Preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder and application of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder in latent fingerprint imaging
By preparing boron, nitrogen and sulfur co-doped room temperature phosphorescence carbon dot powder, the problem of fluorescent materials being disturbed by matrix background fluorescence in latent fingerprint display is solved, and long-term phosphorescence display and high-quality latent fingerprint imaging are achieved, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202510416274.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-07-08
AI Technical Summary
Existing fluorescent materials are susceptible to fluorescence on the substrate surface during latent fingerprint display. Traditional room temperature phosphorescent materials have problems such as harsh preparation, poor stability, and high toxicity, and the phosphorescence duration is short.
Thioamide compounds and boric acid are used as raw materials to prepare boron, nitrogen and sulfur co-doped room temperature phosphorescence carbon dot powder by pyrolysis, for latent fingerprint imaging, and the phosphorescence pattern is captured by turning off the light source after excitation of ultraviolet light.
It realizes blue phosphorescence display that can last for 20 seconds after the excitation light source is turned off, effectively eliminates background fluorescence interference and obtains high-quality latent fingerprint images. The method is simple and the raw materials are easy to obtain, and it is suitable for industrial production.
Smart Images
Figure CN120270980A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of luminescent carbon nanomaterials, and in particular to a method for preparing boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder and its application in latent fingerprint imaging. Background Art
[0002] Fingerprint recognition technology stands out among many biometric information recognition technologies and becomes a key means of personal identification due to its uniqueness, lifelong permanence and high collectability. However, in actual applications, it faces "latent fingerprints" that are not easily detected by the naked eye and need to be visualized before identification.
[0003] Fluorescent nanomaterials have attracted much attention in the field of latent fingerprint imaging due to their advantages such as simple synthesis, wide application range and high imaging resolution. However, fluorescent materials must be excited by ultraviolet light in real time to obtain fluorescent fingerprints. The background fluorescence on the surface of the fingerprint-bearing matrix will seriously weaken or even completely submerge the fluorescence signal of the fingerprint lines. The background fluorescence interference on the surface of the matrix is an insurmountable problem for fluorescent materials in latent fingerprint visualization. Room temperature phosphorescent materials can continue to emit light after the excitation light source is turned off. This luminescence characteristic can effectively avoid the interference of background fluorescence, and has created a new direction for latent fingerprint visualization without background fluorescence interference. At present, traditional room temperature phosphorescent materials mainly include transition metal / rare earth-based inorganic materials, metal organic complexes and specific pure organic compounds. However, these materials have significant defects. For example, metal-based phosphorescent materials rely on rare metals and have harsh preparation conditions; pure organic systems face problems such as short afterglow life, poor stability and high toxicity, which seriously restrict practical applications. In recent years, room temperature phosphorescent carbon dots have broken through the limitations of traditional phosphorescent materials with the characteristics of cheap and abundant raw materials, simple preparation, low toxicity, good biocompatibility and excellent optical properties.
[0004] Incorporating heteroatoms or heavy atoms into carbon dots can promote spin-orbit coupling and enhance intersystem crossing from singlet to triplet states, thereby achieving phosphorescent emission of carbon dots. These strategies have become a research hotspot for carbon-based phosphorescent materials. Patent literature has reported on the realization of phosphorescence by doping carbon dots with boron, nitrogen, phosphorus, and halogen atoms, such as boron and nitrogen co-doped room temperature phosphorescent carbon dots, which can show visible phosphorescence, but generally last for a short time. Summary of the invention
[0005] The purpose of the present invention is to provide a method for preparing boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder and its application in latent fingerprint imaging, so as to solve the problems existing in the above-mentioned prior art.
[0006] To achieve the above object, the present invention provides the following solutions:
[0007] One of the technical solutions of the present invention: A preparation method of boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder, comprising the following steps:
[0008] Dissolve a thioamide compound and boric acid in water, and perform a pyrolysis reaction to obtain the boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder.
[0009] Further, the thioamide compound includes any one of thioacetamide, 2-methylthiopropionamide, or thiobenzamide.
[0010] Further, the mass ratio of the thioamide compound to boric acid is (0.03 - 0.2):(3 - 5).
[0011] Further, the temperature of the pyrolysis reaction is 180 - 260 °C, and the time is 0.5 - 3 h.
[0012] Two of the technical solutions of the present invention: A boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder prepared by the above preparation method.
[0013] Three of the technical solutions of the present invention: An application of the above boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder in latent fingerprint imaging.
[0014] Four of the technical solutions of the present invention: An application of the above boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder in latent fingerprint imaging on the surface of a matrix with background fluorescence interference.
[0015] Further, the method of the application includes:
[0016] When using the boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder to develop latent fingerprints on the surface of a matrix with background fluorescence interference, after excitation by an ultraviolet light source, turn off the excitation light source, and the fingerprint presents blue phosphorescence, and a phosphorescent fingerprint image can be obtained by taking a photo.
[0017] Even further, the method of the application includes:
[0018] (1) Take an appropriate amount of the boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder on the surface of a matrix with background fluorescence interference carrying latent fingerprints, shake it up and down to let the powder evenly slide over the position of the latent fingerprints on the matrix surface. After the fingerprints appear, shake off the excess powder on the matrix surface or gently blow off the excess powder with an ear bulb;
[0019] (2) Use 254 nm ultraviolet light to irradiate the surface of the matrix. After turning off the ultraviolet excitation light source, the background fluorescence of the matrix immediately disappears, and the complete fingerprint pattern presents bright blue phosphorescence. The fingerprint lines are clear and continuous, and the fingerprint detail features are clear and distinguishable. Take a photo with a digital camera to obtain a high-quality latent fingerprint image.
[0020] The present invention discloses the following technical effects:
[0021] (1) The present invention uses thioamide compounds and boric acid as reaction raw materials, and synthesizes boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder with good dispersibility, uniform morphology and fine spherical particles through a one-step pyrolysis method. The boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder exhibits blue phosphorescence for up to 20 seconds after being excited by ultraviolet light, and the phosphorescence emission intensity is high and the duration is longer. When the prepared carbon dot powder is applied to the imaging of latent fingerprints on the surface of a background fluorescent matrix, a clear phosphorescent fingerprint spectrum can be captured up to 13 seconds after the excitation light source is turned off, ensuring that there is ample time to capture the fingerprint image after the excitation light source is turned off, and the strong background fluorescence interference on the surface of the fingerprint bearing matrix can be effectively eliminated, so as to achieve high-quality imaging of latent fingerprints without background interference.
[0022] (2) The method of the present invention is simple and rapid, does not require strict condition control and does not rely on high-precision equipment. The raw materials are cheap and readily available, and are easy to synthesize in large quantities. It is easy to achieve industrial-scale production and commercial application. It has an excellent effect on the anti-background interference of latent fingerprints, and shows great practical application value in the field of latent fingerprint detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0024] Figure 1 The transmission electron microscopy image and particle size distribution diagram of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1, wherein (A) is a transmission electron microscopy image, and (B) is a particle size distribution diagram;
[0025] Figure 2 The X-ray diffraction pattern of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1;
[0026] Figure 3 The phosphorescence emission spectra of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1 under excitation light of different wavelengths;
[0027] Figure 4 The phosphorescence attenuation effect diagram of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powders prepared in Example 1, Example 4 and Example 5 after the excitation light source is turned off, wherein (A) is Example 1, (B) is Example 4, and (C) is Example 5;
[0028] Figure 5It is the fingerprint phosphorescence decay effect diagram shown after the boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder prepared in Example 1 is excited and then the light source is turned off;
[0029] Figure 6 It is the latent fingerprint imaging effect diagram of the boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder prepared in Example 1 under different conditions;
[0030] Figure 7 It is the imaging effect diagram of the boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder prepared in Example 1 for the latent fingerprint level 1 to 3 detail features. Detailed implementation manners
[0031] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.
[0032] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.
[0033] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.
[0034] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are only exemplary.
[0035] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, that is, they are meant to include but not be limited to.
[0036] It should be noted that those aspects not described in detail in the present invention are all conventional operation means in the art and are not the focus of the present invention.
[0037] Example 1
[0038] A preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder:
[0039] Weigh 60 mg of thioacetamide and 3 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 200 °C for 1 h and then naturally cool it to room temperature to obtain a glassy solid, and obtain boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder after grinding.
[0040] Example 2
[0041] A preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder:
[0042] Weigh 30 mg of thioacetamide and 3 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 240 °C for 3 h and then naturally cool it to room temperature to obtain a glassy solid, and obtain boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder after grinding.
[0043] Example 3
[0044] A preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder:
[0045] Weigh 200 mg of thioacetamide and 5 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 260 °C for 0.5 h and then naturally cool it to room temperature to obtain a glassy solid, and obtain boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder after grinding.
[0046] Example 4
[0047] A preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder:
[0048] Weigh 120 mg of 2-methylthiopropionamide and 3 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 180 °C for 1 h and then naturally cool it to room temperature to obtain a glassy solid, and obtain boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder after grinding.
[0049] Example 5
[0050] A preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder:
[0051] Weigh 200 mg of thioacetanilide and 3 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 240 °C for 1 h, and then naturally cool it to room temperature to obtain a glassy solid. After grinding, a boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder is obtained.
[0052] Comparative Example 1
[0053] Preparation method of phosphorescent carbon dot powder:
[0054] Weigh 60 mg of thiourea and 3 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 200 °C for 1 h, and then naturally cool it to room temperature to obtain a glassy solid. After grinding, a phosphorescent carbon dot powder is obtained. After turning off the 254 nm excitation light source, the blue phosphorescence only appears for 6 s.
[0055] Comparative Example 2
[0056] Preparation method of phosphorescent carbon dot powder:
[0057] Weigh 96 mg of L-cysteine and 3 g of boric acid, dissolve them in 20 mL of deionized water to prepare a mixed solution; place the prepared mixed solution in a muffle furnace, pyrolyze it at 200 °C for 1 h, and then naturally cool it to room temperature to obtain a glassy solid. After grinding, a phosphorescent carbon dot powder is obtained. After turning off the 254 nm excitation light source, the blue phosphorescence only appears for 3 s.
[0058] Effect Example 1
[0059] Characterization of boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder:
[0060] (1) The transmission electron microscopy image and particle size distribution diagram of the boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder prepared in Example 1 are shown in Figure 1 , Figure 1 . (A) in it is the transmission electron microscopy image, and (B) is the particle size distribution diagram.
[0061] It can be seen from Figure 1 that the boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder prepared in Example 1 is evenly dispersed, is a spherical-like particle with uniform morphology, has a narrow size distribution range, is mainly distributed between 1.66 and 4.06 nm, and the average particle size is 2.84 nm.
[0062] (2) The X-ray diffraction pattern of the boron, nitrogen, and sulfur co-doped room-temperature phosphorescent carbon dot powder prepared in Example 1 is shown in Figure 2 .
[0063] It can be seen from Figure 2It can be seen that there is a broad diffraction peak at 25.1°, corresponding to the characteristic peak of graphite carbon. In addition, the characteristic diffraction peaks at 14.9°, 28.6° and 41.5° are attributed to the characteristic peaks of boron oxide, indicating the formation of a boron oxide matrix.
[0064] (3) The phosphorescence emission spectra of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1 under excitation lights of different wavelengths are shown in Figure 3 .
[0065] From Figure 3 it can be seen that the phosphorescence emission exhibits excitation-dependent characteristics. As the excitation light wavelength increases, the phosphorescence emission intensity first increases and then gradually decreases. However, the emission wavelength of the phosphorescence does not shift significantly with the change of the excitation light wavelength and is all around 430 nm, because the phosphorescence emissions generated by excitation lights of different wavelengths mainly originate from the same luminescence center.
[0066] When the excitation wavelength is 250 nm, the best phosphorescence emission peak is at 428 nm, presenting blue phosphorescence.
[0067] (4) The boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Examples 1 to 5 was excited by ultraviolet light (excitation wavelength: 254 nm), and the phosphorescence decay effect of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder was observed after turning off the excitation light source.
[0068] Among them, the phosphorescence decay effect diagrams of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Examples 1, 4 and 5 are shown in Figure 4 , Figure 4 where (A) is Example 1, (B) is Example 4, and (C) is Example 5.
[0069] From Figure 4 it can be seen that the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Examples 1, 4 and 5 can present blue phosphorescence for up to 20 s.
[0070] Moreover, the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Examples 2 and 3 can also present blue phosphorescence for up to 20 s.
[0071] Application Example 1
[0072] Application of a boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder in latent fingerprint imaging:
[0073] (1) Use a spatula to take an appropriate amount of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder and place it on the surface of the matrix with background fluorescence interference that bears latent fingerprints. Shake it up and down to let the powder evenly slide over the position of the latent fingerprints on the matrix surface. After the fingerprints appear, shake off the excess powder on the matrix surface or gently blow off the excess powder with an ear bulb;
[0074] (2) Irradiate the surface of the substrate with 254 nm ultraviolet light. After turning off the ultraviolet excitation light source, the complete fingerprint pattern shows bright blue phosphorescence. The fingerprint lines are clear and continuous, and the fingerprint detail features are distinct and distinguishable. By using a digital camera to take pictures, high-quality latent fingerprint images can be obtained.
[0075] After turning off the excitation light source, the fingerprint phosphorescence decay effect diagram shown by the boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1 is shown in Figure 5 .
[0076] From Figure 5 it can be seen that even when the excitation light source irradiation is stopped and shooting is delayed for 13 s, the fingerprint image is still clearly recognizable.
[0077] Application Example 2
[0078] Application of a boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder in latent fingerprint imaging on the surface of a substrate with a fluorescent interference background:
[0079] (1) Use a spatula to take an appropriate amount of the boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1 and place it on the surface of the substrate with a background fluorescence interference (strong background fluorescence and complex background patterns) that bears latent fingerprints. Shake it up and down to let the powder evenly slide over the position of the latent fingerprint on the substrate surface. After the fingerprint appears, shake off the excess powder on the substrate surface or gently blow off the excess powder with an ear bulb;
[0080] (2) Irradiate the surface of the substrate with 254 nm ultraviolet light. After turning off the ultraviolet excitation light source, the background fluorescence of the substrate immediately disappears. The complete fingerprint pattern shows bright blue phosphorescence. The fingerprint lines are clear and continuous, and the fingerprint detail features are distinct and distinguishable. By using a digital camera to take pictures, high-quality latent fingerprint images can be obtained. The results are shown in Figure 6 .
[0081] From Figure 6 it can be seen that when the substrate bearing latent fingerprints has strong background fluorescence and complex background patterns, the fingerprint signal under daylight is difficult to distinguish due to the serious interference of the background pattern; under the action of ultraviolet light, strong background fluorescence is generated on the surface of these substrates, and the fingerprint ridges are completely annihilated by the background fluorescence, and the fingerprint signal cannot be recognized. After the ultraviolet light source is turned off, the background fluorescence of the substrate immediately disappears, presenting a blue phosphorescent fingerprint pattern with a clear and complete outline, clear and continuous lines. The bright blue phosphorescence emitted by the fingerprint lines forms a strong visual contrast with the black background, completely eliminating the strong interference of the background fluorescence on the fingerprint signal.
[0082] The effect diagram of the boron, nitrogen, and sulfur co-doped room temperature phosphorescent carbon dot powder prepared in Example 1 for showing the 1st to 3rd level characteristic details of latent fingerprints is shown in Figure 7 .
[0083] From Figure 7 it can be seen that some key areas and characteristic structures in the fingerprint are clearly and distinctly reflected. The first-level features of the fingerprint, the core and the triradiate papillary lines, are continuously reflected; the second-level features, such as islands, bifurcations, endings, and short ridges, are clearly and obviously reflected; and the third-level features, sweat pores and wrinkles, are finely reflected.
[0084] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.
Claims
1. A preparation method of boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder, characterized in that, It includes the following steps: Dissolve a thioamide compound and boric acid in water, and carry out a pyrolysis reaction to obtain the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder.
2. The preparation method according to claim 1, characterized in that, The thioamide compound includes any one of thioacetamide, 2-methylthiopropionamide or thiobenzamide.
3. The preparation method according to claim 1, characterized in that, The mass ratio of the thioamide compound to boric acid is (0.03 - 0.2):(3 - 5).
4. The preparation method according to claim 1, wherein The temperature of the pyrolysis reaction is 180 - 260 °C, and the time is 0.5 - 3 h.
5. A boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder prepared by the preparation method according to any one of claims 1 - 4.
6. An application of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder according to claim 5 in latent fingerprint imaging.
7. An application of the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder according to claim 5 in latent fingerprint imaging on the surface of a matrix with background fluorescence interference.
8. The application according to claim 7, wherein The method of the application includes: When using the boron, nitrogen and sulfur co-doped room temperature phosphorescent carbon dot powder to develop latent fingerprints on the surface of a matrix with background fluorescence interference, after excitation by an ultraviolet light source, turn off the excitation light source, the fingerprint presents blue phosphorescence, and a phosphorescent fingerprint image can be obtained by taking a photo.