A nano-silver modified MOF foam nickel substrate, a preparation method and application thereof

Abstract

This invention discloses a nano-silver modified MOF nickel foam substrate, its preparation method, and its application. The preparation method employs electrochemical deposition, sequentially modifying a cobalt-nickel precursor and nano-silver onto pretreated nickel foam to obtain a nano-silver modified MOF nickel foam substrate. This substrate can be used for tetracycline detection. In this invention, the nano-silver modified MOF nickel foam substrate exhibits uniformly dispersed silver particles covering the surface of the MOF nickel foam substrate, and forms abundant Raman hot spots in the gaps, demonstrating a significant Raman enhancement effect, providing a basis for improving the accuracy and sensitivity of tetracycline detection. When this nano-silver modified MOF nickel foam substrate is used as a sensing electrode for tetracycline detection, the detection limit is 10⁻⁶. ‑11 mol L ‑1 It exhibits extremely high detection sensitivity. The recovery rate is between 80% and 120%, and the relative standard deviation is less than 7%, demonstrating very high detection accuracy.

Description

Technical Field

[0001] This invention belongs to the field of food safety technology and relates to the detection of tetracycline, specifically to a nano-silver modified MOF foam nickel substrate, its preparation method and its application. Background Technology

[0002] Tetracycline is the most basic compound among tetracycline antibiotics. It was originally extracted from Streptomyces aureus and its molecular formula is C6H2O. 22 H 24 N2O8. Tetracycline has advantages such as good oral efficacy, stable drug activity, and strong antibacterial and bactericidal effects, and has been widely used in the treatment of infectious diseases in livestock, humans, and animals. The use of tetracycline has greatly promoted the development of animal husbandry. However, because tetracycline cannot be completely digested, absorbed, and degraded by humans and animals, it has also had adverse effects on the environment and flora and fauna.

[0003] Studies have shown that approximately 50-80% of tetracyclines enter the environment in their original form or other forms, spreading through land use, aquaculture, and surface runoff and infiltration. They then accumulate in plants and animals, eventually reaching humans through the food chain. The accumulation of tetracyclines in the human body not only adversely affects the teeth and bone development of infants and young children but also causes irreversible damage to organs such as the liver and kidneys. Furthermore, tetracyclines can disrupt the body's normal flora, reducing the immunity of the elderly, children, and cancer patients, leading to secondary infections. Therefore, establishing and continuously improving a rapid and effective detection and monitoring system for tetracyclines is of great significance for ensuring human health.

[0004] Chinese patent CN 108201878 B, authorized by the patent, modifies a metal-organic framework using a water-soluble liquid carbon dot solution to prepare a carbon dot-modified metal-organic framework adsorbent material, which is then used for the detection of tetracycline. While this invention has advantages such as being non-toxic, low-cost, highly efficient, rapidly synthesized, energy-efficient, and simple to operate, the accuracy and sensitivity for tetracycline detection need further improvement. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a nano-silver modified MOF foam nickel substrate, its preparation method, and its application, thereby solving the technical problem that the detection accuracy and sensitivity of tetracycline in existing technologies need to be further improved.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing a nano-silver modified MOF foam nickel substrate involves electrochemical deposition, in which a cobalt-nickel precursor and nano-silver are sequentially modified onto pretreated foam nickel to obtain a nano-silver modified MOF foam nickel substrate.

[0008] The present invention also has the following technical features:

[0009] The method specifically includes the following steps:

[0010] Step 1: Preprocessing;

[0011] Pretreated nickel foam was obtained by sequentially treating it with dilute hydrochloric acid, anhydrous ethanol, and deionized water, followed by cleaning the surface of the nickel foam.

[0012] Step 2: Prepare cobalt-nickel precursors;

[0013] Cobalt nitrate, nickel nitrate, and HmIM were added to an aqueous methanol solution and mixed thoroughly to obtain a cobalt-nickel precursor.

[0014] Step 3: Prepare MOF foam nickel substrate;

[0015] Using the pretreated nickel foam obtained in step one as the working electrode, a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and the cobalt-nickel precursor obtained in step two as the electrolyte solution for electrochemical deposition, a first electrochemical deposition was performed to obtain a MOF nickel foam substrate. The conditions for the first electrochemical deposition were: deposition voltage of -0.3 to -1.0 V and deposition time of 200 to 500 s.

[0016] Step four: Perform nano-silver modification;

[0017] Using the MOF nickel foam substrate obtained in step three as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode, a second electrochemical deposition was performed in a silver nitrate solution to obtain a nano-silver modified MOF nickel foam substrate. The conditions for the second electrochemical deposition were: deposition voltage of -0.1 to -0.3 V and deposition time of 5 to 15 min.

[0018] Specifically, in step two, the mass fraction ratio of methanol to water in the methanol-water solution is 19:1.

[0019] Specifically, in step two, the molar ratio of cobalt nitrate, nickel nitrate, and HmIM in the cobalt-nickel precursor is 1:1:8.

[0020] Specifically, in step four, the molar concentration of the silver nitrate solution is 0.05 mol / L. -1 .

[0021] The present invention also protects the application of the nano-silver modified MOF foam nickel substrate prepared by the method described above in tetracycline detection.

[0022] The method used in this application includes the following steps:

[0023] Step 1: Establish the relationship between Raman intensity and tetracycline concentration;

[0024] The nano-silver modified MOF nickel foam substrate was immersed in a series of tetracycline standard solutions, and Raman spectroscopy was performed to measure a value of 1313 cm⁻¹. -1 The Raman intensity at 1313 cm⁻¹ is determined by the logarithm of the molar concentration of the tetracycline standard solution and the value at 1313 cm⁻¹. -1 A scatter plot of the Raman intensity at the specified location was generated. After linear fitting, a linear equation was obtained between the Raman intensity and the logarithm of the tetracycline concentration, as shown in Equation IV:

[0025] y = 365.21x + 3827.39 (Equation IV)

[0026] In the formula:

[0027] y represents the tetracycline standard solution at 1313 cm⁻¹ -1 Raman intensity at the location;

[0028] x represents the logarithm of the molar concentration of the tetracycline standard solution;

[0029] Step two, conduct the test;

[0030] A nano-silver modified MOF foam nickel substrate was immersed in the sample to be tested, and the Raman spectrum was measured at 1313 cm⁻¹. -1 The Raman intensity at a certain point is used to calculate and obtain the molar concentration of tetracycline in the sample by substituting the Raman intensity of the sample into Equation IV.

[0031] Specifically, in step two of the method used in this application, the conditions for Raman spectroscopy scanning are: using an excitation wavelength of 785 nm and excitation for 10 s.

[0032] Compared with the prior art, the present invention has the following technical effects:

[0033] (I) The nano-silver modified MOF foam nickel substrate of the present invention, due to the supporting effect of MOF material, the nano-silver particles are uniformly dispersed and covered on the surface of MOF foam nickel substrate, and abundant Raman hot spots are formed in the gaps, showing a significant Raman enhancement effect, which provides a basis for improving the detection accuracy and sensitivity of tetracycline.

[0034] (II) The nano-silver modified MOF foam nickel substrate of the present invention has good reproducibility and excellent time stability, can be stored for a long time, and can still meet the detection requirements after long-term storage.

[0035] (III) The nano-silver modified MOF foam nickel substrate was used for the detection of tetracycline, and the detection limit was 10. -11 molL -1 It exhibits extremely high detection sensitivity. The recovery rate is between 80% and 120%, and the relative standard deviation is less than 7%, demonstrating very high detection accuracy. Attached Figure Description

[0036] Figure 1 A schematic diagram of the process for preparing nano-silver modified MOF foam nickel substrate.

[0037] Figure 2(A) is a scanning electron microscope image of pretreated nickel foam.

[0038] Figure 2(B) is a magnified scanning electron microscope image of pretreated nickel foam.

[0039] Figure 2(C) is a scanning electron microscope image of the MOF nickel foam substrate.

[0040] Figure 2(D) is a magnified scanning electron microscope image of the MOF nickel foam substrate.

[0041] Figure 2(E) is a scanning electron microscope image of the silver nanoparticle-modified MOF foam nickel substrate.

[0042] Figure 2(F) is a magnified scanning electron microscope image of the silver nanoparticle-modified MOF foam nickel substrate.

[0043] Figure 2(G) shows the EDX elemental mapping of the nano-silver modified MOF foam nickel substrate.

[0044] Figure 3(A) shows the XPS spectra of MOF nickel foam substrate and MOF nickel foam substrate modified with nano-silver;

[0045] In the figure, CoNiMOF@Ag represents a silver-modified MOF nickel foam substrate, and CoNiMOF represents a MOF nickel foam substrate.

[0046] Figure 3(B) shows the Ni 2p XPS spectrum of the silver-modified MOF foam nickel substrate.

[0047] Figure 3(C) shows the Co 2p XPS spectrum of the silver-modified MOF foam nickel substrate.

[0048] Figure 3(D) shows the Ag 3d XPS spectrum of the silver-modified MOF foam nickel substrate.

[0049] Figure 4(A) shows the Raman spectra of different test substrates in the performance test of the embodiment; in the figure, S1 represents MOF nickel foam substrate modified with nano-silver mixed with R6G, S2 represents nickel foam substrate modified with nano-silver mixed with R6G, S3 represents MOF nickel foam substrate modified with nano-silver without R6G, S4 represents MOF nickel foam substrate mixed with R6G, S5 represents MOF nickel foam substrate without R6G, S6 represents pretreated nickel foam mixed with R6G, and S7 represents pretreated nickel foam without R6G.

[0050] Figure 4(B) shows the Raman spectra of 10 test points on a MOF nickel foam substrate modified with R6G nanosilver.

[0051] Figure 4(C) shows 10 test points on a MOF nickel foam substrate modified with R6G nanosilver at a depth of 611 cm⁻¹. -1 Raman spectrum at [location].

[0052] Figure 4(D) shows 10 test points on a MOF nickel foam substrate modified with R6G nanosilver at 1359 cm⁻¹. -1 Raman spectrum at [location].

[0053] Figure 5(A) shows the Raman spectrum of the MOF foam nickel substrate modified with R6G nanosilver as a function of time.

[0054] Figure 5(B) shows the MOF foam nickel substrate modified with R6G nanosilver at 1359 cm⁻¹. -1 Raman spectrum of Raman intensity at a given location as a function of time.

[0055] Figure 6(A) shows the Raman spectra of different molar concentrations of tetracycline on the MOF foam nickel substrate modified with nano-silver.

[0056] Figure 6(B) shows the tetracycline molecule at 1313 cm⁻¹. -1 Scatter plot of signal intensity at displacement versus molar concentration of tetracycline.

[0057] Figure 6(C) shows the linear equation between Raman intensity and the logarithm of tetracycline concentration in the application example.

[0058] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0059] In this invention:

[0060] MOF stands for Metal-Organic Framework.

[0061] HmIM refers to 2-methylimidazole.

[0062] SERS refers to surface-enhanced Raman spectroscopy.

[0063] R6G refers to Rhodamine 6G.

[0064] RSD refers to the relative standard deviation.

[0065] It should be noted that, unless otherwise specified, all raw materials and solutions used in this invention are those known in the prior art.

[0066] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0067] Example:

[0068] This embodiment provides a method for preparing a nano-silver modified MOF foam nickel substrate, such as... Figure 1 As shown, the method specifically includes the following steps:

[0069] Step 1: Preprocessing;

[0070] First, 3 mol L... -1 Pretreated nickel foam of 10×20×1mm was pretreated for 15 minutes with dilute hydrochloric acid, anhydrous ethanol and deionized water, and then the surface of the nickel foam was cleaned to obtain pretreated nickel foam.

[0071] In this embodiment, as shown in Figures 2(A) and 2(B), the surface of the pretreated nickel foam obtained in step one has a three-dimensional structure and a smooth surface.

[0072] Step 2: Prepare cobalt-nickel precursors;

[0073] 10 mL of cobalt nitrate mother liquor, 10 mL of nickel nitrate mother liquor, and 10 mL of HmIM mother liquor were added to 50 mL of methanol aqueous solution and mixed thoroughly to obtain the cobalt-nickel precursor. The final concentrations of cobalt nitrate, nickel nitrate, and HmIM in the cobalt-nickel precursor were 2.5 mmol / L. -1 2.5 mmol / L -1 0.2 mol L -1 .

[0074] In this embodiment, the methanol-water solution is composed of methanol and water, and the mass fraction ratio of methanol to water is 19:1.

[0075] Step 3: Prepare MOF foam nickel substrate;

[0076] Using the pretreated nickel foam obtained in step one as the working electrode, a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and the cobalt-nickel precursor obtained in step two as the electrolyte solution for electrochemical deposition, a MOF nickel foam substrate was obtained after deposition at a constant voltage of -5.0V for 300s.

[0077] In this embodiment, the reaction mechanism for preparing MOF foam nickel substrate by electrochemical deposition is as follows:

[0078] First, as shown in Equation I, after metal ions are mixed with HmIM, M(HmIM)4 will be rapidly generated. 2+ M represents Co and Ni:

[0079] M 2+ +4HmIM→M(HmIM)4 2+ Formula I.

[0080] Then, as shown in Formula II, in the subsequent electrochemical synthesis process, OH is formed by reducing H2O on the working electrode. - :

[0081] 2H2O+2e - →H2+2OH - Formula II.

[0082] Finally, as shown in Equation III, OH - With M(HmIM)4 2+ Further reaction forms M(mIM)2, which is deposited on the surface of the pretreated nickel foam substrate:

[0083] M(HmIM)4 2+ +OH - →M(mIM)2+2HmIM+2H2O Formula III.

[0084] In this embodiment, as shown in Figures 2(C) and 2(D), after electrodeposition in step three, the precursor film grows uniformly on the surface of the nickel foam, and the surface of the nickel foam becomes rough, proving the successful synthesis of the MOF nickel foam substrate.

[0085] Step four: Perform nano-silver modification;

[0086] Using the MOF nickel foam substrate prepared in step three as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode, at 0.05 mol L... -1 Nano-silver modified MOF nickel foam substrate was prepared by deposition in silver nitrate solution at a constant voltage of -0.15V for 10 min.

[0087] In this embodiment, the final characterization of the nano-silver modified MOF foam nickel substrate is as follows:

[0088] As shown in Figures 2(E) and 2(F), due to the supporting effect of the MOF material, the nano-silver particles are uniformly covered on the surface of the MOF foam nickel substrate, providing a large number of surface-enhanced Raman spectroscopy hotspots for the detection of tetracycline.

[0089] As shown in Figure 2(G), Ag, C, O, N, Ni and Co are uniformly dispersed on the substrate surface.

[0090] As shown in Figure 3(A), the XPS spectrum confirms the presence of Co, Ni, C, O, and N. The appearance of the 3d peak of Ag in the XPS spectrum indicates that the nano-silver particles were successfully modified onto the MOF nickel foam substrate.

[0091] As shown in Figure 3(B), Ni 2p 3 / 2 and Ni 2p 1 / 2 The peaks appear at 855.6 eV and 873.3 eV, respectively, while the peaks at 861.7 eV and 880.2 eV correspond to Ni 2p 3 / 2 and Ni 2p 1 / 2 .

[0092] As shown in Figure 3(C), Co 2p 3 / 2 and Co 2p 1 / 2 The peaks at 781.4 eV and 796.4 eV correspond to the energy bands, while the peaks at 786.7 and 803.7 eV correspond to Co 2p, respectively. 3 / 2 and Co 2p 1 / 2 The accompanying peak.

[0093] As shown in Figure 3(D), in the spectrum of Ag 3d, Ag 3d 3 / 2 and Ag 3d 1 / 2 The corresponding energy bands are located at 368.2 and 374.8 eV.

[0094] The above spectra demonstrate the successful synthesis of nano-silver modified MOF foam nickel substrate.

[0095] Performance testing:

[0096] In this embodiment, R6G was used as a probe molecule to study the SERS enhancement performance of the substrate to be tested on R6G. The substrate to be tested included: pretreated nickel foam, MOF nickel foam substrate, silver nanoparticle-modified nickel foam substrate (the preparation process of the silver nanoparticle-modified nickel foam substrate included steps one and four), and silver nanoparticle-modified MOF nickel foam substrate.

[0097] The performance test process is as follows:

[0098] First, immerse the substrate to be tested in an aqueous solution with a molar concentration of 10. -6 mol L -1The substrate was immersed in an R6G solution for 1 hour, then removed and dried. After mixing, 10 test points were randomly selected on each substrate to measure Raman signals to examine the reproducibility of the SERS substrate. Pretreated nickel foam without R6G, MOF nickel foam substrate without R6G, and MOF nickel foam substrate modified with nano-silver without R6G were used as controls. The Raman signal measurement conditions were: excitation wavelength of 785 nm for 10 s.

[0099] Third, immerse the substrate to be tested in an aqueous solution with a molar concentration of 10. -6 mol L -1 In the R6G solution, Raman signals were measured every ten days to examine the stability of the SERS substrate. To eliminate random errors, five substrates were used in parallel experiments for each test group.

[0100] The results of the performance test are as follows:

[0101] (A) As shown in Figure 4(A), the background noise of different test substrates is relatively small and easy to distinguish. The Raman characteristic peaks of R6G appear at 611, 773, 1166, 1314, 1359, 1509, 1590 and 1650 cm⁻¹. -1 The displacement was observed at the site, but not on the pretreated nickel foam and MOF nickel foam substrates. Compared with the nano-silver modified nickel foam substrate, the nano-silver modified MOF nickel foam substrate not only dispersed the nano-silver, but also formed abundant Raman hot spots in the gaps, thus exhibiting a significant Raman enhancement effect.

[0102] The Raman intensity of R6G on the silver-modified MOF nickel foam substrate is twice that on the silver-modified nickel foam substrate, indicating that the preparation of the silver-modified MOF nickel foam substrate has a strong enhancing effect on R6G. This is because the MOF material has excellent adsorption properties for target molecules, which accelerates the approach of target molecules to the substrate, thereby significantly enhancing the SERS signal.

[0103] (B) The reinforcing factor of the nano-silver modified MOF foam nickel substrate was analyzed. The reinforcing factor was calculated and obtained using Equation V:

[0104]

[0105] In the formula:

[0106] EF represents the enhancement factor;

[0107] I SERS The SERS strength of the nano-silver modified MOF foam nickel substrate against R6G is indicated.

[0108] C NOR This indicates the concentration of R6G without a reinforced substrate;

[0109] I NOR This represents the SERS intensity of R6G measured without a reinforced substrate;

[0110] C SERS The concentration of R6G detected on the nano-silver modified MOF foam nickel substrate is indicated.

[0111] Choose R6G at 1359cm -1 The characteristic peak intensity at that location was calculated, yielding an average enhancement factor of approximately 1.2 × 10⁻⁶. 7 This indicates that the nano-silver modified MOF foam nickel substrate possesses excellent SERS performance. The high-performance SERS can likely be attributed to the substrate structure's abundant sharp edges, tips, coupled branches, and electromagnetic enhancement from noble metal generation, as well as the pre-concentration effect of the nano-silver modified MOF foam nickel substrate on the substrate.

[0112] (C) As shown in Figure 4(B), the difference in peak intensity at different test points on the substrate is very small, indicating high reliability of the test. Based on R6G at 611 and 1359 cm⁻¹... -1 The standard deviation of the Raman intensity at a given location is calculated by... Figure 4(C) and 4(D) It can be seen that R6G is at 611 and 1359cm. -1 The standard deviations at the values ​​were 8.47% and 9.91%, respectively, which are less than 10%, indicating that the prepared nano-silver modified MOF foam nickel substrate has good reproducibility.

[0113] (D) As shown in Figures 5(A) and 5(B), the nano-silver modified MOF nickel foam substrate is relatively stable within 20 days. Over time, the SERS intensity of R6G begins to decrease significantly after 20 days. Notably, even with a storage time of 40 days, the decrease in SERS intensity remains within 10%, basically meeting the testing requirements. These results demonstrate that the nano-silver modified MOF nickel foam substrate exhibits excellent time stability.

[0114] Application example:

[0115] This application example demonstrates the use of nano-silver modified MOF foam nickel substrate as a sensing electrode for tetracycline detection. The method specifically includes the following steps:

[0116] Step 1: Establish the relationship between Raman intensity and tetracycline concentration;

[0117] The nano-silver modified MOF nickel foam substrates prepared in the examples were immersed in a series of tetracycline standard solutions, and Raman spectroscopy was performed to measure a value of 1313 cm⁻¹. -1The Raman intensity at 1313 cm⁻¹ is determined by the logarithm of the molar concentration of the tetracycline standard solution and the value at 1313 cm⁻¹. -1 A scatter plot of the Raman intensity at the specified location is shown in Figure 6(B). A linear equation was obtained after linear fitting, showing the relationship between the Raman intensity and the logarithm of the tetracycline concentration, as shown in Equation IV:

[0118] y = 365.21x + 3827.39 (Equation IV)

[0119] In the formula:

[0120] y represents the tetracycline standard solution at 1313 cm⁻¹ -1 Raman intensity at the location;

[0121] x represents the logarithm of the molar concentration of the tetracycline standard solution.

[0122] In this application example, the molar concentration of the tetracycline standard solution is 10. -3 mol L -1 10 -4 mol L -1 10 -5 molL -1 10 -6 mol L -1 10 -7 mol L -1 10 -8 mol L -1 10 -9 mol L -1 10 -10 mol L -1 10 -11 mol L -1 and 10 -12 molL -1 The conditions for Raman spectroscopy scanning were: an excitation wavelength of 785 nm and an excitation time of 10 s.

[0123] In this application example, as shown in Figure 6(A), the Raman characteristic peaks of tetracycline are at 520, 707, 1067, 1129, 1266, 1313, 1442, 1586, and 1620 cm⁻¹. -1 The Raman characteristic peaks of tetracycline appear at the displacement point. These peaks can be divided into two intervals: 1319–1655 cm⁻¹. -1 This corresponds to some high-intensity vibrations, including CO bond vibrations and NH2 shear vibrations (1655 cm⁻¹). -1 Symmetrical stretching of CC, bending vibration of COH (1623cm) -1 ), NH2 at 1555cm -1Shear vibration at 1453 cm⁻¹, CO₂ bending vibration, CH₄ at 1453 cm⁻¹ -1 The rocking vibration and CH at 1316cm -1 The swaying vibration.

[0124] The second region of tetracycline exhibits lower Raman intensity, including cyclic respiration of the benzene ring, with CC and CO at 1288 cm⁻¹. -1 The stretching, CH at 1174cm -1 rocking vibration, CC tensile vibration and CH at 1139cm -1 The rocking vibration, ring deformation of the benzene ring, and CH appear at 944 cm⁻¹ -1 The oscillating vibration at the location, while tetracycline at 710 cm -1 The Raman peaks correspond to the cyclic breathing of the benzene ring and the CH3 rocking vibration. Furthermore, peaks of 1623, 1174, 944, and 710 cm⁻¹ were observed in the Raman peaks of tetracycline. -1 The shift of several spectral bands is because the aromatic ring includes amide and secondary amine groups, which are the most hydrophilic and polar positions in the molecule and are spatially separated from the hydrophobic positions.

[0125] In this application example, as shown in Figure 6(C), at low concentrations, the logarithm of the molar concentration of tetracycline is linearly correlated with its Raman intensity, with a linear range of 10. -5 ~10 -10 mol L -1 The squared correlation coefficient of the linear equation is 0.991, indicating a high degree of agreement between the linear equations. The detection limit is 10. -11 mol L -1 The levels are far below the minimum detection limit required by the state, indicating that the nano-silver modified MOF foam nickel substrate has high sensitivity for tetracycline detection and has a great advantage in detecting tetracycline residues in food, effectively achieving trace detection of tetracycline.

[0126] Step two, conduct the test;

[0127] The nano-silver modified MOF nickel foam substrate prepared in the example was immersed in the sample to be tested, and Raman spectroscopy was performed to measure a depth of 1313 cm⁻¹. -1 The Raman intensity at the point is used to calculate and obtain the molar concentration of tetracycline in the sample by substituting the Raman intensity of the sample into Equation IV in step two.

[0128] In this application example, the samples to be tested are tap water, lake water, and milk. Tetracycline at different molar concentrations was added to the samples. The molar concentration of tetracycline added to the tap water sample was 10. -5 mol L -1The additional tetracycline molar concentration added to the lake water sample was 10. -7 mol L -1 The additional tetracycline molar concentration added to the milk sample was 10. -9 mol L -1 Because the sample to be tested may not contain tetracycline, it is added to ensure that tetracycline can be detected. However, in actual testing, it is not necessary to add tetracycline.

[0129] In this application example, the sample to be tested was subjected to three independent tests, and the average value was taken as the final result. The test results showed that the recovery rate of tetracycline in the sample solution was between 80% and 120%, and the relative standard deviation was less than 7%, indicating that the detection accuracy was very high.

Claims

1. An application of a nano-silver modified MOF foam nickel substrate in tetracycline detection, characterized in that, The method used in this application includes the following steps: Step 1: Establish the relationship between Raman intensity and tetracycline concentration; The nano-silver modified MOF nickel foam substrate was immersed in a series of tetracycline standard solutions, and Raman spectroscopy was performed to measure a value of 1313 cm⁻¹. -1 The Raman intensity at 1313 cm⁻¹ is determined by the logarithm of the molar concentration of the tetracycline standard solution and the relationship between 1313 cm⁻¹. -1 A scatter plot of the Raman intensity at the specified location was generated. After linear fitting, a linear equation was obtained between the Raman intensity and the logarithm of the tetracycline concentration, as shown in Equation IV: Equation IV: y = 365.21x + 3827.39 In the formula: y represents the tetracycline standard solution at 1313 cm⁻¹ -1 Raman intensity at the location; x represents the logarithm of the molar concentration of the tetracycline standard solution; Step two, conduct the test; A nano-silver modified MOF foam nickel substrate was immersed in the sample to be tested, and the Raman spectrum was measured at 1313 cm⁻¹. -1 The Raman intensity at the point is used to calculate and obtain the molar concentration of tetracycline in the sample by substituting the Raman intensity of the sample into Equation IV. The nano-silver modified MOF foam nickel substrate was prepared by the following method: using an electrochemical deposition method, cobalt-nickel precursor and nano-silver were sequentially modified onto pretreated foam nickel to obtain the nano-silver modified MOF foam nickel substrate. The method specifically includes the following steps: Step 1: Perform preprocessing; The nickel foam was pretreated by sequentially using dilute hydrochloric acid, anhydrous ethanol and deionized water, and then the surface of the nickel foam was cleaned to obtain pretreated nickel foam. Step 2, prepare cobalt-nickel precursor; Cobalt nitrate, nickel nitrate, and HmIM were added to an aqueous methanol solution and mixed thoroughly to obtain a cobalt-nickel precursor. Step 3: Prepare MOF foam nickel substrate; Using the pretreated nickel foam obtained in step one as the working electrode, a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and the cobalt-nickel precursor obtained in step two as the electrolyte solution for electrochemical deposition, a first electrochemical deposition was performed to obtain a MOF nickel foam substrate. The conditions for the first electrochemical deposition were: deposition voltage of -0.3 to -1.0 V and deposition time of 200 to 500 s. Step 4: Perform nano-silver modification; Using the MOF nickel foam substrate obtained in step three as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode, a second electrochemical deposition was performed in a silver nitrate solution to obtain a nano-silver modified MOF nickel foam substrate. The conditions for the second electrochemical deposition were: deposition voltage of -0.1 to -0.3 V and deposition time of 5 to 15 min.

2. The application as described in claim 1, characterized in that, In step two, the conditions for Raman spectroscopy scanning are: an excitation wavelength of 785 nm and an excitation time of 10 s.

3. The application as described in claim 1, characterized in that, In step 2, the mass fraction ratio of methanol to water in the methanol-water solution is 19:

1.

4. The application as described in claim 1, characterized in that, In step 2, the molar ratio of cobalt nitrate, nickel nitrate, and HmIM in the cobalt-nickel precursor is 1:1:

8.

5. The application as described in claim 1, characterized in that, In step 4, the molar concentration of the silver nitrate solution is 0.05 mol / L. -1 .

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