Preparation method of room-temperature solid-state phosphorescence stable double-matrix carbon nanodots and application thereof

Abstract

This invention relates to the field of luminescent materials technology, specifically to a method for preparing room-temperature solid-state phosphorescent stable dual-matrix carbon nanodots and their applications. The method uses dextrin, 3-aminopropyltriethoxysilane, and boric acid as raw materials. By simultaneously introducing a silicon matrix and a boron matrix to form a dual-matrix system, the method combines the excellent stability of the silicon matrix with the unique electronic modulation capabilities of boron. Room-temperature solid-state phosphorescent stable dual-matrix carbon nanodots are synthesized via a hydrothermal method. After three cycles of water immersion-drying, the phosphorescence intensity of the obtained dual-matrix carbon nanodots decreases by only 6% to 7%. The carbon nanodots synthesized by this method have broad application prospects in the fields of anti-counterfeiting and information encryption.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a method for preparing room-temperature solid phosphorescent stable dual-matrix carbon nanodots and their applications. Background Technology

[0002] Carbon dots have become a hot topic in phosphorescent materials research due to their advantages such as simple synthesis, optical tunability, good biocompatibility, and low cost. However, achieving room-temperature long-afterglow phosphorescence or simultaneously obtaining stable fluorescence and phosphorescence dual emission still faces many challenges for carbon dot materials. To excite and stabilize the phosphorescence of carbon dots, researchers usually adopt matrix encapsulation or matrix immobilization strategies to confine the carbon dots in a rigid environment to suppress molecular vibrational relaxation and block oxygen quenching, thereby improving triplet lifetime and phosphorescence quantum yield. Currently commonly used matrix materials include polymers, inorganic salts, zeolites, and silica. These matrices can endow carbon dots with room-temperature phosphorescence properties to some extent, but single rigid matrices still have limitations such as difficulty in synergistically optimizing phosphorescence and fluorescence properties, short phosphorescence lifetime, and low phosphorescence efficiency. In addition, achieving controllable dual emission, room-temperature stability, tunable emission color, and large-scale, reproducible preparation processes remain key technical bottlenecks in this field.

[0003] Researchers have proposed using silane coupling agents or organosilicon polymers with both hydrophilic and lipophilic groups as auxiliary matrices to promote the uniform dispersion of CDs in solid-state systems through interfacial interactions. The silicon-oxygen network structure within these matrices also provides a rigid protective environment, effectively stabilizing the triplet excited state. Recent studies have further confirmed that the synergistic introduction of silane coupling agents and organosilicon polymers into the system can produce a matrix synergistic effect, significantly enhancing the phosphorescence emission intensity of CDs.

[0004] CN114605993B discloses a carbon nanodot with delayed fluorescence and room-temperature phosphorescence emission, its preparation method, and its applications. The method involves preparing carbon nanodots with delayed fluorescence and room-temperature phosphorescence emission via a hydrothermal method using boric acid, citric acid, and diethanolamine. Triplet excitons are immobilized by covalent bonds formed by BC bonds and nitrogen atoms, reducing non-radiative inactivation and extending afterglow lifetime. However, these carbon nanodots cannot be recycled, making effective recovery and reuse difficult, which limits their long-term application value in optoelectronic devices, bioimaging, and anti-counterfeiting materials. Summary of the Invention

[0005] To address the problem that carbon nanodots cannot be recycled in existing technologies, this invention provides room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots and their preparation method.

[0006] This invention is achieved through the following technical solution: A method for preparing room temperature solid phosphorescent stable dual-matrix carbon nanodots. The dual-matrix carbon nanodots undergo a 6% to 7% decrease in phosphorescence intensity after being subjected to a water immersion-drying process for 3 cycles.

[0007] Preferably, the dual-matrix carbon nanodots have graphitized structural features.

[0008] Preferably, the optimal emission wavelength of the dual-matrix carbon nanodots is 360 nm.

[0009] Preferably, the lifetime of the dual-matrix carbon nanodots is 0.03~1.51 s under 360 nm excitation.

[0010] A method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots involves a single hydrothermal reaction using dextrin, boric acid, and 3-aminopropyltriethoxysilane as raw materials to obtain room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots. Specific steps include: Step 1: Dissolve dextrin, boric acid and 3-aminopropyltriethoxysilane in deionized water, and heat and stir to obtain mixed solution A; Step 2: Continue heating the mixed solution A to carry out a hydrothermal reaction to obtain product B; Step 3: Cool product B to obtain room temperature solid phosphorescent stable dual-matrix carbon nanodots.

[0011] Preferably, in step 1, the ratio of dextrin, boric acid and 3-aminopropyltriethoxysilane is (0.05~0.5 g): (1~3 g): (1~3 mL).

[0012] Preferably, in step 1, the heating and stirring process is carried out at a temperature of 60-80°C for 10-20 minutes.

[0013] Preferably, in step 2, the hydrothermal reaction is carried out at a temperature of 180~200℃ for 2~4 hours.

[0014] Preferably, in step 3, the yield of the dual-matrix carbon nanodots is 10-20%.

[0015] Application of a room-temperature solid phosphorescently stable dual-matrix carbon nanodot preparation method in the fields of anti-counterfeiting and information encryption.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention presents a room-temperature solid-state phosphorescently stable dual-matrix carbon nanodot that is non-toxic, exhibits excellent solid-state phosphorescence stability, long room-temperature phosphorescence lifetime, high quantum yield, and long-term storage capability. The prepared carbon nanodots show broad application prospects in anti-counterfeiting and information encryption fields. The afterglow duration observed with the naked eye exceeds 19 s, the room-temperature phosphorescence lifetime reaches 1.36 s, and the photoluminescence quantum yield reaches 14.7% under 360 nm excitation. Simultaneously, the dual-matrix carbon nanodots possess excellent stability; after two cycles of water immersion-drying, the phosphorescence intensity of the carbon nanodots remains essentially unchanged, and after three cycles, the phosphorescence intensity decreases by only 6.55%, demonstrating excellent solid-state phosphorescence stability. It has been successfully applied in anti-counterfeiting and information encryption.

[0017] This invention discloses a method for preparing room-temperature solid-state phosphorescent stable dual-matrix carbon nanodots. The method uses dextrin, 3-aminopropyltriethoxysilane, and boric acid as raw materials. By simultaneously introducing a silicon matrix and a boron matrix to form a dual-matrix system, the method combines the excellent stability of the silicon matrix with the unique electronic modulation ability of boron. Room-temperature solid-state phosphorescent stable dual-matrix carbon nanodots are then synthesized via a hydrothermal method. Furthermore, this preparation method uses simple, non-toxic, and harmless raw materials, requires no calcination, and allows for easy temperature control, thus simplifying the process.

[0018] During the preparation process, 3-aminopropyltriethoxysilane and boric acid are added simultaneously. This introduces N and B atoms, and the co-doping of N and B atoms significantly reduces the band gap between the singlet and triplet states, which is beneficial for the ISC process and increases the number of triplet excitons. The C=N and C=O bonds formed on the carbon dot surface can induce (n-π*) transitions, promoting the ISC process. Furthermore, the silica structure formed by the silane precursor effectively coats the carbon dots. Subsequently, the boric acid hydrothermal process forms a matrix, stabilizing the silica structure within the boron oxide matrix, creating a double matrix protection. This structure effectively suppresses the vibrational and rotational movements of the carbon dot chromophores, thereby stabilizing the triplet excitons by restricting non-radiative transitions, improving the optical performance of room-temperature phosphorescence, and achieving an ultra-long afterglow time. Attached Figure Description

[0019] Figure 1 This is a transmission electron microscope (TEM) image of room-temperature solid phosphorescently stable dual-matrix carbon nanodots prepared in Example 1 of this invention. Figure 2 The particle size distribution of room-temperature solid phosphorescently stable dual-matrix carbon nanodots prepared in Example 1 of this invention is shown in Figure 1. Figure 3 The UV-Vis absorption spectrum of room-temperature solid phosphorescently stable dual-matrix carbon nanodots prepared in Example 1 of this invention; Figure 4The fluorescence spectra of room-temperature solid phosphorescently stable dual-matrix carbon nanodots prepared in Example 1 of this invention under different wavelength excitations are shown. Figure 5 The lifetime decay diagram of the room-temperature solid phosphorescently stable dual-matrix carbon nanodots prepared in Example 1 of the present invention under 360 nm excitation. Figure 6 The solid-state phosphorescence stability of the carbon nanodots prepared in Example 1 of this invention was studied by performing a "water immersion-drying" cycle. Figure 7 This diagram illustrates the application of room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots prepared in Example 1 of this invention in the fields of anti-counterfeiting and information encryption. Detailed Implementation

[0020] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0021] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0022] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0023] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0024] This invention discloses a method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots. The method involves a single hydrothermal reaction using dextrin, boric acid, and 3-aminopropyltriethoxysilane as raw materials to obtain room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots. Specific steps include: Step 1: Dissolve dextrin, boric acid and 3-aminopropyltriethoxysilane in deionized water in a ratio of (0.05~0.5 g):(1~3 g):(1~3 mL), and stir at 60~80℃ for 10~20 min to ensure complete dissolution, thus obtaining mixed solution A.

[0025] All of the above raw materials are commercially available products. Boric acid (H3BO3) is of analytical grade, dextrin (C6nH10nO5n·xH2O) is of analytical grade, and 3-aminopropyltriethoxysilane (C9H23NO3Si) is of analytical grade. All of them are manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] Step 2: The mixed solution A is continuously heated and placed in an oven at 180~200℃ for hydrothermal reaction for 2~4 hours to obtain product B; Step 3: Cool product B to obtain room temperature solid phosphorescent stable dual-matrix carbon nanodots.

[0027] This invention discloses a method for preparing room-temperature solid-state phosphorescent stable dual-matrix carbon nanodots. The rigid framework of the silicon matrix effectively restricts the vibration and rotation of the carbon dot luminescence center, protects the triplet exciton, and regulates the energy level structure of the carbon dots through the coordination or bonding of boron elements, thereby enhancing their intersystem crossing (ISC) efficiency and ultimately realizing carbon nanodots with both fluorescence and phosphorescence emission characteristics.

[0028] This invention also discloses a method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots. The yield of these dual-matrix carbon nanodots is 10-20%, and they exhibit graphitized structural characteristics with an optimal emission wavelength of 360 nm. Testing showed that after two cycles of water immersion-drying, the phosphorescence intensity of the carbon nanodots remained essentially unchanged. After three cycles, the phosphorescence intensity decreased by 6.55%. The carbon nanodots have a diameter of 2-4 nm, exhibit a broad absorption peak in the 200-700 nm range, and a relatively broad shoulder peak in the 250-400 nm range, demonstrating light absorption characteristics. Under 360 nm excitation, their lifetime is 0.03-1.51 s, with an average lifetime of 1.36 s.

[0029] This invention also discloses a method for preparing room temperature solid phosphorescently stable dual-matrix carbon nanodots, and the application of the obtained dual-matrix carbon nanodots in anti-counterfeiting inks, high-end certificates, luxury goods certificates, high-end tobacco and alcohol packaging and other anti-counterfeiting and information encryption fields, wherein the room temperature is 20℃~30℃.

[0030] Example 1 Step 1: Dissolve 0.05 g dextrin, 2 g boric acid and 1.5 mL 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0031] Depend on Figure 1 It can be seen that the carbon nanoparticles are uniformly distributed in the matrix, with a lattice spacing of 0.21 nm, corresponding to the

[100] crystal plane of graphite, indicating that the product has typical graphitized structural characteristics, and the diameter of the carbon nanoparticles is about 3 nm.

[0032] Depend on Figure 2 It can be seen that the diameter of the carbon nanodot is 3 nm.

[0033] Depend on Figure 3 As can be seen, the carbon nanodots prepared in this embodiment exhibit a broadened absorption peak at 298 nm, and a relatively broad shoulder peak appears near 355 nm. The carbon dots constructed by the dual matrix composite exhibit excellent light absorption characteristics.

[0034] Depend on Figure 4 It can be seen that the optimal emission wavelength of the carbon nanodots prepared in this embodiment is 360 nm.

[0035] Depend on Figure 5 It can be seen that the carbon nanodots prepared in this embodiment have a lifetime of 0.03~1.51s under 360 nm excitation, with an average lifetime of 1.36s; Depend on Figure 6 It can be seen that after multiple cycles of the "water immersion-drying" process, the phosphorescence intensity of the carbon nanodots prepared in this embodiment decreased by 6.55%, indicating that the solid phosphorescence stability of carbon nanodots prepared by the synergistic effect of the two matrices is good.

[0036] The obtained carbon nanodots were subjected to ultraviolet excitation-emission testing, and the results are as follows: Figure 7 As shown, by Figure 7 Figure a shows that under 365 nm light source illumination, the pattern "888" exhibits a blue afterglow; after the lamp is turned off, the emitted light color changes to the green number "668," and the afterglow image remains clearly discernible after 8 seconds. In Figure b, under 365 nm ultraviolet light excitation, the panda-bamboo composite pattern emits blue light; after the lamp is turned off, both switch to green light. Eight seconds after excitation stops, the bamboo afterglow completely disappears, while the panda pattern maintains its green afterglow, indicating that this material has significant application potential in information encryption and anti-counterfeiting fields.

[0037] Example 2 Step 1: Dissolve 0.05 g of dextrin and 2 g of boric acid in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0038] Example 3 Step 1: Dissolve 0.05 g of dextrin and 1.5 mL of 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to ensure complete dissolution, thus obtaining mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: Product B was cooled, and no afterglow was observed.

[0039] Example 4 Step 1: Dissolve 2 g of boric acid and 1.5 mL of 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to ensure complete dissolution, thus obtaining mixed solution A. Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0040] Example 5 Step 1: Dissolve 0.05 g dextrin, 2 g boric acid and 1.5 mL 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 180°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0041] Example 6 Step 1: Dissolve 0.05 g dextrin, 2 g boric acid and 1.5 mL 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 220°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0042] Example 7 Step 1: Dissolve 0.1 g dextrin, 2 g boric acid and 1.5 mL 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0043] Example 8 Step 1: Dissolve 0.2 g dextrin, 2 g boric acid and 1.5 mL 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0044] Example 9 Step 1: Dissolve 0.5 g dextrin, 2 g boric acid and 1.5 mL 3-aminopropyltriethoxysilane in deionized water, and stir at 60°C for 20 min using a heated magnetic stirrer to fully dissolve them, to obtain mixed solution A; Step 2: Place the mixed solution A in an oven and heat it at 200°C for 2 hours to obtain product B; Step 3: After cooling product B, room temperature solid phosphorescent stable dual-matrix carbon nanodots are obtained.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A dual-matrix carbon nanodots prepared by a method of claim 1, wherein, After the dual-matrix carbon nanodots were subjected to a water immersion-drying process for three cycles, the phosphorescence intensity decreased by 6% to 7%.

2. The room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 1, characterized in that, These dual-matrix carbon nanodots exhibit graphitized structural features.

3. The room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 1, characterized in that, The optimal emission wavelength for this dual-matrix carbon nanodot is 360 nm.

4. The room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 1, characterized in that, The lifetime of these dual-matrix carbon nanodots under 360 nm excitation is 0.03~1.51 s.

5. A method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots as described in any one of claims 1 to 4, characterized in that, A single hydrothermal reaction was carried out using dextrin, boric acid, and 3-aminopropyltriethoxysilane as raw materials to obtain room-temperature solid phosphorescently stable dual-matrix carbon nanodots. The specific steps included: Step 1: Dissolve dextrin, boric acid and 3-aminopropyltriethoxysilane in deionized water, and heat and stir to obtain mixed solution A; Step 2: Continue heating the mixed solution A to carry out a hydrothermal reaction to obtain product B; Step 3: Cool product B to obtain room temperature solid phosphorescent stable dual-matrix carbon nanodots.

6. The method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 5, characterized in that, In step 1, the ratio of dextrin, boric acid and 3-aminopropyltriethoxysilane is (0.05~0.5 g): (1~3 g): (1~3 mL).

7. The method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 5, characterized in that, In step 1, the temperature is 60~80℃ and the time is 10~20 min when heating and stirring.

8. The method for preparing room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 5, characterized in that, In step 2, the hydrothermal reaction is carried out at a temperature of 180~200℃ for 2~4 hours.

9. The room-temperature solid-state phosphorescently stable dual-matrix carbon nanodots according to claim 5, characterized in that, In step 3, the yield of the dual-matrix carbon nanodots is 10-20%.

10. The application of room temperature solid phosphorescently stable dual-matrix carbon nanodots as described in any one of claims 1 to 4 in the fields of anti-counterfeiting products and information encryption.

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