A carbon nanofiber self-supporting film anode material and its preparation method and a capacitive deionization anode material for electrochemical chlorine removal

Abstract

The present invention belongs to the technical field of environmental material synthesis, and specifically relates to a carbon nanofiber self-supporting thin film anode material and a preparation method thereof, as well as a capacitive deionization anode material for electrochemical chlorine removal. The present invention provides a carbon nanofiber self-supporting thin film anode material, which is composed of a carbon nanofiber membrane material, wherein the carbon nanofiber membrane material includes a plurality of multi-channel carbon nanofibers (BiNCs@MCNF) loaded with bismuth nanoclusters. The carbon nanofibers prepared by the present invention using PAN and PMMA as electrospinning precursors have a hollow multi-channel structure. The carbonization process of converting PAN into carbon nanofibers is combined with the carbon thermal reduction process of converting Bi(NO3)3·5H2O into bismuth nanoclusters. The two processes occur simultaneously, without the need for secondary operations or the addition of other raw materials, making the in-situ preparation of metallic bismuth nanoclusters simple, feasible and efficient. The prepared carbon nanofiber membrane electrode material has excellent mechanical properties and can be directly used as the anode of CDI.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental material synthesis, and in particular relates to a carbon nanofiber self-supporting thin film anode material and a preparation method thereof, as well as a capacitor deionization anode material for electrochemical chlorine removal. Background Art

[0002] The imbalance between water supply and demand is becoming increasingly prominent, and water purification has become a hot topic. In the total urban water consumption, industrial water consumption accounts for 60-80%, of which circulating cooling water accounts for the largest proportion, accounting for about 70-80% of industrial water consumption. Circulating cooling water is widely used in industries such as steel, metallurgy, electricity, and petrochemicals. In the circulating cooling water system, as the number of cycles increases, chloride ions (Cl - ) is a typical non-volatile substance that is very easy to cause corrosion, seriously threatening production efficiency and safety. - Removal technologies mainly include precipitation, evaporation concentration, ion exchange, adsorption, and reverse osmosis. However, these methods all have problems such as varying degrees of membrane fouling, complex operations, and high operating costs.

[0003] As an emerging ion separation process, capacitive deionization (CDI) technology is different from traditional Cl - The removal process is different. CDI has the advantages of no secondary pollution, easy regeneration, long cycle life and low energy consumption. - It has great application potential in the removal of chlorine. Electrode materials are the core components of CDI, and their design directly affects the performance of CDI technology. Among the CDI anode chlorine removal materials currently studied, Cl - The electrodes with the largest removal capacity are mainly Ag / AgCl and Bi / BiOCl electrodes, which are based on conversion reactions. Ag / AgCl electrodes are expensive and have limited practical application value. Bi / BiOCl electrodes have a theoretical capacity comparable to Ag / AgCl electrodes, but due to the large volume changes they undergo during charge and discharge, their cyclability is a challenge.

[0004] Therefore, CDI anode materials with good cycle stability and high chlorine removal capacity are in urgent need of research. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a carbon nanofiber self-supporting thin film anode material and a preparation method thereof, as well as a capacitive deionization anode material for electrochemical chlorine removal.

[0006] To achieve the above objectives, the solutions adopted by the present invention are as follows:

[0007] In a first aspect, the present invention provides a carbon nanofiber self-supporting thin film anode material, which is composed of a carbon nanofiber membrane material, wherein the carbon nanofiber membrane material includes a plurality of multi-channel carbon nanofibers loaded with bismuth nanoclusters (BiNCs@MCNF).

[0008] In a second aspect, the present invention further provides a method for preparing the carbon nanofiber self-supporting thin film anode material as described above, comprising the following steps:

[0009] Step (1), adding bismuth nitrate hydrate powder, polyacrylonitrile and polymethyl methacrylate into an organic solvent to obtain a mixed suspension;

[0010] Step (2), electrospinning the mixed suspension to obtain a Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane;

[0011] Step (3) pre-oxidizes the Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane, and then carbonizes and carbon thermally reduces it to obtain a carbon nanofiber self-supporting thin film anode material for electrochemical chlorine removal.

[0012] Preferably, in step (1), the organic solvent is selected from at least one of ethyl acetate, isopropyl acetate, n-propyl acetate, isobutyl acetate, ethanol, ethylene glycol, propylene glycol, methanol, isopropanol, tert-butanol, diethyl ether, 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, methyl tert-butyl ether, cyclopentyl methyl ether, diphenyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, toluene, trifluorotoluene, cyclohexane, n-heptane, xylene, acetonitrile, propionitrile, butyronitrile, dichloromethane, chloroform, dichloroethane, chlorobenzene and dibromoethane, preferably N,N-dimethylformamide.

[0013] Preferably, in step (1), bismuth nitrate hydrate powder, polyacrylonitrile and polymethyl methacrylate are added to an organic solvent in sequence to obtain a mixed suspension.

[0014] Preferably, in step (1), the particle size of the bismuth nitrate hydrate powder is 600-1000 mesh; the mass ratio of the bismuth nitrate hydrate powder, polyacrylonitrile and polymethyl methacrylate is (1-3):2:2; and the mass concentration of the mixed suspension is 26.37% to 36.92%.

[0015] Preferably, in step (2), the setting parameters of the electrospinning process are: two 10 mL plastic syringes equipped with stainless steel needles, a syringe push speed of 0.05-0.10 mm / min, a voltage of 15-18 V, a receiving distance of 18-22 cm, a receiving drum speed of 70-90 rpm, a translation speed of 450-550 mm / min, a translation distance of 80-120 mm, a temperature of 25 ° C, a humidity of 35%, and a spinning time of 7-9 h.

[0016] Preferably, in step (3), the pre-oxidation process is carried out in a muffle furnace, the pre-oxidation temperature is 240-260° C., the pre-oxidation time is 0.5-1.5 h, and the atmosphere is air; during the pre-oxidation process, a semicircular corundum crucible with a cover is used for tension drawing.

[0017] Preferably, the temperature rising program of the pre-oxidation is: from 20°C to 200°C at a heating rate of 5°C / min; then from 200°C to 250°C at a heating rate of 1°C / min.

[0018] Preferably, in step (3), the carbonization process is to carbonize PAN / PMMA in the Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane to form multi-channel carbon nanofibers, and the carbon thermal reduction process is to carbon thermally reduce the Bi(NO3)3·5H2O in the Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane into bismuth nanoclusters loaded on the multi-channel carbon nanofibers; the carbonization process and the carbon thermal reduction process are both carried out in a tubular furnace, the carbonization and carbon thermal reduction temperatures are 850-950°C, and the carbonization and carbon thermal reduction times are 1-3h.

[0019] In a third aspect, the present invention also provides a capacitive deionization anode material for electrochemical chlorine removal, characterized in that it is the above-mentioned carbon nanofiber self-supporting thin film anode material and the carbon nanofiber self-supporting thin film anode material prepared by the above-mentioned preparation method, and is composed of a carbon nanofiber membrane material, wherein the carbon nanofiber membrane material includes a plurality of multi-channel carbon nanofibers loaded with bismuth nanoclusters (BiNCs@MCNF).

[0020] According to the present invention, carbon nanofibers prepared using PAN and PMMA as electrospinning precursors have a hollow multi-channel structure. PAN serves as the carbon source, and PMMA serves as a sacrificial template for the channels. During the spinning process, PAN and PMMA undergo phase separation. Subsequently, during carbonization, PAN is converted into a carbon skeleton with excellent conductivity, promoting electron transport. PMMA undergoes pyrolysis, forming a hollow channel structure that facilitates ion migration during electrochemical chlorine removal.

[0021] The present invention cleverly combines the carbonization process of converting PAN into carbon nanofibers with the carbothermal reduction process of converting Bi(NO3)3·5H2O into bismuth nanoclusters. The two occur simultaneously, eliminating the need for secondary operations or the addition of other raw materials, making the in situ preparation of metallic bismuth nanoclusters simple, feasible, and efficient.

[0022] The nanochannels of the multichannel carbon nanofibers, formed by pre-oxidation and carbonization of PAN and PMMA, confine Bi(NO₃)₃·5H₂O, resulting in smaller bismuth nanoclusters generated in situ within the channels. The small size of the bismuth nanoclusters and the encapsulation of the multichannel carbon nanofibers significantly mitigate the bulk expansion caused by the conversion of Bi to BiOCl during the chlorine removal process, thereby improving the long-term cycling stability of the chlorine removal electrode.

[0023] The present invention precisely controls the heating rate and tension stretching during the pre-oxidation process to ensure that the finally prepared carbon nanofiber membrane electrode material has excellent mechanical properties and can be directly used as the anode of CDI without the addition of conventional binders and conductive agents, thus avoiding tedious operations such as slurry preparation and film coating.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The carbon nanofibers prepared by the present invention using PAN and PMMA as electrospinning precursors have a hollow multi-channel structure. The carbonization process of converting PAN into carbon nanofibers is combined with the carbon thermal reduction process of converting Bi(NO3)3·5H2O into bismuth nanoclusters. The two processes occur simultaneously without the need for secondary operations or the addition of other raw materials. This makes the in-situ preparation of metallic bismuth nanoclusters simple, feasible, and efficient. The prepared carbon nanofiber membrane electrode material has excellent mechanical properties and can be directly used as the anode of CDI. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is an X-ray diffraction (XRD) diagram of bismuth nanoclusters and multi-channel carbon nanofibers grown in situ confined on the multi-channel carbon nanofibers of the present invention.

[0027] Figure 2 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of bismuth nanoclusters and multi-channel carbon nanofibers grown in situ confined on the multi-channel carbon nanofibers of the present invention.

[0028] Figure 3 An optical picture showing the toughness of the in-situ confined growth bismuth nanocluster electrode material of the multi-channel carbon nanofiber of the present invention.

[0029] Figure 4This is a graph showing the chlorine removal rate of bismuth nanoclusters and multi-channel carbon nanofibers grown in situ confined on the multi-channel carbon nanofibers of the present invention.

[0030] Figure 5 This is a graph showing the chlorine removal capacity of bismuth nanoclusters grown in situ on the multi-channel carbon nanofibers of the present invention at different voltages.

[0031] Figure 6 This is a graph showing the chlorine removal capacity and energy-normalized chloride ion adsorption capacity of bismuth nanoclusters grown in situ on the multi-channel carbon nanofibers of the present invention within 100 cycles. DETAILED DESCRIPTION

[0032] The present invention is further illustrated below with reference to the following examples. The various master alloys used in the present invention are commercially available products. The following examples will help those skilled in the art further understand the present invention, but are not intended to limit the present invention in any way. Those skilled in the art will appreciate that variations and improvements can be made without departing from the spirit of the present invention. Any equivalent transformations made using the present invention's description, or any direct or indirect application in other related technical fields, are encompassed within the scope of protection of the present invention.

[0033] The invention provides a carbon nanofiber self-supporting film anode material and a preparation method thereof, as well as a capacitor deionization anode material using the same for electrochemical chlorine removal.

[0034] <Preparation Method of In-Situ Confined Growth of Bismuth Nanoclusters on Multi-channel Carbon Nanofibers>

[0035] A method for preparing bismuth nanoclusters by in-situ confined growth of multi-channel carbon nanofibers comprises the following steps:

[0036] (1) Weighing bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), grinding it with an agate mortar, adding it to N,N-dimethylformamide (DMF), and stirring for a certain period of time to obtain a first mixed suspension;

[0037] (2) adding polyacrylonitrile (PAN) to the first mixed suspension and stirring thoroughly to obtain a second mixed suspension;

[0038] (3) adding polymethyl methacrylate (PMMA) to the second mixed suspension and stirring thoroughly to obtain a third mixed suspension;

[0039] (4) injecting the third mixed suspension into an electrospinning device and performing an electrospinning operation to obtain a Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane;

[0040] (5) The composite nanofiber membrane was pre-oxidized, carbonized, and then carbon-thermally reduced to obtain a multi-channel carbon nanofiber (BiNCs@MCNF) self-supporting thin film anode material loaded with bismuth nanoclusters that can be used for electrochemical chlorine removal.

[0041] In fact, in step (4), PAN and PMMA phase separation and axial stretching occurred, and Bi(NO3)3·5H2O was uniformly arranged in the fiber, creating good conditions for the subsequent multi-channel in situ confined growth of bismuth nanoclusters.

[0042] In fact, in step (5), the carbonization of PAN, the pyrolysis of PMMA and the carbothermal reduction of Bi(NO3)3·5H2O occur simultaneously, thereby obtaining bismuth nanoclusters with in-situ confined growth of multi-channel carbon nanofibers.

[0043] Wherein, in step (1), the particle size of Bi(NO3)3·5H2O is 800 mesh, the stirring time is 30 min, and the volume of DMF is 20 mL.

[0044] In step (2), the amount of PAN added was 2 g, the stirring temperature was room temperature, the stirring speed was 600 rpm, and the stirring time was 6 h.

[0045] In step (3), the amount of PMMA added is 2 g, the stirring temperature is room temperature, the stirring speed is 600 rpm, and the stirring time is 6 h.

[0046] In step (4), the electrospinning process was performed using the following parameters: plastic syringes: two 10 mL plastic syringes equipped with 21-gauge stainless steel needles; syringe push speed: 0.08 mm / min; voltage: 15-18 V; receiving distance: 18-22 cm; receiving drum speed: 80 rpm; translation speed: 500 mm / min; translation distance: 100 mm; temperature: 25°C; humidity: 35%; spinning time: 8 h.

[0047] In step (5), the pre-oxidation process is carried out in a muffle furnace, and the muffle furnace parameters are set as follows: 20-200°C, heating rate 5°C / min; 200-250°C, heating rate 1°C / min; pre-oxidation time: 1h.

[0048] In step (5), a semicircular corundum crucible with a cover having a length of 100 mm, a width of 40 mm, a radius of 20 mm, and a volume of 40 mL is used for tension drawing during the pre-oxidation process.

[0049] In step (5), the carbon thermal reduction process is carried out in a tube furnace, and the parameters of the tube furnace are set as follows: high-purity argon atmosphere, carbonization temperature 900°C, heating rate 5°C / min, and insulation time 2h.

[0050] <In-situ confined growth of bismuth nanoclusters on multi-channel carbon nanofibers>

[0051] The bismuth nanoclusters grown in situ confined on multi-channel carbon nanofibers are obtained by the above preparation method.

[0052] <Application of in-situ confined growth of bismuth nanoclusters on multi-channel carbon nanofibers>

[0053] Bismuth nanoclusters grown in situ on multi-channel carbon nanofibers are used as anode materials in capacitive deionization technology and in electrochemical chlorine removal.

[0054] The present invention will be further described below with reference to the examples.

[0055] Example 1:

[0056] The preparation method of the multi-channel carbon nanofiber in-situ confined growth bismuth nanoclusters (BiNCs@MCNF-1) of this embodiment includes the following steps:

[0057] (1) Weigh 1 g of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), grind it to 800 mesh using an agate mortar, add it to 20 mL of N,N-dimethylformamide (DMF), and stir for 30 min.

[0058] (2) Add 2 g of polyacrylonitrile (PAN) to the above suspension and stir magnetically at 600 rpm for 6 h.

[0059] (3) Add 2 g of polymethyl methacrylate (PMMA) to the above suspension and stir magnetically at 600 rpm for 6 h to obtain a spinning solution.

[0060] (4) The spinning solution was injected into two 10 mL plastic syringes equipped with No. 21 stainless steel needles at a speed of 0.08 mm / min. The syringes were placed in an electrospinning machine with a voltage of 15-18 V, a receiving distance of 18-22 cm, a receiving drum speed of 80 rpm, a translation speed of 500 mm / min, and a translation distance of 100 mm. The temperature was set at 25°C and the humidity was 35%. The electrospinning process lasted for 8 h to obtain a Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane.

[0061] (5) A composite nanofiber membrane with an area of 100 mm × 50 mm was cut and tensioned and fixed in a semicircular corundum crucible with a lid of 100 mm in length, 40 mm in width, 20 mm in radius, and 40 mL in volume. The crucible was then placed in a muffle furnace and heated at a rate of 5°C / min between 20 and 200°C and 1°C / min between 200 and 250°C, maintaining the temperature at 250°C for 1 h. The crucible was then transferred to a tube furnace, introduced with high-purity argon, and heated to 900°C at a rate of 5°C / min and maintained for 2 h to obtain the BiNCs@MCNF-1 chlorine removal electrode.

[0062] Example 2:

[0063] The preparation method of in-situ confined growth of bismuth nanoclusters (BiNCs@MCNF-2) on multi-channel carbon nanofibers of this embodiment comprises the following steps:

[0064] (1) Weigh 2 g of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), grind it to 800 mesh using an agate mortar, and then add it to 20 mL of N,N-dimethylformamide (DMF) and stir for 30 min.

[0065] (2) Add 2 g of polyacrylonitrile (PAN) to the above suspension and stir magnetically at 600 rpm for 6 h.

[0066] (3) Add 2 g of polymethyl methacrylate (PMMA) to the above suspension and stir magnetically at 600 rpm for 6 h to obtain a spinning solution.

[0067] (4) The spinning solution was injected into two 10 mL plastic syringes equipped with No. 21 stainless steel needles at a speed of 0.08 mm / min. The syringes were placed in an electrospinning machine with a voltage of 15-18 V, a receiving distance of 18-22 cm, a receiving drum speed of 80 rpm, a translation speed of 500 mm / min, and a translation distance of 100 mm. The temperature was set at 25°C and the humidity was 35%. The electrospinning process lasted for 8 h to obtain a Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane.

[0068] (5) A composite nanofiber membrane with an area of 100 mm × 50 mm was cut and tensioned and fixed in a semicircular corundum crucible with a lid of 100 mm in length, 40 mm in width, 20 mm in radius, and 40 mL in volume. The crucible was then placed in a muffle furnace and heated at a rate of 5°C / min between 20 and 200°C and 1°C / min between 200 and 250°C, maintaining the temperature at 250°C for 1 h. The crucible was then transferred to a tube furnace, introduced with high-purity argon gas, and heated to 900°C at a rate of 5°C / min and maintained for 2 h to obtain a BiNCs@MCNF-2 chlorine removal electrode.

[0069] Example 3:

[0070] The preparation method of the multi-channel carbon nanofiber in-situ confined growth bismuth nanoclusters (BiNCs@MCNF-3) of this embodiment includes the following steps:

[0071] (1) Weigh 3 g of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), grind it to 800 mesh using an agate mortar, and then add it to 20 mL of N,N-dimethylformamide (DMF) and stir for 30 min.

[0072] (2) Add 2 g of polyacrylonitrile (PAN) to the above suspension and stir magnetically at 600 rpm for 6 h.

[0073] (3) Add 2 g of polymethyl methacrylate (PMMA) to the above suspension and stir magnetically at 600 rpm for 6 h to obtain a spinning solution.

[0074] (4) The spinning solution was injected into two 10 mL plastic syringes equipped with No. 21 stainless steel needles at a speed of 0.08 mm / min. The syringes were placed in an electrospinning machine with a voltage of 15-18 V, a receiving distance of 18-22 cm, a receiving drum speed of 80 rpm, a translation speed of 500 mm / min, and a translation distance of 100 mm. The temperature was set at 25°C and the humidity was 35%. The electrospinning process lasted for 8 h to obtain a Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane.

[0075] (5) A composite nanofiber membrane with an area of 100 mm × 50 mm was cut and tensioned and fixed in a semicircular corundum crucible with a lid of 100 mm in length, 40 mm in width, 20 mm in radius, and 40 mL in volume. The crucible was then placed in a muffle furnace and heated at a rate of 5°C / min between 20 and 200°C and 1°C / min between 200 and 250°C, maintaining the temperature at 250°C for 1 h. The crucible was then transferred to a tube furnace, introduced with high-purity argon, and heated to 900°C at a rate of 5°C / min and maintained for 2 h to obtain a BiNCs@MCNF-3 chlorine removal electrode.

[0076] Comparative Example 1:

[0077] This comparative example is multichannel carbon nanofiber (MCNF), and its preparation method includes the following steps:

[0078] (1) Add 2 g of polyacrylonitrile (PAN) to 20 mL of N,N-dimethylformamide (DMF) and stir magnetically at 600 rpm for 6 h.

[0079] (2) Add 2 g of polymethyl methacrylate (PMMA) to the above solution and stir magnetically at 600 rpm for 6 h to obtain a spinning solution.

[0080] (3) The spinning solution was injected into two 10 mL plastic syringes equipped with No. 21 stainless steel needles at a speed of 0.08 mm / min. The syringes were placed in an electrospinning machine with a voltage of 15–18 V, a receiving distance of 18–22 cm, a receiving drum speed of 80 rpm, a translation speed of 500 mm / min, and a translation distance of 100 mm. The temperature was set to 25°C and the humidity to 35%. The electrospinning process lasted for 8 h to obtain a PAN / PMMA nanofiber membrane.

[0081] (4) A nanofiber membrane with an area of 100 mm × 50 mm was cut and tensioned and fixed in a semicircular corundum crucible with a lid of 100 mm in length, 40 mm in width, 20 mm in radius, and 40 mL in volume. The membrane was then placed in a muffle furnace and heated at a rate of 5°C / min between 20°C and 200°C and at a rate of 1°C / min between 200°C and 250°C, maintaining the temperature at 250°C for 1 h. The crucible was then transferred to a tube furnace, infused with high-purity argon gas, and heated at a rate of 5°C / min to 900°C, where it was maintained for 2 h to obtain a MCNF dechlorination electrode.

[0082] <Experiment>

[0083] The following experiments were carried out using the products of the above examples and comparative examples.

[0084] <Experiment 1>

[0085] The purpose of this experiment is to characterize the crystal structure of the prepared multi-channel carbon nanofibers with in-situ confined growth of bismuth nanoclusters (Examples 1, 2 and 3) and multi-channel carbon nanofibers (Comparative Example 1).

[0086] Figure 1 The X-ray diffraction (XRD) test results of the multi-channel carbon nanofiber (MCNF) prepared by comparative example 1 and the multi-channel carbon nanofiber in-situ confined growth bismuth nanoclusters (BiNCs@MCNF) prepared by the preparation methods of examples 1, 2, and 3 are shown. BiNCs@MCNF-1, BiNCs@MCNF-2, and BiNCs@MCNF-3 represent the addition amounts of the precursor Bi(NO3)3·5H2O, respectively, of 1g, 2g, and 3g. Figure 1As shown, the broad peak at 2θ=24.94° in the MCNF prepared in the comparative example without bismuth nanoclusters is a typical diffraction peak of graphite carbon, which comes from the product after carbonization of PAN. After adding Bi(NO3)3·5H2O, all samples (Example 1, Example 2 and Example 3) showed diffraction peaks at 2θ=27.266°, 38.134° and 39.736°, which correspond to the (012), (104) and (110) crystal planes of metallic bismuth, respectively, and are consistent with the standard card PDF#85-1331. In addition, since the bismuth nanoclusters obtained are relatively small in size and overlap with the carbon peak, their XRD peaks are not very sharp. The above analysis proves the successful preparation of in-situ confined growth of bismuth nanoclusters in multi-channel carbon nanofibers.

[0087] Experiment 2

[0088] The purpose of this experiment is to characterize the microscopic morphology of the in-situ confined growth of bismuth nanoclusters in the multi-channel carbon nanofibers prepared in Example 2 and the multi-channel carbon nanofibers prepared in Comparative Example 1.

[0089] Figure 2 The results of plane and cross-sectional photography of the multi-channel carbon nanofibers (MCNF) obtained in Comparative Example 1 and the multi-channel carbon nanofiber in-situ confined growth bismuth nanoclusters (BiNCs@MCNF) prepared in Example 2 using scanning electron microscopy (SEM, top and bottom) and transmission electron microscopy (TEM, middle). As shown in the figure, the prepared fibers have a diameter of about 400 to 600 nm and have channels with a diameter of about 10 to 50 nm. MCNF presents a hollow one-dimensional multi-channel structure, and obvious bismuth nanoclusters appear in the sample after adding Bi(NO3)3·5H2O. The above microscopic morphology analysis shows that MCNF has the structural advantages of electron transport and ion diffusion required for subsequent electrochemical dechlorination applications. At the same time, smaller bismuth nanoclusters also pave the way for high dechlorination capacity and long-term dechlorination cycle stability.

[0090] <Experiment 3>

[0091] The purpose of this experiment is to characterize the mechanical properties of the in-situ confined growth of bismuth nanoclusters on the multi-channel carbon nanofibers prepared in Example 2.

[0092] Figure 3This is an optical image of a multichannel carbon nanofiber membrane loaded with bismuth nanoclusters prepared using the aforementioned method. As shown, the resulting BiNCs@MCNF membrane is a flexible, self-supporting film with good toughness that can be bent into any angle. This also demonstrates that the fiber membrane prepared by this invention can be used directly as a chlorine removal electrode, eliminating the need for the binders and conductive agents required in conventional electrode preparation. This eliminates the subsequent steps of slurry mixing and coating, significantly shortening production time and simplifying the process.

[0093] <Experiment 4>

[0094] The purpose of this experiment is to explore the electrochemical chlorine removal rate of the multi-channel carbon nanofibers prepared in Example 1, Example 2 and Example 3 with in-situ confined growth of bismuth nanoclusters and the multi-channel carbon nanofibers prepared in Comparative Example 1.

[0095] Figure 4 For NaCl concentration of 1000 mg L -1 The average electrochemical chlorine removal rate of the samples prepared in Example 1, Example 2, and Example 3 varies with time under an applied voltage of 1.4 V. As shown in the figure, the chlorine removal rate of all samples increases first and then decreases. Among them, BiNCs@MCNF-2 reaches a maximum chlorine removal rate of 21.41 mg at about 80 s. Cl - / g Anode / min, then gradually stabilized and maintained at about 5.55mg Cl - / g Anode / min fast chlorine removal rate.

[0096] <Experiment 5>

[0097] The purpose of this experiment is to explore the electrochemical chlorine removal capacity of the in-situ confined growth of bismuth nanoclusters on the multi-channel carbon nanofibers prepared in Example 2.

[0098] Figure 5 For BiNCs@MCNF-2 at a NaCl concentration of 1000 mg L -1 The applied voltage is 1.2V, 1.4V, and 1.6V respectively, and the electrochemical dechlorination capacity changes with time. As shown in the figure, BiNCs@MCNF-2 reaches 236.74mg in 60min. Cl - / g Anode High chlorine removal capacity.

[0099] <Experiment 6>

[0100] The purpose of this experiment is to explore the long-term cyclic stability of electrochemical chlorine removal by in-situ confined growth of bismuth nanoclusters on multi-channel carbon nanofibers prepared in Example 2.

[0101] Figure 6 For BiNCs@MCNF-2 at a NaCl concentration of 1000 mg L -1 , the applied voltage is 1.4V, and 100 charge / discharge cycles are performed. As shown in the figure, it is calculated that after 100 adsorption / desorption cycles, BiNCs@MCNF-2 still has a 90.89% chlorine removal capacity retention rate. At the same time, within 100 cycles, its energy-normalized adsorbed Cl - , ENAC) maintained at 0.02~0.24mg Cl - / J is within a small fluctuation range. The above analysis shows that the sample of the present invention has high efficiency and low consumption in the application of electrochemical chlorine removal, as well as excellent long-term cycle life, and has great practical value.

[0102] The above description of the embodiments is intended to facilitate understanding and use of the present invention by those skilled in the art. Those skilled in the art will readily be able to make various modifications to these embodiments and apply the general principles described herein to other embodiments without resorting to creative effort. Therefore, the present invention is not limited to the above-described embodiments. Any improvements or modifications made by those skilled in the art based on the principles of the present invention that do not depart from the scope of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A carbon nanofiber self-supporting thin film anode material, characterized in that: Composed of a carbon nanofiber membrane material, the carbon nanofiber membrane material includes a plurality of multi-channel carbon nanofibers loaded with bismuth nanoclusters; The method for preparing the carbon nanofiber self-supporting thin film anode material comprises the following steps: Step (1) adding bismuth nitrate hydrate powder, polyacrylonitrile and polymethyl methacrylate to an organic solvent to obtain a mixed suspension; the particle size of the bismuth nitrate hydrate powder is 600-1000 mesh; the mass ratio of the bismuth nitrate hydrate powder, polyacrylonitrile and polymethyl methacrylate is 1-3:2:2; and the mass concentration of the mixed suspension is 26.37% to 36.92%; In step (2), the mixed suspension is subjected to electrostatic spinning to obtain a Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane; the setting parameters of the electrospinning process are: two 10 mL plastic syringes equipped with stainless steel needles, a syringe push speed of 0.05-0.10 mm / min, a voltage of 15-18 V, a receiving distance of 18-22 cm, a receiving drum speed of 70-90 rpm, a translation speed of 450-550 mm / min, a translation distance of 80-120 mm, a temperature of 25°C, a humidity of 35%, and a spinning time of 7-9 h; Step (3), the Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane is first pre-oxidized, then carbonized and carbon-thermally reduced to obtain a carbon nanofiber self-supporting thin film anode material for electrochemical chlorine removal; The pre-oxidation process is carried out in a muffle furnace at a pre-oxidation temperature of 240-260° C., a pre-oxidation time of 0.5-1.5 h, and an air atmosphere; during the pre-oxidation process, a semicircular corundum crucible with a cover is used for tension drawing; The pre-oxidation temperature program is: from 20°C to 200°C at a heating rate of 5°C / min; then from 200°C to 250°C at a heating rate of 1°C / min; The carbonization process is to carbonize PAN / PMMA in the Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane to form multi-channel carbon nanofibers, and the carbon thermal reduction process is to carbon thermally reduce Bi(NO3)3·5H2O in the Bi(NO3)3·5H2O / PAN / PMMA nanofiber membrane to bismuth nanoclusters supported on the multi-channel carbon nanofibers; the carbonization process and the carbon thermal reduction process are both carried out in a tubular furnace, the carbonization and carbon thermal reduction temperatures are 850-950°C, and the carbonization and carbon thermal reduction times are 1-3 hours.

2. The carbon nanofiber self-supporting thin film anode material according to claim 1, characterized in that: In step (1), the organic solvent is selected from at least one of ethyl acetate, isopropyl acetate, n-propyl acetate, isobutyl acetate, ethanol, ethylene glycol, propylene glycol, methanol, isopropyl alcohol, tert-butanol, ether, 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, methyl tert-butyl ether, cyclopentyl methyl ether, diphenyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, toluene, trifluorotoluene, cyclohexane, n-heptane, xylene, acetonitrile, propionitrile, butyronitrile, dichloromethane, chloroform, dichloroethane, chlorobenzene and dibromoethane.

3. A capacitive deionization anode material for electrochemical chlorine removal, characterized in that: The carbon nanofiber self-supporting thin film anode material comprises the carbon nanofiber self-supporting thin film anode material according to claim 1 or 2, and is composed of a carbon nanofiber membrane material, wherein the carbon nanofiber membrane material comprises a plurality of multi-channel carbon nanofibers loaded with bismuth nanoclusters.

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