chile, Santiago, Chile
• Robert A. Welch Foundation 18
![Page 19: Synthesis of CdS quantum dots and optimization of conditions in conventional and microwave heating methods S. D. Hettiarachchi and T. G. Chasteen Department](https://reader037.vdocument.in/reader037/viewer/2022102906/56649ce25503460f949ae183/html5/thumbnails/19.jpg)
Thank you
19