Preparation method of novel titanium-based photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh and application of novel titanium-based photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh in removal of 2, 4-DCP

Abstract

The invention provides a preparation method of a novel photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh and application of the novel photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh to power generation and pollutant removal in a photocatalytic fuel cell system, and belongs to the technical field of environmental engineering. The preparation method comprises the following steps: taking a titanium mesh as a substrate, firstly preparing a titanium dioxide nanotube array (TiO2NTs) by adopting an anodic oxidation method, then loading ZnIn2S4 to the TiO2NTs by adopting a one-step hydrothermal method, and finally obtaining the ZnIn2S4 / TiO2NTs / Ti mesh composite photocatalytic fuel cell anode material. The preparation method is simple in preparation process, low in equipment requirement, green, environment-friendly and low in cost. The prepared ZnIn2S4 / TiO2NTs / Ti mesh material is used as a photo-anode material, a platinum sheet is used as a cathode to construct a photocatalytic fuel cell system, and the photocatalytic fuel cell has good degradation and power generation capabilities. Under simulated sunlight irradiation, when 2, 4-dichlorophenol (2, 4-DCP) with the concentration of 10 mg / L is used as a substrate, the degradation rate within 150 min reaches about 90%, the open-circuit voltage is 0.4 V, and the photocurrent density is 0.22 mA / cm < 2 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental engineering, and particularly relates to a preparation method of a novel titanium-based photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh and its application in generating electricity and removing pollutants in a photocatalytic fuel cell system. Background Art

[0002] Chlorophenol (CPs) pollutants are a kind of highly toxic and recalcitrant organic pollutants that are not easily degraded in the natural environment. The wide production and use of CPs will cause them to enter the environment and cause pollution due to their persistence and non-biodegradability. In addition, CPs are harmful to aquatic organisms and humans due to their high bioaccumulation, carcinogenicity, genotoxicity, endocrine disruption ability, etc. Technologies such as biodegradation, adsorption, and advanced oxidation processes such as ozone oxidation and photocatalysis have been proposed to remove chlorophenol pollutants. However, these traditional technologies have problems such as incomplete degradation, generating secondary by-products with higher toxicity and stronger persistence; being unable to utilize the chemical energy in pollutants, resulting in energy waste. Photocatalytic fuel cells (PFCs) have been recognized as a promising advanced oxidation technology. It couples fuel cell technology with photocatalysis technology to generate electricity while degrading pollutants, realizing the resource utilization of wastewater. In a photocatalytic fuel cell, the selection of the anode material is crucial. Among the existing semiconductor photoanodes used for PFCs, TiO2 has been the most widely used due to its non-toxicity, stable chemical properties, and high cost-effectiveness. In particular, highly ordered TiO2 nanotube arrays prepared by electrochemical anodic oxidation have been proven to have very excellent electron mobility in restricted paths. And titanium mesh has the advantages of facilitating mass diffusion of air and liquid, being conducive to photocatalytic degradation of pollutants, and having high photocatalytic activity. However, although the TiO2 nanotube arrays grown in-situ on titanium mesh have great advantages in a three-dimensional network structure, the wide bandgap and high carrier recombination rate of the TiO2 semiconductor are still the main problems restricting its application in photocatalytic fuel cells. ZnIn2S4 is a semiconductor material with a layered structure and adjustable bandgap. Its bandgap can be adjusted to be as narrow as 2.06 - 2.85 eV, and it has a wider absorption spectrum (570 nm), so it can absorb visible light. Therefore, attaching ZnIn2S4 to the surface of TiO2NTs / Ti to form a heterojunction can reduce the bandgap of TiO2NTs / Ti, solve the problem of easy recombination of photo-generated electron-hole pairs in TiO2NTs, and at the same time improve the utilization rate of visible light by TiO2NTs / Ti.

[0003] Currently, TiO2 materials are modified by means of microscopic morphology regulation, element doping, and heterojunction recombination to prepare titanium-based materials with more excellent performance to make up for the defects of single-component TiO2 materials.

[0004] When preparing TiO2-based photocatalytic materials, different morphologies of TiO2 can be obtained by controlling conditions such as precursor concentration, electrolyte composition, anodization time, and electrolyte pH. Common morphologies of TiO2 include nanotubes, nanorods, and nanocones. Among them, TiO2 nanotube arrays with a large specific surface area and high regularity have attracted increasing attention in the preparation of high-efficiency titanium-based photoanodes.

[0005] Low light utilization efficiency and the recombination of electron-hole pairs are the biggest obstacles to the large-scale practical application of TiO2 photocatalytic technology. Heterojunction engineering utilizes the bandgap matching between different semiconductors to enable the orderly transfer of photoelectrons and holes between different semiconductors, achieving efficient separation of electrons and holes. Summary of the Invention

[0006] The content of the present invention aims to provide a novel titanium-based photoanode for efficient photoelectric conversion, solve the problem of neglect and waste of chemical energy in pollutants in traditional sewage treatment technologies, and propose a preparation method of a novel titanium-based photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh and its application in generating electricity and removing pollutants in a photocatalytic fuel cell system.

[0007] To achieve the above objectives, the present invention adopts the following method: A preparation method of a ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material, in which a TiO2 nanotube array is in-situ constructed on a titanium mesh by anodization, and then sheet-like or nanoflower-like ZnIn2S4 is grown on the surface of the nanotubes by hydrothermal method to obtain the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material.

[0008] Place TiO2NTs / Ti mesh in an aqueous solution containing ZnCl2, InCl3·4H2O, and TAA, and use the hydrothermal method to grow nano-sheet-like or nanoflower-like ZnIn2S4 on TiO2NTs / Ti mesh to obtain the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material.

[0009] The aqueous solution containing ZnCl2, InCl3·4H2O, and TAA contains 25 mM ZnCl2, 50 mM InCl3·4H2O, and 100 mM TAA in every 100 mL of water.

[0010] The hydrothermal reaction temperature is 150 °C, and the reaction time is 15 min; after hydrothermal treatment, it is dried in an oven at 60 °C, and the required material is obtained after drying.

[0011] The TiO2NTs / Ti mesh is obtained by anodizing the pretreated titanium mesh to get the unformed TiO2NTs / Timesh, which is then taken out after annealing treatment in a muffle furnace for later use.

[0012] The anodization uses the pretreated titanium mesh as the working electrode and a platinum sheet as the counter electrode. The two electrodes are placed opposite each other in the electrolyte with a spacing of 2 cm, and oxidized for 120 min at a constant DC voltage of 20 V. Then it is rinsed and dried, and annealed in a muffle furnace with a heating rate of 1 °C / min and maintained at 450 °C for 180 min.

[0013] The electrolyte is prepared by adding 0.42 g of NaF and 6.9 g of NaHSO4·H2O to every 100 mL of water.

[0014] A ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material prepared by the described method, in which the regular nanosheets or nanoflower-like structures prepared by the described method are uniformly loaded on the surface of the TiO2NTs / Ti mesh to form the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material.

[0015] An application of the described ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material, where the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material is used as a photoanode for the application of degrading pollutants and generating electricity in a photocatalytic fuel cell.

[0016] An application of the described ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material for degrading 2,4-DCP and generating electricity in a photocatalytic fuel cell.

[0017] Compared with the prior art, the advantages of the present invention are as follows: The present invention loads ZnIn2S4 on TiO2NTs by a simple one-step hydrothermal method. The test results show that the narrow bandgap of ZnIn2S4 improves the utilization rate of visible light by TiO2NTs and forms a type-II heterojunction with TiO2, enhancing the separation rate of photo-generated electrons and holes. In addition, due to the resistance of ZnIn2S4 to photocorrosion, the electrode can operate under long-term illumination, greatly improving the service life of the titanium-based photoanode material. Brief Description of the Drawings

[0018] Figure 1 It is the scanning electron microscope (SEM) image of TiO2NTs / Ti mesh provided by Example 1 of the present invention;

[0019] Figure 2 It is the SEM image of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material provided by Example 1 of the present invention;

[0020] Figure 3 are the distribution maps of Ti, O, Zn, In, and S elements in the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material provided in Example 1 of the present invention;

[0021] Figure 4 are the XPS spectra of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material provided in Example 1 of the present invention: (a) full spectrum, (b) Ti 2p, (c) O 1s, (d) Zn 2p, (e) In, and (f) S fine spectra;

[0022] Figure 5 are the ultraviolet-visible diffuse reflectance visible spectra (UV-vis DRS) of the TiO2NTs / Ti mesh and ZnIn2S4 / TiO2NTs / Ti mesh composite photoanodes provided in Example 1 of the present invention;

[0023] Figure 6 are the photocurrent I-t curves of the TiO2NTs / Ti mesh and ZnIn2S4 / TiO2NTs / Ti mesh provided in Example 1 of the present invention under intermittent light illumination;

[0024] Figure 7 are the degradation rates of 2,4-DCP by the TiO2NTs / Ti mesh and ZnIn2S4 / TiO2NTs / Ti mesh composite photoanodes provided in Example 1 of the present invention in a photocatalytic fuel cell using 2,4-DCP as a fuel.

[0025] Figure 8 is the long-term photocurrent I-t curve of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode provided in Example 1 of the present invention using 2,4-DCP as a fuel under continuous light illumination.

[0026] Figure 9 is the degradation rate of 2,4-DCP after multiple uses of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode provided in Example 1 of the present invention in a photocatalytic fuel cell using 2,4-DCP as a fuel under continuous light illumination. Detailed implementation manners

[0027] The following further elaborates on the specific implementation manners of the present invention in conjunction with examples and drawings. The following examples are used to illustrate the present invention, but do not limit the content of the present invention.

[0028] In this invention, TiO2NTs / Ti mesh is in-situ grown on the surface of a titanium mesh by anodic oxidation, and nano-sheet or nano-flower shaped ZnIn2S4 is loaded onto the surface of TiO2NTs / Ti mesh by a hydrothermal method to obtain a ZnIn2S4 / TiO2NTs / Timesh composite photoanode material.

[0029] In this invention, TiO2NTs / Ti mesh is in-situ constructed on the surface of a titanium mesh by anodic oxidation, and then nano-sheet or nano-flower shaped ZnIn2S4 is loaded onto the surface of TiO2NTs / Ti mesh by a simple one-step hydrothermal method. By taking advantage of the advantages of ZnIn2S4 such as narrow bandgap, wide light absorption range, and anti-photo-corrosion, ZnIn2S4 is coupled with TiO2NTs / Ti mesh. This not only improves the visible light absorption ability of TiO2NTs / Ti mesh by using the narrow bandgap of ZnIn2S4, but also forms a type-II heterojunction with a matched energy band between ZnIn2S4 and TiO2NTs / Timesh to improve the carrier separation efficiency, and utilizes the anti-photo-corrosion property of ZnIn2S4 to increase the service life of the titanium-based photoanode.

[0030] Example 1:

[0031] The preparation process of a novel titanium-based photocatalytic fuel cell anode material ZnIn2S4 / TiO2NTs / Ti mesh includes the following steps:

[0032] Pretreatment of the titanium mesh: Cut a 100-mesh titanium mesh into pieces of 2 cm×4 cm, immerse them in acetone, ethanol, and ultrapure water respectively for ultrasonic treatment for 15 min, wash them with deionized water, and then put them in an oven at 60°C for drying for later use.

[0033] Preparation of TiO2NTs / Ti mesh: TiO2NTs / Ti mesh is prepared by anodic oxidation. Weigh 0.42 g of NaF and 6.90 g of NaHSO4·H2O and dissolve them in 100 mL of deionized water to prepare an anodizing electrolyte. Use the pretreated titanium mesh as the working electrode and a platinum sheet as the counter electrode, and process them at a direct current voltage of 20 V for 120 min. Subsequently, rinse the titanium mesh with deionized water and ethanol multiple times to remove the residual electrolyte on the surface, and then put it in an oven at 60°C for drying. After drying, anneal it at 450°C for 180 min at a heating rate of 1°C / min to finally obtain TiO2NTs / Ti mesh in-situ grown on the titanium mesh (see Figure 1 )

[0034] Preparation of ZnIn2S4 / TiO2NTs / Ti mesh: ZnIn2S4 was loaded onto TiO2NTs / Timesh by a one-step hydrothermal method. 0.17 g of ZnCl2, 0.73 g of InCl3·H2O, and 0.37 g of TAA were dissolved in 50 mL of deionized water and transferred to a stainless-steel autoclave with a polytetrafluoroethylene liner. The TiO2NTs / Ti mesh obtained in the previous step was immersed in it, and the reaction was carried out at 150 °C for 15 min. After taking out the sample, it was repeatedly rinsed with deionized water and ethanol and dried in an oven at 60 °C to obtain the ZnIn2S4 / TiO2NTs / Ti mesh photoanode.

[0035] Morphology characterization of the obtained ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material: The morphology of the synthesized composite material was detected by a Quanta 250FEG scanning electron microscope (SEM) from FEI Company, USA (see Figure 2 ).

[0036] Chemical composition characterization of the obtained ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material: X-ray photoelectron spectroscopy was tested using an ESCALAB 250 from Thermo Fisher Scientific, USA. With the C 1s peak at 284.8 eV as the standard peak, the chemical composition of the synthesized material was studied (see Figure 3 and 4 ).

[0037] Light absorption performance test of the obtained ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material: The ultraviolet-visible diffuse reflectance spectrum of the sample was characterized by a UV-9000s from Shanghai Yuanxi Instruments Co., Ltd., and the wavelength range was 200 - 800 nm (see Figure 5 ).

[0038] The above-prepared ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material was used as the photoanode, and a platinum sheet was used as the cathode. Using a CHI 760E electrochemical workstation from Shanghai Chenhua Instruments Co., Ltd., the photocurrent I-t curve under intermittent light illumination was measured (see Figure 6 ).

[0039] The above-prepared ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material was used as the photoanode, and a platinum sheet was used as the cathode. Degradation and power generation experiments were carried out in a photocatalytic fuel cell using 2,4-DCP as the fuel (see Figure 7 and Figure 8 ).

[0040] Electrochemical tests were carried out on the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material:

[0041] The electrochemical tests were performed using a CHI 760E electrochemical workstation from Shanghai Chenhua Instrument Co., Ltd. The light source simulating visible light was a 300 W xenon lamp, with an AM 1.5 G filter, and the light energy density was 100 mW / cm 2 . The electrochemical tests were all carried out in a 0.5 M Na2SO4 solution.

[0042] Photocurrent density (I-t) test: The photocurrent density of the composite photoanode was tested under intermittent visible light. The composite photoanode was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. The open-circuit voltage test was carried out under a three-electrode system. The composite photoanode material was irradiated with the visible light source provided by the xenon lamp for 200 s every 10 s.

[0043] Degradation experiments were carried out on the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material:

[0044] The degradation experiments were carried out in a two-compartment reactor. The light source simulating visible light was a 300 W xenon lamp, with an AM 1.5 G filter, and the light energy density was 100 mW / cm 2 . The degradation experiments were all carried out in a mixed solution of 0.5 M Na2SO4 and 10 mg / L 2,4-DCP.

[0045] Degradation experiment test: The degradation rate of 2,4-DCP by the composite photoanode in a photocatalytic fuel cell with 2,4-DCP as the fuel was tested under continuous visible light. The composite photoanode was used as the working electrode and a platinum sheet as the counter electrode, and the degradation experiment was carried out under a two-electrode system.

[0046] Continuous power generation tests were carried out on the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material:

[0047] The continuous power generation tests were carried out in a two-compartment reactor. The light source simulating visible light was a 300 W xenon lamp, with an AM 1.5 G filter, and the light energy density was 100 mW / cm 2 . The continuous power generation tests were all carried out in a mixed solution of 0.5 M Na2SO4 and 10 mg / L 2,4-DCP.

[0048] Continuous power generation test: The photocurrent density of the composite photoanode in a photocatalytic fuel cell with 2,4-DCP as the fuel was tested under continuous visible light. The composite photoanode was used as the working electrode and a platinum sheet as the counter electrode, and the continuous power generation test was carried out under a two-electrode system.

[0049] The prepared ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material was used as the photoanode, and a platinum sheet was used as the cathode. The experiment of degrading 2,4-DCP after repeated use in a photocatalytic fuel cell with 2,4-DCP as the fuel (see Figure 9 )

[0050] The following results are used to illustrate the effects of the present invention:

[0051] Figure 1 This is the result after SEM testing of TiO2NTs / Ti mesh. The results show that the TiO2 film is composed of a closely arranged nanotube array with an average diameter of 30 - 50 nm.

[0052] Figure 2 This is the result after SEM testing of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode. The results show that in the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material, ZnIn2S4 is uniformly loaded on the surface of the nanotube array in a regular nanosheet or nanoflower-like structure, and the surface of TiO2NTs / Ti mesh is uniformly covered.

[0053] Figure 3 This is the EDS spectrum of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode. It can be seen that the main elements in the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode are Ti, O, Zn, In, and S.

[0054] Figure 4 This is the result after XPS testing of the TiO2 nanotube array and the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode. In Figure 4 (a), peaks of Ti 2p, O1s, C 1s, Zn 2p, In 3d, and S 2p are observed in the full spectrum of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material. Among them, the binding energies at 458.2 eV and 464.0 eV indicate the presence of Ti 2p3 / 2 and Ti 2p1 / 2 in TiO2 ( Figure 4 b). Figure 4 (c) shows the high-resolution XPS spectrum of the O element. The peak at about 529.7 eV comes from lattice oxygen (OL), while the peak at about 531.3 eV is related to adsorbed oxygen (OA). Figure 4 (d) shows the Zn 2p3 / 2 and Zn 2p1 / 2 of Zn2+ in the composite material, corresponding to peaks at 1021.7 eV and 1044.8 eV respectively. For the In 3d XPS spectrum ( Figure 4e), at a binding energy of 444.9 eV, the peak corresponds to In 3d5 / 2, and at 452.5 eV it corresponds to In 3d3 / 2. Figure 4 (f) It can be seen that the peak values of S 2p are 161.7 eV and 162.8 eV respectively, corresponding to S 2p3 / 2 and S 2p1 / 2 respectively.

[0055] Figure 5 are the results after ultraviolet-visible diffuse reflection tests on the TiO2NTs / Ti mesh and ZnIn2S4 / TiO2NTs / Ti mesh composite photoanodes. The results show that the absorption edges of TiO2NTs / Ti and ZnIn2S4 are approximately 524 nm and 550 nm respectively. After introducing ZnIn2S4 nanosheets, the absorption edge of ZnIn2S4 / TiO2NTs / Ti mesh is significantly red-shifted, and the absorption edge is approximately 600 nm.

[0056] Figure 6 is the photocurrent I-t curve change diagram of TiO2NTs / Ti mesh and ZnIn2S4 / TiO2NTs / Ti mesh under intermittent light illumination. When the light is turned on, the photocurrent density of ZnIn2S4 / TiO2NTs / Ti mesh is significantly higher than that of TiO2NTs / Timesh, indicating that the recombination of ZnIn2S4 accelerates charge transfer and inhibits the recombination of photo-generated carriers.

[0057] Figure 7 is the degradation rate of 2,4-DCP by the TiO2NTs / Ti mesh and ZnIn2S4 / TiO2NTs / Ti mesh composite photoanodes in a photocatalytic fuel cell using 2,4-DCP as fuel. Before turning on the light source, dark adsorption is carried out for 60 min first; within 30 - 90 min after illumination, the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode has a significant degradation effect on 2,4-DCP, and the degradation rate reaches about 90% at 150 min, which is 40% higher than the degradation rate of the photocatalytic fuel cell with TiO2NTs / Ti mesh as the photoanode.

[0058] Figure 8 is the long-term photocurrent I-t curve of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode using 2,4-DCP as fuel under continuous light illumination. The obtained photocurrent density is maintained at 0.22 mA / cm within 1.5 h 2 , indicating that the composite photoanode can continuously generate electricity in a photocatalytic fuel cell system using 2,4-DCP as fuel and has good stability.

[0059] Figure 9It is the degradation rate of 2,4-DCP after the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode is repeatedly used in a photocatalytic fuel cell with 2,4-DCP as the fuel under continuous light illumination. After the fifth use, the degradation rate of 2,4-DCP by this composite photoanode is still between 88% and 90%, indicating the anti-photocorrosion and stability of the photoanode material.

[0060] The composite photoanode of the present invention is modified by a narrow-bandgap catalyst ZnIn2S4, which improves the absorption ability of the original titanium-based photoanode for visible light and increases its utilization rate of visible light.

[0061] Preparation of a carbon-modified and modified copper foam electro-Fenton cathode material: ZnIn2S4 and TiO2NTs / Ti mesh have a band alignment to form a type-II heterojunction, which improves the separation efficiency of photogenerated electrons and holes; effectively improves the stability of the photoanode, enabling it to continuously degrade pollutants and generate electricity under long-term light illumination. It has the advantages of a simple synthesis method and high photoelectric conversion efficiency.

[0062] Finally, it should be noted that the specific implementation cases described above are only the specific implementation manners of the present invention, but the protection scope of the present invention is not limited to the above cases. For those skilled in the art, improvements or substitutions made according to the above description should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention is subject to the protection scope of the claims.

Claims

1. Preparation method of a novel anode material ZnIn2S4 / TiO2NTs / Ti mesh for a photocatalytic fuel cell based on titanium, characterized in that: Construct a TiO₂ nanotube array (TiO₂NTs / Ti mesh) on a 3D titanium mesh by anodic oxidation, and then grow nanosheet or nanoflower-like ZnIn₂S₄ on the surface of the nanotubes by a one-step hydrothermal method to obtain a ZnIn₂S₄ / TiO₂NTs / Ti mesh composite photoanode material.

2. The preparation method of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material according to claim 1, wherein: Place the TiO₂NTs / Ti mesh in an aqueous solution containing ZnCl₂, InCl₃·4H₂O, and thioacetamide (TAA), and use the hydrothermal method to load nanosheet or nanoflower-like ZnIn₂S₄ on the surface of the nanotubes to obtain a ZnIn₂S₄ / TiO₂NTs / Timesh composite photoanode material.

3. The preparation method of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode according to claim 2, wherein: The aqueous solution containing ZnCl₂, InCl₃·4H₂O, and TAA contains 25 mM ZnCl₂, 50 mM InCl₃·4H₂O, and 100 mM TAA in every 100 mL of water.

4. The preparation method of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode according to claim 2, characterized in that: The hydrothermal reaction temperature is 150 °C and the reaction time is 15 min; after hydrothermal treatment, it is dried in an oven at 60 °C, and the required material is obtained after drying.

5. The preparation method of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode according to claim 1, characterized in that: The TiO₂NTs / Ti mesh is obtained by anodic oxidation of the pretreated titanium mesh to get undetermined TiO₂NTs / Timesh, which is then taken out after annealing treatment in a muffle furnace for later use.

6. The preparation method of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode according to claim 5, characterized in that: The anodic oxidation uses the pretreated titanium mesh as the working electrode and a platinum sheet as the counter electrode. The two electrodes are placed opposite each other in the electrolyte with a spacing of 2 cm, and oxidized at a constant DC voltage of 20 V for 120 min. Then it is rinsed and dried, and annealed in a muffle furnace with a heating rate of 1 °C / min and maintained at 450 °C for 180 min.

7. The preparation method of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode according to claim 6, characterized in that: The electrolyte is prepared by adding 0.42 g of NaF and 6.9 g of NaHSO₄·H₂O to every 100 mL of water.

8. A method for preparing a ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode prepared by the method described in claim 1, characterized in that: A ZnIn₂S₄ / TiO₂NTs / Ti mesh composite photoanode in which the nanosheet or nanoflower-like ZnIn₂S₄ structure is uniformly distributed on the surface of the TiO₂NTs / Ti mesh is prepared by the method described in Claim 1.

9. Application of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode material according to claim 8, characterized in that: The application of the ZnIn₂S₄ / TiO₂NTs / Ti mesh composite photoanode material as a photoanode for degrading pollutants and generating electricity in a photocatalytic fuel cell.

10. Application of the ZnIn2S4 / TiO2NTs / Ti mesh composite photoanode according to claim 9, characterized in that: The pollutant is 10 mg / L 2,4-DCP.

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