Preparation method of long-life room-temperature phosphorescent carbon dot and silicon dioxide composite material

Abstract

The invention relates to a long-life room-temperature phosphorescent carbon dot-silicon dioxide composite material, which is prepared by the following steps: adding trinitropyrene and boric acid into an aqueous solution of sodium hydroxide, fully dissolving the trinitropyrene and the boric acid through ultrasonic treatment, carrying out hydrothermal reaction to obtain a brown solution, and freeze-drying to obtain brown carbon dot powder. Placing the powder in a beaker, and adding tetraethyl orthosilicate and ammonia water to obtain a milk white solution; and centrifuging, washing, drying, grinding and calcining the obtained milky white solution to obtain the long-life room-temperature phosphorescent carbon dot-silicon dioxide composite material. The preparation method is characterized in that the long-life room-temperature phosphorescent carbon dot and silicon dioxide composite material is obtained by a calcination method and has the advantages of simplicity and convenience in operation, high yield and the like. In addition, the long-service-life room-temperature phosphorescent carbon dot-silicon dioxide composite material prepared by a calcination method realizes that green phosphorescence can be seen by naked eyes for 30 seconds after an ultraviolet lamp is turned off. And the medicines used for preparation are nontoxic, harmless and low in price.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon dot nano material preparation, and specifically relates to a method for preparing a long-life room temperature phosphorescent carbon dot@silicon dioxide composite material. Background Art

[0002] Room temperature phosphorescent materials are materials that can still emit light when the external excitation light source stops. Their potential applications in photonics, organic electronics and bioelectronics have attracted great attention in the past decade. However, existing room temperature phosphorescent materials mainly include rare earth phosphors, organometallic complexes and pure organic complexes. These materials usually have problems such as complex preparation process, heavy metal toxicity and high cost, which limit the widespread application of room temperature phosphorescent materials. Therefore, it is a huge challenge to develop a new generation of room temperature phosphorescent materials with long life and high efficiency that are easy to prepare, green and economical.

[0003] As a new type of zero-dimensional luminescent nanocarbon material, carbon dots are widely used in photoelectrocatalysis, biomedicine, and sensing fields due to their many advantages such as tunable optical properties, good biocompatibility, non-toxicity, pollution-free and low cost. However, due to the instability of the triplet excited state, the carbon dot group has low intersystem crossing and fast non-radiative transition, which reduces the quantum yield and phosphorescence lifetime of carbon dot-based room temperature phosphorescent materials. In order to solve these problems, researchers have incorporated carbon dots into rigid frameworks such as silica, because the rigid framework can effectively limit the vibration and rotation of carbon dots to suppress the loss caused by non-radiative transitions. Therefore, this strategy can significantly improve the lifetime of carbon dot-based room temperature phosphorescent materials. However, the preparation process and regulation method of carbon dot-based room temperature phosphorescent materials are relatively cumbersome, which increases the complexity of the reaction. Therefore, it is of vital importance to use a simple calcination method to prepare carbon dot-based room temperature phosphorescent composite materials with long lifetime.

[0004] The methods reported so far for preparing carbon dot-based room temperature phosphorescent materials still have the disadvantages of complex preparation process, high cost, short phosphorescence lifetime, etc., which are not conducive to their practical application. Therefore, it is necessary to develop a simple method for preparing carbon dot-based room temperature phosphorescent nanomaterials. Summary of the invention

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a method for preparing a long-life room temperature phosphorescent carbon dot@silicon dioxide composite material.

[0006] One of the objects of the present invention is to provide a simple and easy calcination method.

[0007] The second object of the present invention is to provide a long-life room temperature phosphorescent carbon dot@silicon dioxide composite material.

[0008] The long-life room temperature phosphorescent carbon dot@silica composite material prepared by the present invention is prepared by calcination method using trinitropyrene, boric acid, tetraethyl orthosilicate and ammonia water as raw materials. The preparation process includes the following specific steps: 1. First, add 10-50 mg of trinitropyrene, 1-5 g of boric acid and 0.4-1.2 g of sodium hydroxide to 10 mL of deionized water to obtain a yellow solution; 2. Place the yellow solution obtained in step 1 in a polytetrafluoroethylene reactor and react at 150-210° C. for 4-12 hours to obtain a brown solution; 3. Freeze-dry the brown solution obtained in step 2 for 12-24 hours to obtain a brown powder; 4. Take out 0.6-1 g of the brown powder obtained in step 3, add 120-160 mL of deionized water and 20-40 mL of anhydrous ethanol solution, and then add 14.2-16.2 mL of tetraethyl orthosilicate and 0.6-1 mL of ammonia water. After stirring for 6-10 hours, a milky white solution is obtained; 5. Centrifuge the milky white solution obtained in step 4 at 8000 rpm for 10 minutes to separate the supernatant from the milky white precipitate. Wash the milky white precipitate with anhydrous ethanol for 3 times and finally dry it in an oven at 60-80°C for 12-36 hours to obtain a white solid. 6. Grind the white solid obtained in step 5 and place it in a muffle furnace and calcine it at 450-550° C. for 1-3 hours to obtain a long-life room temperature phosphorescent carbon dot@silica composite material.

[0009] Beneficial effects of the present invention: 1. The present invention provides a long-life room temperature phosphorescent carbon dot@silicon dioxide composite material and a preparation method thereof, wherein the composite material is prepared by calcination using trinitropyrene, boric acid, tetraethyl orthosilicate and ammonia water as raw materials, and only requires common laboratory equipment, without special equipment, and the process is simple and easy to operate; 2. The room temperature phosphorescence of the long-life room temperature phosphorescent carbon dots@silica composite material obtained by this method can be seen with the naked eye as green phosphorescence for up to 30 seconds after the UV light is turned off; 4. The drugs used in the present invention are non-toxic, harmless and inexpensive, and are simple to prepare and take a short time. No complicated steps are required after preparation, and they are particularly suitable for batch and low-cost preparation, and are suitable for industrial-scale production and commercial applications; BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments or the description of the prior art will be briefly introduced with drawings below, but the drawings in the following description are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 This is a high-resolution transmission electron microscopy image of the long-life room-temperature phosphorescent carbon dot@silicon dioxide composite material prepared in Example 1 of the present invention.

[0012] Figure 2 This is a Fourier infrared image of the long-life room temperature phosphorescent carbon dot@silicon dioxide composite material prepared in Example 1 of the present invention.

[0013] Figure 3 This is an X-ray diffraction pattern of the long-life room temperature phosphorescent carbon dot@silicon dioxide composite material prepared in Example 1 of the present invention.

[0014] Figure 4 These are state diagrams of the long-life room temperature phosphorescent carbon dot@silica composite material in Examples 1-3 and Comparative Example 1 under sunlight, under 365nm ultraviolet light, and after turning off the light. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] All other embodiments obtained by ordinary technicians in the field without creative work in the embodiments of the present invention belong to the scope of protection of the present invention.

[0017] Unless otherwise specified, the experimental methods described in the embodiments are all conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0018] Embodiment 1: First, 30 mg of trinitropyrene, 3 g of boric acid and 0.8 g of sodium hydroxide were added to 10 mL of deionized water to obtain a yellow solution; the yellow solution was placed in a polytetrafluoroethylene reactor and reacted at 180°C for 8 hours to obtain a brown solution; the brown solution was freeze-dried for 18 hours to obtain a brown powder; 0.8 g of the brown powder was taken out and placed in a beaker, 140 mL of deionized water and 30 mL of anhydrous ethanol were added, 15.2 mL of tetraethyl orthosilicate and 0.8 mL of ammonia water were added during stirring, and then stirred for 8 hours to obtain a milky white solution. The milky white solution was centrifuged at 8000 rpm for 10 minutes, and the supernatant in the centrifuge tube was removed to obtain a milky white precipitate; the milky white precipitate was washed with anhydrous ethanol 3 times, and finally placed in a 70°C oven to dry for 24 hours to obtain a white solid for grinding, and placed in a muffle furnace for calcination at 500°C for 2 hours to obtain a long-life room temperature phosphorescent carbon dot@silica composite material.

[0019] Embodiment 2: First, 50 mg of trinitropyrene, 1 g of boric acid and 1.2 g of sodium hydroxide were added to 10 mL of deionized water to obtain a yellow solution; the yellow solution was placed in a polytetrafluoroethylene reactor and reacted at 210°C for 4 hours to obtain a brown solution; the brown solution was freeze-dried for 12 hours to obtain a brown powder; 1 g of the brown powder was taken out and placed in a beaker, added to a mixed solution of 160 mL of deionized water and 20 mL of anhydrous ethanol, 16.2 mL of tetraethyl orthosilicate and 0.6 mL of ammonia water were added during stirring, and then stirred for 10 hours to obtain a milky white solution, which was centrifuged at 8000 rpm for 10 minutes, and the supernatant in the centrifuge tube was removed to obtain a milky white precipitate; the milky white precipitate was washed 3 times with anhydrous ethanol, and finally dried in an oven at 80°C for 36 hours to obtain a white solid grind, and placed in a muffle furnace for calcination at 550°C for 2 hours to obtain a long-life room temperature phosphorescent carbon dot@silica composite material.

[0020] Embodiment 3: First, 10 mg of trinitropyrene, 5 g of boric acid and 0.4 g of sodium hydroxide were added to 10 mL of deionized water to obtain a yellow solution; the yellow solution was placed in a polytetrafluoroethylene reactor and reacted at 150°C for 12 hours to obtain a brown solution; the brown solution was freeze-dried for 36 hours to obtain a brown powder; 0.6 g of the obtained carbon point powder was taken out and placed in a beaker, added to a mixed solution of 120 mL of deionized water and 40 mL of anhydrous ethanol, 14.2 mL of tetraethyl orthosilicate and 1 mL of ammonia water were added during stirring, and then stirred for 6 hours to obtain a milky white solution. The milky white solution was then centrifuged at 8000 rpm for 10 minutes, the supernatant obtained was separated from the milky white precipitate, the milky white precipitate was washed 3 times with anhydrous ethanol, and placed in a 60°C oven for 12 hours to obtain a white solid. The obtained powder was ground and calcined at 450°C in a muffle furnace for 4 hours to obtain a long-life room temperature phosphorescent carbon point@silica composite material.

[0021] Figure 1 This is a high-resolution transmission electron microscopy image of the long-life room temperature phosphorescent carbon dot@silicon dioxide composite material prepared in Example 1. Figure 1 It can be seen that the prepared long-life room temperature phosphorescent carbon dots@silica composite material is uniformly distributed.

[0022] Figure 2 This is a Fourier transform infrared spectrum of the long-life room temperature phosphorescent carbon dots@silicon dioxide composite material prepared in Example 1. Figure 2 It can be seen that at 1045 cm -1 It is Si-O- Si- stretching vibration, indicating that covalent bonds are generated on the surface of the long-life room temperature phosphorescent carbon dots@silica composite material.

[0023] Figure 3 This is the X-ray diffraction pattern of the long-life room temperature phosphorescent carbon dots@silicon dioxide composite material prepared in Example 1. Figure 3 It can be seen that the composite material θ =20.74° has an obvious characteristic peak of silica diffraction, indicating the formation of a silica matrix.

[0024] Figure 4 The long-life room temperature phosphorescent carbon dot@silicon dioxide composite material prepared in Examples 1-3 is shown in the following states: under sunlight, under 365 nm ultraviolet light, and after the light is turned off. Figure 4 It can be seen that the prepared Example 1 is visible to the naked eye for up to 30 s under ultraviolet light, while the long-life room temperature phosphorescent carbon dot@silica composite materials prepared in other Examples 2-3 are visible to the naked eye for a relatively short time under ultraviolet light.

[0025] Obviously, those skilled in the art can make various changes and modifications to the method for preparing a long-life room temperature phosphorescent carbon dot@silicon dioxide composite material described in the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a long-life room temperature phosphorescent carbon dot@silicon dioxide composite material, comprising the following steps: First, 10-50 mg of trinitropyrene, 1-5 g of boric acid and 0.4-1.2 g of sodium hydroxide are added to 10 mL of deionized water to obtain a yellow solution; the yellow solution is placed in a polytetrafluoroethylene reactor and reacted at 150-210°C for 4-12 hours to obtain a brown solution; the brown solution is freeze-dried for 12-24 hours to obtain a brown powder; 0.5-1 g of the powder is taken out and added to 120-160 mL of deionized water and 25-40 mL of anhydrous ethanol solution, 14.2-16.2 mL of tetraethyl orthosilicate and 0.6-1 mL of ammonia water, and stirred for 6-10 minutes. hours to obtain a milky white solution; the obtained milky white solution is centrifuged at a speed of 8000 rpm for 10 minutes, the supernatant in the centrifuge tube is removed to obtain a milky white precipitate, the milky white precipitate is washed 3 times with anhydrous ethanol, and finally placed in a 60-80°C oven to dry for 12-36 hours to obtain a white solid; and calcined in a muffle furnace at 450-550°C for 2-4 hours to obtain a long-life room temperature phosphorescent carbon dot@silica composite material.

2. The method for preparing the long-life room temperature phosphorescent carbon dots@boron dioxide composite material according to claim 1, characterized in that: The amount of trinitropyrene used is 30 mg, the amount of boric acid used is 3 g, the amount of sodium hydroxide used is 0.8 g, the amount of tetraethyl orthosilicate used is 15.2 mL, and the amount of ammonia water used is 0.8 mL.

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