A nano-silver-MXene composite and a preparation method and application thereof

Abstract

The application discloses a kind of nano silver-MXene compound and its preparation method and application, it is related to material technical field.The nano silver-MXene compound includes MXene nanosheet and the nano silver distributed on the surface of the MXene nanosheet.By loading nano silver particles on the surface of MXene nanosheet, its electromagnetic coefficient can be improved.Compared with pure AgNPs, SERS performance is significantly improved, and it can realize stable, sensitive and quantitative detection on polystyrene (PS), polymethyl methacrylate (PMMA) and other nano plastics, and the operation is simple, and the cost is low.The application also simulates the decomposition of foamed polystyrene (EPS) by using a shaker, and proves that a certain amount of plastic is decomposed into water under laboratory simulation conditions.The actual water samples of seafood market, river and seawater are analyzed.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a nano-silver-MXene composite, its preparation method, and its application. Background Technology

[0002] With the continuous increase in the production and consumption of plastic products globally, plastic pollution is becoming one of the world's most pressing environmental problems. Plastics in the environment can break down into nanoplastics under the combined effects of sunlight ultraviolet radiation, mechanical damage, weathering, and biodegradation. These nanoplastics are easily ingested by organisms and accumulate in their bodies, causing cytotoxicity, oxidative stress, immunotoxicity, neurotoxicity, and reproductive toxicity.

[0003] In related technologies, nanoplastics are often detected using methods such as pyrolysis-gas chromatography / mass spectrometry (pyrolysis-GC / MS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. While pyrolysis-gas chromatography / mass spectrometry can accurately detect content, its operation is complex, time-consuming, and costly. TEM and SEM typically only obtain morphological and structural information about nanoplastics, not precise content detection. Infrared spectroscopy has low spatial resolution and is easily affected by water. Raman spectroscopy has low sensitivity. These limitations restrict their application in nanoplastic detection.

[0004] Therefore, there is a need to provide a method for the quantitative detection of nanoplastics. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a nano-silver-MXene composite that enables stable, sensitive, and quantitative detection of polystyrene (PS) nanoplastics.

[0006] The present invention also provides the application of the above-mentioned nano-silver-MXene composite in the detection of nanoplastics.

[0007] The nanosilver-MXene composite according to a first aspect of the present invention includes MXene nanosheets and nanosilver distributed on the surface of the MXene nanosheets.

[0008] The nano-silver-MXene composite according to embodiments of the present invention has at least the following beneficial effects:

[0009] Loading silver nanoparticles onto the surface of MXene nanosheets can improve their electromagnetic coefficient. Compared to AgNPs alone, the SERS performance is significantly improved. The silver nanoparticle-MXene composite of the examples enables stable, sensitive, and quantitative detection of nanoplastics such as polystyrene (PS) and polymethyl methacrylate (PMMA), and is simple to operate and inexpensive.

[0010] According to some embodiments of the present invention, the MXene nanosheets comprise Ti3C2T x Ti2CT x V2CT x Ta2CT x TiVCT x Mo2CT x Nb2CT x Nb4C3T x Mo2TiC2T x and Mo2Ti2C3T x At least one of the following. Preferably Ti3C2T. x .

[0011] According to some embodiments of the present invention, the number of layers of the MXene nanosheet is 1 to 10.

[0012] According to some embodiments of the present invention, the surface of the nano-silver is coated with citrate ions.

[0013] According to some embodiments of the present invention, the nano-silver is obtained by reducing silver ions with a reducing agent. The reducing agent includes at least one selected from sodium citrate, potassium citrate, sodium borohydride, polyvinylpyrrolidone, and ascorbic acid.

[0014] According to some embodiments of the present invention, the silver nanoparticles are adsorbed onto the surface of the MXene nanosheets. The silver nanoparticle-MXene composite is synthesized via a self-assembly method, which is simple and easy to operate.

[0015] According to some embodiments of the present invention, the particle size of the nanosilver is 20-70 nm.

[0016] According to some embodiments of the present invention, the mass ratio of the nanosilver to the MXene nanosheets is 1:0.02 to 0.18. More specifically, it can be 1:0.1 to 0.18.

[0017] According to some embodiments of the present invention, the MXene nanosheets are Nb2CT. x The mass ratio of the silver nanoparticles to the MXene nanosheets is 1:0.02 to 0.18. More specifically, it can be 1:0.1 to 0.18.

[0018] According to some embodiments of the present invention, the MXene nanosheets are Ti3C2T. x The mass ratio of the nanosilver to the MXene nanosheets is 1:0.02 to 0.17. More specifically, it can be 1:0.08 to 0.14.

[0019] The method for preparing the above-described nano-silver-MXene composite according to a second aspect embodiment of the present invention includes the following steps:

[0020] A solution containing the aforementioned silver nanoparticles and MXene nanosheets was prepared, and the reaction was carried out to obtain the silver nanoparticle-MXene composite.

[0021] According to some embodiments of the present invention, the reaction time is 1 to 10 hours, or more specifically, 4 to 6 hours.

[0022] According to some embodiments of the present invention, the method for preparing the nano-silver includes the following steps:

[0023] Ag + The nano-silver is obtained by reacting the solution of the reducing agent with the solution at 50–150°C.

[0024] According to some embodiments of the present invention, the Ag + The reaction time with the reducing agent is 0.5 to 2 hours.

[0025] According to some embodiments of the present invention, the method for preparing the MXene nanosheets includes the following steps:

[0026] The MXene powder was subjected to intercalation and ultrasonic treatment in sequence to obtain the MXene nanosheets.

[0027] According to some embodiments of the present invention, the intercalation process includes treating the MXene powder with an organic base.

[0028] According to some embodiments of the present invention, the organic base includes at least one of TPAOH, TMAOH, and TMBOH.

[0029] According to some embodiments of the present invention, the treatment concentration of the organic base is 20% to 30%. For example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%.

[0030] According to some embodiments of the present invention, the processing time for the intercalation process is 12h to 48h.

[0031] According to some embodiments of the present invention, the ultrasonic treatment time is 30 to 60 minutes.

[0032] According to some embodiments of the present invention, the ultrasonic treatment is an ice-water bath treatment in an inert gas environment.

[0033] A SERS substrate according to a third aspect of the present invention comprises the above-described nano-silver-MXene composite.

[0034] Application of the above-described nano-silver-MXene composite or the above-described SERS substrate in the detection of nanoplastics according to the fourth aspect of the present invention.

[0035] According to some embodiments of the present invention, the nanoplastics include PS and PMMA.

[0036] A method for detecting nanoplastics according to a fifth aspect embodiment of the present invention includes the following steps:

[0037] S1. Using the above-mentioned nano-silver-MXene composite or the above-mentioned SERS substrate, obtain the linear relationship between the intensity and concentration of the characteristic SERS peaks of the nanoplastics.

[0038] S2. Mix the sample solution to be tested with the above-mentioned nano-silver-MXene composite or the above-mentioned SERS substrate and perform detection to obtain the intensity of the characteristic SERS peak of the nanoplastic in the sample to be tested. Combined with the linear relationship obtained in step S1, calculate the content of nanoplastic in the sample solution to be tested.

[0039] According to some embodiments of the present invention, in step S2, the above-mentioned silver nano-MXene composite or the above-mentioned SERS substrate is mixed with the test sample solution in solution form. The volume ratio of the silver nano-MXene composite or SERS substrate solution to the test sample solution is 1:0.25 to 4. More specifically, it can be 1:0.33 to 1. For example, it can be 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1.

[0040] According to some embodiments of the present invention, step S2 further includes mixing the coagulant with the sample solution to be tested.

[0041] According to some embodiments of the present invention, the coagulant comprises at least one of KI, Mg2SO4, and NaCl. The coagulant is used to shorten the distance between the nanoplastic and the SERS substrate, thereby enhancing the SERS signal. The introduction of KI enhances the compatibility between the substrate and the nanoplastic.

[0042] According to some embodiments of the present invention, the final concentration of the coagulant is 0.01M to 0.03M. For example, it can be 0.01M, 0.014M, 0.018M, 0.022M, 0.026M or 0.03M.

[0043] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0044] Figure 1 The images show the UV-vis spectrum (a), XRD spectrum (b), and XPS spectrum (cf) of the nano-silver-MXene composite in Example 4; where d, e, and f are the high-resolution spectra of Ag 3d, C 1s, and Nb 3d, respectively.

[0045] Figure 2 The UV-vis spectrum (a), XRD spectrum (b), and XPS spectrum (cf) of the nano-silver-MXene composite in Example 9 are shown; where d, e, and f are the high-resolution spectra of Ag 3d, Ti 2p, and C1s, respectively.

[0046] Figure 3 The morphology and elemental characterization results of the nano-silver-MXene composite in Example 4 are shown; where a, b, and c are Nb2CT, respectively. x AgNPs and Ag / Nb2CT x -14% of the SEM images, d and e are Ag / Nb2CT. x -14% of TEM images, f for Ag / Nb2CT x -14% Selected-area electron diffraction (SAED) image, g for Ag / Nb2CT x HAADF and EDX elemental mapping images of Ag, Nb, and C elements in -14%;

[0047] Figure 4 Morphology and elemental characterization results of the nano-silver-MXene composite in Example 9; where a, b, and c are Ti3C2T x Ag NPs and Ag / Ti3C2T x -11% of the SEM images, d and e are Ag / Ti3C2T x -11% of the TEM image, f for Ag / Ti3C2T x Selected region electron diffraction (SAED) image with -11% g for Ag / Ti3C2T x HAADF and EDX elemental mapping images of Ag, Ti, and C elements in -11%;

[0048] Figure 5 For different nanosilver-Nb2CT x The detection results of the composite on PS nanoplastics; where Figure a shows the detection results of the nano-silver-MXene composite of Example 1 on PS nanoplastics at different mixing volume ratios, and Figure b shows the results of Figure a at 1002 cm⁻¹.-1 The corresponding SERS intensity is shown in Figure c, which represents the detection results of the nano-silver-MXene composite of Examples 1-5 on nanoplastic PS at a mixing volume ratio of 2:1 (nano-silver-MXene composite solution: nanoplastic solution). Figure d is the result of Figure c at 1002 cm⁻¹. -1 The corresponding SERS intensity at that location;

[0049] Figure 6 For different nano-silver-Ti3C2T x The detection results of the composite on PS nanoplastics; where Figure a shows the detection results of the nano-silver-MXene composite of Example 8 on PS nanoplastics at different mixing volume ratios, and Figure b shows the results of Figure a at 1002 cm⁻¹. -1 The corresponding SERS intensity is shown in Figure c, which represents the detection results of the nano-silver-MXene composite of Examples 6-11 on nanoplastic PS at a mixing volume ratio of 2:1 (nano-silver-MXene composite solution: nanoplastic solution). Figure d is the result of Figure c at 1002 cm⁻¹. -1 The corresponding SERS intensity at that location;

[0050] Figure 7 The results of the nano-silver-MXene composite in Example 4 on PS nanoplastics of different particle sizes are shown below. Figures a, c, and e are the SERS spectra of PS nanoplastics with particle sizes of 50 nm, 300 nm, and 500 nm, respectively. Figures b, d, and f are the PS nanoplastic concentrations as a function of 1002 cm⁻¹ in figures a, c, and e, respectively. -1 Correspondence diagram of SERS intensity at various locations;

[0051] Figure 8 The results of the nano-silver-MXene composite in Example 9 on PS nanoplastics of different particle sizes are shown below. Figures a, c, and e are the SERS spectra of PS nanoplastics with particle sizes of 50 nm, 300 nm, and 500 nm, respectively. Figures b, d, and f are the PS nanoplastic concentrations as a function of 1002 cm⁻¹ in figures a, c, and e, respectively. -1 Correspondence diagram of SERS intensity at various locations;

[0052] Figure 9 The results of the detection of nano-silver-MXene composite on PMMA nanoplastic in Example 4 are shown.

[0053] Figure 10 The results of the detection of nano-silver-MXene composite on PMMA nanoplastic in Example 9 are shown.

[0054] Figure 11 A schematic diagram of the lake water sampling location (a) and the detection results of the nano-silver-MXene complex on the lake water in Examples 4 (b) and 9 (c);

[0055] Figure 12 The results of the detection stability test of the nano-silver-MXene complex in Example 4 are shown in Figure a; where Figure a shows the SERS intensity detection results at 9 different random sites, and Figure b shows the SERS intensity detection results of Figure a at 1002 cm⁻¹. -1 The corresponding SERS intensity at that location;

[0056] Figure 13 Figure 9 shows the SERS intensity test results of the nano-silver-MXene complex; Figure a shows the SERS intensity test results at 9 different random sites, and Figure b shows the SERS intensity test results of Figure a at 1002 cm⁻¹. -1 The corresponding SERS intensity at that location;

[0057] Figure 14 The results of the nano-silver-MXene composite in Example 4 on the detection of PS nanoplastics after EPS decomposition under simulated real-world conditions are shown in Figure a. Figure a shows the SERS intensity detection results at different time points, and Figure b shows the SERS intensity of Figure a at 1002 cm⁻¹. -1 The corresponding SERS intensity at that location;

[0058] Figure 15 The results of the nano-silver-MXene composite of Example 9 on the detection of PS nanoplastics after EPS decomposition under simulated real-world conditions are shown in Figure a. Figure a shows the SERS intensity detection results at different time points, and Figure b shows the SERS intensity of Figure a at 1002 cm⁻¹. -1 The corresponding SERS intensity at that location;

[0059] Figure 16 The results of the detection of the nano-silver-MXene complex in Example 4 on the water samples (a) of the seafood market, (b) of the Tiansha River, (c) of the Xijiang River, and (d) of the Huangmaohai Sea are shown.

[0060] Figure 17 The results of the detection of the nano-silver-MXene complex in Example 9 on the water samples (a) of the seafood market, (b) of the Tiansha River, (c) of the Xijiang River, and (d) of the Huangmaohai Sea are shown.

[0061] Figure 18 This is a schematic diagram showing the sampling locations of the water samples from the seafood market (Fengle Market) (a), the Tiansha River (b), the Xijiang River (c), and the Huangmaohai Sea (d). Detailed Implementation

[0062] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0063] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0064] In the description of this invention, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0065] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0066] In the embodiments of the present invention, the lake water involved in detection examples 4 and 6 was taken from Donghu Lake in Jiangmen Donghu Park.

[0067] Example 1

[0068] This embodiment provides a nano-silver-MXene complex, and the specific preparation process is as follows:

[0069] (1) Preparation of nano-silver (AgNPs): 100 mL of silver nitrate aqueous solution with a concentration of 1 mmol / L was heated to boiling under reflux and kept boiling for 5 min. Then, 2 mL of sodium citrate aqueous solution with a concentration of 1 wt% was added and kept boiling for 1 h. After cooling under natural conditions, the solution was centrifuged and washed to obtain AgNPs. AgNPs were then redispersed in ultrapure water to obtain AgNPs solution.

[0070] (2) Preparation of few-slice Nb2CT x Solution: Add 160mg Nb2CT x After immersing the powder in 20 mL of 25% TMAOH solution and stirring for 24 h, centrifuge at 8000 rpm for 30 min, collect the lower solid layer, and wash the solid with ethanol and water. Disperse the solid in 30 mL of deionized water, then sonicate in an ice-water bath for 15 min (frequency 40 kHz, power 300 W) under nitrogen protection, and shake vigorously for about 10 min. Repeat the sonication and shaking process three times. Centrifuge at 3500 rpm for 30 min to remove the undifferentiated Nb2CT.x Collect the supernatant solution to obtain the few-layer Nb2CT. x Solution.

[0071] (3) Preparation of nano-silver-MXene complex: 15 mL of AgNPs solution (1 mg / mL) and 1 mL of few-layer Nb2CT were mixed. x The solution (0.3 mg / mL) was mixed and stirred for 5 h, centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the precipitate was washed three times to obtain the nano-silver-MXene complex (Ag / Nb2CT). x -2%).

[0072] Example 2

[0073] This embodiment provides a nano-silver-MXene composite (Ag / Nb2CT) x -6%), the preparation process is basically the same as in Example 1, the only difference is that the few-layer Nb2CT in step (3) is used. x The concentration of the solution was changed from 0.3 mg / mL to 0.9 mg / mL.

[0074] Example 3

[0075] This embodiment provides a nano-silver-MXene composite (Ag / Nb2CT) x -10%), the preparation process is basically the same as in Example 1, the only difference is that the concentration of the few-layer Nb2CTx solution in step (3) is replaced by 1.5 mg / mL instead of 0.3 mg / mL.

[0076] Example 4

[0077] This embodiment provides a nano-silver-MXene composite (Ag / Nb2CT) x -14%), the preparation process is basically the same as in Example 1, the only difference being: the few-layer Nb2CT in step (3) is used. x The concentration of the solution was changed from 0.3 mg / mL to 2.1 mg / mL.

[0078] Example 5

[0079] This embodiment provides a nano-silver-MXene composite (Ag / Nb2CT) x -18%), the preparation process is basically the same as in Example 1, the only difference being: the few-layer Nb2CT in step (3) is used. x The concentration of the solution was changed from 0.3 mg / mL to 2.7 mg / mL.

[0080] Example 6

[0081] This embodiment provides a nano-silver-MXene complex, and the specific preparation process is as follows:

[0082] (1) Preparation of nano silver (Ag NPs): 100 mL of silver nitrate aqueous solution with a concentration of 0.18 g / L was heated to boiling under reflux and kept boiling for 5 min. Then, 2 mL of sodium citrate aqueous solution with a concentration of 1 wt% was added and kept boiling for 1 h. After cooling under natural conditions, the solution was centrifuged and washed to obtain Ag NPs. Ag NPs were then redispersed in ultrapure water to obtain Ag NPs solution.

[0083] (2) Preparation of few-layer Ti3C2T x Solution: Add 320mg Ti3C2T x After immersing the powder in 40 mL of 25% TMAOH solution and stirring for 24 h, centrifuge at 8000 rpm for 30 min, collect the lower solid layer, and wash the solid with ethanol and water. Disperse the solid in 60 mL of deionized water, then sonicate in an ice-water bath for 15 min (frequency 40 kHz, power 300 W) under nitrogen protection, shake vigorously for about 10 min repeatedly, repeat three times, and then centrifuge at 3500 rpm for 30 min to remove the undifferentiated Ti3C2T. x Collect the supernatant solution to obtain a few-layer Ti3C2T x Solution.

[0084] (3) Preparation of nano-silver-MXene complex: 10 mL of Ag NPs solution (1 mg / mL) and 1 mL of few-layer Ti3C2T x The solution (0.2 mg / mL) was mixed and stirred for 5 h, centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the washing was repeated 3 times to obtain the nano-silver-MXene complex (Ag / Ti3C2T). x -2%).

[0085] Example 7

[0086] This embodiment provides a nano-silver-MXene composite (Ag / Ti3C2T) x -5%), the preparation process is basically the same as in Example 6, the only difference is that the few-layer Ti3C2T in step (3) is removed. x The concentration of the solution was changed from 0.2 mg / mL to 0.5 mg / mL.

[0087] Example 8

[0088] This embodiment provides a nano-silver-MXene composite (Ag / Ti3C2T) x -8%), the preparation process is basically the same as in Example 6, the only difference is that the few-layer Ti3C2T in step (3) is removed. xThe concentration of the solution was changed from 0.2 mg / mL to 0.8 mg / mL.

[0089] Example 9

[0090] This embodiment provides a nano-silver-MXene composite (Ag / Ti3C2T) x -11%), the preparation process is basically the same as in Example 6, the only difference being: the few-layer Ti3C2T in step (3) is removed. x The concentration of the solution was changed from 0.2 mg / mL to 1.1 mg / mL.

[0091] Example 10

[0092] This embodiment provides a nano-silver-MXene composite (Ag / Ti3C2T) x -14%), the preparation process is basically the same as in Example 6, the only difference being: the few-layer Ti3C2T in step (3) is removed. x The concentration of the solution was changed from 0.2 mg / mL to 1.4 mg / mL.

[0093] Example 11

[0094] This embodiment provides a nano-silver-MXene composite (Ag / Ti3C2T) x -17%), the preparation process is basically the same as in Example 6, the only difference being: the few-layer Ti3C2T in step (3) is removed. x The concentration of the solution was changed from 0.2 mg / mL to 1.7 mg / mL.

[0095] Detection Example 1

[0096] This test example examines the UV-vis spectra, XRD spectra, XPS spectra, SEM images, TEM images, selected area electron diffraction (SAED) images, HAADF and EDX elemental mapping images of the nano-silver-MXene composites of Examples 4 and 9.

[0097] The results are as follows Figure 1-4 As shown.

[0098] Ultraviolet spectroscopy can reflect the particle size of silver nanoparticles, and the particle size can be estimated using the following formula:

[0099] λ max =2.3579d + ​​303.8;

[0100] Where λ max The position of the main peak is denoted by d, and d represents the average size of the silver nanoparticles.

[0101] AgNPs, Ag / Nb2CT x -14%, Ag / Ti3C2Tx The -11% maximum absorption peak is at 408 nm, and the calculated particle size is 44.19 nm. Nb₂CT loaded... x Ti3C2T x There was no significant displacement forward or backward, indicating that Nb2CT x Ti3C2T x The loading had no significant effect on the particle size of the silver nanoparticles. For example... Figure 1 Figure a in the middle and Figure 2 As shown in Figure a.

[0102] Ag / Nb2CT x In the XRD pattern of -14%, some sharp peaks can be observed at 38.0°, 44.1°, 64.3°, 77.3°, and 81.30°, which belong to the (111), (200), (220), (311), and (222) crystal planes of silver (JCPDS card number 04-0783). Ag / Ti3C2T x Some sharp peaks can be observed at 38.0° and 44.1° in the -11% XRD pattern, which belong to the (111) and (200) crystal planes of silver (JCPDS card number 04-0783). In Nb2CT... x or Ti3C2T x After loading Ag NPs, no significant changes were observed in any of the crystal planes, indicating that the nanosilver in Nb2CT... x or Ti3C2T x The loading on the crystal has no significant effect on the crystal form. For example... Figure 1 Figure b in the middle and Figure 2 As shown in Figure b.

[0103] XPS observation revealed that Ag / Nb2CT x -14% and Ag / Ti3C2T x -11% of the composite material contains Ag, C, O, Nb and Ag, C, O, Ti, respectively. For example... Figure 1 middle df diagram, Figure 2 As shown in the df plot. Ag / Nb2CT x The three-dimensional Ag spectrum of the -14% composite material showed two peaks at 368.0 eV and 374.0 eV; the tangent values ​​of the two peaks were approximately 6.0 eV, belonging to the Ag 3d 5 / 2 peak and Ag 3d 3 / 2 peak of metallic silver, respectively. This indicates that AgNPs were successfully loaded onto Nb2CT. x On nanosheets. Ag / Nb2CT xThe C1s spectrum of the -14% composite material shows four peaks at 282.1 eV, 284.69 eV, 285.81 eV, and 288.26 eV, which are attributed to C-Nb, CC, C-OH, and CF bonds, respectively. For Nb 3d, the peaks at 203.23 eV and 206.03 eV belong to C-Nb bonds. In Ag / Nb2CT... x Characteristic signals of O-Nb-O bonds located at 207.53 eV and 210.33 eV can be observed in the -14% composite material, which may be due to Nb2CT. x This is caused by the slow oxidation of the surface of small fragments in air. Ag / Ti3C2T x The three-dimensional Ag spectrum of the -11% composite material showed two peaks at 368.0 eV and 374.0 eV; the separation between the two peaks was approximately 6.0 eV, belonging to the Ag 3d 5 / 2 and Ag 3d 3 / 2 peaks of metallic silver, respectively. This indicates that AgNPs were successfully loaded onto Ti3C2T x On nanosheets. Ag / Ti3C2T x The C1s spectrum of the -11% composite material showed four peaks at 282.2 eV, 284.8 eV, 286.4 eV, and 288.9 eV, which were attributed to C-Ti, CC, CO, and CF bonds, respectively. For Ti 32p, three sets of doublets were detected with an area ratio of 2:1 and a separation of 5.7 eV, corresponding to Ti-C, Ti-CC, CO, and CF bonds, respectively. x O y And TiO2.

[0104] Nb2CT x No longer possessing an accordion-like structure, but instead being peeled into sheet-like Nb2CT x .like Figure 3 As shown in Figure a. Ti3C2T x Same. For example... Figure 4 As shown in Figure a.

[0105] Furthermore, silver nanoparticles were successfully prepared and loaded onto few-layer Nb2CT. x or Ti3C2T x Above. (As shown) Figure 3 Chinese BD diagram Figure 4 As shown in the middle bd diagram.

[0106] Ag / Nb2CT x HRTEM images of the -14% composite material show lattice fringe spacings of 0.239 nm and 0.23 nm, respectively, corresponding to the (111) plane of AgNPs and the Nb2CT plane. x (006) side. Figure 3The circles in the middle f figure represent the polycrystalline structure of the SERS substrate, corresponding to AgNPs (111), (200) and Nb2CT. x (006) Reflection of a plane.

[0107] Ag / Ti3C2T x HRTEM images of the -11% composite material show lattice fringe spacings of 0.20 nm and 0.33 nm, corresponding to the (200) plane of AgNPs and Ti3C2T, respectively. x (0110) face. Figure 4 The circles in the middle f figure represent the polycrystalline structure of the SERS substrate, corresponding to AgNPs (111), (200) and Ti3C2T. x Reflection of the (0110) plane.

[0108] EDS elemental mapping results showed that C, Nb / Ti, O, and Ag were uniformly distributed, indicating that silver nanoparticles were uniformly loaded on few-layer Nb2CT. x superior.

[0109] Detection Example 2

[0110] This test example uses the nano-silver-MXene composite from Examples 1-11 to test the nanoplastic PS.

[0111] 1. The nanoplastic PS (300 nm) was diluted with ultrapure water to 0.1 mg / mL to obtain a nanoplastic solution. The nano-silver-MXene composite was diluted with ultrapure water to a concentration of 1 mg / mL to obtain a nano-silver-MXene composite solution. The nano-silver-MXene composite solution was mixed with 40 μL of nanoplastic solution at volume ratios of 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, and 4:1, respectively. 20 μL of KI solution (0.15 M) was added, and after thorough mixing, 30 μL of the mixed solution was dropped onto a 5 × 5 mm silicon wafer using a glass pipette. After drying at 50 °C for 1 h, SERS detection was performed. All Raman spectral results were baseline corrected in this experiment.

[0112] The results are as follows Figure 5 and 6 As shown.

[0113] As the volume of the nano-silver-MXene complex solution increases, the SERS intensity first increases and then decreases, with optimal activity observed at a ratio of 2:1. For example, regarding nano-silver-Nb2CT... xThe SERS intensity of the complex increased from 24 counts at a 1:4 ratio to 549 counts at a 2:1 ratio, and then decreased. This is likely because when the concentration of the nanosilver-MXene complex is low, it provides too few hotspot signals, resulting in low SERS intensity. When the substrate concentration is too high, some nanoplastics may be covered, leading to the loss of the SERS signal from these nanoplastics.

[0114] With Nb2CT x or Ti3C2T x With increasing load, its SERS performance exhibits a volcano-shaped change, yielding Nb2CT. x The optimal load is 14% for Ti3C2T x The optimal loading was 11%. Specifically, the SERS activity at the optimal loading of 14% was 3.8 times that of the unloaded substrate (Ag NPs). This indicates that MXene loading can improve the SERS activity of the substrate. The reason for the initial increase followed by a decrease may be that when the MXene content is low, it cannot provide more active sites for Ag NPs, while when the MXene content is high, it may cover Ag NPs, preventing MXene from providing SERS hotspots for PS, thus affecting the SERS signal.

[0115] 2. Dilute PS nanoplastics of different particle sizes (50nm, 300nm, 500nm) with ultrapure water to a concentration of 9×10⁻⁶. -7 mg / mL, 10 -6 mg / mL, 10 -5 mg / mL, 7×10 -5 mg / mL, 9×10 -5 mg / mL, 10 -4 mg / mL, 10 -3 mg / mL, 10 -2 mg / mL, 10 -1 Nanoplastic solutions were obtained by diluting the nano-silver-MXene composite from Example 4 or Example 9 with ultrapure water to a concentration of 1 mg / mL. The nano-silver-MXene composite solution was then mixed with 40 μL of nanoplastic solution at a volume ratio of 2:1. 20 μL of KI solution (0.15 M) was added, and after thorough mixing, 30 μL of the mixture was dropped onto a 5 × 5 mm silicon wafer using a glass pipette. After drying at 50 °C for 1 h, SERS detection was performed. All Raman spectral results underwent baseline correction in this experiment.

[0116] The results are as follows Figure 7 and Figure 8 As shown.

[0117] The nano-silver-MXene complexes of Examples 4 and 9 exhibited good qualitative and quantitative detection capabilities for PS of different particle sizes and concentrations.

[0118] The limit of detection for 50 nm PS nanoplastics using the nano-silver-MXene composite in Example 4 was 9 × 10⁻⁶. -5 mg / mL, at 10 -4 ~10 -1 Within the concentration range of mg / mL, 1002cm -1 The SERS intensity at the concentration decreased with decreasing concentration, and showed a good linear relationship (R0). 2 =0.973). Similarly, nanoplastics with particle sizes of 300 nm and 500 nm also showed similar detection results, with a limit of detection of 7 × 10⁻⁶. -5 and 9×10 -5 mg / mL, R 2 They are 0.982 and 0.987 respectively. For example... Figure 7 As shown.

[0119] The limit of detection for 50 nm PS nanoplastics by the nano-silver-MXene composite in Example 9 was 9 × 10⁻⁶. -7 mg / mL mg / mL, at 10 -6 Within the concentration range of ~1 mg / mL, 1002 cm -1 The SERS intensity at the concentration decreased with decreasing concentration, and showed a good linear relationship (R0). 2 =0.982); the lowest detection limit for 300nm PS nanoplastics is 9×10⁻⁶. -7 mg / mL, at 10 -6 Within the concentration range of ~1 mg / mL, 1002 cm -1 The SERS intensity at that location decreased with decreasing concentration, and at 10 -6 ~10 -1 A good linear relationship was observed within the concentration range of mg / mL (R0). 2 =0.990); the lowest detection limit for 500nm PS nanoplastics is 9×10⁻⁶. -7 mg / mL, at 10 -6 Within the concentration range of ~1 mg / mL, 1002 cm -1 The SERS intensity at that location decreased with decreasing concentration, and at 10 -6 ~10 -1 A good linear relationship was observed within the concentration range of mg / mL (R0). 2 =0.995). For example... Figure 8 As shown.

[0120] Detection Example 3

[0121] This test example uses the nano-silver-MXene composites from Examples 4 and 9 to detect the nanoplastic PMMA (300 nm).

[0122] PMMA nanoplastic (300 nm) was diluted with ultrapure water to concentrations of 4 mg / mL, 2 mg / mL, 1 mg / mL, and 0.5 mg / mL, respectively, to obtain nanoplastic solutions. The nanosilver-MXene composite from Example 4 or Example 9 was diluted with ultrapure water to a concentration of 1 mg / mL to obtain a nanosilver-MXene composite solution. The nanosilver-MXene composite solution was mixed with 40 μL of nanoplastic solution at a volume ratio of 2:1, and 20 μL of KI solution (0.15 M) was added. After thorough mixing, 30 μL of the mixture was dropped onto a 5 × 5 mm silicon wafer using a glass pipette. After drying at 50 °C for 1 h, SERS detection was performed. All Raman spectral results were baseline corrected in this experiment.

[0123] The results are as follows Figure 9 and 10 As shown.

[0124] The nanosilver-MXene complexes in Examples 4 and 9 were able to successfully detect PMMA (300 nm) at concentrations above 0.5 mg / mL. This may be because PMMA has a lower Raman cross section, resulting in a weaker signal intensity compared to PS.

[0125] Detection Example 4

[0126] This test example examines the detection stability of the nano-silver-MXene composites from Examples 4 and 9, and their detection performance on PS nanoplastics generated during the simulated natural degradation of EPS under experimental conditions. The lake water sampling locations are as follows: Figure 11 As shown in Figure a.

[0127] 1. Add 40 μL containing 10 -2 Lake water with mg / mL PS (300nm) and 80μL containing Ag / Nb2CT x After mixing a 14% solution (1 mg / mL) (the treatment corresponding to Example 9 is: 40 μL containing 10...) -1 Lake water with mg / mL PS (300nm) and 80μL containing Ag / Ti3C2T x A mixture of -11% solutions was added, followed by 20 μL of KI solution (0.15 M). After thorough mixing, 30 μL of the mixture was dropped onto a 5 × 5 mm silicon wafer using a glass pipette. After drying at 50 °C for 1 h, Raman spectra were collected at nine randomly selected locations on the nanosilver-MXene composite. All Raman spectral results underwent baseline correction in this experiment.

[0128] The detection results of the nano-silver-MXene complex in Examples 4 and 9 on lake water are as follows: Figure 11 As shown.

[0129] Calculations showed that the RSD of the nine sets of data in Example 4 was 5.06%. Figure 12 As shown.

[0130] Calculations showed that the RSD of the nine sets of data in Example 9 was 2.32%. Figure 13 As shown.

[0131] The nano-silver-MXene composite of the present invention exhibits good detection stability.

[0132] 2. Cut 0.7g of EPS into small pieces and place them in 180mL of lake water. Place the mixture on a shaker to simulate a real environment (the decomposition process of EPS under natural conditions). Samples were taken on days 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24. The lake water before adding EPS was used as the sample for day 0. A solution containing the nano-silver-MXene complex (1mg / mL) from Example 4 was mixed with 40μL of water sample at a volume ratio of 2:1. 20μL of KI solution (0.15M) was added, and after thorough mixing, 30μL of the mixture was dropped onto a 5×5mm silicon wafer using a glass pipette. After drying at 50℃ for 1h, SERS detection was performed. All Raman spectral results underwent baseline correction in this experiment.

[0133] 0.7g of EPS was cut into small pieces and placed in 180mL of lake water, then placed on a shaker to simulate a real environment (the decomposition process of EPS under natural conditions). Samples were taken on days 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, and 25; the lake water before the addition of EPS was used as the sample for day 0. A solution containing the nano-silver-MXene complex of Example 9 (1mg / mL) was mixed with 40μL of water sample at a volume ratio of 2:1, and 20μL of KI solution (0.15M) was added. After thorough mixing, 30μL of the mixed solution was dropped onto a 5×5mm silicon wafer using a glass pipette. After drying at 50℃ for 1h, SERS detection was performed. All Raman spectral results were baseline corrected in this experiment.

[0134] The results are as follows: Figure 14 and 15 As shown.

[0135] The nano-silver-MXene composite of the present invention can successfully monitor the decomposition of EPS at different time points.

[0136] Case 5

[0137] This test example uses the nano-silver-MXene composites from Examples 4 and 9 to detect the nanoplastic PS in actual samples.

[0138] Water samples were collected from the seafood market, Tiansha River, Xijiang River, and Huangmaohai Lake. Sampling locations are as follows: Figure 18 As shown, 40 μL of water sample was mixed with 80 μL of solution containing nano-silver-MXene complex (1 mg / mL), followed by the addition of 20 μL of KI solution (0.15 M). After thorough mixing, 30 μL of the mixture was dropped onto a 5 × 5 mm silicon wafer using a glass pipette. After drying at 50 °C for 1 h, SERS detection was performed. All Raman spectral results were baseline corrected in this experiment. The equivalent concentration of the actual water sample was calculated using the linear relationship curve between the concentration corresponding to the 300 nm particle size and the SERS signal.

[0139] The results are as follows Figure 16-17 As shown in Table 1. The sampling locations for water samples are as follows: Figure 18 As shown.

[0140] Table 1. Equivalent concentration of 300 nm polystyrene microplastics in different water samples

[0141]

[0142]

[0143] Note: The water samples tested in Examples 4 and 9 were from different batches at the same location, which is why there are fluctuations in the data.

[0144] The Raman characteristic peaks of PS appeared in water samples from four different locations. The equivalent concentration was highest in the Tiansha River sample and lowest in the seafood market sample. For the nano-silver-MXene complex in Example 4, the SERS signal in the seafood market sample was weak, below the confidence interval of the experimental method, therefore the equivalent concentration could not be calculated. The detection of PS in the seafood market sample may be due to the widespread use of EPS containers for seafood transportation.

[0145] This also indicates that the nano-silver-MXene composite of the present invention can be used for the detection of actual water samples.

[0146] Case 6

[0147] This test example uses the nano-silver-MXene complex from Examples 4 and 9 for spiked recovery experiments.

[0148] Nanoplastic PS (50, 300, and 500 nm) was diluted to different concentrations (1, 10, and 100 μg / mL) with lake water (the same lake water used in the EPS simulated degradation experiment in Example 4). Then, 40 μL of PS was mixed with 80 μL of Ag / Nb2CT. x -14% or Ag / Ti3C2T x A solution of -11% (1 mg / mL) was mixed, and 20 μL of KI solution (0.15 M) was added. After thorough mixing, 30 μL of the mixture was dropped onto a 5 × 5 mm silicon wafer using a glass pipette. After drying at 50 °C for 1 h, SERS detection was performed. All Raman spectral results were baseline corrected in this experiment.

[0149] The detection results of Examples 4 and 9 are shown in Tables 2 and 3, respectively.

[0150] Table 2

[0151]

[0152] Table 3

[0153]

[0154] The recoveries of PS samples with different particle sizes and concentrations ranged from 93.4% to 107.9%, with RSDs below 10%. This confirms the feasibility of the nano-silver-MXene composite of the present invention in the detection of actual water samples.

[0155] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. Application of nano-silver-MXene composite or SERS substrate including said nano-silver-MXene composite in the detection of nanoplastics; The nano-silver-MXene composite comprises MXene nanosheets and nano-silver distributed on the surface of the MXene nanosheets; The nano-silver has a particle size of 20~70 nm; the mass ratio of the nano-silver to the MXene nanosheets is 1:0.02~0.18; The MXene nanosheets include Ti3C2T x Ti2CT x V2CT x Ta2CT x TiVCT x Mo2CT x Nb2CT x Nb4C3T x Mo2TiC2T x and Mo2Ti2C3T x At least one of them; The MXene nanosheets have 1 to 10 layers.

2. The application according to claim 1, characterized in that, The preparation method of the nano-silver-MXene complex includes the following steps: A solution containing the aforementioned silver nanoparticles and MXene nanosheets was prepared, and the reaction was carried out to obtain the silver nanoparticle-MXene composite.

3. The application according to claim 2, characterized in that, The reaction time is 1 to 5 hours.

4. The application according to claim 2, characterized in that, The method for preparing the MXene nanosheets includes the following steps: The MXene powder was subjected to intercalation and ultrasonic treatment in sequence to obtain the MXene nanosheets.

5. A method for detecting nanoplastics, characterized in that, Includes the following steps: S1. Obtain the linear relationship between the intensity and concentration of the characteristic SERS peaks of the nanoplastic using the nano-silver-MXene composite or the SERS substrate described in any one of claims 1 to 4. S2. The sample solution to be tested is mixed with the nano-silver-MXene composite or the SERS substrate described in any one of claims 1 to 4 and detected to obtain the intensity of the characteristic SERS of the nanoplastics in the sample to be tested. Combined with the linear relationship obtained in step S1, the content of nanoplastics in the sample solution to be tested is calculated.

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