Ni-mof / ti3c2t for capacitive deionization technology x Composite electrode material and preparation method and application thereof

Abstract

This invention provides a Ni-MOF / Ti3C2T for capacitive deionization technology. x Composite electrode materials, their preparation methods, and applications are disclosed. The preparation method includes: dissolving fluoride in an aqueous HCl solution to prepare an etching solution; adding Ti3AlC2 powder to the etching solution, stirring, transferring to a reaction vessel, reacting at 80–100°C for 3–6 days, collecting the precipitate, washing the precipitate with deionized water by centrifugation until the pH of the supernatant is 6–7, and then washing with anhydrous ethanol by centrifugation 3–5 times; after centrifugation and washing, adding to an aqueous LiCl solution, reacting, and then washing the product with deionized water by centrifugation 3–5 times to obtain Ti3C2T. x Materials; Ti3C2T x The material was dispersed in an ethanol solution, Ni(NO3)2·6H2O was added and stirred to obtain a first solution; H3BTC was dissolved in ethanol to obtain a second solution; the first and second solutions were mixed and transferred to a reaction vessel, and reacted at 130–170 °C for 18–30 h; after naturally cooling to room temperature, the material was washed 3–5 times by centrifugation with anhydrous ethanol, and then freeze-dried to obtain Ni-MOF / Ti3C2T. x Composite electrode material. The Ni-MOF / Ti3C2T of this invention... x Composite electrode materials exhibit good electrochemical performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment, and particularly relates to a Ni-MOF / Ti3C2T x Composite electrode material and preparation method and application thereof. BACKGROUND

[0002] Under the challenges of global shortage of freshwater resources, aggravated water pollution and other environmental problems, it is of great practical significance to develop water treatment technology. Capacitive deionization technology has great application potential and wide application prospect in the field of water treatment due to its low energy consumption, in-situ regeneration, no secondary pollution to the environment and other advantages.

[0003] The key to capacitive deionization technology is the preparation of high-performance electrode materials. Among them, the Faraday electrode material realizes the deintercalation of ions through redox reaction, and can avoid the common ion effect of conventional carbon materials, so that the capacitive deionization performance is improved.

[0004] Ti3C2T x (T x Functional groups such as -OH, -F) is a new type of two-dimensional layered structure Faraday electrode material, which is gradually applied in the fields of catalysis, secondary battery, capacitive desalination and the like. However, in practical application, Ti3C2T x is easy to collapse and stack, causing the active sites to be covered, the ion diffusion dynamics to be low, and thus affecting the electrochemical performance. SUMMARY

[0005] In view of this, the purpose of the present application is to provide a Ni-MOF / Ti3C2T x Composite electrode material and preparation method and application thereof for capacitive deionization technology to improve the existing problems in capacitive deionization technology.

[0006] The present application provides a preparation method of a Ni-MOF / Ti3C2T x Composite electrode material for capacitive deionization technology, which comprises the following steps:

[0007] 1) Dissolve fluoride in an aqueous HCl solution to obtain an etching solution;

[0008] 2) Slowly add Ti3AlC2 powder to the etching solution, stir uniformly, then transfer to a reaction kettle, and react at 80-100 °C for 3-6 days to collect the precipitate, then centrifugally wash the precipitate with deionized water until the pH of the supernatant is 6-7, and then centrifugally wash the precipitate with anhydrous ethanol for 3-5 times; after centrifugal washing, add to a LiCl aqueous solution for reaction, and then centrifugally wash the product with deionized water for 3-5 times to obtain Ti3C2T x material.

[0009] 3) dispersing the Ti3C2T x dispersing the material into ethanol solution, adding Ni(NO3)2·6H2O and stirring to obtain a first solution;

[0010] 4) dissolving H3BTC in ethanol to obtain a second solution;

[0011] 5) mixing the first solution and the second solution and transferring into a reaction kettle, reacting at 130-170 °C for 18-30 h; after the reaction is completed, naturally cooling to room temperature, centrifuging and washing the product with anhydrous ethanol for 3-5 times, and freeze-drying to obtain a Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology.

[0012] Preferably: in step 1), the fluoride is one or both of LiF and NaF, the concentration of HCl in the aqueous HCl solution is 5-7 mol / L, and the ratio of the mass of the fluoride to the volume of the aqueous HCl solution is 1 g:30-50 mL.

[0013] Preferably: in step 2), the reaction kettle is shaken 3-5 times a day during the reaction.

[0014] Preferably: in step 2), the ratio of the mass of the Ti3AlC2 powder to the volume of the aqueous HCl solution is 1 g:30-60 mL, the concentration of the aqueous LiCl solution is 50-70 g / L, the reaction in the aqueous LiCl solution is 1-3 h, and the ratio of the mass of the Ti3AlC2 powder to the volume of the aqueous LiCl solution is 1 g:10-30 mL.

[0015] Preferably: in step 3), the ratio of the mass of the Ti3C2T x The ratio of the mass of the Ti3C2T

[0016] Preferably: in step 5), the molar ratio of Ni(NO3)2·6H2O to H3BTC is 1.5-2:1, the freezing temperature is in the range of-15 to-30 °C, and the drying time is 24-48 h.

[0017] The application also provides a Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology.

[0018] The application also provides a Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology.

[0019] The application uses the design idea of composite materials, utilizes Ti3C2T x The surface-rich groups have an adsorption effect on metal ions, in-situ growth method is adopted to grow Ni-MOF nanoparticles on Ti3C2T x , Ni-MOF is introduced into the Ti3C2T x structure, and a tightly coupled Ni-MOF / Ti3C2T x composite electrode material is constructed, so that the problems of a large reduction of exposed active sites and low ion diffusion kinetics caused by self-stacking effect are solved, the conductivity of Ni-MOF is improved, and additional pseudo-capacitance contribution is provided. x In this way, the respective characteristics of Ti3C2T x and Ni-MOF are fully utilized, and the properties of each component are maximally integrated, so that the Ni-MOF / Ti3C2T x composite electrode material of the application has good electrochemical performance.

[0020] Experimental data show that, under the same conditions, the CV curve area and redox peak intensity of the Ni-MOF / Ti3C2T x composite electrode material of the application are obviously larger than those of Ti3C2T x , indicating that the specific capacitance is obviously enhanced and the redox reaction kinetics is fast.

[0021] The Ni-MOF / Ti3C2T x composite electrode material of the application is applied to a composite electrode material for removing ions in a capacitive deionization technology, which can effectively improve the removal rate and promote the development of the capacitive deionization technology, and make a certain contribution to solving the problem of water resource shortage. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiments will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope, and other related drawings can be obtained by those skilled in the art without creative labor on the premise of not paying creative labor.

[0023] Figure 1 The SEM images of Ti3C2T x ( Figure 1 a) and Ni-MOF / Ti3C2T x electrode material (b) prepared in Embodiment 1 of the application are shown in Figs. 1 and 2, respectively. Figure 1

[0024] Figure 2 ​Ti3C2T prepared in Example 1 of the present application x and Ni-MOF / Ti3C2T x Comparison chart of electrochemical performance of electrode materials measured by electrochemical workstation;

[0025] Figure 3 Ti3C2T prepared in Example 1 of the present application x and Ni-MOF / Ti3C2T x Variation curve of removal rate of Cr(VI) of electrode materials (voltage 1.0 V, concentration of Cr(VI) measured by ultraviolet-visible spectrophotometer by national standard method). DETAILED DESCRIPTION

[0026] The technical solutions of the present application are further described below in combination with specific examples, however, the specific methods and descriptions used in the examples do not limit the protection scope of the present application.

[0027] It should be noted that, in the following examples, the devices, reagents, processes, parameters, etc. involved are conventional devices, reagents, processes, parameters, etc. unless otherwise specified, and will not be described in the examples. All ranges listed include all point values within the range. The "room temperature" refers to the conventional ambient temperature, which can be 10-30°C.

[0028] Example 1

[0029] Ni-MOF / Ti3C2T of the present example x The preparation process of the composite electrode material is as follows:

[0030] 1) Dissolve 1.5 g of LiF in 60 mL of 6 mol / L HCl aqueous solution to obtain an etching solution;

[0031] 2) Slowly add 1.5 g of Ti3AlC2 powder to the etching solution obtained in step 1), stir uniformly, then transfer to a reaction kettle, react at 90°C for 5 days, shake the reaction kettle 3 times a day. Collect the precipitate, centrifuge and wash the precipitate with deionized water until the supernatant pH is 6 (centrifuge speed is 4500 rpm), then centrifuge and wash with anhydrous ethanol; after centrifugal washing, add to 25 mL of 60 g / L LiCl aqueous solution and react for 2 h, then repeatedly centrifuge and wash the obtained product with deionized water (centrifuge speed is 3500 rpm) to obtain Ti3C2T x material;

[0032] 3) The Ti3C2T xThe material was dispersed in 20 mL of ethanol solution, and then 2.25 mmol of Ni(NO3)2·6H2O was added and stirred to obtain the first solution;

[0033] 4) Dissolve 1.25 mmol H3BTC in 10 mL of ethanol to obtain a second solution;

[0034] 5) Then, the first solution from step 3) and the second solution from step 4) were mixed and transferred to a reaction vessel, and reacted at 150ºC for 24 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The product was washed five times with anhydrous ethanol by centrifugation, and then freeze-dried at -20℃ for 48 h to obtain Ni-MOF / Ti3C2T. x Composite electrode materials.

[0035] The Ti3C2T prepared in this embodiment x and Ni-MOF / Ti3C2T x SEM images of electrode materials are shown below. Figure 1 As shown, from Figure 1 As can be seen from the etched Ti3C2T x The material has an accordion-like structure and a smooth surface; after being composited with Ni-BTC ( Figure 1 b), Ni-BTC / Ti3C2T x Ni-BTC particles are uniformly attached to the surface of the material.

[0036] The Ti3C2T prepared in this embodiment x and Ni-MOF / Ti3C2T x A comparison of the electrochemical performance of electrode materials is shown in the figure below. Figure 2 As shown, from Figure 2 It can be seen that the obvious redox peaks on the CV curve indicate that Ti3C2T x With Ni-MOF / Ti3C2T x Composite electrode materials are typical battery-type electrodes. Among them, Ni-MOF / Ti3C2T... x The area of ​​the CV curve and the intensity of the redox peak are significantly greater than those of Ti3C2T. x The area under the CV curve and the intensity of the redox peak indicate a significantly enhanced specific capacitance and rapid redox reaction kinetics.

[0037] The Ti3C2T prepared in this embodiment x and Ni-MOF / Ti3C2T x The removal rate curve of Cr(VI) by the electrode material is shown in the figure. Figure 3 As shown, by Figure 3 As can be seen from this, Ti3C2T xThe removal rate of Cr(VI) was significantly increased after combining with Ni-MOF. Ti3C2T x The removal rate of Cr(VI) was 76.5% in Ni-MOF / Ti3C2T x The composite electrode material achieved a Cr(VI) removal rate of 94.1%, indicating that the Ni-MOF / Ti3C2T electrode prepared in this embodiment exhibits good performance. x Composite electrode materials can effectively remove heavy metal Cr(VI) and have good application prospects.

[0038] Example 2

[0039] The Ni-MOF / Ti3C2T in this embodiment x The preparation process of the composite electrode material is as follows:

[0040] 1) Dissolve 1.5 g NaF in 60 mL of 5 mol / L HCl aqueous solution to obtain an etching solution;

[0041] 2) Slowly add 1.5 g of Ti3AlC2 powder to the etching solution, stir well, and then transfer to a reaction vessel. React at 100 ºC for 5 days, shaking the reaction vessel 3 times daily. Collect the precipitate and wash it with deionized water by centrifugation until the pH of the supernatant reaches 6 (centrifuge speed: 4500 rpm), then wash it with anhydrous ethanol by centrifugation. After centrifugation and washing, add it to 25 mL of 60 g / L LiCl aqueous solution and react for 2 h. Then repeatedly wash the obtained product with deionized water by centrifugation (centrifuge speed: 3500 rpm) to obtain Ti3C2T x Material;

[0042] 3) Take the Ti3C2T obtained in step 2) x Disperse the solution into 20 mL of ethanol solution, then add 2.25 mmol of Ni(NO3)2·6H2O and stir to obtain the first solution;

[0043] 4) Dissolve 1.25 mmol H3BTC in 10 mL of ethanol to obtain a second solution;

[0044] 5) Then, the first solution obtained in step 3) and the second solution obtained in step 4) were mixed and transferred to a reaction vessel, and reacted at 150 ºC for 24 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The product was washed three times with anhydrous ethanol by centrifugation, and then freeze-dried at -20 ºC for 48 hours to obtain Ni-MOF / Ti3C2T. x Composite electrode materials.

[0045] Example 3

[0046] The Ni-MOF / Ti3C2T in this embodiment xThe preparation process of the composite electrode material is as follows:

[0047] 1) 1.0 g of LiF was dissolved in 50 mL of 6 mol / L HCl aqueous solution to obtain an etching solution;

[0048] 2) 1.5 g of Ti3AlC2 powder was slowly added into the etching solution, stirred uniformly, and then transferred into a reaction kettle, and reacted at 90 °C for 5 days. The reaction kettle was shaken 3 times a day. The precipitate was collected and centrifuged with deionized water until the pH of the supernatant was 6 (the centrifuge speed was 4500 rpm), and then centrifuged with anhydrous ethanol. After centrifugal washing, it was added into 25 mL of 60 g / L LiCl aqueous solution and reacted for 2 h, and then repeatedly centrifuged with deionized water (the centrifuge speed was 3500 rpm) to obtain Ti3C2T x material;

[0049] 3) The Ti3C2T x obtained in step 2) was dispersed into 20 mL of ethanol solution, 4.5 mmol of Ni(NO3)2·6H2O was added and stirred to obtain a first solution;

[0050] 4) 2.5 mmol of H3BTC was dissolved in 10 mL of ethanol to obtain a second solution;

[0051] 5) Then the first solution of step 3) and the second solution obtained in step 4) were mixed and transferred into a reaction kettle, and reacted at 150 °C for 24 hours. After the reaction was completed, it was naturally cooled to room temperature, centrifuged with anhydrous ethanol for 5 times, and then freeze-dried at -20 °C for 24 h to obtain a Ni-MOF / Ti3C2T x composite electrode material.

[0052] The above-described embodiments are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

Claims

1. A Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology. x A method for producing a composite electrode material, characterized by, The method comprises the following steps: 1) dissolving fluoride in aqueous HCl solution to prepare an etching solution; 2) slowly add Ti3AlC2 powder into the etching solution, stir uniformly, then transfer to the reaction kettle, collect the precipitate after reacting at 80~100 ºC for 3~6 days, centrifugal wash the precipitate with deionized water until the pH of supernatant is 6~7, then centrifugal wash 3~5 times with anhydrous ethanol, after centrifugal washing, add into LiCl aqueous solution for reaction, centrifugal wash the product with deionized water for 3~5 times after reaction, to obtain Ti3C2T x material; wherein the concentration of LiCl aqueous solution is 50~70 g / L, the reaction time in LiCl aqueous solution is 1~3 h, and the ratio of Ti3AlC2 powder mass to LiCl aqueous solution volume is 1 g:10~30 mL; 3) dispersing the Ti3C2T x material into an ethanol solution, adding Ni(NO3)2·6H2O and stirring to obtain a first solution; wherein the mass of the Ti3C2T x powder and the number of moles of Ni(NO3)2·6H2O are in the ratio 20-200 mg: 1 mmol; 4) dissolving H3BTC in ethanol to prepare a second solution; 5) mixing the first and second solutions and transferring them into a reaction vessel and reacting at 130-170 °C for 18-30 h; upon completion of the reaction, the product is washed with absolute ethanol by centrifugation 3-5 times and freeze-dried to obtain Ni-MOF / Ti3C2T x composite electrode material; wherein the molar ratio of Ni(NO3)2-6H2O and H3BTC is 1.5-2:

1.

2. The Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology of claim 1. x The preparation method of the composite electrode material is characterized in that: In step 1), the fluoride is one or both of LiF and NaF, the concentration of HCl in the aqueous HCl solution is 5-7 mol / L, and the mass of the fluoride to the volume of the aqueous HCl solution is 1 g: 30-50 mL.

3. The Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology of claim 1. x The preparation method of the composite electrode material is characterized by comprising the following steps: In step 2), the reaction kettle is shaken 3-5 times a day during the reaction.

4. The Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology of claim 1. x A method for preparing a composite electrode material, characterized by: In step 2), the mass of the Ti3AlC2 powder to the volume of the aqueous HCl solution is 1 g: 30-60 mL.

5. The Ni-MOF / Ti3C2T x composite electrode material for capacitive deionization technology of claim 1. x A method for preparing a composite electrode material, characterized by: In step 5), the freezing temperature is in the range of-15 to-30℃, and the drying time is 24-48 h.

6. A Ni-MOF / Ti3C2T composite electrode material for capacitive deionization technology. x Composite electrode material characterized in that, The method is prepared by any one of claims 1-5.

7. The Ni-MOF / Ti3C2T composite electrode material according to claim 6, wherein the Ti3C2T is MXene. x Use of the composite electrode material in water treatment.

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