Preparation method and application of single-crystal-sequence mesoporous transition metal nitride

Abstract

The invention discloses a preparation method of a single-crystal-sequence mesoporous transition metal nitride, which comprises the following steps: (1) immersing an ordered mesoporous SBA-15 template into a hydrogen peroxide solution for ultrasonic treatment, and carrying out centrifugal separation, cleaning and drying to obtain hydroxylated SBA-15; (2) dipping the hydroxylated SBA-15 in an absolute ethyl alcohol solution of transition metal salt, stirring to adsorb metal ions, performing centrifugal separation, and performing freeze drying to obtain a metal ion / SBA-15 compound; (3) mixing the metal ion / SBA-15 compound with molten salt according to a set mass ratio, putting the mixture into a tubular furnace, introducing a mixed atmosphere of N and inert gas, heating, carrying out a nitridation reaction, and carrying out heat preservation to obtain a nitridation intermediate; and (4) repeatedly cleaning and filtering the nitridation intermediate with deionized water, soaking the nitridation intermediate with a strong alkali solution, filtering, cleaning and drying to obtain the SCOM-TMNs. The product prepared by the method disclosed by the invention can be directly used for preparing a surface-enhanced Raman spectrum detection substrate, and has important significance on detection of toxic and harmful substances in consumer goods.

Description

TECHNICAL FIELD

[0001] The present application belongs to the cross field of nanomaterial synthesis and spectral detection technology, and particularly relates to a single crystal sequence mesoporous transition metal nitride (SCOM-TMNs) with surface enhanced Raman effect, and a precise synthesis method and application thereof in surface enhanced Raman spectrum detection. BACKGROUND

[0002] Transition metal nitrides (TMNs) have a wide application prospect in the fields of catalysis, energy storage and sensing due to their metal-like conductivity, excellent thermal stability and corrosion resistance. However, the formation of TMNs needs to overcome a very high reaction energy barrier, and the traditional synthesis methods (such as direct nitridation method and ammonia thermal method) have problems such as harsh reaction conditions (high temperature > 1000℃, high pressure), low product crystallinity, small specific surface area and uncontrollable structure, which limit the performance of TMNs.

[0003] As a core means for trace detection, the structure and performance requirements of the substrate material for surface enhanced Raman spectrum technology are strict. The existing SERS substrate mainly depends on noble metals (gold and silver), but the noble metals have high cost and poor stability; the non-noble metal substrate (such as metal oxide) has defects such as inherent Raman signal interference and limited enhancement effect. Therefore, the development of TMNs materials with high crystallinity, high specific surface area, no background interference and excellent surface enhanced Raman spectrum performance is a key technical gap in the current field. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a single crystal sequence mesoporous transition metal nitride (SCOM-TMNs) with surface enhanced Raman effect and a preparation method and application thereof.

[0005] Specifically, the present application provides the following technical solutions: In a first aspect, the present application provides a molten salt / template synergistic strategy for precisely preparing SCOM-TMNs, and a preparation method of a single crystal sequence mesoporous transition metal nitride, comprising the following steps: (1) immersing ordered mesoporous SBA-15 (commercial, pore size about 6~8 nm, specific surface area > 800 m² / g) as a template into a hydrogen peroxide solution (hydroxylating agent) for ultrasonic treatment to realize template hydroxylation, and then centrifuging, washing and drying to obtain hydroxylated SBA-15 (SBA-15 / OH); (2) using transition metal salt (or a mixture thereof) and anhydrous ethanol as raw materials to prepare a metal salt ethanol solution; immersing the hydroxylated SBA-15 in the anhydrous ethanol solution of the transition metal salt, stirring and adsorbing metal ions at a set speed, centrifuging after adsorption is completed, and freeze-drying to obtain a metal ion / SBA-15 composite; (3) The metal ion / SBA-15 composite is mixed with molten salt (potassium chloride) at a set mass ratio, ground, and then placed in a tube furnace, and N is introduced into the mixed atmosphere, and the nitrogenization reaction is carried out at a set heating rate to a target temperature and kept at the target temperature, to obtain a nitrogenized intermediate; (4) The nitrogenized intermediate is repeatedly cleaned and filtered with deionized water to remove the molten salt, and then soaked in a strong alkali solution to remove the SBA-15 template, and then filtered, cleaned, and dried to obtain SCOM-TMNs.

[0006] In the present application, specific adsorption sites are introduced by template hydroxylation to realize uniform filling of metal ions in SBA-15 mesopores; the sintering of crystal grains in the nitrogenization process is inhibited by the molten salt isolation effect, and the ordered growth of crystals is ensured by the confinement effect of SBA-15 mesopores; and finally the molten salt and the template are removed by post-processing to obtain SCOM-TMNs with both "single crystal structure" and "ordered mesopores". The SCOM-TMNs have a pore size of 5-7 nm, a pore wall thickness of 3-5 nm, a regular and controllable morphology, a specific surface area of 103.8-135.6 m² / g, and excellent localized surface plasmon resonance effect and surface enhanced Raman spectrum performance without inherent Raman background interference.

[0007] In the preparation method of the single-crystal ordered mesoporous transition metal nitride, in step (1): The mass concentration of the hydrogen peroxide solution is 28%-32%, the ultrasonic treatment temperature is 25-30℃, and the ultrasonic treatment time is 8-12 min; The centrifugal separation speed is 8000 r / min, and the time is 10 min; the cleaning is repeated three times (20 mL each time) with deionized water to remove residual ; The drying is vacuum drying, the drying temperature is 40-60℃, and the drying time is 4-6 h.

[0008] In the preparation method of the single-crystal ordered mesoporous transition metal nitride, in step (2): The transition metal salt is selected from one or more of tungsten chloride (WC ), molybdenum chloride (MoC ), vanadium chloride (VC ), titanium chloride (TiC ), cobalt chloride (CoC ) (two or more are selected when preparing doped SCOM-TMNs); ​The concentration of the anhydrous ethanol solution of the transition metal salt is 0.03~0.12 mol / L, the stirring speed is 180~220 r / min, and the adsorption time is 2~5 h; The freeze-drying temperature is -75~-85℃, the vacuum degree is <10Pa, and the freeze-drying time is 18~30 h.

[0009] The method for preparing single-crystal ordered mesoporous transition metal nitrides according to the present invention, wherein when preparing doped SCOM-TMNs (such as Mo / WN, V / TiN), the anhydrous ethanol solution of the transition metal salt contains two or more transition metal salts, and the mass fraction of the doped metal is 0.3%~6%.

[0010] The method for preparing single-crystal ordered mesoporous transition metal nitrides according to the present invention, wherein in step (3): The molten salt is potassium chloride, and the mass ratio of the metal ion / SBA-15 complex to potassium chloride is 1:1.5~6. The mixing and grinding time is 15 min to ensure the material is uniform. The inert gas is nitrogen or argon, and the mixed atmosphere contains N2. The volume ratio of the gas to the inert gas is 1:1~4, and the total gas flow rate is 50 mL / min; The heating rate is 0.8~1.2℃ / min, the target nitriding temperature is 580~620℃, the holding time is 1~3h, and before heating, inert gas must be purged for 30 min to remove air from the tube furnace.

[0011] In the preparation method of the single-crystal ordered mesoporous transition metal nitride of the present invention, step (4) is as follows: The first cleaning was performed by using deionized water and magnetic stirring at 60°C for 1 hour. This cleaning was repeated 3 to 5 times. The strong alkali solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the strong alkali solution is 0.8~2.2 mol / L; The soaking temperature is 55~85℃, and the soaking time is 2~5 h; The second cleaning involves first washing and filtering with deionized water 3-5 times, then washing and filtering with anhydrous ethanol 1-2 times (30 mL each time). The drying is done under vacuum at a temperature of 60-80℃ for 12-24 hours.

[0012] In this invention, by employing the preferred raw material ratios, processing parameters, and reaction conditions in the above steps, the structure and performance of SCOM-TMNs can be further optimized. The integrity of the single-crystal lattice is improved, the mesoporous order is higher, the specific surface area and pore volume remain stable, and it exhibits superior localized surface plasmon resonance and surface-enhanced Raman spectroscopy effects.

[0013] The preparation method of the single crystal sequence mesoporous transition metal nitride, wherein the SCOM-TMNs include single component SCOM-TMNs and doped SCOM-TMNs; the single component SCOM-TMNs are selected from SCOM-WN, SCOM-MoN, SCOM-VN, SCOM-TiN and SCOM-CoN; and the doped SCOM-TMNs are selected from SCOM-Mo / WN, SCOM-W / MoN, SCOM-V / TiN and SCOM-Ti / VN.

[0014] In a second aspect, the application provides the single crystal sequence mesoporous transition metal nitride (SCOM-TMNs) prepared by the above-mentioned molten salt / template synergistic strategy.

[0015] In a third aspect, the application provides an application of the single crystal sequence mesoporous transition metal nitride (SCOM-TMNs) prepared by the above-mentioned molten salt / template synergistic strategy in Raman spectrum detection, wherein the single crystal sequence mesoporous transition metal nitride is used as a surface enhanced Raman spectrum detection substrate.

[0016] The preparation method of the single crystal sequence mesoporous transition metal nitride of the application is different from the prior art (beneficial effects) in that: The preparation process of the single crystal sequence mesoporous transition metal nitride (SCOM-TMNs) provided by the application has strong controllability, the prepared single crystal sequence mesoporous transition metal nitride has regular and controllable morphology, has good repeatability and stability, has strong local surface plasmon resonance effect and excellent surface enhanced Raman spectrum effect, and can be directly used for preparing a surface enhanced Raman spectrum detection substrate, which has important significance for the detection of toxic and harmful substances in consumer goods.

[0017] The preparation method of the single crystal sequence mesoporous transition metal nitride of the application and the application thereof will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only show some embodiments of the application, and other accompanying drawings can be obtained by those skilled in the art without any creative effort on the basis of these accompanying drawings.

[0019] Figure 1 The XRD spectrum of the SCOM-WN prepared in the embodiment 1 of the application; Figure 2This is a SEM image of the SCOM-WN prepared in Example 1 of the present invention; Figure 3 The SCOM-WN prepared in Example 1 of this invention has a concentration of 10 -9 Surface-enhanced Raman spectra of M R6G; where the horizontal axis represents the Raman shift (in cm). -1 The vertical axis represents the Raman light intensity (Counts); Figure 4 The XRD pattern of SCOM-MoN prepared in Example 2 of this invention; Figure 5 The image shown is an HRTEM image of the SCOM-MoN prepared in Example 2 of this invention. Figure 6 The SCOM-MoN pair prepared in Example 2 of this invention has a concentration of 10. -9 Surface-enhanced Raman spectra of M for R6G; Figure 7 The XRD pattern of SCOM-VN prepared in Example 3 of this invention; Figure 8 The image shown is a TEM image of the SCOM-VN prepared in Example 3 of this invention. Figure 9 The SCOM-VN prepared in Example 3 of this invention has a concentration of 10 -9 Surface-enhanced Raman spectra of M for R6G; Figure 10 The XRD pattern of SCOM-TiN prepared in Example 4 of this invention; Figure 11 The image shown is a TEM image of the SCOM-TiN prepared in Example 4 of this invention. Figure 12 The SCOM-TiN pair prepared in Example 4 of this invention has a concentration of 10 -9 Surface-enhanced Raman spectra of M for R6G; Figure 13 TEM image of the random WN particle aggregates prepared in Comparative Example 1; Figure 14 TEM image of the grain-sintered WN prepared in Comparative Example 2; Figure 15 The image is a TEM image of a WN with severely disrupted order, prepared as Comparative Example 3. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] Unless otherwise specified, specific techniques or conditions in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market.

[0022] Example 1

[0023] This embodiment provides a method for preparing single-crystal ordered mesoporous nanowires (SCOM-WN): (1) Immerse commercially available ordered mesoporous SBA-15 (1.0 g, pore size 6-8 nm) in a 30% mass concentration of [unclear - likely a specific solution or solution]. The solution (20 mL) was transferred to a 300W ultrasonic cleaner and ultrasonically treated at 28℃ for 10 min; then centrifuged at 8000 r / min for 10 min, washed three times with deionized water (20 mL each time), and vacuum dried at 45℃ for 5 h to obtain hydroxylated SBA-15 (SBA-15 / OH).

[0024] (2) WC Dissolve (0.4 g) in anhydrous ethanol (10 mL) and stir until clear; add the above SBA-15 / OH (1.0 g), and magnetically stir at 200 r / min for 3 h at 25 °C; centrifuge at 8000 r / min for 10 min, and freeze-dry at -80 °C for 24 h to obtain / SBA-15 complex.

[0025] (3) The SBA-15 complex (1.0 g) and KCl (1.0 g) were thoroughly ground for 15 min and transferred to an alumina boat; the mixture was then passed through a tube furnace. (99.999%) Purge for 30 minutes, then switch to N / Mixed atmosphere (volume ratio 1:2, total flow rate 50 mL / min); heated to 600 °C at 1 °C / min and held at that temperature for 1.5 h; naturally cooled to room temperature to obtain the nitrided intermediate.

[0026] (4) Add the nitriding intermediate to deionized water (50 mL), stir at 60 °C for 1 h, centrifuge at 8000 r / min for 10 min, and wash with deionized water 4 times; add 1.5 mol / L NaOH solution (30 mL), stir at 70 °C for 3 h; centrifuge again, wash with deionized water 3 times and anhydrous ethanol once, and vacuum dry at 70 °C for 18 h to obtain SCOM-WN.

[0027] The final sample obtained was subjected to XRD ( Figure 1 ), SEM ( Figure 2 Characterization revealed that the final product was SCOM-WN, which was used as the SERS substrate. Figure 3 The lowest detection concentration for R6G is 10. -9 M.

[0028] Example 2

[0029] This embodiment provides a method for preparing single-crystal ordered mesoporous MoN (SCOM-MoN): (1) Immerse commercially available ordered mesoporous SBA-15 (1.0 g, pore size 6-8 nm) in a 30% mass concentration of [unclear - likely a specific solution or solution]. The solution (20 mL) was transferred to a 300W ultrasonic cleaner and ultrasonically treated at 28℃ for 10 min; then centrifuged at 8000 r / min for 10 min, washed three times with deionized water (20 mL each time), and vacuum dried at 45℃ for 5 h to obtain hydroxylated SBA-15 (SBA-15 / OH).

[0030] (2) MoC (0.35 g) was dissolved in anhydrous ethanol (10 mL), and SBA-15 / OH (1.0 g) was added. The mixture was stirred at 180 r / min for 4 h at 25 °C; centrifuged at 8000 r / min for 10 min; and freeze-dried at -75 °C for 30 h to obtain Mo. / SBA-15 complex.

[0031] (3) Will Mo The SBA-15 complex (1.0 g) was ground with KCl (1.5 g) for 15 min, and then passed through a tube furnace. Purge for 30 minutes, then pass N through. / (Volume ratio 1:3, total flow rate 50 mL / min); heat to 580℃ at 0.8℃ / min, hold for 2 h; cool naturally to obtain the nitrided intermediate.

[0032] (4) Add the nitriding intermediate to deionized water (50 mL), stir at 60 °C for 1 h, centrifuge at 8000 r / min for 10 min, and wash with deionized water 4 times; 2.0 mol / L KOH solution (30 mL), stir at 65 °C for 4 h; centrifuge again, wash with deionized water 3 times and anhydrous ethanol once, and vacuum dry at 70 °C for 18 h. After washing and drying, SCOM-MoN is obtained.

[0033] The final sample obtained was subjected to XRD ( Figure 4 ), HRTEM Figure 5 Characterization revealed that the final product was SCOM-MoN, which was used as a SERS substrate. Figure 6 The lowest detection concentration for R6G is 10. -9 M.

[0034] Example 3

[0035] This embodiment provides a method for preparing single-crystal ordered mesoporous VN (SCOM-VN): (1) Immerse commercially available ordered mesoporous SBA-15 (1.0 g, pore size 6-8 nm) in a 30% mass concentration of [unclear - likely a specific solution or solution]. The solution (20 mL) was transferred to a 300W ultrasonic cleaner and ultrasonically treated at 28℃ for 10 min; then centrifuged at 8000 r / min for 10 min, washed three times with deionized water (20 mL each time), and vacuum dried at 45℃ for 5 h to obtain hydroxylated SBA-15 (SBA-15 / OH).

[0036] (2) VC (0.32 g) was dissolved in anhydrous ethanol (10 mL), and SBA-15 / OH (1.0 g) was added. The mixture was stirred at 200 r / min for 5 h at 25 °C. After centrifugation, it was freeze-dried at -80 °C for 22 h to obtain V. / SBA-15 complex.

[0037] (3) Grind the complex (1.0 g) with KCl (2.0 g) for 15 min, and then heat it in a tube furnace with N2. / Under a (volume ratio of 1:4) atmosphere, the temperature was increased to 620℃ at a rate of 1.2℃ / min and held for 1 h to obtain the nitrided intermediate.

[0038] (4) Add the nitriding intermediate to deionized water (50 mL), stir at 60 °C for 1 h, centrifuge at 8000 r / min for 10 min, and wash with deionized water 4 times; add 1.0 mol / L NaOH solution (30 mL), stir at 80 °C for 3 h; centrifuge again, wash with deionized water 3 times and anhydrous ethanol once, and vacuum dry at 70 °C for 18 h. After washing and drying, SCOM-VN is obtained.

[0039] The final sample obtained was subjected to XRD ( Figure 7 ), TEM Figure 8 Characterization revealed that the final product was SCOM-VN, which was used as the SERS substrate. Figure 9 The lowest detection concentration for R6G is 10. -9 M.

[0040] Example 4

[0041] This embodiment provides a method for preparing doped single-crystal ordered mesoporous TiN (SCOM-TiN): (1) Immerse commercially available ordered mesoporous SBA-15 (1.0 g, pore size 6-8 nm) in a 30% mass concentration of [unclear - likely a specific solution or solution]. The solution (20 mL) was transferred to a 300W ultrasonic cleaner and ultrasonically treated at 28℃ for 10 min; then centrifuged at 8000 r / min for 10 min, washed three times with deionized water (20 mL each time), and vacuum dried at 45℃ for 5 h to obtain hydroxylated SBA-15 (SBA-15 / OH).

[0042] (2) TiC (0.28 g) was dissolved in anhydrous ethanol (10 mL, Mo doping mass fraction 0.5%), and SBA-15 / OH (1.0 g) was added. The mixture was stirred at 220 r / min for 3.5 h at 25 °C. After centrifugation, it was freeze-dried at -85 °C for 20 h to obtain Mo. - / SBA-15 complex.

[0043] (3) Grind the complex (1.0 g) with KCl (0.8 g) for 15 min, and then heat it in a tube furnace with N2. / Under a (volume ratio of 1:2) atmosphere, the temperature was increased to 600℃ at a rate of 1℃ / min and held for 1.5 h to obtain the nitrided intermediate.

[0044] (4) Add the nitriding intermediate to deionized water (50 mL), stir at 60 °C for 1 h, centrifuge at 8000 r / min for 10 min, and wash with deionized water 4 times; add 1.5 mol / L NaOH solution (30 mL), stir at 70 °C for 3 h; centrifuge again, wash with deionized water 3 times and anhydrous ethanol once, and vacuum dry at 70 °C for 18 h to obtain SCOM-TiN.

[0045] The final sample obtained was subjected to XRD ( Figure 10 ), TEM Figure 11 Characterization revealed that the final product was SCOM-TiN, which was used as the SERS substrate. Figure 12 The lowest detection concentration for R6G is 10. -9 M.

[0046] Example 5

[0047] The difference from Example 3 is as follows: In step (1), The solution had a mass concentration of 28%, the ultrasonic treatment temperature was 25℃ for 12 min, and the vacuum drying temperature was 40℃ for 6 h. In step (4), the NaOH solution was 0.8 mol / L, stirred at 85℃ for 2 h, and centrifuged again, washed 5 times with deionized water and 1 time with anhydrous ethanol, and vacuum dried at 60℃ for 24 h. Other steps were consistent with Example 3, and a sample similar to that in Example 3 was finally obtained. Using this sample as a SERS substrate, the lowest detection concentration of R6G reached 10. -9 M.

[0048] Example 6

[0049] The difference from Example 4 is as follows: In step (1), The solution concentration was 32%, the ultrasonic treatment temperature was 30℃ for 8 min, and the vacuum drying temperature was 60℃ for 4 h; in step (2), the stirring time was 2 h, and the freeze-drying time was 18 h; in step (3), N / The volume ratio was 1:1, the incubation time was 3 hours, the NaOH solution in step (4) was 2.2 mol / L, the mixture was stirred at 55°C for 5 hours, and after centrifugation, it was washed twice with anhydrous ethanol and dried under vacuum at 80°C for 12 hours. Everything else was the same as in Example 4, and a sample similar to that in Example 3 was finally obtained. Using this sample as a SERS substrate, the lowest detection concentration of R6G reached 10. -9 M.

[0050] The preparation method of this invention has strong process controllability. Through the synergistic effect of template hydroxylation and molten salt, it effectively solves the problems of uncontrollable structure and low crystallinity in the synthesis of traditional TMNs. The prepared SCOM-TMNs can realize the customized synthesis of single-component (WN, MoN, VN, TiN, CoN) and doped (Mo / WN, W / MoN, etc.) TMNs. They have strong local surface plasmon resonance effect and outstanding surface-enhanced Raman spectroscopy effect, providing key material support for the development of surface-enhanced Raman spectroscopy detection substrates.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that, in step (1), "commercial ordered mesoporous SBA-15 is immersed in a solution with a mass concentration of 30%". The hydroxylation process of "solution and ultrasonic treatment at 28℃ for 10 min" was omitted, and unhydroxylated raw SBA-15 was used directly for subsequent steps. As a result, under the same experimental conditions, single-crystal ordered mesoporous WN (SCOM-WN) could not be generated; only random WN particle aggregates were obtained, without any ordered mesoporous structure (e.g., ...). Figure 13 ).

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 1 is that the step (3) is changed from " The step of "mixing and grinding the SBA-15 complex with KCl at a 1:1 mass ratio" is omitted; directly... The SBA-15 composite was subjected to a nitriding reaction in a tube furnace. Under identical experimental conditions, single-crystal ordered mesoporous WN (SCOM-WN) could not be generated. The product exhibited severe grain sintering (particle size > 500 nm), and the mesoporous structure completely collapsed (e.g., ...). Figure 14 ).

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 1 is that the "WC" in step (2) is changed. The solution was prepared by dissolving in anhydrous ethanol to a concentration of 0.04 mol / L. This was then adjusted to a concentration of 0.2 mol / L WC. Ethanol solution (exceeding the preferred concentration range of 0.03~0.12 mol / L), under the same experimental conditions, failed to generate structurally complete single-crystal ordered mesoporous WN (SCOM-WN). Metal ions excessively accumulated within the SBA-15 mesopores, and after nitridation, formed WN particles that blocked the mesopores, severely disrupting the ordered structure (e.g., Figure 15 ).

[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a single-crystal ordered mesoporous transition metal nitride, characterized in that: Includes the following steps: (1) The ordered mesoporous SBA-15 template was immersed in hydrogen peroxide solution and ultrasonically treated to achieve template hydroxylation. After centrifugation, washing and drying, hydroxylated SBA-15 was obtained. (2) The hydroxylated SBA-15 was immersed in an anhydrous ethanol solution of a transition metal salt, and the metal ions were adsorbed by stirring at a set speed. After the adsorption was completed, the metal ion / SBA-15 complex was obtained by centrifugation and freeze-drying. (3) The metal ion / SBA-15 composite and molten salt are thoroughly mixed and ground according to the set mass ratio, placed in a tube furnace, and N is introduced. The mixture is heated to the target temperature at a set heating rate in a mixed atmosphere with an inert gas to carry out a nitriding reaction and held at the temperature to obtain a nitriding intermediate. (4) The nitriding intermediate is first washed and filtered repeatedly with deionized water to remove molten salt, and then soaked in a strong alkali solution to remove the SBA-15 template. After filtration, washing and drying, SCOM-TMNs are obtained.

2. The method for preparing single-crystal ordered mesoporous transition metal nitrides according to claim 1, characterized in that: In step (1): The hydrogen peroxide solution has a mass concentration of 28%~32%, the ultrasonic treatment temperature is 25~30℃, and the ultrasonic treatment time is 8~12 min; The centrifugation speed was 8000 r / min and the time was 10 min; The cleaning process involves rinsing the filter three times with deionized water, using 20 mL each time, to remove residue. ; The drying process is vacuum drying, with a drying temperature of 40~60℃ and a drying time of 4~6 hours.

3. The method for preparing single-crystal ordered mesoporous transition metal nitrides according to claim 1, characterized in that: In step (2): The transition metal salt is selected from one or more of tungsten chloride, molybdenum chloride, vanadium chloride, titanium chloride, and cobalt chloride; The concentration of the anhydrous ethanol solution of the transition metal salt is 0.03~0.12 mol / L, the stirring speed is 180~220 r / min, and the adsorption time is 2~5 h; The freeze-drying temperature is -75~-85℃, the vacuum degree is <10Pa, and the freeze-drying time is 18~30 h.

4. The method for preparing single-crystal ordered mesoporous transition metal nitrides according to claim 3, characterized in that: When preparing doped SCOM-TMNs, the anhydrous ethanol solution of the transition metal salt contains two or more transition metal salts, and the mass fraction of the doped metal is 0.3% to 6%.

5. The method for preparing single-crystal ordered mesoporous transition metal nitrides according to claim 1, characterized in that: In step (3): The molten salt is potassium chloride, and the mass ratio of the metal ion / SBA-15 complex to potassium chloride is 1:1.5~6, with a mixing and grinding time of 15 min. The inert gas is nitrogen or argon, and the N in the mixed atmosphere is... The volume ratio of the gas to the inert gas is 1:1~4, and the total gas flow rate is 50 mL / min; The heating rate is 0.8~1.2℃ / min, the target nitriding temperature is 580~620℃, and the holding time is 1~3h. Before heating, inert gas should be purged for 30 min to remove air from the tube furnace.

6. The method for preparing single-crystal ordered mesoporous transition metal nitrides according to claim 1, characterized in that: In step (4): The first cleaning was performed by using deionized water and magnetic stirring at 60°C for 1 hour. This cleaning was repeated 3 to 5 times. The strong alkali solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the strong alkali solution is 0.8~2.2 mol / L; The soaking temperature is 55~85℃, and the soaking time is 2~5 h; The second cleaning involves first washing and filtering with deionized water 3-5 times, then washing and filtering with anhydrous ethanol 1-2 times. The drying is done under vacuum at a temperature of 60-80℃ for 12-24 hours.

7. The method for preparing single-crystal ordered mesoporous transition metal nitrides according to claim 1, characterized in that: The SCOM-TMNs include single-component SCOM-TMNs and doped SCOM-TMNs; the single-component SCOM-TMNs are selected from SCOM-WN, SCOM-MoN, SCOM-VN, SCOM-TiN, and SCOM-CoN; the doped SCOM-TMNs are selected from SCOM-Mo / WN, SCOM-W / MoN, SCOM-V / TiN, and SCOM-Ti / VN.

8. The product prepared by the method for preparing single-crystal ordered mesoporous transition metal nitrides according to any one of claims 1 to 7 is a single-crystal ordered mesoporous transition metal nitride with surface-enhanced Raman effect.

9. The application of the single-crystal ordered mesoporous transition metal nitride with surface-enhanced Raman effect as described in claim 8 in Raman spectroscopy detection, wherein, The single-crystal ordered mesoporous transition metal nitride is used as a substrate for surface-enhanced Raman spectroscopy detection.

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