Method for preparing bicolor graphene quantum dots through microwave radiation manner
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A graphene quantum dot, graphene technology, applied in graphene, chemical instruments and methods, luminescent materials, etc., can solve problems such as low yield, and achieve long-term stable existence, good dispersion, and excellent fluorescent properties.
Inactive Publication Date: 2012-07-25
NANJING UNIV
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Embodiment 1
[0017] Embodiment 1. Preparation of yellow-green graphene quantum dots
[0018] Prepare 30mL 0.5mg mL according to the method of Hummers -1 Graphene oxide solution, and add 8 mL concentrated HNO 3 (65%) and 2 mL concentrated H 2 SO 4 (98%), mixed evenly, and then the mixture was placed in a microwave oven and reacted for 3h at a power of 240W, and the product was a brown transparent solution containing a black precipitate. After cooling to room temperature, the product was lightly sonicated for a few minutes, then adjusted to pH 8 with NaOH in an ice-water bath, and then filtered with a 0.22 μm microporous membrane to remove large pieces of graphene oxide to obtain a dark yellow solution. Finally, the solution was dialyzed (cut-off molecular weight: 8000-10000Da), and yellow-green fluorescent GQDs were obtained.
Embodiment 2
[0019] Embodiment 2. has the preparation of the graphene quantum dot of blue fluorescence
[0020] Gained dark yellow filtrate in embodiment 2 is before dialysis, adds 1g NaBH 4 Stir the reaction vigorously at room temperature for 2h, the color of the solution turns light yellow, add HNO dropwise 3 The solution (65%) terminated the reaction and adjusted the pH to 8, then filtered through a 0.22 μm microporous membrane and dialyzed (cut-off molecular weight: 8000-10000Da) to obtain GQDs with bright blue fluorescence.
Embodiment 3
[0021] Embodiment 3. Preparation of yellow-green graphene quantum dots
[0022] "Add 8mL concentrated HNO of embodiment 1 3 and 2 mL concentrated H 2 SO 4 "Change" to "add 16mL concentrated HNO 3 and 4 mL concentrated H 2 SO 4 ", other conditions of preparation are with embodiment 1, obtain the product similar to embodiment 1.
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Abstract
The invention relates to a method for preparing yellow-green-fluorescent graphene quantum dots. The method comprises the following steps of: adding concentrated NHO3 and concentrated H2SO4 to an oxidized graphene solution, uniformly mixing, placing a mixture in a microwave oven to react, cooling down to be at the room temperature, carrying out an ultrasonic operation, regulating a pH value to be 8, and carrying out millipore filtration and dialysis to obtain yellow-green-fluorescent graphene quantum dots with the quantum yield reaching up to 11.7%; and further reducing the yellow-green graphene quantum dots through NaBH4 to obtain blue graphene quantum dots, wherein the quantum yield reaches up to 22.9%. According to the method for preparing the bicolor graphene quantum dots through the microwave radiation manner, the yellow-green or blue graphene quantum dots are represented through an AFM (Atomic Force Microscope) and a high-resolution TEM (Transmission Electron Micorscope) so that the prepared graphene quantum dots have excellent dispersibility, the granular sizes are mainly in the range of 2-7nm, the average grain diameter is 4.5nm, and the average height of the quantum dots is 1.2nm. The manufactured graphene quantum dots have excellent dispersibility underwater, can stably exist for a long term, have excellent fluorescence property and can be applied to biological mark and sensor analysis.
Description
technical field [0001] The invention relates to a microwave preparation method of two-color graphene quantum dots. Background technique [0002] Graphene has created a research boom in various fields due to its good performance, and the research on the fluorescence properties of graphene and its derivatives has also attracted more and more interest from scientists. However, since graphene is a zero-gap material, its fluorescence effect is almost impossible to observe (cf.: Eda, G.; Lin, Y.Y.; Mattevi, C.; Yamaguchi, H.; Chen, H.A.; Chen, I.S.; Chen, C.W.; Chhowalla, M. Adv. Mater. 2010, 22, 505; Loh, K.P.; Bao, Q.; Eda, G.; Chhowalla, M. Nature Chem. The methods that can make graphene generate energy gaps have attracted extensive attention of researchers, and these methods include doping (see: Jeon, K.J.; Lee, Z.; Pollak, E.; Moreschini, L.; Bostwick, A.; Park, C.M.; Mendelsberg, R.; Radmilovic, V.; Kostecki, R.; Richardson, T.J.; Rotenberg, E. ACS Nano 2011, 5, 1042.), or...
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