Covalent triazine organic framework-cucurbituril composite material and application thereof

Abstract

The application provides a covalent triazine organic framework-cucurbituril composite material and application thereof, and belongs to the technical field of electrochemical detection of environmental pollutants. The specific steps comprise the following steps: synthesizing a CTF material, combining host-guest interaction of cucurbituril [7], and synthesizing a nano cuprous oxide@cucurbituril [7] / covalent triazine organic framework composite material with a cuprite crystal form through a wet chemical reduction precipitation method. The composite material can be used for modifying a glassy carbon electrode to obtain a high-sensitivity electrochemical sensor. The electrochemical sensor constructed in the application has rapid response, high sensitivity and a wide linear range, and is expected to realize on-site detection of p-nitrophenol in water.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrochemical sensors, and particularly relates to a Cu2O@CB[7] / CTF-F / GCE electrochemical sensor for identifying p-nitrophenol. BACKGROUND

[0002] P-nitrophenol (PNP) is an important industrial raw material for producing pesticides, explosives and dyes, and also causes difficult-to-treat water pollution. Once p-nitrophenol enters the body, it can cause related symptoms of blood, liver and central nervous system, and even cancer. Therefore, based on the toxic properties of p-nitrophenol, its trace detection has become a key research topic in the fields of food, agriculture and environmental chemistry. In recent years, researchers have established various analysis methods to detect p-nitrophenol, such as traditional detection methods of chromatography, electrophoresis, fluorescence, etc. Although these methods have developed to a relatively mature level, due to the disadvantages of complex equipment, time-consuming, expensive and personnel training, it is crucial to establish a simple, inexpensive and reliable qualitative and quantitative analysis system. With the continuous development of detection technology, electrochemical methods have become the most promising technology at present due to their low cost, simple operation, short time consumption and low detection limit.

[0003] With the development of nanomaterials, the application of low-cost and simple-preparation transition metal materials in electrochemical sensors effectively amplifies the electrochemical signal of p-nitrophenol and achieves good detection effect. At present, copper nanomaterials have good catalytic reduction activity for p-nitrophenol. The new covalent triazine organic framework material is a kind of porous carbon material, which can be used as a substrate material for copper-based materials due to its large specific surface area and good electrical conductivity. In addition, cucurbituril [7] has good chemical stability, and the electronegative carbonyl portal at both ends can facilitate the fixation and stabilization of the composite of copper nanomaterials and covalent triazine organic framework. SUMMARY

[0004] The application aims to provide a cuprous oxide@cucurbituril [7] / covalent triazine organic framework composite material and its application.

[0005] The technical solution for achieving the application is as follows:

[0006] The cuprous oxide@cucurbituril [7] / covalent triazine organic framework composite material (Cu2O@CB[7] / CTF) and its preparation method are as follows:

[0007] Step 1, mix the covalent triazine organic framework and potassium hydroxide in ethanol, and after the ethanol is completely evaporated at room temperature, calcine for a period of time;

[0008] Step 2, after cooling, wash the reaction product obtained in step 1 with 1M hydrochloric acid, deionized water and ethanol in sequence, and dry to obtain the modified covalent triazine organic framework;

[0009] Step 3, mixing cucurbituril [7] and modified covalent triazine organic framework in water, stirring, then quickly pouring copper salt solution into it to obtain a mixed solution;

[0010] Step 4, quickly dropping NaOH solution into the mixed solution obtained in step 3, and then slowly dropping NaBH4 solution into it to obtain a suspension;

[0011] Step 5, sealing the suspension obtained in step 4 and heat treating for a period of time, cooling, washing with deionized water and ethanol in sequence, and vacuum drying to obtain the composite material.

[0012] Preferably, the covalent triazine organic framework is prepared by the following steps:

[0013] Mixing and grinding biphenyl-4,4'-dicyanate (DCBP) and ZnCl2 in a certain mass ratio, transferring to a quartz ampoule, sealing after vacuumizing, heating to 400℃ under N2 atmosphere, keeping the temperature for 40h, cooling, soaking the obtained reaction product in 1M dilute hydrochloric acid solution for 24h, washing with deionized water until neutral, washing with ethanol, and drying at 120℃ to obtain the covalent triazine organic framework CTF-F;

[0014] wherein the mass ratio of DCBP to ZnCl2 is 1.0:3.0-4.0; the temperature rising rate is 2℃ / min.

[0015] Preferably, in step 1, the mass ratio of the covalent triazine organic framework to potassium hydroxide is 1:1, the calcination temperature is 700℃, and the calcination time is 5h.

[0016] Preferably, in step 3, the mass ratio of cucurbituril [7], modified covalent triazine organic framework and copper salt is 1:1:1.

[0017] Preferably, in step 4, the concentration of NaOH solution is 0.6M, and the concentration of NaBH4 solution is 1M.

[0018] Preferably, in step 4, the molar ratio of copper salt, NaOH and NaBH4 is 1:6:50.

[0019] Preferably, in step 5, the heat treatment temperature is 60℃, and the time is 24h; the vacuum drying temperature is not higher than 60℃.

[0020] The above cuprous oxide@cucurbituril [7] / covalent triazine organic framework composite material is used in constructing a p-nitrophenol electrochemical sensor.

[0021] Preferably, the composite material is used as an electrode material for measuring p-nitrophenol.

[0022] Compared with the prior art, the application has the beneficial effects that:

[0023] (1) The prepared cucurbituril[7] / covalent triazine organic framework has a good stabilizing effect on copper oxide nanometer.

[0024] (2) The prepared copper oxide@cucurbituril[7] / covalent triazine organic framework composite material has good electrocatalytic reduction performance on p-nitrophenol.

[0025] (3) The prepared Cu2O@CB[7] / CTF / GCE sensor has high sensitivity, fast response and simple use in detection by differential pulse voltammetry. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram for Cu2O@CB[7] / CTF electrochemical detection of p-nitrophenol.

[0027] Figure 2 It is an FTIR spectrum of CTF, CB[7], Cu2O@CB[7], Cu2O@CB[7] / CTF.

[0028] Figure 3 It is a chronoamperometric response curve of CTF / GCE, Cu2O@CB[7] / GCE, Cu2O@CB[7] / CTF / GCE modified electrode at-0.7V.

[0029] Figure 4 It is a DPV detection diagram of Cu2O@CB[7] / CTF / GCE electrochemical sensor in PBS solution (pH 7.0) of different concentrations of p-nitrophenol.

[0030] Figure 5 It is a linear calibration curve of different concentrations of p-nitrophenol and response current under the action of Cu2O@CB[7] / CTF / GCE electrochemical sensor. DETAILED DESCRIPTION

[0031] The embodiment is implemented under the premise of the technical scheme of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0032] In combination Figure 1 , the application synthesizes a cucurbituril[7] functionalized modified covalent triazine organic framework loaded with copper oxide nanoclusters, uses the modified covalent triazine organic framework as a substrate, combines the copper oxide nanoclusters to the surface of the substrate through the electronegativity of the carbonyl portal of cucurbituril[7], forms a stable electrode material, modifies the electrode material on the surface of a glassy carbon electrode, and constructs a p-nitrophenol electrochemical sensor to realize rapid, sensitive and efficient electrochemical detection of p-nitrophenol. The specific process is as follows:

[0033] Step 1, 1.0 g of biphenyl-4,4'-dicyan (DCBP) and 3.4 g of ZnCl2 were mixed and ground, transferred to a quartz ampoule, vacuum sealed, and calcined at 400 DEG C for 40 h.

[0034] Step 2, after cooling, the reaction product obtained in step 1 was fully soaked with 1M hydrochloric acid, washed with deionized water until neutral, and then washed with ethanol, and dried at 120 DEG C to obtain a covalent triazine organic framework CTF-F.

[0035] Step 3, a mixture of CTF-F and potassium hydroxide in a mass ratio of 1:1 was mixed with ethanol, and after the ethanol was completely evaporated at room temperature, the mixture was calcined at 700 DEG C for 4 h.

[0036] Step 4, after cooling, the reaction product obtained in step 3 was sequentially washed with 1M hydrochloric acid, deionized water and ethanol, and dried at 60 DEG C to obtain a modified covalent triazine organic framework CTF.

[0037] Step 5, 125 mg of copper salt was dissolved in 10 mL of water, denoted as solution A, 116.3 mg of cucurbituril [7] and 100 mg of covalent triazine organic framework CTF were mixed and dissolved in 10 mL of water, denoted as solution B, and solution A was quickly poured into solution B to obtain a mixed solution C.

[0038] Step 6, 10 mL of 0.6M NaOH solution was quickly added dropwise to the solution C obtained in step 5 to obtain a suspension D, and then 50 mL of 1M NaBH4 solution was added dropwise to obtain a suspension E.

[0039] Step 7, the suspension E was sealed and placed in an oil bath at 60 DEG C for 24 h.

[0040] Step 8, after cooling, the reaction product obtained in step 7 was sequentially washed with deionized water and ethanol, and dried at 50 DEG C to obtain a cuprous oxide@cucurbituril [7] / covalent triazine organic framework (Cu2O@CB[7] / CTF) composite material.

[0041] The instruments used for performance testing in the present application are: NICOLET IS10 Fourier infrared spectrometer of China Thermo Fisher Scientific Co., Ltd., and CHI 760E electrochemical workstation of Shanghai Chenhua.

[0042] The specific embodiments of the present application will be further described below with reference to the accompanying drawings.

[0043] Example 1: Preparation of Cu2O@CB[7] / CTF composite material

[0044] (I) Preparation and modification of CTF

[0045] (1) 1.0 g of DCBP and 3.4 g of ZnCl2 were mixed and ground uniformly, and the mixture was transferred to a quartz ampoule, which was vacuum sealed.

[0046] (2) The mixture was calcined at 400°C for 40 h, and then cooled. The product was washed with dilute hydrochloric acid and deionized water, and dried at 120°C to obtain CTF-F.

[0047] (3) CTF-F and KOH in a mass ratio of 1:1 were placed in ethanol, and after the ethanol was completely evaporated at room temperature, the mixture was heated in a tube furnace at a rate of 2°C / min to 700°C under an argon gas flow, and reacted for 5 h.

[0048] (4) After cooling, the reactants were washed with 1M hydrochloric acid, deionized water and ethanol in sequence until a neutral mixture was obtained, and finally the sample was dried at 60°C to obtain CTF.

[0049] (B) Preparation of Cu2O@CB[7] / CTF

[0050] (1) 125 mg of CuSO4·5H2O was dissolved in 10 mL of deionized water, denoted as solution A; 100 mg of CTF and 116.3 mg of CB[7] were dissolved in 10 mL of water, denoted as solution B.

[0051] (2) Solution A was quickly poured into solution B, and after stirring vigorously for 10 min, 10 mL of 0.6M NaOH solution was quickly added to the mixed solution to form a suspension.

[0052] (3) Under vigorous stirring, 50 mL of fresh 1M NaBH4 solution was added dropwise to the suspension, and the resulting black suspension was heated at 60°C for 24 h.

[0053] (4) After cooling, the reactants were washed with ethanol and deionized water alternately, and dried at 50°C under vacuum to obtain the final product Cu2O@CB[7] / CTF.

[0054] (5) The product was comprehensively characterized, and the results are shown in Figure 2 The FTIR spectrum shows that the characteristic peaks of Cu2O@CB[7] / CTF correspond one-to-one to those of CB[7], O-Cu-O and CTF, indicating the successful synthesis of the composite material.

[0055] Comparative Example 1: Preparation of Cu2O@CB[7] nanocomposite

[0056] (1) 250 mg of CuSO4·5H2O and 232.6 mg of CB[7] were dissolved in 10 mL of deionized water, respectively, and denoted as solutions C and D.

[0057] (2) Pour solution C into solution D quickly, stir vigorously for 10 min, then quickly add 10 mL of 0.8M NaOH solution into the mixed solution to form a blue suspension.

[0058] (3) Slowly drop 50 mL of 1M fresh NaBH4 solution into the suspension under vigorous stirring, and seal the obtained black suspension at 60°C for 24 h.

[0059] (4) After cooling, wash the reaction product with ethanol and deionized water alternately, and dry it under vacuum at 50°C to obtain the final product Cu2O@CB[7].

[0060] Application Example:

[0061] (I) Construction of p-nitrophenol electrochemical sensor

[0062] (1) Cleaning of glassy carbon electrode: polish the surface of glassy carbon electrode (GCE) with α-Al2O3 of particle size 0.3 μm and 0.05 μm successively, rinse with deionized water, and dry with nitrogen to obtain a pure glassy carbon electrode (GCE).

[0063] (2) Take 4 mg of the composite material (modification material) prepared in Example 1 and Comparative Example 1, and uniformly disperse them in 300 μL of isopropanol and 650 μL of deionized water containing 50 μL of 5 wt% Nafion. Then, drop 5 μL of the prepared suspension on the surface of GCE, and dry it at room temperature to obtain a p-nitrophenol electrochemical sensor based on different modification materials, i.e., CTF / GCE, Cu2O@CB[7] / GCE, and Cu2O@CB[7] / CTF / GCE working electrode.

[0064] (II) Performance determination of p-nitrophenol electrochemical sensor

[0065] Use a three-electrode system, and use the p-nitrophenol electrochemical sensor based on different modification materials prepared above as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, and 0.1M PBS solution (pH 7.0) as electrolyte solution. Meanwhile, prepare a PBS working solution (10 mM) containing p-nitrophenol, and use an electrochemical workstation to determine the performance by various methods.

[0066] Use chronoamperometry, and apply a potential of -0.70 V. During the test, continuously add a p-nitrophenol solution of a certain concentration into the electrolyte, and the time interval is 50 s. Record the relationship curve between response time and current value, i.e., the i-t graph of different sensors for PNP, and the results are as follows: Figure 3As shown in the figure, it can be found that after adding PNP of the same concentration, the current response of the Cu2O@CB[7] / CTF / GCE sensor increases continuously and reaches a steady state in a relatively short time, and has a relatively high current response value, so the Cu2O@CB[7] / CTF modified electrode prepared in the application has high sensitivity.

[0067] The differential pulse voltammetry method was used to test the response curve of the Cu2O@CB[7] / CTF / GCE sensor to PNP of different concentrations in the voltage range of-0.35V to-0.85V, and the results are shown in the figure. Figure 4 As shown in the figure, it can be found that there is a good linear relationship between the PNP concentration and the response current, and the response current has good stability, so the Cu2O prepared in the application can exist stably under the synergistic protection of CTF and CB[7], and the relationship curve between the response current and the PNP concentration is recorded, and the results are shown in the figure. Figure 5 As shown in the figure, the linear range is 1-500μM and 0.5-1mM respectively, and the detection limit is 0.094μM and 59.72μM respectively.

[0068] In summary, the Cu2O@CB[7] / CTF electrochemical sensor based on cuprous oxide@cucurbituril[7] / covalent triazine organic framework composite material has fast response, high sensitivity and stability. In addition, the sensor can be flexibly used for real-time identification of p-nitrophenol in water, so that the method can be widely used in actual industrial and agricultural production.

Claims

1. A method for the preparation of a covalent triazine organic framework-cucurbituril composite material, characterized in that, The specific steps are as follows: Step 1, the covalent triazine organic framework and potassium hydroxide are mixed in ethanol, evaporated at room temperature, and calcined for a period of time after the ethanol is completely evaporated; Step 2, after cooling, the reaction product obtained in step 1 is washed with 1 M hydrochloric acid, deionized water and ethanol in turn, and dried to obtain a modified covalent triazine organic framework; Step 3, cucurbituril [7] and the modified covalent triazine organic framework are mixed in water, stirred, and a copper salt solution is quickly poured into it, to obtain a mixed solution; Step 4, NaOH solution is quickly added to the mixed solution obtained in step 3, and then NaBH4 solution is slowly added to obtain a suspension; Step 5, the suspension obtained in step 4 is sealed and heat treated for a period of time, cooled, washed with deionized water and ethanol in turn, and vacuum dried to obtain the composite material; The covalent triazine organic framework is prepared by the following steps: A certain mass ratio of diphenyl-4,4'-dicyan (DCBP) and ZnCl2 is uniformly mixed and ground, transferred to a quartz ampoule, vacuum sealed, heated to 400°C under N2 atmosphere, and kept for 40 h. After cooling, the obtained reaction product is soaked in 1 M dilute hydrochloric acid solution for 24 h, washed with deionized water until neutral, then washed with ethanol, and dried at 120°C to obtain the covalent triazine organic framework CTF-F; The mass ratio of DCBP to ZnCl2 is 1.0:3.0-4.0, and the heating rate is 2°C / min.

2. The method of claim 1, wherein, In step 1, the mass ratio of covalent triazine organic framework to potassium hydroxide is 1:1, the calcination temperature is 700°C, and the calcination time is 5 h.

3. The method of claim 1, wherein, In step 3, the mass ratio of cucurbituril [7], modified covalent triazine organic framework and copper salt is 1:1:

1.

4. The method of claim 1, wherein, In step 4, the concentration of NaOH solution is 0.6 M, and the concentration of NaBH4 solution is 1 M.

5. The method of claim 1, wherein, In step 4, the molar ratio of copper salt, NaOH and NaBH4 is 1:6:

50.

6. The method of claim 1, wherein, In step 5, the heat treatment temperature is 60°C, and the time is 24 h; the vacuum drying temperature is not higher than 60°C.

7. The covalent triazine organic framework-cucurbituril composite material prepared by the method of any one of claims 1-6.

8. The use of the covalent triazine organic framework-cucurbituril composite material prepared by the method of any one of claims 1-6 in constructing a p-nitrophenol electrochemical sensor.

9. Use according to claim 8, wherein the compound is ###0002### The use of the composite material as an electrode material for determining p-nitrophenol.

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