An amidoxime hydrotalcite-sb2o3 composite material, a preparation method and application thereof

Abstract

The application discloses a kind of amidoxime hydroslate-antimony alkene composite material and its preparation method and application, by first on the surface of hydroslate modification amino group, then using amino group graft modification cyano group, the cyano group is converted into hydroxamic acid group by amidoxime reaction, obtain amidoxime hydroslate;The amidoxime hydroslate dispersion is formed by dispersion, then with antimony alkene dispersion liquid is mixed and is mutually stacked to form two-dimensional layered composite material, by centrifugation, dry obtain.This composite material can effectively inhibit the agglomeration of antimony alkene and hydroslate nanosheet, and can increase the active site of material and uranium ion combination, be applied to the electrochemical detection of uranium ion, with high conductivity, high stability of antimony alkene, and high specificity adsorption of hydroslate.

Description

Technical Field

[0001] The present invention relates to an amidoximated hydrotalcite-antimonene composite material and a preparation method and application thereof, and in particular to an amidoximated hydrotalcite-antimonene composite material used as a modified electrode and a preparation method thereof, belonging to the technical field of composite material preparation. Background Art

[0002] In today's society, nuclear energy, as a vital form of energy, occupies a significant position in the global energy supply. However, the operation of the nuclear industry is accompanied by the generation of large quantities of uranium-containing wastewater. The uranium in this wastewater, due to its high chemical toxicity and long-lived radioactivity, poses a potential threat to the environment and human health. The World Health Organization has set a strict standard for uranium concentration in drinking water, not exceeding 30 μg / L. This requires effective and real-time methods for trace uranium detection.

[0003] Traditionally, fluorescence, atomic absorption spectrometry, and inductively coupled plasma mass spectrometry have been used to detect uranium content in water. These methods offer high sensitivity and good detection limits. However, these methods rely on expensive equipment and cumbersome sample pretreatment steps, making them unsuitable for rapid on-site testing.

[0004] In this context, electrochemical methods have become a highly promising alternative due to their ease of operation, low cost, and good selectivity, and are particularly suitable for rapid on-site screening. Electrode modification is a key strategy to improve the performance of electrochemical sensors, and the application of new high-performance materials has become a research focus. For example, antimonene, an emerging nitrogen-based two-dimensional material, exhibits excellent electrocatalytic performance and high electron transfer efficiency due to its unique wrinkled honeycomb atomic structure and large specific surface area, and has shown broad application prospects in many fields, such as energy storage and biomedicine. Despite this, the surface of antimonene lacks adsorption sites that specifically recognize uranyl ions, which limits its application as a probe material in uranyl ion detection.

[0005] Layered double hydroxides (LDHs, also known as hydrotalcite, have a general chemical formula of [M 2+ 1-x M 3+ x (OH - )2] x+ (A n- ) x / n mH2O, where M 2+ is a divalent metal cation, M 3+ is a trivalent metal cation, A n-Hydrotalcite (HT) is a kind of two-dimensional structural material, which has been widely used in the field of adsorption due to its low cost, high chemical stability and easy modification. The amidoxime group has high chelation affinity for uranium and is one of the groups that are currently recognized as having excellent selectivity for uranium. It is a feasible scheme to modify hydrotalcite with amidoxime for the detection of uranyl ions. However, the amidoxime-modified hydrotalcite material still has the problems of layer stacking and aggregation, which leads to a decrease in active sites, and relatively low electrical conductivity, which affects electron transfer. These factors to some extent restrict the in-depth development of the material in the field of electrochemical sensors.

[0006] Therefore, it is a technical problem to be solved to seek new strategies to combine these superior materials, solve the limitations of existing methods, and develop a uranyl ion sensor with high sensitivity, selectivity and adaptability for rapid on-site detection. SUMMARY

[0007] In view of the technical problems existing in the prior art, a first object of the present application is to provide an amidoxime-modified hydrotalcite-antimonene composite material. The material uses the amidoxime group, which has high chelation affinity for uranium, as a modification group of hydrotalcite to improve the selective adsorption performance of the material. At the same time, the hydrotalcite is loaded on an antimonene substrate with high electrical conductivity, which can effectively inhibit the aggregation of antimonene and hydrotalcite nanosheets, and increase the active sites of the material combined with uranyl ions. The composite material has high electrical conductivity, high stability of antimonene, and high specific adsorption of amidoxime-modified hydrotalcite.

[0008] A second object of the present application is to provide a preparation method of the amidoxime-modified hydrotalcite-antimonene composite material. The method has the advantages of low cost, simple operation and easy scaling.

[0009] A third object of the present application is to provide an application of the amidoxime-modified hydrotalcite-antimonene composite material. The material is used as a modified electrode for the electrochemical detection of uranyl ions, which has the advantages of high sensitivity, high selectivity, simple and rapid operation, low cost and rapid and simple detection, and is suitable for on-site rapid detection.

[0010] In order to achieve the above technical purposes, the present application provides a preparation method of an amidoxime-modified hydrotalcite-antimonene composite material. The method is to modify the surface of hydrotalcite with amino groups, and then graft and modify the amino groups with cyano groups. The cyano groups are converted into hydroxamic acid groups through amidoxime reaction to obtain amidoxime-modified hydrotalcite. The amidoxime-modified hydrotalcite is dispersed to form a colloidal dispersion liquid, and then mixed with an antimonene dispersion liquid to form a two-dimensional layered composite material. After centrifugation and drying, the composite material is obtained.

[0011] The key of the technical scheme of the present application is to use the amidoxime group with high chelation affinity to uranium as a modification group of hydrotalcite to improve the selective adsorption performance of the material, and the specific modification process is to first aminoize the hydrotalcite, then cyanate and aminoxime to obtain the amidoxime hydrotalcite; the principle of the amidoxime modification is to graft the amino group through the dehydration condensation reaction of the hydroxyl group on the surface of the hydrotalcite and the hydrolyzed silane coupling agent, then use glutaraldehyde as a crosslinking agent, the aldehyde group at one end of the glutaraldehyde reacts with the primary amine group on the surface of the hydrotalcite to graft on the surface of the hydrotalcite, the aldehyde group at the other end reacts with the primary amine group of 2,3-diamino-2-butenedinitrile to introduce the cyano group, and finally the cyano group reacts with hydroxylamine hydrochloride to obtain the amidoxime hydrotalcite. Then the few-layer antimonene solution and the hydrotalcite colloidal solution are uniformly mixed and subjected to stirring treatment, so that the antimonene and the hydrotalcite nanosheet are mutually stacked to form a two-dimensional layered composite material, which greatly increases the active sites of the composite material, and at the same time, the hydrotalcite is loaded on the antimonene substrate with high conductivity through the self-assembly of the two, which can effectively inhibit the agglomeration of the antimonene and the hydrotalcite nanosheet, and increase the active sites of the material combined with the uranyl ion, so that the composite material has high conductivity, high stability of the antimonene and high specificity adsorption of the hydrotalcite.

[0012] As a preferred scheme, the amino group on the surface of the hydrotalcite is modified by hydrolysis of the amino silane coupling agent, and the commonly used amino silane coupling agent is KH-550.

[0013] As a preferred scheme, the cyano group is grafted and modified by using glutaraldehyde to crosslink 2,3-diamino-2-butenedinitrile through an amine aldehyde condensation reaction.

[0014] As a preferred scheme, the amidoxime reaction is carried out by adding anhydrous sodium carbonate to adjust the pH of the system and in an ethanol aqueous solution.

[0015] As a preferred scheme, the preparation method of the amidoxime hydrotalcite material in the present application is as follows: after the amino group is grafted and modified on the hydrotalcite, an amino-modified hydrotalcite material is obtained; after the aldehyde group is grafted and modified on the amino-modified hydrotalcite material and glutaraldehyde, an aldehyde-modified hydrotalcite material is obtained; the aldehyde-modified hydrotalcite material is subjected to a condensation reaction with 2,3-diamino-2-butenedinitrile to obtain a cyanated modified hydrotalcite material; and the cyanated modified hydrotalcite material is subjected to an amidoxime reaction with hydroxylamine hydrochloride.

[0016] As a preferred scheme, the solid-liquid ratio of the hydrotalcite and the amino silane coupling agent is (0.25-2.5) g:(1-10) mL; the reaction condition for grafting modification of the amino group is that the temperature is 40-100 DEG C, and the time is 6-24 h; the solid-liquid ratio of the amino-modified hydrotalcite material and glutaraldehyde is (0.5-5) g:(1-20) mL; the reaction condition for grafting modification of the aldehyde group is that the temperature is 20-100 DEG C, and the time is 2-12 h, the mass ratio of the aldehyde-modified hydrotalcite material and 2,3-diamino-2-butene dicyanide is (0.1-2):(0.5-4); the condensation reaction condition is that the temperature is 20-80 DEG C, and the time is 2-12 h. The mass ratio of the cyan-modified hydrotalcite material and hydroxylamine hydrochloride is (0.1-1):(0.2-2); the reaction condition of the amidoxime is that the temperature is 60-100 DEG C, and the time is 6-24 h.

[0017] As a preferred scheme, the degree of amidoximation of the hydrotalcite (i.e. the ratio of the number of amidoxime groups to the number of atoms of the hydrotalcite substrate) is 0.1-20 at.%, and is further preferably 1-10 at.%. If the degree of amidoximation of the hydrotalcite is too low, the selective adsorption capacity of the uranium ion is not enough, and the ideal detection effect cannot be achieved; if the degree of amidoximation is too high, the amidoxime group may react with other substances in the environment, thereby generating an additional electrochemical signal and interfering with the detection of the target substance.

[0018] As a preferred scheme, the size of the hydrotalcite is 0.3-3 μm, and the shape is at least one of a sheet, a rod and a sphere. The adsorption performance of the hydrotalcite in the selected range of the present application is excellent, and is further preferably 0.5-1 μm in size and a sheet in shape.

[0019] As a preferred scheme, the structural general formula of the hydrotalcite substrate is [M 2+ 1-x M 3+ x (OH - )2] x+ (A n- ) x / n ·mH2O; wherein, M 2+ and M 3+ are in a ratio of (2-5):1; M 2+ includes at least one of Mg 2+ , Ni 2+ and Zn 2+ ; M 3+ includes at least one of Al 3+ and Fe 3+ ; A n- includes CO3 2-, NO 3- and at least one of C1 - Further preferably, the hydrotalcite substrate is nickel-aluminum hydrotalcite (chemical formula Ni 0.75 Al 0.25 (OH)2(NO3) 0.25 , and the element ratio of M 2+ to M 3+ is 3:1. Compared with other types of hydrotalcite, nickel-aluminum hydrotalcite has low preparation cost, is easy to obtain, has high surface adsorption capacity and reaction activity, is conducive to the preparation of the composite material, and enhances the ability of the composite material to enrich uranyl ions.

[0020] As a preferred solution, the mass ratio of the amidoxime hydrotalcite colloidal dispersion solution to the antimonene dispersion solution is (1-4):1.

[0021] As a preferred solution, the concentration of the amidoxime hydrotalcite colloidal dispersion solution is 1-10 g / L; further preferably, 1-2 g / L.

[0022] The concentration and mass ratio of the amidoxime hydrotalcite colloidal dispersion solution to the antimonene dispersion solution in the present application will significantly affect the number of amidoxime hydrotalcite nanosheets. If the concentration and volume of the amidoxime hydrotalcite nanosheets are too high, excessive agglomeration and stacking will occur, thereby reducing the active sites of the composite material and affecting the detection effect.

[0023] As a preferred solution, the concentration of the antimonene dispersion solution is 0.5-5 g / L, wherein the purity of the antimonene is ≥95 wt.%, the thickness is one to one hundred atomic layers, and the lateral size is ≥10 nm. Further preferably, the concentration of the antimonene dispersion solution is 0.5-1 g / L, the purity of the antimonene is ≥99 wt.%, the thickness is one to twenty atomic layers, and the lateral size is ≥100 nm. If the thickness of the antimonene is too large, the specific surface area will be reduced, thereby reducing the efficiency of the composite with the hydrotalcite. Meanwhile, the increase in the thickness hinders the charge transport within the composite material, which is not conducive to the sensitivity of the composite material as an electrochemical sensing probe.

[0024] As a preferred solution, at least one of water, ethanol, methanol, N,N-dimethylformamide, dimethyl sulfoxide, and N-methyl pyrrolidone is used as the dispersion solution for the amidoxime hydrotalcite colloidal dispersion solution, and the purity of the reagent is experimental purity or above. In the present application, the amidoxime hydrotalcite is added to the selected dispersion solution, and a stable dispersion is formed after stirring, thereby reducing the stacking of the hydrotalcite nanosheets. Further preferably, the dispersion solution is at least one of anhydrous ethanol, N,N-dimethylformamide, and N-methyl pyrrolidone, and the purity of the reagent is analytical purity.

[0025] As a preferred solution, the mixing time is 1-12 h. The amidoxime-hydrotalcite and antenae can be fully stacked on each other within the selected mixing time of the present application, and the mixing time is further preferably 1-2 h.

[0026] The present application also provides an amidoxime-hydrotalcite-antenae composite material obtained by the above preparation method. The composite material has high conductivity and stability of antenae and high specific adsorption of amidoxime-hydrotalcite.

[0027] The present application also provides an application of the amidoxime-hydrotalcite-antenae composite material as a modified electrode for electrochemical detection of uranyl ions. The present application uses the amidoxime-hydrotalcite-antenae composite material as a probe material to modify the working electrode surface of an electrochemical sensor, and uses the high conductivity and stability of antenae, the high specific adsorption of amidoxime-hydrotalcite, and the layered structure formed by the amidoxime-hydrotalcite and antenae to obtain a method for electrochemical detection of uranyl ions with high sensitivity, high selectivity, and simple and rapid operation. The method is low in cost, simple and rapid, and suitable for on-site rapid detection.

[0028] As a preferred solution, the preparation process of the modified electrode is as follows: mixing the amidoxime-hydrotalcite-antenae composite material with a binder to obtain a uniform and stable suspension. An appropriate working electrode is selected and polished, and then the suspension is coated on the surface of the polished working electrode to form a uniform suspension film. The coated working electrode is dried in an oven, and the amidoxime-hydrotalcite-antenae composite material is fixed on the electrode surface by the binder to obtain an amidoxime-hydrotalcite-antenae composite material modified working electrode.

[0029] As a preferred solution, the binder includes but is not limited to Nafion, polyvinylidene fluoride, polyacrylic acid, polyvinyl alcohol, polytetrafluoroethylene, carboxymethyl cellulose, chitosan, sodium alginate, β-cyclodextrin, and other oil-based or water-based binders suitable for the amidoxime-hydrotalcite-antenae, with a content of 1-20 wt.%. Further preferably, the liquid binder is an oil-based or water-based binder with a content of 3-10 wt.% of Nafion, polyvinylidene fluoride, polyacrylic acid, and polyvinyl alcohol.

[0030] As a preferred scheme, the electrochemical detection condition is that the pH is 2-4 and the enrichment time is 2-10 min. At a lower pH, a large number of positively charged hydrogen ions will compete with the uranium ions for adsorption, occupy the active sites on the surface of the composite material, hinder the complexation of the composite material to the uranium ions, and reduce the detection performance of the composite material; with the increase of the pH value, the content of hydrogen ions in the solution is relatively reduced, and the U(VI) ions also exist in the form of uranium ions, so that the adsorption performance is increased; and when the pH is too high, the species distribution of the U(VI) ions is gradually changed into a form mainly composed of other complexes, and the content of the uranium ions is greatly reduced, thereby reducing the adsorption of the composite material to the U(VI) ions.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1) The present application provides an amidoxime-modified hydrotalcite-antimonene composite material, which uses the amidoxime group with high chelation affinity to uranium as a modification group of hydrotalcite to improve the selective adsorption performance of the material, and simultaneously loads the hydrotalcite on an antimonene substrate with high conductivity, which can effectively inhibit the agglomeration of the antimonene and the hydrotalcite nanosheet, and increase the active sites for the combination of the material and the uranium ions, so that the composite material has high conductivity, high stability of the antimonene, and high specific adsorption of the hydrotalcite.

[0033] 2) The amidoxime-modified hydrotalcite-antimonene composite material of the present application can be modified on the working electrode surface of an electrochemical sensor as a probe material, and through the synergistic use of the high conductivity and high stability of the antimonene and the high specific adsorption of the amidoxime-modified hydrotalcite, a method for electrochemically detecting uranium ions with high sensitivity, high selectivity and simple and rapid operation is obtained, the method is low in cost, simple and rapid, and is suitable for on-site rapid detection. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a preparation process diagram of the amidoxime-modified hydrotalcite-antimonene composite material and the preparation of the modified electrode.

[0035] Figure 2 is a schematic diagram of the atomic structure model of the amidoxime-modified hydrotalcite-antimonene composite material.

[0036] Figure 3 is an X-ray diffraction (XRD) spectrum of the amidoxime-modified nickel-aluminum hydrotalcite (AO-NiAl-LDHs), antimonene and the amidoxime-modified nickel-aluminum hydrotalcite-antimonene composite material (AO-NiAl-LDHs / antimonene) with a mass ratio of 2:1, 3:1 and 4:1 in Example 1.

[0037] Figure 4are SEM pictures of the amidoxime-modified nickel-aluminum hydrotalcite-antimony phthalocyanine composite materials in Example 1 and Comparative Example 1, wherein Figure 4 (a) is the mass ratio of AO-NiAl-LDHs to antimony phthalocyanine of 2:1; Figure 4 (b) is the mass ratio of 5:1.

[0038] Figure 5 are CV diagrams of different modified electrodes in Example 1 (mass ratio of 2:1), Comparative Example 2 and Comparative Example 3 in 0.1 M KCl solution containing 5 mM [Fe(CN)6] 3- / 4- .

[0039] Figure 6 are EIS diagrams of different modified electrodes in Example 1 (mass ratio of 2:1), Comparative Example 2 and Comparative Example 3 in 0.1 M KCl solution containing 5 mM [Fe(CN)6] 3- / 4- .

[0040] Figure 7 are differential pulse voltammetry (DPV) diagrams of the detection of uranyl ions in different pH solutions in Example 1 (mass ratio of 2:1) and Comparative Example 4.

[0041] Figure 8 are differential pulse voltammetry (DPV) diagrams of the detection of uranyl ions in different enrichment times in Example 1 (mass ratio of 2:1). DETAILED DESCRIPTION

[0042] In order to further illustrate the present application, the following detailed description of the present application is made in conjunction with the examples, but it should be understood that these examples are implemented on the premise of the technical solutions of the present application, and detailed implementation manners and specific operation processes are given, which are only for further illustrating the features and advantages of the present application, and are not a limitation on the claims of the present application, and the protection scope of the present application is not limited to the following examples.

[0043] The preparation of the composite material of the present application and the manufacturing process diagram of the modified electrode thereof are shown in Figure 1 , and the schematic diagram of the atomic structure model of the composite material is shown in Figure 2 .

[0044] The preparation process of the amidoxime-modified nickel-aluminum hydrotalcite used in the examples and comparative examples of the present application is as follows:

[0045] Ni(NO3)2, 0.005 mol Al(NO3)3, 0.04 mol NaOH and 0.01 mol NaNO3 were added into 100 mL of deionized water, and after stirring at room temperature for 1 h, the solution was transferred into a 100 mL reaction kettle with a polytetrafluoroethylene liner, and reacted at 100°C for 24 h. After the reaction was completed, the reaction kettle was cooled to room temperature, and the precipitate was collected by centrifugation, washed with deionized water until neutral, and then dried at 60°C for 12 h to obtain a nickel-aluminum hydrotalcite (NiAl-LDHs) powder.

[0046] 0.5 g of NiAl-LDHs and 5 mL of KH-550 silane coupling agent were weighed into 50 mL of anhydrous ethanol, and stirred at 80°C for 12 h. The solid product obtained by the reaction was washed with anhydrous ethanol and deionized water three times, respectively, and the centrifugal precipitate was placed in a 60°C drying oven for 12 h to obtain amino-modified nickel-aluminum hydrotalcite (NH2-NiAl-LDHs). 0.5 g of NH2-NiAl-LDHs and 1 mL of glutaraldehyde (12%) were added into 100 mL of anhydrous ethanol, and stirred at room temperature for 3 h. The solid product after the reaction was washed with anhydrous ethanol by centrifugation three times, and the precipitate was placed in a 60°C drying oven for 12 h to obtain aldehyde-modified nickel-aluminum hydrotalcite (CHO-NiAl-LDHs).

[0047] 0.5 g of CHO-NiAl-LDHs and 0.5 g of 2,3-diamino-2-butenedinitrile were weighed into 100 mL of anhydrous ethanol, and stirred at room temperature for 3 h. The solid product after the reaction was washed with anhydrous ethanol by centrifugation three times, and dried at 60°C for 12 h to obtain cyano-modified nickel-aluminum hydrotalcite (CN-NiAl-LDHs).

[0048] 0.5 g of NH2OH·HCl was dissolved in 100 mL of an ethanol aqueous solution (V 乙醇 :V 水 = 9:1), and the pH value of the solution was adjusted to 7.0 by adding anhydrous sodium carbonate. Then, 0.25 g of CN-NiAl-LDHs was added, and the mixture was stirred at 80°C for 6 h to allow the cyano group to completely undergo amidoxime reaction. The suspension after the reaction was washed with anhydrous ethanol and deionized water by centrifugation until the supernatant was neutral, and the precipitate was placed in a 60°C drying oven for 12 h to obtain AO-NiAl-LDHs powder.

[0049] Example 1

[0050] 1) Preparation of amidoxime nickel-aluminum hydrotalcite-antimony olefin

[0051] According to the mass ratio of AO-NiAl-LDHs to antimony olefin of 2:1, 3:1 and 4:1, 50 mg, 75 mg and 100 mg of amidoxime nickel-aluminum hydrotalcite (chemical formula Ni 0.75Al 0.25 (OH)2(NO3) 0.25 , the degree of amine oxime is 5.0 at.%, the size is 0.5 pm, and the shape is flaky) were added into 50 mL of anhydrous ethanol respectively, and after stirring for 1 h, stable dispersions were formed. Meanwhile, 25 mg of antimonene powder was re-dispersed in 25 mL of anhydrous ethanol by ultrasonic treatment for 30 min to obtain an antimonene dispersion (in which the purity of antimonene was 99%, the thickness was from a monolayer to 30 atomic layers, and the lateral size was 300 nm to 1 pm). Then, the two were uniformly mixed, and the antimonene and hydrotalcite nanosheets were allowed to stack on each other by Van der Waals force by stirring for 12 h. Finally, centrifugal treatment was performed at a speed of 10,000 rpm / min for 20 min, and the centrifugal precipitate was placed at 60 °C for drying for 12 h to obtain a powder of amine oxime nickel-aluminum hydrotalcite-antimonene composite material.

[0052] The amine oxime nickel-aluminum hydrotalcite-antimonene composite material was characterized by XRD, Figure 3 The X-ray diffraction patterns of amine oxime nickel-aluminum hydrotalcite (AO-NiAl-LDHs), antimonene, and amine oxime nickel-aluminum hydrotalcite-antimonene (AO-NiAl-LDHs / antimonene) are shown. The XRD pattern of AO-NiAl-LDHs has the classic characteristic peaks of the (003), (006), (009), (110), and (113) crystal planes of hydrotalcite material at 2q of 11.60°, 23.13°, 35.06°, 61.09°, and 62.33°; the XRD pattern of antimonene shows characteristic diffraction peaks at 2q of 23.71°, 28.73°, 40.11°, 41.97°, and 51.63°, corresponding to the (003), (012), (104), (110), (202) crystal planes of antimonene nanosheets, which match the PDF standard card of bulk Sb (PDF # 35-0732). The XRD patterns of AO-NiAl-LDHs / antimonene composite materials with different mass ratios all have the typical characteristic peaks of hydrotalcite and antimonene, indicating that the antimonene and hydrotalcite nanosheets are stacked on each other by Van der Waals force to form a layered structure, and the composite material is successfully prepared.

[0053] Figure 4 (a) is the SEM image of amine oxime nickel-aluminum hydrotalcite-antimonene composite material with a mass ratio of amine oxime nickel-aluminum hydrotalcite to antimonene of 2:1, and it can be seen that the hydrotalcite material is relatively uniformly distributed on the surface of antimonene. For the composite materials obtained with mass ratios of amine oxime nickel-aluminum hydrotalcite to antimonene of 3:1 and 4:1, the number of hydrotalcite nanosheets increases slightly, but part of the agglomeration also occurs, so there is no obvious difference in the detection performance of the three ratios of composite materials.

[0054] 2) Electrode preparation

[0055] The electrode surface was polished with 0.05, 0.3 and 1.0 μm alumina powder, respectively, and then placed in nitric acid (50%), anhydrous ethanol and deionized water for 60 seconds in sequence, and finally dried with nitrogen.

[0056] Weigh 5 mg of the amidoximated hydrotalcite-antimonene composite powder prepared in Example 1 (the mass ratio of amidoximated hydrotalcite to antimonene is 2:1) into 5 mL of anhydrous ethanol solution, add 50 μL of Nafion solution and mix well to obtain a 1 mg / mL amidoximated hydrotalcite-antimonene solution. Take 10 μL of the 1 mg / mL amidoximated hydrotalcite-antimonene solution and evenly drop-coat it on the surface of the glassy carbon electrode. Dry it at 40°C for 12 h to obtain the modified working electrode (AO-NiAl-LDHs / antimonene / GCE).

[0057] Comparative Example 1

[0058] The only difference between this comparative example and Example 1 is that the mass ratio of amidoxime nickel aluminum hydrotalcite to antimonene is 5:1. The other steps and conditions are the same to obtain AO-NiAl-LDHs / antimonene composite material, the SEM image of which is shown in FIG. Figure 4 (b) Compared with Figure 4 (a) At this time, the addition of excessive AO-NiAl-LDHs nanosheets causes more agglomeration and stacking of AO-NiAl-LDHs on the surface of antimonene, which to some extent affects the generation of active sites of the composite material and the electrochemical detection performance of the modified electrode.

[0059] Comparative Example 2

[0060] The only difference between this comparative example and Example 1 is that no antimonene solution is added, and the remaining steps and conditions are the same to obtain an AO-NiAl-LDHs modified glassy carbon electrode (AO-NiAl-LDHs / GCE).

[0061] Comparative Example 3

[0062] The only difference between this comparative example and Example 1 is that AO-NiAl-LDHs is not added, and the remaining steps and conditions are the same to obtain an antimonene-modified glassy carbon electrode (antimonene / GCE).

[0063] Comparative Example 4

[0064] The comparative example is different from example 1 only in that AO-NiAl-LDHs is replaced by NiAl-LDHs, and the rest of the steps and conditions are consistent, to obtain a NiAl-LDHs / antimonene modified glassy carbon electrode (NiAl-LDHs / antimonene / GCE).

[0065] Application test example 1

[0066] The materials of example 1 (mass ratio of 2:1), comparative example 2, comparative example 3 and comparative example 4 were respectively taken as the working electrode, Ag / AgCl was taken as the reference electrode, and platinum wire was taken as the auxiliary electrode, and the three together constituted a three-electrode system, and an electrochemical workstation of Shanghai Chenhua CHI660D type was used for electrochemical test.

[0067] In a solution containing 5.0 mM [Fe(CN)6] 3- / 4- and 0.1 M KCl, electrochemical characterization was carried out by cyclic voltammetry (CV), and the CV parameters were as follows: the scanning rate was 0.1 V / s, the high potential was 0.8 V, the low potential was -0.3 V, the sampling interval was 0.001 V, the duration was 2 s, and the sensitivity was 1×10 -4 A / V. As shown in Figure 5 , a pair of symmetrical redox peaks appeared in the cyclic voltammograms of all modified electrodes. When AO-NiAl-LDHs and antimonene were respectively modified on the glassy carbon electrode, the peak current corresponding to AO-NiAl-LDHs was significantly smaller than that of antimonene. The reason is that, compared with antimonene, the conductivity and charge transfer ability of the hydrotalcite material itself are poor, which hinders the redox reaction of [Fe(CN)6] 3- / 4- . When AO-NiAl-LDHs / antimonene was modified on the glassy carbon electrode, the peak current was significantly increased compared with the former two, indicating that antimonene and hydrotalcite nanosheets combined to form a layered structure stacked on each other, reducing the agglomeration of the two materials, which is conducive to the charge transfer on the material surface and the redox reaction of [Fe(CN)6] 3- / 4- . These results confirm the successful preparation of the composite material and the completion of the modification of the electrode surface, and also confirm the synergistic effect between the amidoxime nickel aluminum hydrotalcite and antimonene.

[0068] Electrochemical impedance (EIS) test was carried out in a solution containing 5.0 mM [Fe(CN)6] 3- / 4- and 0.1 M KCl, and the EIS parameters were as follows: the frequency range was 0.1 Hz-1000000 Hz, the amplitude was 0.005 V, and the duration was 2 s. The results are shown in Figure 6 . As can be seen from the figure, the electrochemical impedance plots of the modified electrodes all showed a typical semicircle, and the charge transfer resistance (R ct) is equal to the semicircular diameter of the Nyquist plot, which is related to the electrochemical properties of the electrode surface modification material. The R ct values of AO-NiAl-LDHs, antimonene and AO-NiAl-LDHs / antimonene are 3862 Ω, 1081 Ω and 738.8 Ω, respectively. It can be seen from the results that antimonene has better conductivity than hydrotalcite material. After the glassy carbon electrode is modified with the amidoxime hydrotalcite-antimonene composite material, the R ct value is further reduced, showing the best charge transfer ability and conductivity. The results are consistent with the CV method, further confirming the successful preparation of the probe material.

[0069] Application Test Example 2

[0070] 1) Electrochemical detection performance of working electrodes at different pH values

[0071] The modified electrodes of Example 1 (mass ratio of 2:1) and Comparative Example 4 were selected, and then the solutions with a uranyl ion concentration of 0.1 mg / L and pH values of 2.0, 2.3, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 were detected by differential pulse voltammetry (DPV). All electrochemical test experiments were completed in 0.1 M KCl solution, and the parameters of differential pulse voltammetry (DPV) were as follows: potential increment was 4 mV, amplitude was 50 mV, pulse width was 50 ms, sampling width was 16.7 ms, pulse period was 0.2 s, duration was 2 s, and scanning range was -0.8-1.0 V.

[0072] The results are as follows: Figure 7The peak current first increased and then decreased gradually with the increase of pH value. The reason for this phenomenon may be that at lower pH value, a large number of positively charged hydrogen ions will compete with the adsorption of uranyl ions and occupy the active sites on the surface of the material, hindering the complexation of the material to the uranyl ions, and reducing the detection performance of the material. When the pH value is increased to 2.5, the content of hydrogen ions in the solution is relatively reduced, and the U(VI) ions also exist in the form of uranyl ions. Therefore, the peak current reaches a maximum value at this time. However, when the pH value is higher than 3, the species distribution of U(VI) ions gradually changes to other complex forms, and the content of uranyl ions is greatly reduced, which is also not conducive to the adsorption of the material to U(VI) ions, so the peak current also decreases. Therefore, the pH value is further optimized to 2.3-3.0, and the optimal pH value is further determined to be 2.5. At the same time, the experimental results of the electrochemical detection of uranyl ions by the AO-NiAl-LDHs / antimonene / GCE of Example 1 and the NiAl-LDHs / antimonene / GCE of Comparative Example 4 are compared, which shows that the amidoxime group produces a strong adsorption effect in the detection process, thereby increasing the detection performance of the composite material.

[0073] 2) Electrochemical detection performance of working electrodes with different enrichment times

[0074] The modified electrode of Example 1 (mass ratio of 2:1) was selected, and then the peak current of the enrichment time of 0, 1, 2, 3, 4, 5, 6, 8, 10, 12 and 16 min was studied; the concentration of uranyl ions was 0.1 mg / L, and the differential pulse voltammetry (DPV) was used for detection. All electrochemical test experiments were completed in 0.1 M KCl solution, and the parameters of differential pulse voltammetry (DPV) were as follows: potential increment was 4 mV, amplitude was 50 mV, pulse width was 50 ms, sampling width was 16.7 ms, pulse period was 0.2 s, duration was 2 s, and scanning range was -0.8-1.0 V.

[0075] Figure 8 is the relationship curve of peak current and enrichment time. The results show that the peak current gradually increases with the prolongation of the enrichment time, and until 10 min, the active sites on the surface of the material almost reach adsorption saturation, and the current does not increase significantly.

Claims

1. A method for preparing an amidoximated hydrotalcite-antimonene composite material, characterized in that: The hydrotalcite surface is first modified with amino groups, and then the amino groups are used to graft-modify cyano groups. The cyano groups are converted into hydroxamic acid groups through an amidoxime reaction to obtain amidoxime hydrotalcite; the amidoxime hydrotalcite is dispersed to form an amidoxime hydrotalcite colloidal dispersion, which is then mixed with an antimonene dispersion to form a two-dimensional layered composite material, which is then centrifuged and dried to obtain the composite material; The modification of amino groups on the surface of hydrotalcite is achieved by hydrolysis of aminosilane coupling agent; The grafting modification of cyano groups with amino groups is achieved by cross-linking 2,3-diamino-2-butenedinitrile with glutaraldehyde through an amine-aldehyde condensation reaction; The concentration of the antimonene dispersion is 0.5-5 g / L, wherein the purity of the antimonene is ≥95 wt.%, the thickness is from a single atomic layer to a hundred atomic layers, and the lateral size is ≥100 nm.

2. The method for preparing an amidoximated hydrotalcite-antimonene composite material according to claim 1, wherein: The amidoximation degree of the amidoximated hydrotalcite is 0.1 to 20 at.%.

3. The method for preparing an amidoximated hydrotalcite-antimonene composite material according to claim 1 or 2, characterized in that: The mass ratio of the amidoximated hydrotalcite colloidal dispersion to the antimonene dispersion is (1-4):1; The concentration of the amidoximated hydrotalcite colloidal dispersion is 1-10 g / L.

4. The method for preparing the amidoximated hydrotalcite-antimonene composite material according to claim 3, wherein: The amidoximated hydrotalcite colloidal dispersion liquid uses at least one of water, ethanol, methanol, N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone as the dispersion liquid.

5. The method for preparing an amidoximated hydrotalcite-antimonene composite material according to claim 1, wherein: The mixing time is 1 to 12 hours.

6. An amidoximated hydrotalcite-antimonene composite material, characterized in that: Obtained by the preparation method according to any one of claims 1 to 5.

7. The use of the amidoximated hydrotalcite-antimonene composite material according to claim 6, characterized in that: It is used as a modified electrode for the electrochemical detection of uranyl ions.

8. The use of the amidoximated hydrotalcite-antimonene composite material according to claim 7, characterized in that: The conditions for the electrochemical detection are: pH 2-4, and enrichment time 2-10 min.

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