Preparation of ultrafast uranyl response AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode and uranyl detection application thereof

Abstract

The invention discloses preparation of an ultrafast uranyl response AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode and uranyl detection application of the ultrafast uranyl response AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode. The method comprises the steps that oily carbon cloth is subjected to plasma cleaning and then soaked with a mixed solution of ceric ammonium nitrate, water and nitric acid; then soaking in a mixed solution of acrylic acid, acrylonitrile and DMF (Dimethyl Formamide), and heating in a water bath; after being taken out, the polymer coating carbon cloth is added into a mixed solution of hydroxylamine hydrochloride, isopropanol and sodium hydroxide, water bath heating is conducted again, and the polymer coating carbon cloth is obtained. The preparation method comprises the following steps: magnetically stirring and heating PVP-containing propylene glycol in a water bath, quickly adding NaCl, continuously stirring, adding an AgNO3 solution, and magnetically stirring and heating; and collecting the precipitate, and washing with acetone and ethanol respectively to obtain gray AgNWs. The preparation method comprises the following steps: adding 2-methylimidazole and AgNWs into an organic solvent solution containing organic amine to obtain an AgNWs composite solution; wherein in the aqueous solution of the organic amine or the organic solvent solution, the concentration of the organic amine is 8-9%; and mixing organic solvents containing cadmium salt and zinc salt to obtain the zinc-cadmium composite solution. The AgNWs composite solution and the zinc-cadmium composite solution are respectively heated and coated on polymer coating carbon cloth, then the polymer coating carbon cloth is put into an organic solvent containing thiourea, after the mixture is heated in a water bath, vacuum drying is carried out, and the AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode is obtained. According to the invention, the polymer coating carbon cloth is used as a substrate to prepare the AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode, and the flexible photoelectrode has ultrafast uranyl response capability.

Description

Technical Field

[0001] The present invention relates to a flexible material optoelectrode, and particularly to the preparation of an ultrafast uranyl-responsive AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode and its application in uranyl detection. Background Art

[0002] Due to the continuous expansion of the nuclear industry and the extensive application of nuclear technology in multiple fields, the usage of uranium is increasing day by day. As the common existing form of uranium in the environment, the release and accumulation of uranyl in environmental media such as water bodies and soils have caused many problems. Therefore, developing a high-performance detection electrode that can quickly, sensitively, and accurately detect uranyl in the environment is of crucial significance for environmental monitoring, resource recycling, and ensuring human health.

[0003] As a combination of electrochemical (EC) performance and photoexcitation, photoelectrochemical (PEC) measurement has received considerable attention among various sensing methods due to its fast, simple, and economical characteristics. In particular, PEC sensing successfully separates the photoexcitation source from the current detection information, thereby effectively reducing unwanted background noise, which has higher sensitivity than separate optical detection or EC measurement.

[0004] Designing and synthesizing semiconductor nanomaterials and preparing them into sensors has become a feasible solution. CdZnS2 (hereinafter referred to as SCZ) is a typical ternary sulfide solid solution composed of cadmium, zinc, and sulfur elements, and has the advantages of both the wide bandgap of ZnS (3.6 eV) and the narrow bandgap of CdS (2.4 eV). It has been widely studied due to its flexible bandgap and band edge position. CdZnS2 also has the advantages of simple preparation process, strong visible light response, and strong resistance to photocorrosion, and is widely used in the field of PEC sensors.

[0005] An ideal photoactive electrode should have a controllable morphology and surface structure, and the active sites should be evenly distributed. The traditional method for preparing photoactive electrodes is to coat photoactive materials on conductive substrates, such as indium tin oxide electrodes or glassy carbon electrodes. However, the coating method has a major drawback that it often leads to the aggregation of nanomaterials, thereby reducing the active surface area. In addition, the use of adhesives will increase the complexity of the preparation process, and the degradation of adhesives will cause unnecessary loss of photoactive materials, thus reducing the catalytic performance. Therefore, it is highly necessary to in-situ prepare visible-light active materials on conductive substrates. This preparation method can avoid the adverse effects brought by the coating process and improve the conductivity between the diffusion layer and the catalyst support. The in-situ synthesis method can also avoid the use of adhesives, thereby eliminating overpotential and other side reactions and improving the photoelectrochemical performance. Wang et al. constructed a novel photoelectrochemical platform with Sn3O4 (Sn3O4@CFP) in-situ modified on carbon fiber paper as the visible-light active substance and molecularly imprinted polymers (MIPs) as the recognition element (High sensitive visiblelight photoelectrochemical sensor based on in-situ prepared flexibleSn3O4nanosheets and molecularly imprinted polymers[J / OL].Sensors andActuators B:Chemical,2018,271:215-224). Through a simple hydrothermal method, Sn3O4 nanosheets were directly grown on carbon fiber paper to prepare an MIP layer with special selectivity for 2,4-D. This PEC platform exhibited excellent stability, reproducibility, significant convenience and cost-effective advantages, and a low detection limit. The detection of 2,4-D in mung bean sprout samples has been successfully achieved. In addition, metal element doping also has a certain impact on it. Zhang et al. designed and prepared three-dimensional flexible gold nanoparticle-decorated titanium dioxide nanotube arrays for efficient PEC glucose biosensing (Three-dimensionalflexible au nanoparticles-decorated TiO2 nanotube arrays forphotoelectrochemical biosensing[J / OL].Journal ofMaterials Science&Technology,2020,56:162-169). The Schottky barrier formed by the Au@TiO2 heterostructure can effectively separate charge carriers at the junction interface, thereby greatly increasing the concentration and lifetime of the remaining holes in the valence band of titanium dioxide. The separated holes further significantly generate active hydroxyl radicals, which can specifically recognize and oxidize glucose.Therefore, Au@TiO2 exhibits excellent optoelectronic activity and selectivity, far superior to titanium dioxide without modified gold nanoparticles.

[0006] Although it has been recognized that PEC sensing has great potential in the field of substance detection, due to the fact that most flexible photoanodes require complex preparation conditions to obtain good performance and may face problems such as insufficient stability and repeatability in practical applications, therefore, it is still challenging to develop a high-performance PEC photoanode that can be prepared under simple conditions, has high stability and strong repeatability, and can quickly, sensitively, and accurately detect uranyl in the environment. Summary of the Invention

[0007] The object of the present invention is to provide a preparation method of an ultrafast uranyl-responsive AgNWs@CZS@CdZn~ZIF8 flexible photoanode and its application in uranyl detection. By controlling the composite of AgNWs and g-CdZnS2, the uranyl detection performance of g-CdZnS2 is improved.

[0008] To achieve the above object, the present invention provides a preparation method of an AgNWs@CZS@CdZn~ZIF8 flexible photoanode, which method comprises:

[0009] The oily carbon cloth is subjected to plasma cleaning and then soaked in a mixed solution of ammonium cerium nitrate, water, and nitric acid. Then it is immersed in a mixed solution of acrylic acid, acrylonitrile, and DMF and subjected to water bath heating. After taking it out, it is added to a mixed solution of hydroxylamine hydrochloride, isopropanol, and sodium hydroxide and subjected to water bath heating again to obtain a polymer-coated carbon cloth. Propylene glycol containing PVP is magnetically stirred and heated in a water bath, then NaCl is quickly added, and stirring is continued. An AgNO3 solution is added, and it is magnetically stirred and heated. The precipitate is collected and washed with acetone and ethanol respectively to obtain gray AgNWs. 2-Methylimidazole and AgNWs are added to an organic solvent solution containing organic amine to obtain an AgNWs composite solution; wherein, in the aqueous solution or organic solvent solution of the organic amine, the concentration of the organic amine is 8-9%; the organic solvents containing cadmium salt and zinc salt are mixed to obtain a zinc-cadmium composite solution. The AgNWs composite solution and the zinc-cadmium composite solution are respectively heated and coated on the polymer-coated carbon cloth, then it is placed in an organic solvent containing thiourea, the mixture is subjected to water bath heating, and then vacuum dried to obtain an AgNWs@CZS@CdZn~ZIF8 flexible photoanode. The present invention uses a polymer-coated carbon cloth as a substrate to prepare an AgNWs@CZS@CdZn~ZIF8 flexible photoanode with ultrafast uranyl response ability.

[0010] Preferably, the plasma cleaning time is 1-30 min.

[0011] Preferably, the molar ratio of ammonium cerium nitrate, water, and nitric acid is 1:1:1 to 1:600:20; the molar ratio of acrylic acid, acrylonitrile, and DMF is 1:1:1 to 1:10:10.

[0012] Preferably, after the water bath is heated to 40 - 80 °C, it is maintained for 1 - 12 h.

[0013] Preferably, the molar ratio of hydroxylamine hydrochloride, isopropanol, and sodium hydroxide is 1:1:1 to 1:10:10.

[0014] Preferably, the molar ratio of the cadmium salt to the zinc salt and 2 - methylimidazole is 1:1 to 1:20; the mass ratio of AgNWs@ZIF8 to urea is 1:1 to 1:250.

[0015] Preferably, it is coated 1 - 5 times respectively, and the heating temperature is 50 - 90 °C.

[0016] Preferably, the cadmium salt is selected from any one or more of CdI2, CdCl2, CdBr2, CdAc2, Cd(SO4)2, and Cd(NO3)2; the zinc salt is selected from any one or more of ZnI2, ZnCl2, ZnBr2, ZnAc2, Zn(SO4)2, and Zn(NO3)2.

[0017] Another object of the present invention is to provide the AgNWs@CZS@CdZn - ZIF8 flexible optoelectrode prepared by the described method.

[0018] Another object of the present invention is to provide the application of the AgNWs@CZS@CdZn - ZIF8 flexible optoelectrode in the detection of uranyl.

[0019] The preparation of an ultrafast uranyl - responsive AgNWs@CZS@CdZn - ZIF8 flexible optoelectrode and its application in uranyl detection according to the present invention have the following advantages:

[0020] (1) Plasma cleaning the carbon cloth can effectively remove surface oil stains and impurities, increase surface roughness and active functional groups. Then, treating with ammonium cerium nitrate and other solutions and subsequent polymer coatings improves the surface properties of the carbon cloth, enhances its bonding force and compatibility with the subsequent loaded materials, and lays the foundation for the stable structure of the optoelectrode.

[0021] (2) The design of step - by - step coating and reaction enables each component to fully react and combine, forming a uniform and dense AgNWs@CZS@CdZn - ZIF8 structure, effectively improving the light absorption and utilization efficiency of the optoelectrode, and enhancing the separation and transport ability of photo - generated carriers.

[0022] (3) The entire preparation process mainly adopts conventional operations such as water bath heating and magnetic stirring, without the need for complex equipment and harsh reaction conditions. The process is simple and easy to implement, and is easy to scale up production. At the same time, most of the reagents used are common and relatively environmentally friendly, meeting the concept of green chemistry, and having good application prospects and industrialization potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the ultraviolet diffuse reflection spectrum of the flexible optoelectronic grade prepared in Example 1, Comparative Example 2, and Comparative Example 3 of the present invention.

[0024] Figure 2 It is the electrochemical impedance diagram of Example 1 and Comparative Example 2 of the present invention.

[0025] Figure 3 It is the electrochemical photocurrent diagram of Example 1, Comparative Example 1-3 of the present invention.

[0026] Figure 4 It is the ultraviolet-visible absorption spectrum of the flexible optoelectronic grade prepared in Example 1 and Comparative Example 1 of the present invention.

[0027] Figure 5 It is the ultraviolet-visible absorption spectrum of the flexible optoelectronic grade with different uranyl concentrations prepared in Example 1 of the present invention.

[0028] Figure 6 It is the bar chart of the removal rate and extraction rate of the flexible optoelectronic grade with different uranyl concentrations prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Example 1

[0031] A preparation method of an AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode is as follows:

[0032] (1) Prepare a polymer-coated carbon cloth

[0033] After the oily carbon cloth was subjected to plasma cleaning for 20 min, it was wetted with a mixed solution of 0.0005 mol ammonium cerium nitrate, 0.26 mol water, and 0.0053 mol nitric acid. Then it was immersed in a mixed solution of 0.17 mol acrylic acid, 0.61 mol acrylonitrile, and 0.65 mol DMF, and heated in a water bath at 60 °C for 6 h. After taking it out, it was added to a mixed solution of 0.037 mol hydroxylamine hydrochloride, 0.26 mol isopropanol, and 0.05 mol sodium hydroxide, and heated in a water bath at 60 °C for 6 h again to obtain a polymer-coated carbon cloth.

[0034] (2) Preparation of AgNWs composite solution and zinc-cadmium composite solution

[0035] 0.2 mol of 2-methylimidazole and 0.2 ml of AgNWs were added to 108.75 mL of a methanol solution containing 8.75% TEA (triethylamine) to obtain an AgNWs composite solution; 0.01 mol of C4H6O4Zn·2H2O and 0.01 mol of Cd(NO3)2·4H2O were added to 500 mL of methanol and mixed to obtain a zinc-cadmium composite solution.

[0036] (3) Preparation of AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode

[0037] The AgNWs composite solution and the zinc-cadmium composite solution were respectively heated and coated 5 layers on the polymer-coated carbon cloth, and then it was put into 40 ml of methanol containing 1 g of thiourea, and the mixture was heated in a water bath at 60 °C for 6 h and dried under vacuum to obtain an AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode.

[0038] Comparative example 1

[0039] A preparation method of a polymer-coated carbon cloth is as follows:

[0040] It is the same as the preparation method of the polymer-coated carbon cloth in (1) of Example 1.

[0041] Comparative example 2

[0042] A preparation method of an AgNWs flexible optoelectrode is as follows:

[0043] (1) Preparation of polymer-coated carbon cloth

[0044] It is the same as the preparation method of the polymer-coated carbon cloth in (1) of Example 1.

[0045] (2) Preparation of AgNWs composite solution

[0046] It is the same as the preparation method of the AgNWs composite solution in (2) of Example 1.

[0047] (3) Preparation of AgNWs Flexible Photoelectrode

[0048] Heat and apply the AgNWs composite solution in 5 layers on the polymer-coated carbon cloth, then put it into 40 ml of methanol containing 1 g of thiourea, heat the mixture in a water bath at 60 °C for 6 h, and dry it under vacuum to obtain the AgNWs flexible photoelectrode.

[0049] Comparative Example 3

[0050] A preparation method of a CZS@CdZn~ZIF8 flexible photoelectrode is as follows:

[0051] (1) Preparation of polymer-coated carbon cloth

[0052] It is the same as the preparation method of (1) preparing polymer-coated carbon cloth in Example 1.

[0053] (2) Preparation of zinc-cadmium composite solution

[0054] It is the same as the preparation method of (2) preparing zinc-cadmium composite solution in Example 1.

[0055] (3) Preparation of CZS@CdZn~ZIF8 flexible photoelectrode

[0056] Heat and apply the zinc-cadmium composite solution in 5 layers on the polymer-coated carbon cloth, then put it into 40 ml of methanol containing 1 g of thiourea, heat the mixture in a water bath at 60 °C for 6 h, and dry it under vacuum to obtain the AgNWs flexible photoelectrode.

[0057] As Figure 1 shown, it is the ultraviolet diffuse reflection spectrum of the flexible photoelectrodes prepared in Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. The abscissa in the figure is the wavelength, and the ordinate is the absorbance.

[0058] As Figure 2 shown, it is the electrochemical impedance diagram of Example 1 and Comparative Example 2 of the present invention. The abscissa in the figure is the real part impedance, and the ordinate is the imaginary part impedance. It can be seen from the figure that the charge transfer resistance of Example 1 is 7.5 ohms, that is, the charge transfer is faster and the catalytic detection activity is higher; the charge transfer resistance of Comparative Example 2 is 15 ohms, the charge transfer is slower, and the catalytic detection activity is lower.

[0059] As Figure 3 shown, it is the electrochemical photocurrent diagram of Example 1, Comparative Examples 1-3 of the present invention. The abscissa in the figure is the time, and the ordinate is the current. It can be seen from the figure that the photocurrent of Example 1 is -10 μA, and the light absorption efficiency is the best; the photocurrent of Comparative Example 3 is -2 μA, and the light absorption efficiency is better; the photocurrents of Comparative Examples 1 and 2 are almost 0, and the light absorption ability is almost non-existent.

[0060] Experimental Example 1 Photoelectrochemical Uranium(VI) Reduction Detection

[0061] The photoelectric uranyl detection experiment was carried out under the irradiation of a 300W xenon lamp (CEL-PF300-T8E) using a 420nm cut-off filter. The specific process is as follows:

[0062] Place the flexible optoelectrode (the flexible optoelectrode prepared in each example or comparative example) in 50 mL of a 200 mg / L aqueous solution of UO2(NO3)2·6H2O. Irradiate for a period of time to allow sufficient reaction. Denote the initial uranyl concentration as C0, and take an appropriate amount of sample at intervals. At this time, the uranyl concentration is denoted as C. Filter the photocatalyst using a 0.22μm filter head, color the sample using arsenazo colorimetric method, and finally use UV-vis absorption spectroscopy to detect the residual uranyl concentration in the sample to evaluate the reduction detection ability of the flexible optoelectrode.

[0063] As Figure 4 shown, the UV-vis absorption spectra of the flexible optoelectrodes prepared in Example 1 and Comparative Example 1 of the present invention are shown. The abscissa is the wavelength and the ordinate is the relative absorption intensity. It can be seen from the figure that the flexible optoelectrode (polymer-coated carbon cloth) prepared in Comparative Example 1 has a weak absorption ability for uranyl; the flexible optoelectrode (AgNWs@CZS@CdZn~ZIF8) prepared in Example 1 has a strong absorption ability for uranyl and exhibits the characteristics of photo-promoted adsorption.

[0064] As Figure 5 shown, the UV-vis absorption spectra of different uranyl concentrations of the flexible optoelectrode prepared in Example 1 of the present invention are shown. It can be seen from the figure that the flexible optoelectrode (AgNWs@CZS@CdZn~ZIF8) prepared in Example 1 can detect the uranyl concentration range of 30 - 1000 μL. As Figure 6 shown, the bar chart of the removal rate and extraction rate of different uranyl concentrations of the flexible optoelectrode prepared in Example 1 of the present invention is shown. It can be seen from the figure that as the uranyl concentration increases, the extraction rate and removal rate also increase.

[0065] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions of the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A preparation method of an ultrafast uranyl-responsive AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode, characterized in that, The method includes: After subjecting the oily carbon cloth to plasma cleaning, it is soaked with a mixed solution of ammonium cerium nitrate, water, and nitric acid. Then it is immersed in a mixed solution of acrylic acid, acrylonitrile, and DMF, and water bath heating is carried out. After taking it out, it is added to a mixed solution of hydroxylamine hydrochloride, isopropanol, and sodium hydroxide, and water bath heating is carried out again to obtain a polymer-coated carbon cloth. Propylene glycol containing PVP is heated with magnetic stirring in a water bath, then NaCl is quickly added, and stirring is continued. An AgNO3 solution is added, and it is heated with magnetic stirring. The precipitate is collected and washed with acetone and ethanol respectively to obtain gray AgNWs. 2-Methylimidazole and AgNWs are added to an organic solvent solution containing organic amine to obtain an AgNWs composite solution; wherein, in the aqueous solution or organic solvent solution of the organic amine, the concentration of the organic amine is 8-9%; an organic solvent mixture containing cadmium salt and zinc salt is mixed to obtain a zinc-cadmium composite solution. The AgNWs composite solution and the zinc-cadmium composite solution are respectively heated and coated on the polymer-coated carbon cloth, and then it is placed in an organic solvent containing thiourea. After the mixture is heated in a water bath, it is dried under vacuum to obtain an AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode.

2. The preparation method of the AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode according to claim 1, characterized in that, The plasma cleaning time is 1-30 min.

3. The preparation method of the AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode according to claim 1, wherein The molar ratio of ammonium cerium nitrate, water, and nitric acid is 1:1:1-1:600:20; the molar ratio of acrylic acid, acrylonitrile, and DMF is 1:1:1-1:10:

10.

4. The preparation method of the AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode according to claim 1, wherein, The water bath is heated to 40-80 °C and maintained for 1-12 h.

5. The preparation method of the AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode according to claim 1, characterized in that, The molar ratio of hydroxylamine hydrochloride, isopropanol, and sodium hydroxide is 1:1:1-1:10:

10.

6. The preparation method of the AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode according to claim 1, characterized in that, The molar ratio of the cadmium salt to the zinc salt and 2-methylimidazole is 1:1-1:20; the mass ratio of AgNWs@ZIF8 to urea is 1:1-1:

250.

7. The preparation method of the AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode according to claim 1, characterized in that, The coating is carried out 1-5 times respectively, and the heating temperature is 50-90 °C.

8. The preparation method of the AgNWs@CZS@CdZn~ZIF8 flexible optoelectrode according to claim 1, wherein, The cadmium salt is selected from any one or more of CdI2, CdCl2, CdBr2, CdAc2, Cd(SO4)2, and Cd(NO3)2; the zinc salt is selected from any one or more of ZnI2, ZnCl2, ZnBr2, ZnAc2, Zn(SO4)2, and Zn(NO3)2.

9. The AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode prepared by the method according to any one of claims 1-8.

10. The application of the AgNWs@CZS@CdZn-ZIF8 flexible optoelectrode according to claim 9 in the detection of uranyl.

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