Preparation method of self-assembled talcum powder loaded room-temperature phosphorescent carbon dots

Abstract

The invention discloses a preparation method of self-assembled talcum powder loaded room-temperature phosphorescent carbon dots. The preparation method comprises the following steps: grinding and mixing citric acid, phenylenediamine and talcum powder according to a mass ratio, carrying out temperature programming and constant-temperature reaction on the obtained mixture under vacuum and nitrogen protection conditions, naturally cooling, and grinding into powder to obtain the self-assembled talcum powder loaded room-temperature phosphorescent carbon dot material. According to the invention, by utilizing the confinement and rigidity enhancement effects of the two-dimensional layered structure of the talcum powder, non-radiative transition is effectively inhibited, triplet excitons are stabilized, dual emission of blue fluorescence and green long-afterglow phosphorescence is realized, and the longest afterglow time can reach 18 s. The material with both fluorescence and phosphorescence is obtained by introducing talcum powder, the optical property is higher, the application field is greatly expanded, and the application effect is greatly improved. The method disclosed by the invention is simple in process, relatively high in yield and good in repeatability, and the obtained self-assembled talcum powder loaded room-temperature phosphorescent carbon dot material has a good application prospect in the fields of photoelectric devices, anti-counterfeiting encryption, biosensing, environmental monitoring and the like.

Description

Technical Field

[0001] This invention relates to the field of afterglow nanomaterials, and in particular to a method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots. Background Technology

[0002] Room temperature phosphorescent carbon dots (RTP-CDs) are carbon dot materials (CDs) that emit phosphorescence upon photoexcitation at room temperature. Phosphorescence is a photoluminescence phenomenon. When a molecule absorbs light energy and transitions to an excited state, it enters the triplet state through intersystem crossing (ISC), and then releases phosphorescence upon returning to the ground state. Unlike traditional fluorescence, phosphorescence has a long luminescence lifetime (typically in the millisecond to second range), and the color and intensity of the emitted light can be controlled through the material structure. Furthermore, due to its advantages such as low toxicity, good biocompatibility, good photostability, adjustability, and persistent glow signal, it is widely used in fields such as anti-counterfeiting and information protection, bioimaging, environmental monitoring, optoelectronic devices, and light-emitting diodes (LEDs).

[0003] The hydrothermal / solvothermal method is the most commonly used method for preparing phosphorescent carbon dots. It typically uses precursors such as citric acid, urea, and ethylenediamine, which are mixed with deionized water or organic solvents and placed in a high-pressure reactor for high-temperature, high-pressure carbonization. During the reaction, the precursors undergo dehydration, polymerization, carbonization, and doping with nitrogen / boron heteroatoms, forming carbon dots with room-temperature phosphorescence properties. After the reaction, the product is obtained by cooling, centrifugation, dialysis, and drying. However, this method has significant technical drawbacks: long reaction time, low phosphorescence quantum yield, and the triplet state is easily quenched by solvents and oxygen; the product particle size and luminescence properties are non-uniform, resulting in poor batch-to-batch reproducibility; the phosphorescence lifetime and emission wavelength are difficult to precisely control, and phosphorescence is easily quenched in aqueous solutions, limiting its practical application.

[0004] Talc powder is a mineral powder with hydrated magnesium silicate as its main component. It is chemically stable and possesses good acid and alkali resistance, fire resistance, and insulation properties. Due to its unique physicochemical properties and wide range of applications, it has become a research hotspot. Furthermore, the lamellar structure of talc powder can effectively support room-temperature phosphorescent carbon dots (RTP-CDs), enhancing their rigidity and extending their phosphorescence lifetime. Moreover, the diversity of preparation methods (electrochemical oxidation, hydrothermal methods, solvothermal methods, etc.) significantly affects the phosphorescence loading effect and further influences phosphorescence performance.

[0005] Therefore, designing a rapid, efficient, and scientific method to obtain new materials with talc-loaded RTP-CDs and expand their application scenarios is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing self-assembled talc-loaded room-temperature phosphorescent carbon dots. This invention introduces talc to obtain a material that simultaneously possesses fluorescence and phosphorescence. The prepared self-assembled talc-loaded room-temperature phosphorescent carbon dot material can achieve dual emission of blue fluorescence and green long-afterglow phosphorescence, with a maximum afterglow time of up to 18 seconds.

[0007] The technical solution of this invention is: a method for preparing self-assembled talc powder-supported room temperature phosphorescent carbon dots, the specific steps of which are as follows: (1) Weigh citric acid, phenylenediamine and talc in a mass ratio of 1~5:1~5:1~5 and grind them in a mortar until they are completely mixed; so that the organic precursor molecules such as citric acid and phenylenediamine are uniformly adsorbed on the layered surface and interlamellar gaps of talc, so as to better form a hydrogen bond network structure. (2) Transfer the solid mixture obtained in step (1) to a reaction crucible and place it in a temperature-controlled tube furnace for vacuuming-nitrogen purging cycle treatment; (3) Set the temperature to 100~300℃ and react at a constant temperature in a flowing nitrogen atmosphere; so that citric acid and phenylenediamine undergo dehydration condensation and aromatization reaction, and at the same time, a rigid and fixed carbon dot network structure is formed in situ under the confinement of the talc layered structure. (4) After the reaction is complete, the mixture is allowed to cool naturally to room temperature. The resulting product is then ground into powder to obtain the crude carbon dot product. (5) The obtained crude carbon dot product was dissolved and purified by reprecipitation to obtain the self-assembled talc-supported room temperature phosphorescent carbon dot material (TALC@RTP-CDs).

[0008] Then, 5.0 mg of TALC@RTP-CDs solid powder was placed into a solid sample cell, and fluorescence and phosphorescence spectra were tested at a voltage of 400~550V, a slit width of 5~10 nm, and an excitation wavelength of 340~450 nm. The changes in phosphorescence intensity and phosphorescence lifetime before and after the addition of talc were compared.

[0009] Preferably, the phenylenediamine is o-phenylenediamine, m-phenylenediamine, or p-phenylenediamine.

[0010] Preferably, the talc powder has a mesh size of 3000-5000. The mesh size of the talc powder includes, but is not limited to, any one of 3000-5000. More preferably, the mesh size of the talc powder is 3000, 4000, or 5000. Even more preferably, the mesh size of the talc powder is 4000.

[0011] Preferably, in step (1), the mass ratio of citric acid:phenylenediamine:talc is 2:1:1.

[0012] Preferably, the vacuuming process in step (2) is performed at least three times. The vacuuming-nitrogen purging cycle is used to create a low-oxygen, low-water environment.

[0013] Preferably, the temperature in step (3) is set to 200 ℃.

[0014] Preferably, the isothermal reaction time in step (3) is 1 to 6 hours. More preferably, the isothermal reaction time is 2 hours.

[0015] The self-assembled talc-supported room-temperature phosphorescent carbon dot material TALC@RTP-CDs prepared in this invention has the following characteristics: (1) Confined stiffness enhancement effect Talc is a layered magnesium silicate material, and its two-dimensional layered structure enables: ① Provides a physically confined space; ② Suppress the internal and external vibrations of carbon point molecules; ③ Reduce non-radiative transitions; ④ Construct a stable hydrogen bond network.

[0016] Compared with carbon dots without talc, the self-assembled talc-supported room-temperature phosphorescent carbon dot material of the present invention has the following advantages: ① It has both fluorescence and phosphorescence functions; ②The phosphorescence lifetime was significantly increased from <1 s to 5–20 s; ③ Under oxygen exposure conditions, the phosphorescence decay rate decreases by more than 50%.

[0017] The aforementioned performance improvement is not a simple adjustment of the ratio, but rather stems from the spatial confinement and energy level stabilization effect of talc sheets on triplet excitons.

[0018] (2) Technological contributions of vacuum-assisted low-temperature solid-state polymerization The preparation method of this invention constructs a synergistic reaction system of "vacuum-nitrogen flow-low temperature solid-phase polymerization", and its technical effects are reflected in: ① Vacuuming eliminates adsorbed water and oxygen, reducing triplet quenching centers; ② A flowing nitrogen environment reduces the occurrence of side reactions; ③ Low-temperature solid-state reactions avoid solvent-induced structural collapse; ④ Formation of a highly cross-linked, rigid hydrogen-bonded network structure: Citric acid undergoes dehydration condensation and aromatization reactions with phenylenediamine, while simultaneously forming a rigid, fixed carbon dot network structure in situ within the confines of the talc layered structure.

[0019] Compared with conventional solution methods or simple pyrolysis methods, the preparation method of this invention significantly improves the stability of triplet excitons and the duration of phosphorescence.

[0020] This invention features a clear process window, good repeatability, and feasible scale-up, achieving predictable and controllable performance output while ensuring stable material structure construction. The inventors discovered that when the mass ratio of citric acid:m-phenylenediamine:talc is 2:1:1, the reaction temperature is 200℃, the reaction time is 2 h, and the talc powder is 4000 mesh, the obtained TALC@RTP-CDs exhibit the longest phosphorescence lifetime, with small fluctuations in lifetime between sample batches, demonstrating good process stability and repeatability.

[0021] The above results demonstrate that this invention not only significantly improves phosphorescence performance, but also establishes a correspondence between structural construction and luminescence output, transforming material preparation from empirical adjustment to controllable adjustment, thus laying a technical foundation for subsequent continuous and large-scale production.

[0022] This invention prepares TALC@RTP-CDs using a vacuum-assisted low-temperature solid-state polymerization method. Under vacuum and nitrogen protection, the influence of factors such as oxygen and water in the air is avoided, side reactions are reduced, the process is simple and the conditions are controllable, and the prepared TALC@RTP-CDs have superior phosphorescence performance, can emit light stably in room temperature air environment, and significantly extend the phosphorescence lifetime.

[0023] This invention utilizes the confinement and rigidity-enhancing effects of the two-dimensional layered structure of talc powder to effectively suppress nonradiative transitions and stabilize triplet excitons, achieving dual emission of blue fluorescence and long-afterglow green phosphorescence, with an afterglow time of up to 18 s. By introducing talc powder, this invention obtains a material possessing both fluorescence and phosphorescence, resulting in enhanced optical properties and significantly expanding its application areas and effects. For example, in detection applications, dual-mode fluorescence and phosphorescence detection can be employed to improve detection performance; in anti-counterfeiting and encryption applications, the introduction of phosphorescence properties enables dual encryption.

[0024] Meanwhile, the material used in this invention is in solid powder form, which facilitates its composite use with resin, polymer, or coating systems, making it suitable for industrial processing and practical applications. Compared to existing room-temperature phosphorescent materials that rely on inert environments or complex encapsulation conditions, the material of this invention can maintain stable afterglow output under normal environmental conditions, reducing usage costs and application barriers. It has stronger practical value and promotion potential in fields such as security marking, anti-counterfeiting labels, visual inspection, and functional coatings.

[0025] The method of this invention is simple, has a high yield and good repeatability, and the resulting self-assembled talc powder-supported room temperature phosphorescent carbon dot material has good application prospects in optoelectronic devices, anti-counterfeiting encryption, biosensing and environmental monitoring. Attached Figure Description

[0026] Figure 1The fluorescence and phosphorescence emission spectra of TALC@RTP-CDs in Example 1 are shown.

[0027] Figure 2 The phosphorescence time-varying diagram of TALC@RTP-CDs in Example 1 is shown.

[0028] Figure 3 The phosphorescence emission spectrum of TALC@RTP-CDs-1 in Example 2 is shown.

[0029] Figure 4 The phosphorescence time-varying diagram of TALC@RTP-CDs-1 in Example 2 is shown.

[0030] Figure 5 The phosphorescence emission spectrum of TALC@RTP-CDs-2 in Example 3 is shown.

[0031] Figure 6 The fluorescence emission spectrum of CDs in Comparative Example 1 is shown. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the specific embodiments of this invention will be described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Any modifications or equivalent substitutions made based on the inventive concept are within the scope of protection of this invention. Example

[0033] (1) Weigh citric acid, m-phenylenediamine and 4000 mesh talc powder in a mass ratio of 2:1:1 and grind them in a mortar for 30 min until they are completely mixed and uniform, so that the organic precursor molecules citric acid and m-phenylenediamine are uniformly adsorbed on the layered surface and interlayer gaps of talc powder. (2) The solid mixture was transferred to a reaction crucible and placed in a temperature-controlled tube furnace for three cycles of vacuuming and nitrogen filling to create a low-oxygen and low-water environment. (3) Set the temperature to 200 ℃ and react at a constant temperature for 2 h in a flowing nitrogen atmosphere to allow citric acid and m-phenylenediamine to undergo dehydration condensation and aromatization reaction, while forming a rigid fixed carbon dot network structure in situ under the confinement of the talc layered structure. (4) After the reaction is complete, the product is naturally cooled to room temperature and then ground into powder to obtain the crude carbon dot product. (5) After dissolving and reprecipitating the crude carbon dot product, self-assembled talc-supported room temperature phosphorescent carbon dot material (TALC@RTP-CDs) was obtained with a solid yield of 78%. (6) Take 5.0 mg of TALC@RTP-CDs solid powder and put it into the solid sample cell. Set the voltage to 500 V and the slit to 10 nm. Test the fluorescence emission wavelength spectrum under the condition of excitation at 373 nm and the phosphorescence emission wavelength spectrum under the condition of excitation at 368 nm.

[0034] Figure 1 The fluorescence and phosphorescence emission spectra of TALC@RTP-CDs in Example 1 are shown. Figure 2 This is a phosphorescence time-varying plot of TALC@RTP-CDs from Example 1, showing the change in phosphorescence over time. Results analysis: Under 365 nm UV light irradiation, TALC@RTP-CDs exhibit bright blue fluorescence, with the maximum emission peak located at 453 nm (see...). Figure 1 ); immediately after the light source is turned off, it exhibits clearly visible green phosphorescence emission, with the maximum emission peak located at 506 nm (see...). Figure 1 As time progresses, the phosphorescence gradually decays, lasting up to 18 seconds (see...). Figure 2 A significant redshift difference of approximately 53 nm exists between the fluorescence and phosphorescence peaks, indicating the successful construction of an independent triplet emission channel within the system. This remarkable room-temperature phosphorescence phenomenon is primarily attributed to the two-dimensional layered confinement structure provided by the 4000-mesh talc powder: its high specific surface area and interlayer micro-nano spaces allow the organic precursor to be uniformly adsorbed and embedded between the layers during grinding, forming a rigidly fixed carbon dot network during in-situ carbonization in a nitrogen atmosphere at 200 °C. This rigid microenvironment effectively suppresses nonradiative transitions of vibrational groups such as C=O and C–N within the carbon dots, reducing the nonradiative decay rate from the triplet to the ground state. Simultaneously, the low-oxygen environment prevents oxygen quenching of the triplet state, thus significantly extending the phosphorescence lifetime. Compared with Comparative Example 1, under the same precursor ratio and reaction temperature conditions, the transformation from "no phosphorescence" to "continuous green phosphorescence for 18 s" was achieved solely by introducing the talc-confined structure. This represents a qualitative change from nothing to something, fully demonstrating that the talc-confined self-assembly structure is the decisive factor in achieving room temperature phosphorescence, rather than a simple thermal condensation product. Example

[0035] (1) Weigh citric acid, o-phenylenediamine and 3000 mesh talc powder in a mass ratio of 1:1:1 and grind them in a mortar for 30 min until they are completely mixed and uniform, so that the organic precursor molecules are uniformly adsorbed on the layered surface and interlayer gaps of the talc powder. (2) The solid mixture was transferred to a reaction crucible and placed in a temperature-controlled tube furnace for three cycles of vacuuming and nitrogen filling to create a low-oxygen and low-water environment. (3) Set the temperature to 180 °C and react at a constant temperature for 3 h in a flowing nitrogen atmosphere to allow citric acid and o-phenylenediamine to undergo dehydration condensation and aromatization reactions, while forming a rigid and fixed carbon dot network structure in situ under the confinement of the talc layered structure. (4) After the reaction is complete, the mixture is allowed to cool naturally to room temperature. The resulting product is then ground into powder to obtain the crude carbon dot product. (5) After dissolving and reprecipitating the crude product, a self-assembled talc-supported room temperature phosphorescent carbon dot material (TALC@RTP-CDs-1) was obtained with a solid yield of 72%. (5) Take 5.0 mg of TALC@RTP-CDs-1 solid powder and put it into the solid sample cell. Set the voltage to 550 V and the slit to 10 nm. Test the phosphorescence emission wavelength spectrum under the condition of excitation at 326 nm.

[0036] Figure 3 The phosphorescence emission spectrum of TALC@RTP-CDs-1 in Example 2 is shown. Figure 4 The phosphorescence time-mapping diagram of TALC@RTP-CDs-1 in Example 2 is shown. Results analysis: TALC@RTP-CDs-1 exhibits blue fluorescence under 365 nm excitation and emits bluish-green phosphorescence after the light source is turned off, with a maximum emission peak at 500 nm (see...). Figure 3 The duration is approximately 15 seconds. Compared to Example 1, the phosphorescence peak shows a slight blue shift (506 nm → 500 nm) and a slightly shorter lifetime (18 s → 15 s) (see Example 1). Figure 4 This change is mainly related to two factors: First, the ortho-position structure of o-phenylenediamine is more prone to forming intramolecular hydrogen bonds and locally twisted conjugated structures during thermal condensation, resulting in a slightly lower degree of π-conjugation within the carbon dots compared to the meta-system. This leads to a slight increase in the triplet energy level, manifested as a slight blue shift in the emission wavelength. Second, the use of 3000-mesh talc powder results in a slightly lower specific surface area and interlayer dispersion uniformity compared to 4000-mesh talc powder, leading to a slightly weaker confinement intensity. Some triplet excitons exhibit a higher probability of nonradiative decay, thus shortening the afterglow time. However, the system still maintains a long afterglow emission on the order of 15 s, indicating that the method of this invention has good adaptability and controllability to different precursor structures. The phosphorescence performance is not obtained by chance, but is a reproducible technical effect stably achieved under the synergistic effect of talc confinement and low oxygen. Example

[0037] (1) Weigh citric acid, p-phenylenediamine and 5000 mesh talc powder in a mass ratio of 1:2:1 and grind them in a mortar for 30 min until they are completely mixed and uniform, so that the organic precursor molecules are uniformly adsorbed on the layered surface and interlayer gaps of the talc powder. (2) The solid mixture was transferred to a reaction crucible and placed in a temperature-controlled tube furnace for three cycles of vacuuming and nitrogen filling to create a low-oxygen and low-water environment. (3) Set the temperature to 230 °C and react at a constant temperature for 5 h in a flowing nitrogen atmosphere to allow citric acid and p-phenylenediamine to undergo dehydration condensation and aromatization reactions, while forming a rigid and fixed carbon dot network structure in situ under the confinement of the talc layered structure. (4) After the reaction is complete, the mixture is naturally cooled to room temperature and the resulting material is ground into powder to obtain talc-supported room temperature phosphorescent carbon dot material; (5) After dissolving and reprecipitating the crude product, a self-assembled talc-supported room temperature phosphorescent carbon dot material (TALC@RTP-CDs-2) was obtained with a solid yield of 65%. (6) Take 5.0 mg of TALC@RTP-CDs-1 solid powder and put it into the solid sample cell. Set the voltage to 600 V and the slit to 10 nm. Test the phosphorescence emission wavelength spectrum under the condition of excitation at 336 nm.

[0038] Figure 5 The phosphorescence emission spectrum of TALC@RTP-CDs-2 in Example 3 is shown. Results analysis: TALC@RTP-CDs-2 emits blue fluorescence under 365 nm excitation and produces green phosphorescence after the light source is turned off. The maximum emission peak is significantly redshifted to 532 nm (see...). Figure 5 However, the afterglow time is shortened to about 5 s. This phenomenon indicates that under the conditions of 230 ℃ and 5 h, the degree of carbonization is significantly enhanced, the degree of aromatization and π-conjugation range within the system are expanded, and the triplet energy level is further reduced, thus causing the phosphorescence peak to redshift significantly into the long-wavelength region. However, excessively high reaction temperature and excessively long reaction time may also induce over-carbonization, which partially destroys the local rigid hydrogen bond network or weak intermolecular interactions, and generates more structural defects and nonradiative recombination centers, making triplet excitons more susceptible to decay through nonradiative pathways, thereby significantly shortening the afterglow time. These results show that the phosphorescence performance can be wavelength-tuned (in the range of 500–532 nm) by the precursor ratio and reaction conditions, exhibiting designability rather than being predictable by simple ratio changes.

[0039] Comparative Example 1: (1) Weigh citric acid and m-phenylenediamine at a mass ratio of 2:1 and grind them in a mortar for 30 min until they are completely mixed. (2) The solid mixture was transferred to a reaction crucible and placed in a temperature-controlled tube furnace for three cycles of vacuuming and nitrogen filling to create a low-oxygen and low-water environment. (3) Set the temperature to 200 ℃ and react at a constant temperature for 2 h in a flowing nitrogen atmosphere to allow citric acid and m-phenylenediamine to undergo dehydration condensation and aromatization reaction to form a carbon dot network structure. (4) After the reaction is complete, the sample is naturally cooled to room temperature and then ground into powder to obtain the crude carbon dot product. (5) The crude product was dissolved and purified by reprecipitation to obtain self-assembled carbon dot materials (CDs) with a solid yield of 75%; (6) Take 5.0 mg of CDs solid powder and put it into the solid sample cell. Set the voltage to 500 V and the slit to 10 nm. Test the fluorescence emission wavelength spectrum under the condition of excitation at 373 nm.

[0040] Figure 6 The following is the fluorescence emission spectrum of CDs in Comparative Example 1. Results analysis: Only blue fluorescence emission was observed under 365 nm excitation, with a maximum emission peak at 448 nm. No discernible green phosphorescence signal was detected after the light source was turned off (see [link to data]). Figure 6 Although the precursor ratio was the same as in Example 1, and the reaction temperature and time were also consistent, the carbon dots were in a relatively free state during the thermal condensation process because the layered confinement structure of talc was not introduced into the system. Molecular vibrations and rotations were not effectively suppressed, and triplet excitons decayed rapidly through non-radiative transitions after formation and were easily quenched by residual oxygen molecules. Therefore, room-temperature phosphorescence could not be produced. This comparative result clearly shows that the generation of room-temperature phosphorescence does not solely depend on the thermal condensation reaction of citric acid and m-phenylenediamine, but must rely on the two-dimensional rigid confinement microenvironment constructed by talc. The significant difference from "no afterglow" to "afterglow visible for up to 18 s" constitutes a clear leap in technical effect, proving that the method of this invention has substantial technical progress.

[0041] The experimental results of Examples 1–3 and Comparative Example 1 show that the self-assembled talc-supported room-temperature phosphorescent carbon dot system constructed by the method of this invention exhibits significant technical advantages in terms of structural stability, phosphorescence lifetime, and tunability of emission wavelength. First, under the same precursor and heat treatment conditions, the significant difference between the "complete absence of room-temperature phosphorescence" in the comparative example and the "visible green afterglow for up to 18 s" simply due to the introduction of the layered confinement structure of talc indicates that the two-dimensional rigid microenvironment constructed by talc plays a decisive role in the stability of triplet excitons. Second, by changing the aromatic diamine structure, talc particle size, and reaction temperature and time parameters, the phosphorescence emission peak of the material can be tuned within the range of 500–532 nm, and the afterglow time varies between 5–18 s. This indicates that the system can not only stably generate room-temperature phosphorescence but also possesses designable wavelength and lifetime tuning capabilities. Furthermore, the experimental results show that the finer the talc particle size and the higher the degree of confinement, the longer the phosphorescence lifetime. However, excessively high temperatures or excessive carbonization weaken the rigid network structure, leading to a shorter lifetime. This further proves that the phosphorescence behavior originates from the mechanism of enhanced confinement rigidity, rather than simply due to increased carbonization.

[0042] Therefore, it can be seen that the overall technical solution of "in-situ self-assembly of precursor - confined fixation of layered talc powder - synergistic construction of low-oxygen environment" can realize the generation and controllable regulation of long-life room temperature phosphorescence in a heavy metal-free system.

[0043] This invention introduces talc to obtain a material that possesses both fluorescence and phosphorescence, resulting in enhanced optical properties. This greatly expands the application fields and effects. For example, when applied to detection, dual-mode fluorescence and phosphorescence detection can be used to improve detection performance. When applied to anti-counterfeiting encryption, the introduction of phosphorescence properties enables dual encryption.

[0044] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical principles disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots, characterized in that, The preparation method comprises the following steps: (1) Weigh citric acid, phenylenediamine and talc in a mass ratio of 1~5:1~5:1~5 and grind them in a mortar until they are completely mixed. (2) Transfer the solid mixture obtained in step (1) to a reaction crucible and place it in a temperature-controlled tube furnace for vacuuming-nitrogen purging cycle treatment; (3) Set the temperature of the tube furnace to 100~300℃ and react at a constant temperature in a flowing nitrogen atmosphere; (4) After the reaction is complete, the mixture is allowed to cool naturally to room temperature. The resulting product is then ground into powder to obtain the crude carbon dot product. (5) The obtained crude carbon dots were dissolved and purified by reprecipitation to obtain the self-assembled talc-supported room temperature phosphorescent carbon dots.

2. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, The phenylenediamine mentioned is o-phenylenediamine, m-phenylenediamine, or p-phenylenediamine.

3. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, The talc powder has a mesh size of 3000~5000.

4. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, In step (1), the mass ratio of citric acid:phenylenediamine:talc is 2:1:

1.

5. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, The vacuuming process in step (2) is performed at least three times.

6. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, The isothermal reaction time in step (3) is 1 to 6 hours.

7. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, The isothermal reaction time in step (3) is 2 hours.

8. The method for preparing self-assembled talc-supported room-temperature phosphorescent carbon dots according to claim 1, characterized in that, The talc powder has a mesh size of 4000.

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