Bismuth oxyiodide modified oxygen vacancy-enriched titanium dioxide nanotube array as well as preparation method and application thereof

Abstract

The invention discloses a bismuth oxyiodide modified oxygen-vacancy-enriched titanium dioxide nanotube array and a preparation method and application thereof, which realize wide-range and efficient light response efficiency: BiOI (forbidden bandwidth is approximately equal to 1.8 eV) is used as an excellent visible-light-driven photocatalyst and forms a semiconductor heterojunction with TNAs after being loaded, the spectral response range of the material is widened to a visible light wave band, and the visible-light-driven visible-light-driven photocatalyst can be used for preparing a visible-light-driven photocatalyst. And the construction of interface oxygen vacancies also improves the transmission efficiency of photon-generated carriers, so that the photocatalytic efficiency and the visible light utilization rate of the material are greatly improved. The material prepared by the invention can be used for a long time after being fixed in a reactor, and after the material is recycled for 20 times, the degradation rate of typical refractory organic matters in single 60 minutes can still be kept above 90%.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to an oxygen-rich vacancy titanium dioxide nanotube array modified with bismuth iodide oxide, its preparation method, and its application. Background Technology

[0002] Organic pollutants are the most common water pollutants in the current aquatic environment. Among them, artificially synthesized organic additives are an important component of organic pollution in water bodies. They are not easily removed by the self-purification process of water bodies and pose a serious threat to human health and the aquatic environment.

[0003] Currently, conventional drinking water treatment processes are insufficient to remove trace organic pollutants from water bodies, thus necessitating advanced treatment. Ultraviolet (UV) disinfection, a type of photocatalytic water treatment technology, is one of the most widely used methods for advanced water supply and drainage treatment. Titanium dioxide nanotube arrays (TNAs), as a traditional photocatalyst, are frequently incorporated into UV photocatalytic water treatment technologies to improve water treatment efficiency. However, traditional UV photocatalysis and TNA photocatalytic materials suffer from the following technical limitations: 1. High recombination rate of photogenerated carriers: The photoelectron-hole pairs generated during photocatalysis recombine easily, resulting in very limited catalytic efficiency; 2. Poor visible light response efficiency: Due to the wide bandgap of titanium dioxide (~3.2 eV), it can only utilize ultraviolet light (accounting for about 4% of natural sunlight); 3. High operating energy consumption: Existing ultraviolet water treatment technologies rely mainly on artificial ultraviolet light sources, resulting in huge energy consumption when using ultraviolet photocatalytic water treatment technology, and significantly increasing the operating cost of water plants.

[0004] Therefore, there is an urgent need in this field to develop an environmentally friendly, durable composite titanium dioxide nanotube array photocatalytic material with a wide spectral response range to adapt to the low-carbon and low-energy consumption development trend of water treatment processes. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an oxygen-rich vacancy titanium dioxide nanotube array modified with bismuth iodide oxide.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing an array of oxygen-rich vacancy titanium dioxide nanotubes modified with bismuth iodide oxide, comprising, A mixed solution was prepared by mixing deionized water and glycerol, and then ammonium fluoride and ammonium chloride were added and stirred to obtain an electrolyte. Anodizing is performed by using a pure titanium sheet as the anode and a pure platinum sheet as the cathode, and applying a DC voltage between the two electrodes using a DC power supply. The anode material was removed and heated to 500°C at a rate of 10°C / min under a nitrogen atmosphere, and calcined for 1 hour to obtain a deep blue crystalline titanium dioxide nanotube array material, named TNAs. Using TNAs as the working electrode, platinum as the counter electrode, saturated calomel as the reference electrode, and sodium sulfate solution as the electrolyte, a constant potential voltage of -1.5 V was applied between the two electrodes through a DC regulated power supply to reduce the material. The TNAs material was then removed from the solution, dried, and oxygen-rich vacancy TNAs were obtained, which were named OV-TNAs. Immerse OV-TNAs sequentially in bismuth nitrate solution for 10-30 seconds, remove and rinse with ultrapure water for 5-10 seconds, then immerse in potassium iodide solution for 2-3 minutes, remove and rinse with ultrapure water for 5-10 seconds, repeat this process 7-10 times, then clean with nitrogen and dry the surface. The obtained material was calcined at a constant temperature of 300℃ for 2.5 hours to obtain the material, which was named BiOI / OV-TNAs.

[0009] In a preferred embodiment of the preparation method described in this invention, the method for preparing the pure titanium sheet includes: Pure titanium sheets were cut to a fixed size and then ultrasonically cleaned in ethanol, acetone, and deionized water for 15 minutes in sequence to remove surface grease. After that, they were dried by blowing with nitrogen at room temperature.

[0010] As a preferred embodiment of the preparation method of the present invention, the mixed solution is prepared by mixing deionized water and glycerol, wherein the volume ratio of deionized water to glycerol is 1:9.

[0011] In a preferred embodiment of the preparation method described in this invention, the concentration of ammonium fluoride is 0.36 mol / L and the concentration of ammonium chloride is 0.25 mol / L.

[0012] In a preferred embodiment of the preparation method described in this invention, the anodizing is performed by applying a DC voltage between the two electrodes using a DC power supply, wherein the distance between the electrodes is set to 2 cm, the DC voltage is 25 V, and the anodizing time is 1.0 h.

[0013] In a preferred embodiment of the preparation method described in this invention, the concentration of the sodium sulfate solution is 0.5 mol / L.

[0014] In a preferred embodiment of the preparation method described in this invention, the concentration of the bismuth nitrate solution is 5 mmol / L, and the concentration of the potassium iodide solution is 5 mmol / L.

[0015] Another objective of this invention is to overcome the shortcomings of the prior art and provide an oxygen-rich vacancy titanium dioxide nanotube array modified with bismuth iodide oxide.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of bismuth iodide-modified oxygen-rich vacancy titanium dioxide nanotube array in the degradation of recalcitrant organic compounds, wherein the recalcitrant organic compounds include one of bisphenol A, sulfamethoxazole, ofloxacin, bezafibrate, and disodium copper EDTA.

[0017] Beneficial effects of this invention: (1) Greatly improves the separation efficiency of photogenerated carriers: The oxygen vacancies created act as photogenerated electron traps, which reduces the carrier recombination rate by 60% and can generate more oxygen-active substances to promote the oxidation of organic pollutants in water. (2) Achieving wide-range and high-efficiency photoresponse performance: BiOI (bandgap width ≈ 1.8 eV) is an excellent visible light catalyst. After loading, it forms a semiconductor heterojunction with TNAs, which broadens the spectral response range of the material to the visible light band and improves the transport efficiency of photogenerated carriers, thus greatly improving the visible light utilization rate of the material. (3) Energy saving and environmental protection: The composite material prepared by the present invention can operate under sunlight. Compared with the high energy consumption of ultraviolet water treatment technology, the catalytic energy consumption is greatly reduced, and the operating cost is saved. (4) The material can be fixed in water and can be used in a continuous water treatment reactor for a long time. It has strong stability: Unlike disposable powdered catalytic materials, the material prepared by this invention can be fixed in the reactor and used for a long time. After being recycled 20 times, the degradation rate of typical recalcitrant organic matter can still be maintained at more than 90% within a single 60-minute cycle. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1The images shown are scanning electron microscope (SEM) images of BiOI / OV-TNAs materials in this embodiment of the invention, where (a) is a planar morphology image of the material, (b) is a longitudinal morphology image, (c) is a cross-section of a morphology image of the material sample, and (d) is an elemental analysis diagram.

[0019] Figure 2 The image shows the electron paramagnetic spectrum of the BiOI / OV-TNAs material in this embodiment of the invention.

[0020] Figure 3 The visible light response test spectra of BiOI / OV-TNAs and the original TNAAs materials in the embodiments of the present invention are shown.

[0021] Figure 4 The diagram shows a comparison of the degradation efficiency of organic matter in the embodiments of the present invention, wherein (a) is the original TNAs material and (b) is the BiOI / OV-TNAs material. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0023] In this embodiment of the invention, the pure titanium sheet was purchased from Chongqing Platinum Strontium Titanium Technology Co., Ltd., with item number 240403556420233; The pure platinum sheet was purchased from Jiangsu Taizhou Boyan Technology Co., Ltd., item number PT789; The saturated calomel reference electrode was purchased from Shanghai Chenhua Instrument Co., Ltd., item number CHI150. Glycerol was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number G116206; Ammonium fluoride was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number A400053; Ammonium chloride was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number A616422; Sodium sulfate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number S433906; Bismuth nitrate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number B110814; Potassium iodide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number P116279.

[0024] This invention patent first prepares TNAs materials using anodizing, and then, through the introduction of oxygen vacancies at the TiO2 interface and modification with bismuth oxyiodide (BiOI) nanosheets, invents a method for preparing a composite photocatalytic water treatment material. The material preparation process specifically includes the following four steps: 1. Pretreatment of raw titanium sheets; 2. TNAs preparation: anodic oxidation combined with nitrogen calcination; 3. Oxygen vacancy construction: cathodic reduction method; 4. BiOI loading: continuous ion layer adsorption-reaction loading method.

[0025] Example 1 (1) Titanium sheet pretreatment Pure titanium sheets (purity ≥ 99.9%) were cut into fixed sizes and then cleaned in ethanol, acetone, and deionized water for 15 minutes in sequence using an ultrasonic cleaner (SN-FB38S) to remove surface grease. After that, they were dried at room temperature by blowing with nitrogen gas (the pure titanium sheets involved in the following examples and comparative examples are all pre-treated titanium sheets).

[0026] (2) Preparation of TNAs Electrolyte preparation: Prepare a fixed volume mixture of deionized water and glycerol solution (≥99.0%) at a volume ratio of 1:9. Then, take a fixed amount of ammonium fluoride (NH4F) and ammonium chloride (NH4Cl) and uniformly disperse them in the mixture. The molar volume ratio of ammonium fluoride, ammonium chloride and the mixture is 0.36:1 and 0.25:1, respectively, in mol:L. Stir continuously for 20 hours to ensure that the two are completely dissolved in the mixture.

[0027] Anodizing: Pure titanium sheet as anode and pure platinum sheet as cathode are immersed in the above mixture, with the electrode spacing set to 2cm. A DC voltage of 25V is applied between the two electrodes for 1.0 hour for anodizing. Calcination and crystallization: After the above steps are completed, the material is taken out and heated to 500 °C at a rate of 10 °C / min under a nitrogen atmosphere and calcined for 1 hour to obtain a dark blue crystalline TNAs material. (3) Introducing oxygen vacancies to prepare oxygen-vacancy-rich TNAs (OV-TNAs for short) Cathodic reduction: A high-precision electrochemical workstation was used, with TNAs as the working electrode, platinum as the counter electrode, and saturated calomel as the reference electrode; Electrolyte preparation: 0.5 mol / L sodium sulfate (Na2SO4) solution; Electroreduction preparation parameters: A constant potential voltage of -1.5 V was applied between the two electrodes using a DC regulated power supply (DH731SU3A) to reduce the material for 10 minutes. Post-treatment of materials: Remove the materials from the solution and dry them at 80°C for 30 minutes. (4) BiOI modification to prepare BiOI-supported oxygen-rich vacancy TNAs (BiOI / OV-TNAs for short) Continuous ion layer adsorption-reaction method: Prepare 25 mL each of 5 mmol / L bismuth nitrate (Bi(NO3)3·5H2O) and potassium iodide (KI) solutions; immerse OV-TNAs sequentially in the bismuth nitrate solution for 30 seconds, then remove and rinse with ultrapure water for 5 seconds, then immerse in the potassium iodide solution for 2 minutes, and remove and rinse with ultrapure water for 5 seconds. Repeat this process 7 times, then clean with nitrogen and dry the surface; Material calcination, solidification, and crystallization: The obtained material was placed in a tube muffle furnace (OTF-1200X) and calcined at a constant temperature of 300℃ for 2.5 hours to finally obtain BiOI / OV-TNAs-1 material.

[0028] Example 2 This embodiment provides a method for preparing an array of oxygen-rich vacancy titanium dioxide nanotubes modified with bismuth iodide oxide: (1) Prepare a fixed amount of mixed solution by mixing deionized water and glycerol solution (≥99.0%) at a volume ratio of 1:9. Then, take a fixed amount of ammonium fluoride and ammonium chloride and disperse them evenly in the mixed solution. The molar volume ratio of the two to the mixed solution is 0.36:1 and 0.25:1 in mol:L. Then stir continuously for 20 hours to ensure that the two are completely dissolved in the mixed solution. (2) Using pure titanium sheet as anode and pure platinum sheet as cathode, immerse in the above mixture, with the electrode spacing set to 2cm, and apply a DC voltage of 25V between the two electrodes for 1.0 hour for anodizing; (3) Take out the anode material and heat it to 500°C at a rate of 10°C / min under a nitrogen atmosphere. Continue calcining for 1 hour to obtain a deep blue crystalline titanium dioxide nanotube array material, named TNAs. (4) Using TNAs as the working electrode, platinum as the counter electrode, calomel as the reference electrode, and sodium sulfate solution as the electrolyte, a constant potential voltage of -1.5 V was applied between the two electrodes through a DC regulated power supply to reduce the material for 3 minutes. The TNAs material was then removed from the solution, dried, and oxygen-rich vacancy TNAs were obtained and named OV-TNAs-2. (5) Prepare 25 mL each of 5 mmol / L bismuth nitrate (Bi(NO3)3·5H2O) and potassium iodide (KI) solutions; immerse OV-TNAs-2 sequentially in the bismuth nitrate solution for 30 seconds, then remove and rinse with ultrapure water for 5 seconds, then immerse in the potassium iodide solution for 2 minutes, then remove and rinse with ultrapure water for 5 seconds. Repeat this process 3 times, then clean with nitrogen and dry the surface; place the obtained material in a tube muffle furnace (OTF-1200X) and calcine at a constant temperature of 300℃ for 2.5 hours to finally obtain the material, named BiOI / OV-TNAs-2.

[0029] Example 3 This embodiment provides a method for preparing an array of oxygen-rich vacancy titanium dioxide nanotubes modified with bismuth iodide oxide: (1) Prepare a fixed amount of mixed solution by mixing deionized water and glycerol solution (≥99.0%) at a volume ratio of 1:9. Then, take a fixed amount of ammonium fluoride and ammonium chloride and disperse them evenly in the mixed solution. The molar volume ratio of the two substances to the mixed solution is 0.36:1 and 0.25:1 in mol:L. Then stir continuously for 20 hours to ensure that they are completely dissolved in the mixed solution. (2) Using pure titanium sheet as anode and pure platinum sheet as cathode, immerse in the above mixture, with the electrode spacing set to 2cm, and apply a DC voltage of 25V between the two electrodes for 1.0 hour for anodizing; (3) Take out the anode material and heat it to 500°C at a rate of 10°C / min under a nitrogen atmosphere. Continue calcining for 1 hour to obtain a deep blue crystalline titanium dioxide nanotube array material, named TNAs. (4) Using TNAs as the working electrode, platinum as the counter electrode, calomel as the reference electrode, and 0.5 mol / L sodium sulfate solution as the electrolyte, a constant potential voltage of -1.5 V was applied between the two electrodes through a DC regulated power supply to reduce the material for 30 minutes. The TNAs material was then removed from the solution, dried, and oxygen-rich vacancy TNAs were obtained and named OV-TNAs-3. (5) Prepare 25 mL of bismuth nitrate and potassium iodide solutions with a concentration of 5 mmol / L respectively; immerse OV-TNAs sequentially in the bismuth nitrate solution for 30 seconds, then remove and rinse with ultrapure water for 5 seconds, then immerse in potassium iodide solution for 2 minutes, then remove and rinse with ultrapure water for 5 seconds. Repeat this process 14 times, then clean with nitrogen and dry the surface; place the obtained material in a tube muffle furnace (OTF-1200X) and calcine at a constant temperature of 300℃ for 2.5 hours to finally obtain the material, named BiOI / OV-TNAs-3.

[0030] The three materials prepared above (cut to a size of 4×4 cm) were respectively fixed in an aqueous solution and subjected to simulated sunlight (using a xenon lamp as the light source, with a light intensity of 100 mW / cm²) in an air environment at 25°C. 2 A single 60-minute degradation test was conducted on a 50 mL of ofloxacin solution with a concentration of 1 mg / L. The degradation test was repeated three times, and the average value of the three degradation rates was taken. The results are shown in Table 1.

[0031] Table 1. Comparison of degradation rates of ofloxacin by materials prepared in different embodiments As can be seen from Table 2, the bismuth oxyiodide-modified oxygen-vacancy titanium dioxide nanotube array prepared according to the method of Example 1 of this invention has the most efficient photocatalytic water treatment performance. This allows bismuth oxyiodide and titanium dioxide to form a semiconductor heterojunction more fully at their interface to enhance the transfer efficiency of photogenerated carriers. Furthermore, the appropriate construction of interfacial oxygen vacancies can also effectively capture photogenerated electrons, thereby generating more oxygen-active free radicals during the photocatalytic process to degrade organic matter.

[0032] Example 4 Material morphology observation: The surface morphology of the sintered material sample (the sample obtained in Example 1) was observed and analyzed using a field emission scanning electron microscope (Quattro S, Thermo Fisher Scientific). The relevant results are shown in [link to relevant documentation]. Figure 1 .

[0033] Before electron microscopy, the samples were briefly cleaned in ultrapure water using an ultrasonic cleaner to ensure surface cleanliness. After air drying, they were observed under the electron microscope. Because the prepared material has a certain degree of conductivity, the samples were not sputtered with gold for electron microscopy; instead, they were directly adhered to the photoanode samples using conductive adhesive. The electron microscope was operated at 15 kV, and after magnification of 200,000 times, clear microscopic features of the samples were observed.

[0034] from Figure 1 As can be seen from (a)-(c), TiO2 nanotubes grow in close arrangement, with pores at the top of the nanotubes and relatively uniform pore size. The average diameter of the nanotubes is about 150 nm and the wall thickness of a single nanotube is about 15 nm. In addition, petal-shaped nanomaterials grow unevenly on the pores of the nanotubes, indicating that typical petal-shaped bismuth iodide nanomaterials are generated on the surface of TNAs, because BiOI nanoflowers are usually composed of individual curved nanosheets.

[0035] pass Figure 1 (a) and Figure 1 (c) It can be seen that the nanosheet is very thin, with a thickness of approximately 10 nm. This contact method of the nanosheet embedded in the nanotube is beneficial for increasing the interfacial contact area between the nanotube and bismuth oxyiodide. From Figure 1 (b) shows the longitudinal section morphology of the material sample, indicating that the TNA grows vertically on the Ti substrate and is tightly connected to the Ti substrate, with an average tube length of about 700 nm for each nanotube. Figure 1 (c) is a cross-sectional morphological image of the selected material sample. The elemental composition of the sample was analyzed using an energy dispersive spectroscopy (EDS) instrument. The results are as follows: Figure 1 As shown in (d). From Figure 1The results in (d) show that the main elemental signal peaks of the four constituent materials—titanium (Ti), oxygen (O), bismuth (Bi), and iodine (I)—are clearly detected in the sample cross-section. Based on the combined results of the scanning electron microscopy morphology observation and elemental analysis, it is confirmed that bismuth iodide-modified TNAs photocatalytic materials have been successfully prepared.

[0036] Example 5 The formation of oxygen vacancies at the material interface has been determined: The prepared material (sample obtained in Example 1) was subjected to electron paramagnetic resonance (EPR) testing using an electron paramagnetic resonance spectrometer (JES-FA200, JEOL) to verify the presence of trivalent titanium ions (Ti) in the prepared material. 3+ The presence of oxygen vacancies and the corresponding electron paramagnetic test signal peaks of the measured material samples are shown in [the image / data]. Figure 2 .

[0037] pass Figure 2 As can be seen from the signal peaks, two very obvious signal peaks were detected at the horizontal coordinates g=2.002 and g=2.004. Based on previous research, these are precisely due to the presence of Ti in the material. 3+ The presence of oxygen vacancies resulted in a significant response signal peak at this location. This clearly indicates the presence of significant oxygen vacancies in the prepared BiOI / OV-TNAs composite material.

[0038] Example 6 Comparison of photocatalytic response performance with the original TNA material: To further determine whether an ideal semiconductor heterojunction was formed between BiOI and TiO2 semiconductors in the material prepared in this invention to accelerate the separation of photogenerated carriers, the photoresponse current density of the bismuth oxyiodide-modified oxygen-vacancy TNAs (samples obtained in Example 1) and pure TNAs was compared to determine their effectiveness. The pure TNAs material was prepared according to steps (1) to (2) in Example 1.

[0039] Photoresponse current curves are a method used to evaluate the photogenerated electron yield and transport efficiency in photocatalytic materials. Generally, the higher the measured photocurrent density value of a material, the better the photogenerated electron-hole separation effect.

[0040] Using a xenon lamp (CEL-HXF300) to simulate sunlight, the photocells composed of the two materials were measured under simulated visible light illumination (light intensity: 100 mW / cm²) using an electrochemical workstation (Gamry Interface 1010E). 2 The photocurrent response curve generated is shown in the following test procedure: Cut the prepared sheet material to a size of 3×3 cm, and prepare a platinum sheet of the same size. Using the material of this invention as the anode, the platinum sheet as the cathode, and saturated calomel as the reference electrode, place all electrodes vertically in a rectangular quartz container measuring 4×3×6 cm, containing 60 ml of sodium sulfate electrolyte (0.01 mol / L). Turn on the xenon lamp source so that it can vertically irradiate the anode surface, and use an irradiation meter (FZ-A) to measure the light intensity irradiated on the anode, ensuring that this value is 100 mW / cm². 2 The photocurrent density generated between the cathode and anode was then measured using an electrochemical workstation. The test was conducted five times, alternating between dark and light conditions, with a 25-second interval between each measurement. The photocurrent density values ​​were recorded and plotted. The test results are as follows: Figure 3 As shown.

[0041] pass Figure 3 The study found that when the light source is turned on, photovoltaic cell systems composed of different materials all generate corresponding current densities, while no current response occurs when the light source is turned off. This indicates that both TNA and BiOI can be excited by visible light to varying degrees to generate photoelectrons, thus forming photocurrent. However, the overall response intensity remains very weak. Furthermore, the figure shows that when the BiOI / OV-TNAs material prepared in this invention is used as the photoanode, the average photocurrent density reaches 0.130 mA / cm². 2 This value is 4.3 times the average photocurrent density (0.03 mA / cm²) under illumination when the original TNAs are used as photoanodes. 2 This result demonstrates that, compared to single TNAs materials, the synthesized material of this invention has a more efficient visible light response, and the separation of photogenerated carriers is greatly enhanced with the formation of two semiconductor heterojunctions.

[0042] Example 7 Comparison of the degradation efficiency of materials for organic matter: Degradation experiments were conducted on various recalcitrant organic compounds in water using the synthetic materials of this invention and the original TNAs materials, respectively.

[0043] The synthesized BiOI / OV-TNAs material (sample obtained in Example 1) and the original TNAs material (4×4 cm in size) were respectively immobilized in an aqueous solution and subjected to simulated sunlight (using a xenon lamp as the light source, with a light intensity of 100 mW / cm²) in an air environment at 25°C. 2 The degradation tests were performed on 50 mL solutions of various typical recalcitrant organic compounds (including bisphenol A, sulfamethoxazole, ofloxacin, bezafibrate, and copper disodium EDTA (Cu-EDTA)) at a concentration of 1 mg / L for 60 minutes. The final result is as follows Figure 4As shown, the degradation rate of various organic pollutants treated with the synthesized material reached over 95%, which is more than 3.45 times the average degradation rate of the original TNAs materials. This case demonstrates that the photocatalytic material synthesized in this invention possesses a wider spectral response range, highly efficient advanced oxidation water treatment performance, and broad application prospects.

[0044] Example 8 Material stability testing: Using the material prepared by this invention, a cyclic degradation experiment was conducted on ofloxacin, a typical antibiotic drug pollutant in water, to determine the water treatment performance stability of the material.

[0045] The synthesized BiOI / OV-TNAs material (sample obtained in Example 1) (4×4 cm in size) was immobilized in an aqueous solution and subjected to simulated sunlight (using a xenon lamp as the light source, with a light intensity of 100 mW / cm²) in an air environment at 25°C. 2 The degradation test was performed on a 50 mL of ofloxacin solution with a concentration of 1 mg / L for 60 minutes, and the cycle was repeated 20 times.

[0046] The degradation results showed that the average degradation rate of ofloxacin reached over 90% in each degradation process, and the overall degradation of organic matter was relatively thorough (see Table 2). This case demonstrates that the photocatalytic material synthesized in this invention has high stability and strong durability, proving that it can be installed in continuous flow deep treatment reactors in water treatment plants.

[0047] Table 2. Stability test results of BiOI / OV-TNA materials Comparative Example 1 (1) Prepare a fixed amount of mixed solution by mixing deionized water and glycerol solution (≥99.0%) at a volume ratio of 1:9. Then, take a fixed amount of ammonium fluoride and ammonium chloride and disperse them evenly in the mixed solution. The molar volume ratio of the two to the mixed solution is 0.36 and 0.25 in mol:L. Then stir continuously for 20 hours to ensure that the two are completely dissolved in the mixed solution. (2) Using pure titanium sheet as anode and pure platinum sheet as cathode, immerse in the above mixture, with the electrode spacing set to 2cm, and apply a DC voltage of 25V between the two electrodes for 1.0 hour for anodizing; (3) Take out the anode material and heat it to 500°C at a rate of 10°C / min under a nitrogen atmosphere. Continue calcining for 1 hour to obtain a deep blue crystalline titanium dioxide nanotube array material, named TNAs. (4) Using TNAs as the working electrode, platinum as the counter electrode, saturated calomel as the reference electrode, and sodium sulfate solution (0.5 mol / L) as the electrolyte, a constant potential voltage of -1.5 V is applied between the two electrodes through a DC regulated power supply to reduce the material. The TNAs material is then removed from the solution, dried, and oxygen-rich vacancy TNAs are obtained, which are named OV-TNAs. (5) The synthesized OV-TNAs material (4×4 cm in size) was fixed in an aqueous solution and subjected to simulated sunlight (using a xenon lamp as the light source and a light intensity of 100 mW / cm) in an air environment at 25°C. 2 The degradation of ofloxacin, a typical recalcitrant organic compound, was tested in a 50 mL solution with a concentration of 1 mg / L for 60 minutes. Compared with Example 1, the material preparation process of this comparative example did not involve bismuth oxyiodide loading, but was otherwise the same as that of Example 1.

[0048] It was observed that the photocatalytic degradation rate of ofloxacin using this material was 47.3%, which was 51.9% lower than that of the material of this invention, indicating weaker photocatalytic activity.

[0049] Comparative Example 2 (1) Prepare a fixed amount of mixed solution by mixing deionized water and glycerol solution (≥99.0%) at a volume ratio of 1:9. Then, take a fixed amount of ammonium fluoride and ammonium chloride and disperse them evenly in the mixed solution. The molar volume ratio of the two to the mixed solution is 0.36 and 0.25 in mol:L. Then stir continuously for 20 hours to ensure that the two are completely dissolved in the mixed solution. (2) Using pure titanium sheet as anode and pure platinum sheet as cathode, immerse in the above mixture, with the electrode spacing set to 2cm, and apply a DC voltage of 25V between the two electrodes for 1.0 hour for anodizing; (3) Take out the anode material and heat it to 500°C at a rate of 10°C / min under a nitrogen atmosphere. Continue calcining for 1 hour to obtain a deep blue crystalline titanium dioxide nanotube array material, named TNAs. (4) Prepare 25 mL each of 5 mmol / L bismuth nitrate (Bi(NO3)3·5H2O) and potassium iodide (KI) solutions; immerse OV-TNAs sequentially in the bismuth nitrate solution for 30 seconds, then remove and rinse with ultrapure water for 5 seconds, then immerse in the potassium iodide solution for 2 minutes, then remove and rinse with ultrapure water for 5 seconds. Repeat this process 7 times, then clean with nitrogen and dry the surface; place the obtained material in a tube muffle furnace (OTF-1200X) and calcine at a constant temperature of 300℃ for 2.5 hours to finally obtain the material, named BiOI / TNAs material.

[0050] (5) The synthesized OV-TNAs material (4×4 cm in size) was fixed in an aqueous solution and subjected to simulated sunlight (using a xenon lamp as the light source and a light intensity of 100 mW / cm) in an air environment at 25°C. 2 The photocatalytic degradation of ofloxacin, a typical recalcitrant organic compound, was tested in a 50 mL solution with a concentration of 1 mg / L for 60 minutes. Compared with Example 1, the material preparation process of this comparative example did not involve the construction of TiO2 oxygen vacancy defects, but was otherwise the same as that of Example 1.

[0051] The photocatalytic degradation rate of ofloxacin using this material was observed to be 68.4%, which is 30.8% lower than that of the material of this invention. The material possesses certain photocatalytic activity, but its activity is significantly lower than that of the material of this invention.

[0052] Comparative Example 3 (1) Take titanium dioxide powder P25 powder, ultrasonically clean it in pure water and ethanol for 15 minutes, then put it in an 80℃ drying oven to dry for 8 hours, then put it in a muffle furnace, raise it to 250℃ at a rate of 5℃ / min, calcine it for 2.5 hours and then take it out. (2) Dissolve bismuth pentahydrate in ethanol by stirring evenly to obtain mixture a. Disperse the calcined titanium dioxide powder in the mixture and stir continuously for 3 hours to obtain mixture b. The molar volume ratio of bismuth pentahydrate to ethanol in mixture b is 1:10 in mmol: mL and the mass volume ratio of titanium dioxide to ethanol is 1:15 in g: mL. (3) Disperse potassium iodide evenly in deionized water and stir continuously for 2 hours to obtain potassium iodide aqueous solution. The molar volume ratio of potassium iodide to deionized water in the solution is 1:10 in mmol: mL. (4) Mix the mixture b with the potassium iodide aqueous solution and stir continuously for 2 hours. Then, place the mixture in a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 200°C for 8 hours. After that, centrifuge and wash the obtained mixture 3 times each, and dry it in an 80°C drying oven for 12 hours. The resulting solid material is the powdered bismuth iodide-titanium dioxide heterojunction photocatalyst.

[0053] (5) For easy comparison, BiOI / OV-TNAs material was synthesized in Example 1, cut to a size of 4×4 cm, weighed using an electronic balance, and prepared powdered bismuth oxyiodide-titanium dioxide heterojunction photocatalyst of the same weight according to the value.

[0054] The photocatalyst was uniformly dispersed in a quartz glass reactor (4×3×6cm) containing 50mL of ofloxacin solution (concentration 1mg / L). The reactor was then subjected to simulated sunlight at 25℃ (using a xenon lamp as the light source, ensuring the light intensity at the center of the reactor remained at 100 mW / cm²). 2 The ofloxacin solution was subjected to a single 60-minute degradation test, and the degradation was repeated five times to determine the ofloxacin degradation rate each time.

[0055] Each degradation solution was a freshly prepared ofloxacin solution. After a single degradation was completed, the photocatalyst was recovered by centrifuging and washing the solution three times each, and then drying it in an 80°C drying oven for 12 hours before taking it out.

[0056] (6) The BiOI / OV-TNAs material (4×4 cm) prepared in this invention was fixed in an aqueous solution and subjected to simulated sunlight (using a xenon lamp as the light source, with a light intensity of 100 mW / cm) in an air environment at 25°C. 2 The ofloxacin solution (50 mL, 1 mg / L) was subjected to a single 60-minute degradation cycle, and this degradation was repeated five times. The degradation rate was measured each time. The degradation solution used in each cycle was freshly prepared ofloxacin solution. Compared with Example 1, the material prepared in this comparative example is a powdered oxygen-vacancy bismuth iodide-titanium dioxide heterojunction material. This preparation method is a commonly used method for loading BiOI materials onto titanium dioxide powder.

[0057] Comparing the degradation effects of the material of this invention with those of ofloxacin solution after five cycles, it was observed that the degradation effects of the two types of materials were basically the same in the first cycle. However, in the subsequent four cycles, the degradation effect of the powdered material was gradually much lower than that of the material of this invention. In the last cycle, the degradation rate of ofloxacin differed by 77.8% from the degradation rate corresponding to the material of this invention. The material of this invention demonstrates highly efficient catalytic activity and reliable durability.

[0058] Table 3. Comparison of material cyclic degradation stability In summary, the bismuth oxyiodide-modified oxygen-vacancy-rich titanium dioxide nanotube array of this invention exhibits highly efficient photocatalytic water treatment performance under humid conditions. The loading of bismuth oxyiodide not only enhances the visible light response range but also forms a semiconductor heterojunction with titanium dioxide, which is beneficial for the transport of photogenerated carriers. Simultaneously, the construction of oxygen vacancies at the titanium dioxide interface can effectively capture photogenerated electrons. These two elements work synergistically to enhance the generation of free radicals in water, promoting the rapid degradation of stubborn organic matter. Furthermore, compared to powdered photocatalytic materials, the material of this invention can be immobilized in water and possesses long-term durability.

[0059] The preparation method of the material of this invention is relatively simple. Compared with the powdered materials described in other patents, the material of this invention can maintain its catalytic activity for a long time without replacing the main material after continuous use and the activity is reduced. This greatly saves the cost of use.

[0060] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing an array of oxygen-rich vacancy titanium dioxide nanotubes modified with bismuth iodide oxide, characterized in that: include, A mixed solution was prepared by mixing deionized water and glycerol, and then ammonium fluoride and ammonium chloride were added and stirred to obtain an electrolyte. Anodizing is performed by using a pure titanium sheet as the anode and a pure platinum sheet as the cathode, and applying a DC voltage between the two electrodes using a DC power supply. The anode material was removed and heated to 500°C at a rate of 10°C / min under a nitrogen atmosphere, and calcined for 1 hour to obtain a deep blue crystalline titanium dioxide nanotube array material TNAs. Using TNAs as the working electrode, platinum as the counter electrode, calomel as the reference electrode, and sodium sulfate solution as the electrolyte, a constant potential voltage of -1.5 V was applied between the two electrodes through a DC regulated power supply to reduce the material. The TNAs material was then removed from the solution, dried, and oxygen-rich TNAs were obtained. Immerse OV-TNAs sequentially in bismuth nitrate solution for 10-30 seconds, remove and rinse with ultrapure water for 5-10 seconds, then immerse in potassium iodide solution for 2-3 minutes, remove and rinse with ultrapure water for 5-10 seconds, repeat this process 7-10 times, then clean with nitrogen and dry the surface. The obtained material was calcined at a constant temperature of 300℃ to obtain BiOI / OV-TNAs material.

2. The preparation method according to claim 1, characterized in that: The method for preparing the pure titanium sheet includes, Pure titanium sheets were cut to a fixed size and then ultrasonically cleaned in ethanol, acetone, and deionized water for 15 minutes in sequence to remove surface grease. After that, they were dried by blowing with nitrogen at room temperature.

3. The preparation method according to claim 1 or 2, characterized in that: The mixed solution is prepared by mixing deionized water and glycerol, wherein the volume ratio of deionized water to glycerol is 1:

9.

4. The preparation method according to claim 1, characterized in that: The concentration of ammonium fluoride is 0.36 mol / L, and the concentration of ammonium chloride is 0.25 mol / L.

5. The preparation method according to claim 1, characterized in that: The anodizing process involves applying a DC voltage between two electrodes using a DC power supply, wherein the distance between the electrodes is set to 2 cm, the DC voltage is 20 V, and the anodizing time is 1.0 h.

6. The preparation method according to claim 1, characterized in that: The sodium sulfate solution has a concentration of 0.5 mol / L.

7. The preparation method according to claim 1, characterized in that: The concentration of the bismuth nitrate solution is 5 mmol / L, and the concentration of the potassium iodide solution is 5 mmol / L.

8. The bismuth iodide-modified oxygen-vacancy titanium dioxide nanotube array prepared by any of the preparation methods described in claims 1 to 7.

9. The application of the bismuth iodide-modified oxygen-vacancy-rich titanium dioxide nanotube array according to claim 8 in the degradation of recalcitrant organic matter, characterized in that: The recalcitrant organic compounds include one of the following: bisphenol A, sulfamethoxazole, ofloxacin, bezafibrate, and copper disodium EDTA.

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