Initial Pre-lab SubmissionProject 1: Quantum DotGoal The goal of this lab is to synthesize cadmium selenide nanoparticles, distinguish their light absorption and fluorescence emission properties, and relate the quantum dot behavior to macroscopic properties of CdSe. Background A quantum dot is a nanostructure that that can be synthesized from numerous materials that have semi-conductive properties. These semi-conductive properties include the ability to conduct electricity depending on the temperature. A cold temperature makes it so that almost no electricity passes through a semiconductor, while a warmer temperature has the opposite effect (6). Quantum dots also have unique properties that allow them to convert light into almost every color visible to the human eye.
The color characteristics of quantum dots are largely determined by their size and shape. Depending on the size of a quantum dot it can have varying colors and wavelengths. Smaller quantum dots have shorter wavelengths leading to colors such as violet.
While larger quantum dots are the opposite, having longer wavelengths which lead to colors such as red or orange (14). The synthesis of quantum dots can be accomplished at low temperatures in a solvent. When the solvent is dried, quantum dots are left behind.
Some materials that can be utilized in a solvent for the synthesis of quantum dots are Cadmium Oxide, Octadecene, Oleic acid, Selenium, and Triphenylphosphine (14). Cadmium Oxide is one of the most important cadmium compounds with a formula CdO. Cadmium Oxide is produced through burning cadmium vapor in the air, and it ends up as a brown powder. Once it is produced Cadmium Oxide has many uses such as plating baths, creating electrodes for storage batteries, and is used in the process for synthesizing quantum dots (4). Octadecene is a hydrocarbon and an alkene, with the chemical formula C18H36.
Octadecene is a solvent that works well with Oleic-Acid (1). Oleic-Acid is a fatty acid that does not have an color or smell. Oleic-Acid is created through dehydrogenating stearic acid and also occurs naturally in many natural systems such as animals and plants. It is soluble and is mainly used as a component in many foods and soaps. However it also has some uses in pharmaceuticals and most in the synthesis of quantum dots (12). Selenium is an element with the symbol Se, and it is found within metal sulfide ores. Selenium salts are toxic in large amounts however in small amounts is vital to body functions. It often is used when it is a red powder.
Selenium has many applications, it can be used to create glass products, alloys, batteries, and solar cells. As well as in the synthesis of quantum dots (16). Triphenylphosphine is a organophosphorus compound with the formula P(C6H5)3. Triphenylphosphine is created through the reaction between phosphorus trichloride and chlorobenzene. When it is exposed to air, Triphenylphosphine experiences slow oxidation creating Triphenylphosphine oxide.
It has many uses in organic synthesis as well as in the synthesis of quantum dots (19). Quantum dots are incredibly valuable because they have so many uses. These uses branch across many fields including such as science, technology as well as medicine. Quantum dots play a very important role in the advancement of science. For example they have been used as a catalyst to make hydrocarbons. Which are so important in today’s society, because hydrocarbons can be used as fuel for combustion (15).
Enabling the use of many motor application throughout the world. Quantum dots were also used in order to create solar cells that are non-toxic. Allowing for sustainable green energy that is less hazardous and costly to dispose of (13). Another field that quantum dots have revolutionized is the technology industry.
In the technology industry quantum dots are being used to create memory chips with much lower power consumption. They are also used in the production in humidity and pressure sensors, as well as lasers, that that can be used in communication devices. Another part of the technology field greatly improved through the use of quantum dots is television. Televisiona are able to give a much clearer picture with a wider range of colors through the use of quantum dots (13). Quantum dots are also being used in the field of medicine. Their unique properties allow them to treat infections that have become resistant to antibodies. They have also help with the imaging that is used in cancer treatments allowing for cancerous tumor to be pictured (13). Methods chosen Nucleation will be a method used in this experiment.
CdO, Octadecene, and Oleic acid will be combined into an empty round bottom flask. This step is important because the presence of all three is required for the synthesis of quantum dots. In order to mix the CdO, Octadecene, and Oleic acid, a round bottom flask was chosen due to the fact a round bottom flask allows for more uniform heating of liquid. After the CdO, Octadecene, and Oleic acid are added into the round bottom flask, the flask will be placed onto a heating mantle, with a clamp, that is set to 50 volts. The clamp will be used to keep the flask stable while the experiment is running, and the heating mantle will be set to 50 volts in order to keep the solution at a temperature around 225 degrees. This is important because for Quantum dot synthesis a temperature of 225 degrees is required.
On another hotplate triphenylphosphine, selenium, and octadecene will be heated to 180 degrees in order to dissolve the selenium, this is required because the selenium cannot be used for the experiment in its solid state. Any excess of this solution will be stored for additional synthesis if needed. This is in case there is a problem with the experiment or something goes wrong.
Once both the selenium solution and cadmium solution reach the necessary temperature they will be mixed. This is done in order to begin the synthesis of the quantum dots. After the two solutions are mixed, every minute a 1 mL aliquot will be removed from the solution with a pasteur pipet and put into individual test tubes. The pasteur pipet will be used to ensure accuracy because it is able to deliver small amounts of liquid at a time, which is important when working with 1 mL samples. Also each sample will be placed into their own test tube in order to observe the samples by themselves and prevent contamination.
Once every sample is in a test tube a UV light will be shown on them in order to see the fluorescence of the samples. Fluorescence Spectroscopy will be used to analyze the data that is collected. This is because fluorescence spectroscopy is a type of electromagnetic spectroscopy that examines the fluorescence of a sample. The method is used to understand quantum dots based on how size and color are related. Due to this knowing the fluorescence of the sample allows us to examine the color and wavelength of the sample. which is why fluorescence spectroscopy will be used (7). Protocol Materials: (7)10 mL round bottom flask StirrerHot plateClampMagnetic stir bar 1 mL syringe (to measure triphenylphosphine) 1 mL syringe (for selenium solution) 25 mL round bottom flask10 mL pipet (to measure octadecene) 1 mL syringe (to measure oleic acid) Vials9 inch Pasteur pipetsPasteur pipet bulb 1 cm glass or polystyrene small volume cuvettes Ultraviolet light Heating mantle Fluorescence Spectrometer Procedure: (7)The heating mantle will be set up on a ring stand with a clamp.The heating mantle will be set to 50 volts.
Using an analytical balance, 0.20 mg of CdO will be measured and added to a round bottom flask. Using a syringe, 0.6 mL of oleic acid and 10 ml of octadecene will be added into the same empty round bottom flask. The flask will then be inserted into the clamp and placed on the heating mantle.
The CdO mixture will be heated until the thermometer reads 225°C.A separate sand bath hot plate will be set up to the left of the heating mantle. Behind the hot plate, there also will be a ring stand with a clamp. 150 mg of triphenylphosphine, 30 mg of selenium, and 5 mL octadecene will be measured using a syringe or an analytical balance and then it will be added into the second empty round bottom flask. The hot plate will be set to 180°C to dissolve the Se in Triphenylphosphine.The excess Selenium solution will be stored in an dram vial that will be utilized for additional synthesis.
The group members will constantly be monitoring both the Selenium solution and the Cadmium Oxide solution to ensure a successful experiment. Once the CdO solution reaches 225°C and the Se dissolves, the Se solution will be poured into the CdO solution with the clamp. 1 minute after the solutions have been mixed, 1 mL aliquots will be removed at a time with a Pasteur pipet from the round bottom flask.Each aliquot will be taken in 1 minute intervals and each one will be placed in an individual vial/test tube.
The aliquots will then be analyzed with a handheld UV and fluorescence spectrometer. Safety analysis This lab requires the use of chemicals that are hazardous and can be harmful if they are ingested, inhaled, and have skin or eye contact. Whenever any substance is ingested, poison control and a physician should be notified immediately. All tight clothing needs to be removed if any substance is ingested. In the case of any substance being inhaled, the individual needs to either rest or move to a location that has fresh air. If the individual finds it challenging or is unable to breath, they should either receive oxygen or artificial respiration. If any substances come into contact with the eyes, the first step is to check if the individual is wearing contact lenses. If they are, then the lenses need to be removed and the eyes will need to be flushed for a minimum of 15 minutes.
If the individual is not wearing contact lenses, then they should simply flush their eyes. Additionally, some substances require that the individual applies eye ointment. In the case of any substance contacting skin, the area of contact should be flushed with water and covered with emollient.
In order to prevent all of the possible hazards, general safety precautions will be taken. Each student will wear lab coats, goggles, close toed shoes, and rubber gloves at all times. Since the procedure requires the utilization of hot plates and heating mantles, the students will need to be cautious not to burn themselves around both devices. Whenever hot liquids are being transferred between glassware, it is important to use either heat resistant gloves or tongs. The experimentation will be conducted in a fume hood to prevent the hazardous substances from harming the students. (3, 5, 9, 11, 15, 16)Specifics:Octadecene is hazardous with eye contact, skin contact, ingestion, or inhalation.
(9) Oleic acid is slightly hazardous with eye contact, skin contact, ingestion, or inhalation. (11) Triphenylphosphine is extremely hazardous if it is ingested. The substance is hazardous with eye contact, skin contact, and inhalation. The individual’s lips and mouth should also be examined to evaluate the extent of the damage to the tissue.
Additionally, the individual should not be forced to vomit the substance out. (16)Selenium is extremely hazardous if it comes into contact with eyes, if it is ingested, or if it is inhaled. It is only slightly hazardous if it comes into contact with skin.
(15)Cadmium is extremely hazardous if it is ingested or inhaled. If it is either ingested or inhaled, the individual should to be evacuated, tight clothing needs to be loosened, oxygen needs to be provided, or mouth-mouth may need to be provided. The individual’s lips and mouth should also be examined to evaluate the extent of the damage to the tissue.
Additionally, the individual should not be forced to vomit the substance out. (3)Cadmium oxide is extremely hazardous if it is ingested. It is very hazardous if it is inhaled and hazardous if it comes into contact with skin and eyes. This substance is especially dangerous because if individuals are exposed to cadmium oxide for too long, it could result in death. (5)List of References Used 1.1-OCTADECENE (ALPHA-OLEFIN C18), www.chemicalland21.com/industrialchem/organic/1-OCTADECENE.
htm.2. “A Safer, Easier, Faster Synthesis for CdSe Quantum Dot Nanocrystals.” ACS Publications, pubs.acs.org/doi/pdf/10.
1021/ed082p1697.3. “Cadmium MSDS.” Material Safety Data Sheet , www.
“Cadmium Oxide.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., www.britannica.com/science/cadmium-oxide.
5. “Cadmium Oxide MSDS.” Material Safety Data Sheet , www.sciencelab.com/msds.php?msdsId=9923229.
6. Corporation., Hitachi High-Technologies. “1.
Properties of Semiconductors.” 1. Properties of Semiconductors : Hitachi High-Technologies GLOBAL, www.hitachi-hightech.
com/global/products/device/semiconductor/properties.htm 7. “Fluorescence Spectroscopy.” Fluorescence Spectroscopy – an Overview | ScienceDirectTopics,www.sciencedirect.com/topics/biochemistry-genetics-and-molecular- biology/fluorescence-spectroscopy.
8. Nordell, K. J., Boatman, E. M., & Lisensky, G. C. (2005).
A Safer, Easier, Faster Synthesis for CdSe Quantum Dot Nanocrystals. Journal of Chemical Education,82(11), 1697. doi:10.1021/ed082p16979. “Novel Methods of Synthesizing Quantum Dot Materials.” Phys.org – News and Articles on Science and Technology, phys.org/news/2018-01-methods-quantum-dot-materials.
html.10. “Octadecane MSDS.” Material Safety Data Sheet , www.sciencelab.
com/msds.php?msdsId=9925556.11. “Oleic Acid MSDS.” Material Safety Data Sheet , http://www.
“Oleic Acid.” National Center for Biotechnology Information. PubChem Compound Database, U.
S. National Library of Medicine,pubchem.ncbi.nlm.nih.gov/compound/oleic_acid.
13. Quantum Dots and Their Applications,www.understandingnano.com/quantum-dots-Applications.html.
14. “Quantum Dots.” Quantum Dot Pioneers, www.nanosysinc.com/what-we-do/quantum-dots/.15. ScienceIQ.com.
cfm.16. “Selenium – Element Information, Properties and Uses | Periodic Table.” Royal Society of Chemistry – Advancing Excellence in the Chemical Sciences, www.rsc.
org/periodic-table/element/34/selenium.17. “Selenium MSDS.” Material Safety Data Sheet , www.sciencelab.com/msds.
php?msdsId=9924874. 18. “Triphenyl Phosphine MSDS.” Material Safety Data Sheet , www.sciencelab.
” National Center for Biotechnology Information. PubChem Compound Database, U.S.
National Library of Medicine,pubchem.ncbi.nlm.nih.gov/compound/triphenylphosphine.