A cobalt sulfide / titanium carbide / carbon cloth composite anode material, a preparation method and application thereof

Abstract

The application discloses a cobalt sulfide / titanium carbide / carbon cloth composite anode material and a preparation method and application thereof. In order to solve the problems of the existing anode material, such as low efficiency of activating persulfate, limited electron transmission efficiency, difficulty in generating non-radicals, and complex preparation process of titanium carbide material and other materials, the application uses anhydrous ethanol and dimethylformamide as organic solvents, which can improve the solubility and dispersity of the titanium carbide material in the organic solvents and is beneficial to the generation of high-purity metal sulfide in a suitable proportion. Meanwhile, the application realizes the growth of the titanium carbide and the cobalt sulfide on the carbon cloth substrate by using a one-step solvothermal method under high temperature and high pressure, makes the cobalt sulfide grow on the surface and between the layers of the titanium carbide without changing the layered structure of the titanium carbide, and obtains the cobalt sulfide-titanium carbide-carbon cloth composite anode material, which is beneficial to the high-speed electron transmission on the electrode surface under the electric field and the generation of non-radicals. The application belongs to the technical field of electrocatalytic materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, and particularly relates to a cobalt sulfide / titanium carbide / carbon cloth composite anode material as well as a preparation method and application. BACKGROUND

[0002] China is the largest antibiotic production and consumption country in the world. Long-term abuse in various industries has caused antibiotics to accumulate widely and massively in the environment, posing ecological risks to animals, plants and humans. How to effectively remove antibiotics from the water environment is one of the key problems to be solved. Among the currently developed technologies, advanced oxidation technology has significant advantages in terms of degradation effect and economic cost. Further, since the sulfate radical has a higher oxidation-reduction potential, a longer half-life, a wider acid-base range and better selectivity than the hydroxyl radical, the advanced oxidation technology based on activated persulfate has become a research hotspot in this field.

[0003] Among various activation technologies, electric activation technology not only promotes the migration of persulfate in water, but also accelerates the electron transfer efficiency between pollutants and catalysts, which is a very promising activation method. So far, the related research on electrically activated persulfate has mainly focused on the development and optimization of cathode materials, while the reactions occurring on the surface of anode materials are ignored. In fact, persulfate anions are more likely to accumulate on the surface of anodes. Anodes that have been confirmed to be able to activate persulfate include boron-doped diamond electrodes, traditional metal-based anodes (such as TiO2, PbO2) and more affordable carbon-based anodes (such as multi-walled carbon nanotubes, activated carbon cloth), but these anodes have the disadvantages of poor resistance to actual water bodies, low electron transfer efficiency, complex preparation process, etc. Therefore, it is necessary to find an electrically active material with simple preparation method, high electrical activity and high electron transfer rate to further improve the ability of electrically activated persulfate to remove antibiotics.

[0004] In the field of electrically activated persulfate, transition metal sulfides have become excellent substitutes for transition metal oxides, especially cobalt sulfide (CoS), which has a lower cost and a higher electrical activity than cobalt oxide (Co3O4). x S y). As an excellent electron donor, divalent sulfur is conducive to the improvement of electron transfer rate and the exposure of active sites of reducing metal, but the leaching of toxic metal ions and poor dispersibility of the material are not conducive to its practical application. Existing research shows that titanium carbide (Ti3C2) utilizes its two-dimensional layered graphene-like structure to uniformly disperse the catalyst while having high oxygen evolution potential (2.84V), high electron conductivity and other characteristics, which is conducive to the generation of non-radicals. Therefore, the effective compounding of cobalt sulfide and titanium carbide has feasibility in realizing high-efficiency electro-activated peroxymonosulfate. However, there are few related researches on the use of titanium carbide in heterogeneous catalysts, and the compounding process with other materials is complex. Therefore, it is necessary to provide a simple preparation method of cobalt sulfide-titanium carbide-carbon cloth composite anode material. SUMMARY

[0005] The present application is to solve the problems of existing anode materials, such as low efficiency of activating peroxymonosulfate, limited electron transfer efficiency, difficulty in generating non-radicals, and complex preparation process of titanium carbide material and other materials, and further proposes a cobalt sulfide / titanium carbide / carbon cloth composite anode material and a preparation method and application.

[0006] The technical solution adopted by the present application to solve the above problems is as follows:

[0007] A preparation method of a cobalt sulfide / titanium carbide / carbon cloth composite anode material, the specific operation steps are as follows:

[0008] Step one, cut the activated carbon cloth into a certain size, then ultrasonic in deionized water and anhydrous ethanol for 10 min and dry.

[0009] Step two, gradually add lithium fluoride (LiF) and titanium aluminum carbide (Ti3AlC2) powder into 9mol / L hydrochloric acid solution (HCl), and stir in water bath at 35℃ for 24-48h.

[0010] Step three, centrifuge the solution obtained in step two, then wash with deionized water for several times until the pH is about 6, collect the bottom precipitate and freeze-dry for 12-24h to obtain the etched titanium carbide (Ti3C2) powder.

[0011] Step four, mix the Ti3C2 powder obtained in step three with anhydrous ethanol and dimethylformamide (DMF) thoroughly, and stir for 2h.

[0012] Step five, mix cobalt chloride hexahydrate (CoCl2·6H2O) with anhydrous ethanol and DMF thoroughly, ultrasonic for 30min, then add L-cysteine and ultrasonic for 30min.

[0013] Step six, the solution obtained in step four and step five is mixed thoroughly and stirred for 30 min, and the obtained mixed solution and the treated activated carbon cloth are transferred into a 100 mL reaction kettle, the oven is heated from room temperature to 180-220 DEG C at a heating rate of 10-20 DEG C / min, and then the oven is cooled to room temperature after being kept for 24 h.

[0014] Step seven, the material in step six is taken out and washed with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at 60 DEG C for 10-14 h to obtain a cobalt sulfide-titanium carbide-carbon cloth (Co x S y / Ti3C2 / CC) composite anode material.

[0015] Further, the drying temperature in step one is 60-80 DEG C, and the time is 3-4 h.

[0016] Further, the mass-volume ratio of Ti3AlC2, LiF and HCl in step two is (1-2) g:(1.6-2) g:20 mL

[0017] Further, the centrifugal speed in step three is 8000-12000 rpm / min, and the centrifugal time is 5-10 min.

[0018] Further, the mass-volume ratio of Ti3C2 powder, anhydrous ethanol and DMF in step four is (0.034-0.2) g:15 mL:15 mL.

[0019] Further, the mass-volume ratio of CoCl2·6H2O, anhydrous ethanol, DMF and L-cysteine in step five is 0.163 g:10 mL:10 mL:(0.248-0.496) g.

[0020] Further, the molar ratio of cobalt sulfide and titanium carbide in the Co x S y / Ti3C2 / CC composite anode is 1:(0.5-3).

[0021] A cobalt sulfide / titanium carbide / carbon cloth composite anode material is prepared by the preparation method of the cobalt sulfide / titanium carbide / carbon cloth composite anode material.

[0022] The cobalt sulfide / titanium carbide / carbon cloth composite anode material is applied to remove antibiotics in a water environment.

[0023] The beneficial effects of the present application are:

[0024] 1. The application uses anhydrous ethanol and DMF as organic solvents, which can improve the solubility and dispersity of titanium carbide material in organic solvents in a suitable proportion, and is beneficial to the formation of high-purity metal sulfide; meanwhile, the application realizes Ti3C2 and Co x S y Growth on the carbon cloth substrate changes the Ti3C2 layered structure, and Co x S y Grows on the surface and between the layers, and the reaction conditions are simple.

[0025] 2. The application can efficiently activate persulfate under an electric field, and the removal rate of sulfamethoxazole, a refractory pollutant, can reach 100% in 10 min; the degradation kinetics conforms to pseudo-first-order kinetics, and the apparent rate constant is 0.522 min -1 .

[0026] 3. The application utilizes the special multi-layer structure of Ti3C2 to improve the dispersity of active substance Co x S y , and utilizes the redox cycle of different valence titanium to accelerate the electron transfer among the catalyst, persulfate and sulfamethoxazole, thereby improving the electrocatalytic efficiency.

[0027] 4. Compared with the previously reported catalytic system only containing Co x S y and the powder Ti3C2-based catalyst, the application is beneficial to the generation of non-radicals while enhancing the catalytic activity, the contribution rate of singlet oxygen and free radicals is close to 1:1, the catalyst has stronger adaptability to actual water bodies, higher selectivity to pollutants and wider application range. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 SEM picture of the cobalt sulfide-titanium carbide-carbon cloth composite anode material obtained in the specific embodiment 1;

[0029] Figure 2 EDS picture of the cobalt sulfide-titanium carbide-carbon cloth composite anode material obtained in the specific embodiment 1;

[0030] Figure 3 XRD picture of the cobalt sulfide-titanium carbide-carbon cloth composite anode material obtained in the specific embodiment 1;

[0031] Figure 4 Degradation removal curve of the cobalt sulfide-titanium carbide-carbon cloth composite anode material obtained in the specific embodiment 1 in the catalytic degradation of persulfate on sulfamethoxazole;

[0032] Figure 5The pseudo-first-order kinetic plot of the catalytic persulfate degradation of sulfamethoxazole by the cobalt sulfide-titanium carbide-carbon cloth composite anode material obtained for specific embodiment 1 is shown in the following figure. DETAILED DESCRIPTION

[0033] Embodiment 1: A method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material, the specific operation steps of which are as follows:

[0034] Step 1: Cut the activated carbon cloth into 2 cm x 4 cm, then ultrasonic in deionized water and anhydrous ethanol for 10 min and dry at 60℃ for 3-4h.

[0035] Step 2: Gradually add 1.6g LiF and 1.0g 400 mesh Ti3AlC2 powder to 20mL of 9mol / L HCl solution, and stir under water bath at 35℃ for 24h. Centrifuge the reaction solution at 12000rpm / min for 5min, then add deionized water and shake, then centrifuge, repeat multiple times, and the conditions remain unchanged until the pH is about 6.

[0036] Step 3: Collect the bottom precipitate in step 2, freeze-dry for 24h, and obtain Ti3C2 powder.

[0037] Step 4: At room temperature, add 15mL of anhydrous ethanol and DMF to 0.067g of Ti3C2 and stir for 2h.

[0038] Step 5: At room temperature, add 10mL of anhydrous ethanol and DMF to 0.163g of CoCl2·6H2O, ultrasonic for 30min, then add 0.248g of L-cysteine and continue to ultrasonic for 30min.

[0039] Step 6: Mix the solutions obtained in steps 4 and 5 and continue to stir for 30min. Then place the obtained precursor solution and activated carbon cloth together in a 100mL reaction kettle, and heat the reaction kettle from room temperature to 180-220℃ at a heating rate of 10-20℃ / min, and keep the temperature for 24h, then reduce the temperature to room temperature with the oven.

[0040] Step 7: Take out the material in step 6, rinse with deionized water and anhydrous ethanol, and dry in a vacuum drying oven at 60℃ for 10-14h to obtain the composite anode material Co x S y / Ti3C2 / CC. Named as CSTC-1.

[0041] Results: The molar ratio of Co x S y and Ti3C2 in the material prepared in this example is 1:1.

[0042] Figure 1 For the SEM test results of CSTC-1, it can be seen from the figure that the Co x S y grow on the surface and interlayer of the accordion-like multilayer structure Ti3C2, and are jointly loaded on the carbon cloth composed of carbon fibers.

[0043] Figure 2 For the EDS test results of CSTC-1, it can be seen from the figure that C, Ti, Co, S four elements exist on the material surface, and the spatial position distribution of Ti and C two elements corresponds to the accordion-like multilayer structure in Figure 1 , while the spatial position distribution of Co and S two elements corresponds to the cluster-like structure in Figure 1 , and is covered on the surface of the accordion-like structure. Further indicates that the composite is composed of Co x S y and Ti3C2.

[0044] Figure 3 For the XRD test results of CSTC-1, it can be seen from the figure that the diffraction peak of Ti3C2 appears at 2θ = 9.52° and corresponds to the (002) crystal face in the Ti3C2 standard card (PDF #52-0975); the amorphous peaks appearing at 2θ = 15° and 30° are from the carbon cloth; the diffraction peaks of Co9S8 appear at 2θ = 44.83° and 60.90° and correspond to the (422) (533) crystal face in the Co9S8 standard card (PDF #02-1459) respectively; the diffraction peak of Co4S3 appears at 2θ = 65.44° and corresponds to the (112) crystal face in the Co4S3 standard card (PDF #02-1458). The results show that S and Co in the material exist in the form of Co9S8 and Co4S3, while Ti and C exist in the form of Ti3C2.

[0045] The CSTC-1 prepared in this example was tested for the performance of electro-activated peroxymonosulfate degrading sulfamethoxazole. The experiment was carried out in a 300 mL electrolytic cell, and the volume of the reaction solution was 250 mL. CSTC-1 was used as the anode, and a constant voltage of 3 V was applied during the reaction. The amount of peroxymonosulfate applied was 1 mmol / L, and the initial concentration of sulfamethoxazole was 10 mg / L. The temperature was controlled at 25±2℃ throughout the reaction. The degradation performance is shown in Figure 4 . It can be seen from the figure that the degradation rate of sulfamethoxazole reaches 100% at 10 min.

[0046] The sulfamethoxazole degradation kinetics graph of CSTC-1 prepared in this example is shown in Figure 5 . The degradation process follows pseudo-first-order kinetics after fitting, and the oxidation rate constant of CSTC-1 to sulfamethoxazole is 0.522 min-1 .

[0047] To identify the main active species and contribution rate in the process of degrading sulfamethoxazole, the free radical capture experiment and EPR analysis were carried out on the CSTC-1 prepared in this embodiment. It is analyzed that singlet oxygen and sulfate free radicals are the main active species in the process of degrading sulfamethoxazole, and the contribution rate is close to 1:1, while the contribution rate of superoxide radical is very small and can be ignored.

[0048] Specific embodiment two: the difference between this embodiment and specific embodiment one is that the addition amount of Ti3C2 in step 4 is 0.034 g.

[0049] Results: The composite anode material Co x S y / Ti3C2 / CC prepared in this embodiment is Co x S y and the molar ratio of Ti3C2 is 1:0.5, which is named as CSTC-0.5.

[0050] The performance test of electro-activated persulfate degrading sulfamethoxazole was carried out on the CSTC-0.5 prepared in this embodiment. When a constant voltage of 3V is applied to the reaction process, the addition amount of persulfate is 1 mmol / L, the initial concentration of sulfamethoxazole is 10 mg / L, and the temperature control of the whole reaction process is 25±2℃, the degradation rate of sulfamethoxazole by the CSTC-0.5 prepared in this embodiment is 96.44% at 10 min.

[0051] Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that the addition amount of Ti3C2 in step 4 is 0.133 g.

[0052] Results: The composite anode material Co x S y / Ti3C2 / CC prepared in this embodiment is Co x S y and the molar ratio of Ti3C2 is 1:2, which is named as CSTC-2.

[0053] The performance test of electro-activated persulfate degrading sulfamethoxazole was carried out on the CSTC-2 prepared in this embodiment. When a constant voltage of 3V is applied to the reaction process, the addition amount of persulfate is 1 mmol / L, the initial concentration of sulfamethoxazole is 10 mg / L, and the temperature control of the whole reaction process is 25±2℃, the degradation rate of sulfamethoxazole by the CSTC-2 prepared in this embodiment is 98.07% at 10 min.

[0054] Specific embodiment four: the difference between this embodiment and one of the specific embodiments one to three is that the amount of Ti3C2 added in step 4 is 0.2 g.

[0055] Results: the prepared composite anode material Co x S y / Ti3C2 / CC, Co x S y and Ti3C2 have a molar ratio of 1:3, and is named CSTC-3.

[0056] The CSTC-3 prepared in this example was tested for its performance in electro-activated persulfate degradation of sulfamethoxazole. When a constant voltage of 3V was applied to the reaction process, the amount of persulfate applied was 1 mmol / L, the initial concentration of sulfamethoxazole was 10 mg / L, and the temperature was controlled at 25±2℃ throughout the reaction, the degradation rate of sulfamethoxazole by the CSTC-3 prepared in this example was 98.13% at 10 min.

[0057] Comparative example 1:

[0058] The difference between this embodiment and specific embodiment one is that step 4 is not added Ti3C2, 25 mL of anhydrous ethanol and DMF are added to 0.163 g of CoCl2·6H2O at room temperature, and 0.248 g of L-cysteine is added after ultrasonic treatment for 30 min and ultrasonic treatment is continued for 30 min.

[0059] Results: the prepared cobalt sulfide-carbon cloth composite anode material (Co x S y / CC) is named CSTC-0 because the molar ratio of Co x S y and Ti3C2 is 1:0.

[0060] The CSTC-0 prepared in this example was tested for its performance in electro-activated persulfate degradation of sulfamethoxazole. When a constant voltage of 3V was applied to the reaction process, the amount of persulfate applied was 1 mmol / L, the initial concentration of sulfamethoxazole was 10 mg / L, and the temperature was controlled at 25±2℃ throughout the reaction, the degradation rate of sulfamethoxazole by the CSTC-0 prepared in this example was 90.86% at 10 min.

[0061] Comparative example 2:

[0062] The difference between this embodiment and specific embodiment one is that step 5 is not added CoCl2·6H2O and L-cysteine, and step 4 is changed to 25 mL of anhydrous ethanol and DMF are added to 0.2 g of Ti3C2 at room temperature, and ultrasonic treatment is continued for 2 h.

[0063] Results: Titanium carbide-carbon cloth composite anode material (Ti3C2 / CC) was prepared, named TC-3.

[0064] The TC-3 prepared in this embodiment was tested for the performance of electro-activated persulfate degradation of sulfamethoxazole. When a constant voltage of 3V was applied to the reaction process, the amount of persulfate applied was 1mmol / L, the initial concentration of sulfamethoxazole was 10mg / L, and the temperature was controlled at 25±2℃ throughout the reaction, the degradation rate of sulfamethoxazole by the TC-3 prepared in this embodiment was 7.34% in 10min.

[0065] From the above, it can be seen that the redox performance of Ti3C2 itself is limited, but when it is combined with Co x S y , the special multi-layer structure and high electronic conductivity of the composite can improve the performance of the catalyst in activating persulfate to degrade sulfamethoxazole, inhibit the agglomeration of Co x S y , improve the electron transfer rate and facilitate the generation of non-free radicals. Compared with the previously reported anode-activated persulfate degradation of antibiotics system, this system has excellent degradation performance and a high non-free radical contribution rate through a simple preparation process. The present application provides theoretical and technical guidance for the practical application of Ti3C2-based electro-activated persulfate technology.

[0066] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent replacement and improvement of the above embodiments within the scope of the technical solution of the present application, according to the technical essence of the present application, within the spirit and principles of the present application, are all within the protection scope of the present application.

Claims

1. A method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material, characterized in that, The preparation method involves the following steps: Step 1: Cut the activated carbon cloth into a certain size, then sonicate it in deionized water and anhydrous ethanol for 10 minutes and dry it. Step 2: Gradually add lithium fluoride and aluminum carbide powder to a 9 mol / L hydrochloric acid solution and stir in a water bath at 35 °C for 24-48 hours. Step 3: Centrifuge the solution obtained in Step 2 and wash it with deionized water several times until the pH value is 6. Collect the bottom precipitate and freeze-dry it for 12-24 hours to obtain the etched titanium carbide powder. Step 4: Thoroughly mix the titanium carbide powder obtained in Step 3 with anhydrous ethanol and dimethylformamide, and stir for 2 hours; Step 5: Thoroughly mix cobalt chloride hexahydrate with anhydrous ethanol and dimethylformamide, sonicate for 30 minutes, and then add... L - Cysteine ​​and sonication for 30 minutes; Step 6: Mix the solutions obtained in Step 4 and Step 5 thoroughly and stir for 30 minutes. Transfer the resulting mixture and the treated activated carbon cloth to a 100 mL reaction vessel. Heat the mixture from room temperature to 180-220 °C at a heating rate of 10-20 °C / min in an oven and keep it at that temperature for 24 hours. Then cool the mixture to room temperature in the oven. Step 7: After removing the material from Step 6, rinse it with deionized water and anhydrous ethanol, and dry it in a vacuum drying oven at 60 ℃ for 10-14 hours to obtain cobalt sulfide-titanium carbide-carbon cloth composite anode material.

2. The method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 1, characterized in that, In step one, the drying temperature is 60~80 ℃ and the time is 3~4 hours.

3. The method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 1, characterized in that, In step two, the mass-to-volume ratio of aluminum carbide, lithium fluoride, and hydrochloric acid solution is (1~2) g:(1.6~2) g:20 mL.

4. The method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 1, characterized in that, In step three, the centrifugation rate is 8000~12000 rpm / min, and the centrifugation time is 5~10 minutes.

5. The method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 1, characterized in that, In step four, the mass-to-volume ratio of titanium carbide powder to anhydrous ethanol and dimethylformamide is (0.034~0.2) g:15mL:15 mL.

6. The method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 1, characterized in that, In step five, cobalt chloride hexahydrate, anhydrous ethanol, and dimethylformamide are used. L The mass-to-volume ratio of cysteine ​​is 0.163 g: 10 mL: 10 mL: (0.248~0.496) g.

7. The method for preparing a cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 1, characterized in that, In step seven, the molar ratio of cobalt sulfide to titanium carbide in the cobalt sulfide-titanium carbide-carbon cloth composite anode is 1:(0.5~3).

8. A cobalt sulfide / titanium carbide / carbon cloth composite anode material, characterized in that, The cobalt sulfide / titanium carbide / carbon cloth composite anode material is prepared by the preparation method of cobalt sulfide / titanium carbide / carbon cloth composite anode material as described in any one of claims 1-7.

9. The cobalt sulfide / titanium carbide / carbon cloth composite anode material according to claim 8, characterized in that, It is used to remove antibiotics in aquatic environments.

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