Carbon fiber composite tungsten carbide photocatalytic material and preparation method and application thereof

Abstract

The application relates to a carbon fiber composite tungsten carbide photocatalytic material and a preparation method and application thereof. The preparation method comprises the following steps: dissolving milled tungsten trioxide and a polymer in an organic solvent, uniformly stirring to obtain an electrostatic spinning precursor solution; electrostatic spinning is performed on the electrostatic spinning precursor solution to prepare a tungsten trioxide nanofiber film; the tungsten trioxide nanofiber film is sequentially subjected to drying and calcination to obtain a pre-oxidized tungsten trioxide nanofiber film; the pre-oxidized tungsten trioxide nanofiber film is subjected to carbonization treatment in a reducing atmosphere, and finally a membrane-shaped carbon fiber composite tungsten carbide photocatalytic material is obtained. Compared with the prior art, the application can greatly improve the separation and transmission efficiency of photo-generated electrons and holes, and has a good application prospect in photocatalytic reduction of CO2.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and in particular to a carbon fiber composite tungsten carbide photocatalytic material, its preparation method, and its application. Background Technology

[0002] With air pollution and carbon emissions becoming increasingly prominent issues, the development of efficient, stable, and scalable photocatalytic functional materials has become a core research focus in the fields of environmental governance and carbon neutrality. Photocatalysis technology, centered on semiconductor materials, utilizes photogenerated electron-hole pairs generated by light excitation to drive redox reactions. It can achieve environmental governance functions such as the degradation of volatile organic pollutants (VOCs), treatment of industrial organic wastewater, and photocatalytic reduction of CO2, while also possessing advantages such as mild reaction conditions, no secondary pollution, and efficient utilization of solar energy.

[0003] The core of photocatalysis technology lies in the performance of photocatalytic materials, with key indicators being the separation and transport efficiency of photogenerated electron-hole pairs and their responsiveness to visible light. Traditional photocatalytic materials, such as TiO2 and WO3, can only absorb ultraviolet light, which accounts for 3.8% of solar energy, and their rapid recombination rate of photogenerated carriers leads to low quantum efficiency and poor catalytic activity. Although they have been optimized through modification methods such as ion doping and noble metal deposition, the improvement effect is limited and cannot meet the needs of practical applications.

[0004] Tungsten carbide photocatalysts, as novel photocatalysts, possess characteristics such as narrow band gap, wide visible light response range, and strong redox capabilities, making them an important direction for replacing traditional photocatalysts. However, they suffer from problems such as easy powder agglomeration and poor formability, which restrict their catalytic performance and practical applications. To address these shortcomings, researchers have combined tungsten carbide with carbon-based materials. Leveraging the high conductivity and large specific surface area of ​​carbon-based materials, they enhance the separation efficiency of photogenerated electron-hole pairs, while simultaneously providing a stable supporting substrate for the photocatalyst and reducing particle agglomeration. For example, CN114984990A discloses a tubular carbon nitride-based Schottky heterojunction photocatalyst. This photocatalyst uses tubular carbon nitride as a framework, with the surface of the tubular carbon nitride modified with vanadium-doped bismuth iodate and particulate tungsten carbide, and can be used for photocatalytic removal of organic pollutants in the environment. However, the composite materials prepared by the above process have the following problems: the interfacial bonding force between tungsten carbide and carbon-based materials is weak, which easily leads to a decrease in catalytic stability; tungsten carbide is difficult to load evenly on the surface of carbon-based materials, and agglomeration is easy to occur; it is difficult to control the phase composition of tungsten carbide, which in turn limits the effective control of the generation effect of different products in CO2 photocatalytic reduction.

[0005] Therefore, novel tungsten carbide / carbon-based composite materials that can be used for photocatalytic reduction of CO2 still need to be developed. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art by providing a carbon fiber composite tungsten carbide photocatalytic material, its preparation method and application, so as to achieve uniform and firm loading of tungsten carbide photocatalytic material on the carbon fiber surface, improve the visible light photocatalytic activity and long-term stability of the material, and promote its practical application in the field of environmental governance.

[0007] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention provides a method for preparing a carbon fiber composite tungsten carbide photocatalytic material, the method comprising the following steps: S1: Tungsten trioxide that has been ball-milled and polymer are dissolved in an organic solvent and stirred evenly to obtain an electrospinning precursor solution; S2: Electrospinning the electrospinning precursor solution obtained in S1 to prepare tungsten trioxide nanofiber membranes. S3: The tungsten trioxide nanofiber membrane obtained in S2 is dried and calcined sequentially to obtain a pre-oxidized tungsten trioxide nanofiber membrane; S4: The pre-oxidized tungsten trioxide nanofiber membrane obtained in S3 is carbonized in a reducing atmosphere to finally obtain a membrane-like carbon fiber composite tungsten carbide photocatalytic material.

[0008] Furthermore, in step S1, the ball milling time is 3-5 hours.

[0009] Furthermore, in step S1, the rotational speed of the ball mill is 1~20 r / s.

[0010] Furthermore, in step S1, the ball-to-material ratio in the ball mill is 10:1 to 20:1.

[0011] Further, in step S1, the polymer is any one or a combination of polyacrylonitrile, polyvinylpyrrolidone, and polyvinyl alcohol.

[0012] Further, in step S1, the organic solvent is any one or a combination of N,N-dimethylformamide, tetrahydrofuran, N,N-dimethylacetamide, and dichloromethane.

[0013] Further, in step S1, the mass concentration of the polymer in the electrospinning precursor solution is 8~30wt%.

[0014] Furthermore, in step S1, the concentration of tungsten trioxide in the electrospinning precursor solution is 1~5 mol / L.

[0015] Furthermore, in step S1, the stirring time is 24~72 h.

[0016] Furthermore, in step S1, the stirring temperature is 20~60 ℃.

[0017] Furthermore, in step S2, the feed rate of the electrospinning is 0.1~3 mL / h.

[0018] Furthermore, in step S2, the voltage of the electrospinning is 1~30 kV.

[0019] Furthermore, in step S2, the distance between the electrospinning nozzle and the current collector is 10~30 cm.

[0020] Furthermore, in step S2, the rotational speed of the electrospinning roller is 50~350 r / min.

[0021] Furthermore, in step S2, the humidity of the electrospinning process is 25%~35%.

[0022] Furthermore, in step S2, the temperature of the electrospinning is 10~35 ℃.

[0023] Furthermore, in step S3, the drying process employs vacuum drying.

[0024] Furthermore, in step S3, the drying temperature is 40~80 ℃.

[0025] Furthermore, in step S3, the drying time is 2-4 hours.

[0026] Furthermore, in step S3, the calcination is carried out in a muffle furnace.

[0027] Furthermore, in step S3, the calcination time is 1 to 4 hours.

[0028] Furthermore, in step S3, the calcination temperature is 200~400 ℃.

[0029] Furthermore, in step S4, the reducing atmosphere is a hydrogen-argon mixture.

[0030] Furthermore, the volume percentage of hydrogen in the hydrogen-argon mixture is 3-10%, preferably 5%.

[0031] Furthermore, in step S4, the heating rate of the carbonization treatment is 2~5 °C / min.

[0032] Furthermore, in step S4, the final temperature of the carbonization treatment is 400~1000 ℃, preferably 700~900 ℃.

[0033] Furthermore, in step S4, the carbonization treatment is held at the final temperature for 1 to 5 hours.

[0034] A second aspect of the present invention provides a carbon fiber composite tungsten carbide photocatalytic material, which is prepared by any of the preparation methods described above.

[0035] Furthermore, the photocatalytic material is composed of carbon nanofibers and tungsten carbide and / or tungsten dicarbide uniformly loaded on the surface of the carbon nanofibers.

[0036] Furthermore, the diameter of the carbon nanofibers is 1~2μm.

[0037] The third aspect of this invention provides the application of carbon fiber composite tungsten carbide photocatalytic material in the photocatalytic reduction of CO2.

[0038] Furthermore, the carbon fiber composite tungsten carbide photocatalytic material exhibits a CO generation rate of no less than 4 μmol / g / h in the photocatalytic reduction of CO2.

[0039] Furthermore, the carbon fiber composite tungsten carbide photocatalytic material exhibits a H2 generation rate of no less than 14 μmol / g / h in the photocatalytic reduction of CO2.

[0040] Compared with the prior art, the present invention has the following technical advantages: (1) The tungsten carbide-carbon nanofiber flexible photocatalytic film obtained by the present invention uses carbon fiber as a carrier to uniformly load tungsten carbide and / or ditungsten carbide particles, which improves the visible light catalytic activity, mechanical flexibility and catalytic stability of the composite material, and realizes the efficient preparation of tungsten carbide-carbon nanofiber flexible photocatalytic film.

[0041] (2) This invention prepares tungsten carbide photocatalytic fiber membrane materials with nanoscale morphology and high specific surface area by electrospinning. This material can effectively reduce the mass transfer resistance of reactant adsorption and product desorption diffusion, which is beneficial to the diffusion and reaction of gas molecules. The prepared composite film can greatly improve the separation and transport efficiency of photogenerated electrons and holes, achieve high dispersion of photocatalyst, expose abundant catalytic active centers, and has good application prospects in photocatalytic reduction of CO2.

[0042] (3) This invention achieves uniform and firm loading of tungsten carbide on the carbon fiber surface and precise phase control through synergistic design of precise ball milling pretreatment of tungsten trioxide, optimization of electrospinning process parameters, and control of carbonization and calcination conditions. Specifically, ball milling pretreatment of tungsten trioxide can effectively reduce its particle size and improve its dispersibility, avoiding particle agglomeration during subsequent carbonization; precise control of electrospinning process parameters achieves uniform loading of tungsten trioxide in PAN nanofibers; and control of carbonization parameters enables the reduction and carbonization of tungsten trioxide to form tungsten carbide / ditungsten carbide, significantly improving the bonding force between tungsten carbide and carbon nanofibers.

[0043] (4) The tungsten carbide-carbon nanofiber flexible photocatalytic film prepared by the present invention has good flexibility and mechanical strength, and can be cut, wound and other forming processes according to actual needs.

[0044] (5) The preparation method of the present invention does not require special equipment or harsh conditions, the process is simple, highly controllable, and easy to achieve large-scale production, providing a new technical path for the further application of carbon fiber composite tungsten carbide photocatalytic materials. Attached Figure Description

[0045] Figure 1 This is a photograph of the ball-milled tungsten trioxide-PAN nanofiber membrane obtained in Example 1.

[0046] Figure 2 This is a transmission electron microscope (TEM) image of the ball-milled tungsten trioxide-PAN nanofiber membrane obtained in Example 1.

[0047] Figure 3 This is a photograph of the pre-oxidized tungsten trioxide-PAN nanofiber membrane obtained in Example 1.

[0048] Figure 4 This is a transmission electron microscope (TEM) image of the pre-oxidized tungsten trioxide-PAN nanofiber membrane obtained in Example 1.

[0049] Figure 5 This is a photograph of the tungsten carbide-carbon nanofiber flexible photocatalytic film obtained in Example 1.

[0050] Figure 6 This is a transmission electron microscope (TEM) image of the tungsten carbide-carbon nanofiber flexible photocatalytic thin film obtained in Example 1.

[0051] Figure 7 The XRD diffraction patterns of the tungsten carbide photocatalytic materials obtained in Examples 1-3 are shown in the figures. In the figures, the red curve represents tungsten carbide-carbon nanofibers (W2C-C), the blue curve represents tungsten carbide-tungsten carbide-carbon nanofibers (W2C-WC), and the black curve represents tungsten carbide-carbon nanofibers (WC).

[0052] Figure 8 This is a transmission electron microscope (TEM) image of the tungsten carbide-carbon nanofiber flexible photocatalytic film obtained from unmilled tungsten trioxide as shown in Comparative Example 1.

[0053] Figure 9 This is a photograph of the photocatalytic thin film obtained in Comparative Example 2 after a torsional tensile test.

[0054] Figure 10 The bar chart shows the CO2 reduction performance of the tungsten carbide photocatalytic materials obtained in Examples 1-3. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0056] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0057] Example 1: This embodiment provides a carbon fiber composite tungsten carbide photocatalytic material, specifically a tungsten carbide-carbon nanofiber flexible photocatalytic thin film. The preparation method is as follows: (1) Dissolve 1.2 g of polyacrylonitrile (PAN) in 10 mL of N,N-dimethylformamide (DMF) to prepare a PAN solution with a mass fraction of 12%. After dissolution, add 2.5 mmol of ball-milled tungsten trioxide and stir magnetically at 45 °C for 24 h to form a green, uniform, turbid precursor solution. The ball milling time is 120 min, the rotation speed is 5 r / s, and the ball-to-material ratio is 145 g:20 g.

[0058] (2) Take the above precursor solution and put it into a 10 ml syringe, then place it in an electrospinning machine. Set the spinning conditions: the positive spinning voltage is 10 kV, applied to the tip, the distance between the tip and the receiving plate is 10 cm, the jetting speed is 0.5 mL / h, the roller speed is 180 r / min, the temperature is 20 ℃, and the humidity is 35%. Perform electrospinning according to the set parameters to obtain the following... Figure 1 The tungsten trioxide-PAN nanofiber membrane shown is an example.

[0059] Figure 2 This is a TEM image of the tungsten trioxide-PAN nanofiber membrane. As shown in the image, the electrospun PAN nanofibers exhibit a continuous, smooth one-dimensional structure with random interlacing between fibers forming a three-dimensional porous network. Tungsten trioxide is uniformly loaded onto the fiber surface in the form of nanoparticles and aggregates.

[0060] (3) The prepared tungsten trioxide-PAN nanofiber membrane was dried and stabilized under vacuum in a 60 ℃ constant temperature oven. Then it was calcined in a muffle furnace at 250 ℃ for 2 h to obtain the membrane as shown in the figure. Figure 3 The pre-oxidized tungsten trioxide-PAN nanofiber membrane shown is an example.

[0061] Figure 4This is a TEM image of the pre-oxidized tungsten trioxide-PAN nanofiber membrane. As shown in the figure, the PAN nanofibers still maintain a continuous and uniform one-dimensional long fiber morphology after pre-oxidation treatment. The skeleton structure is intact without obvious damage. WO3 particles are loaded on the fiber surface in the form of nanoscale aggregates without obvious detachment. The loading density is lower than that before pre-oxidation, and the overall structural stability of the fiber membrane is good.

[0062] (4) The pre-oxidized tungsten trioxide-PAN nanofiber membrane was placed in a tube furnace and heated to 800 °C at a rate of 5 °C / min under a hydrogen-argon mixed gas atmosphere (H2 volume content 5%) and calcined for 3 h to finally obtain the membrane as shown in the figure. Figure 5 The tungsten carbide-carbon nanofiber flexible photocatalytic film shown is an example.

[0063] Figure 6 This is a TEM image of the tungsten carbide-carbon nanofiber flexible photocatalytic film. As shown in the image, the carbon nanofiber framework structure is intact after carbonization, and the tungsten carbide particles are uniformly and stably loaded on the fiber surface with a relatively uniform particle size distribution and tight bonding with the carbon nanofiber substrate.

[0064] Example 2: This embodiment provides a carbon fiber composite tungsten carbide photocatalytic material, specifically a tungsten carbide-carbon nanofiber flexible photocatalytic film. The difference from Embodiment 1 is that the heating rate in step (4) of this embodiment is 3 ℃ / min.

[0065] Example 3: This embodiment provides a carbon fiber composite tungsten carbide photocatalytic material, specifically a tungsten carbide-carbon nanofiber flexible photocatalytic film. The difference from Embodiment 1 is that the heating rate in step (4) of this embodiment is 2 °C / min.

[0066] XRD composition analysis was performed on the products of Examples 1-3. Figure 7 The orange diamond-shaped marker JCPDS:35-0776 (WC phase) represents the position of the diffraction peak that appears in WC theory; the blue circular marker JCPDS:51-0539 (W2C phase) represents the position of the diffraction peak that appears in W2C theory.

[0067] As shown in the figure, Example 3 produced pure-phase tungsten carbide-carbon nanofibers (WC) at a heating rate of 2 ℃ / min, Example 2 produced tungsten dicarbide / tungsten carbide composite-carbon nanofibers (W2C-WC) at a heating rate of 3 ℃ / min, and Example 1 produced tungsten dicarbide-carbon nanofibers (W2C-C) at a heating rate of 5 ℃ / min. Therefore, this invention successfully prepared carbon fiber composite tungsten carbide photocatalytic materials of different tungsten carbide types by controlling the parameters of the carbonization process.

[0068] Comparative Example 1: This comparative example provides a carbon fiber composite tungsten carbide photocatalytic material, specifically a tungsten carbide-carbon nanofiber flexible photocatalytic film. The difference from Example 1 is that in this example, tungsten trioxide without ball milling pretreatment is used in step (1).

[0069] Depend on Figure 8 TEM results show that in the tungsten carbide-carbon nanofiber flexible photocatalytic film obtained in this comparative example, the tungsten carbide particles exhibit obvious agglomeration in the carbon fibers, resulting in uneven load distribution.

[0070] Comparative Example 2: This comparative example provides a carbon fiber composite tungsten carbide photocatalytic material, specifically a tungsten carbide-carbon nanofiber flexible photocatalytic film. The difference from Example 1 is that in step (1) of this example, PAN is replaced with PVP (polyvinylpyrrolidone).

[0071] Depend on Figure 9 As can be seen from the photos, the tungsten carbide-carbon nanofiber photocatalytic film obtained by PVP in this comparative example has poor flexibility. After twisting and stretching tests, it broke and fractured, and its mechanical strength properties were poor, which could not meet the molding and use requirements in practical applications.

[0072] Based on the successful preparation of the tungsten carbide-carbon nanofiber photocatalytic film in the above embodiments, this invention further explores its application effect in photocatalytic reduction of CO2.

[0073] The specific testing steps are as follows: A tungsten carbide-carbon nanofiber photocatalytic film was laid flat on the bottom of a quartz reactor, and carbon dioxide (99.99%) was introduced. The quartz reactor was then sealed with a lid and placed in the center of the photocatalytic reactor. A xenon lamp was used to simulate sunlight and irradiated the reactor from the front. After 6 hours, a sample was taken with a microsyringe and injected into a gas chromatograph to determine the content of reduction products in the reactor.

[0074] Depend on Figure 10 It can be seen that the carbon monoxide generation rate using W2C-C is 4.28 μmol / g / h, the carbon monoxide generation rate using W2C-WC is 7.42 μmol / g / h, and the carbon monoxide generation rate using WC is 14.06 μmol / g / h. The hydrogen generation rate using W2C-C is 27.26 μmol / g / h, the hydrogen generation rate using W2C-WC is 29.85 μmol / g / h, and the hydrogen generation rate using WC is 14.06 μmol / g / h. The generation rates of different products in the photocatalytic reduction of CO2 can be controlled by adjusting the carbonization process parameters.

[0075] The tungsten carbide-carbon nanofiber flexible photocatalytic film prepared by this invention can greatly improve the separation and transport efficiency of photogenerated electrons and holes. The photocatalyst has abundant active sites under the support of carbon fibers and has significant photocatalytic activity. It also has good flexibility and mechanical strength, and can be cut, wound and other shaped according to actual needs. It has broad application prospects in the fields of photocatalytic reduction of CO2 and air purification.

[0076] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a carbon fiber composite tungsten carbide photocatalytic material, characterized in that, The preparation method includes the following steps: S1: Tungsten trioxide that has been ball-milled and polymer are dissolved in an organic solvent and stirred evenly to obtain an electrospinning precursor solution; S2: Electrospinning the electrospinning precursor solution obtained in S1 to prepare tungsten trioxide nanofiber membranes. S3: The tungsten trioxide nanofiber membrane obtained in S2 is dried and calcined sequentially to obtain a pre-oxidized tungsten trioxide nanofiber membrane; S4: The pre-oxidized tungsten trioxide nanofiber membrane obtained in S3 is carbonized in a reducing atmosphere to finally obtain a membrane-like carbon fiber composite tungsten carbide photocatalytic material.

2. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S1, the ball milling time is 3~5 h, the ball milling speed is 1~20 r / s, and the ball-to-material ratio is 10:1~20:

1.

3. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S1, the polymer is any one or a combination of polyacrylonitrile, polyvinylpyrrolidone, and polyvinyl alcohol; The organic solvent is any one or a combination of N,N-dimethylformamide, tetrahydrofuran, N,N-dimethylacetamide, and dichloromethane.

4. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S1, the mass concentration of the polymer in the electrospinning precursor solution is 8-30 wt%. The concentration of tungsten trioxide in the electrospinning precursor solution is 1~5 mol / L.

5. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S2, the parameters for electrospinning are: The feeding rate is 0.1~3 mL / h, the voltage is 1~30 kV, the distance between the nozzle and the collector is 10~30 cm, the drum speed is 50~350 r / min, the humidity is 25%~35%, and the temperature is 10~35 ℃.

6. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S3, the drying process employs vacuum drying. The drying temperature is 40~80 ℃, and the drying time is 2~4 h.

7. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S3, the calcination is carried out in a muffle furnace; The calcination time is 1-4 h, and the calcination temperature is 200-400 ℃.

8. The method for preparing a carbon fiber composite tungsten carbide photocatalytic material according to claim 1, characterized in that, In step S4, the reducing atmosphere for the carbonization treatment is a hydrogen-argon mixture. The heating rate of the carbonization treatment is 2~5 ℃ / min, and the final temperature is 400~1000 ℃; The carbonization process is carried out at the final temperature for 1 to 5 hours.

9. A carbon fiber composite tungsten carbide photocatalytic material, characterized in that, Prepared by the preparation method according to any one of claims 1-8; The photocatalytic material is composed of carbon nanofibers and tungsten carbide and / or tungsten dicarbide uniformly loaded on the surface of the carbon nanofibers.

10. The application of the carbon fiber composite tungsten carbide photocatalytic material according to claim 9 in the photocatalytic reduction of CO2, characterized in that, The carbon fiber composite tungsten carbide photocatalytic material exhibits a CO generation rate of no less than 4 μmol / g / h and an H2 generation rate of no less than 14 μmol / g / h in the photocatalytic reduction of CO2.

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