A method for in-situ construction of wide-band wavelength visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructures on titanium surface

Abstract

A method for in situ construction of a wide-band visible / ultraviolet dual heterostructure of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide on a titanium surface, relating to methods for constructing dual heterostructures. The present invention addresses the problem of existing TiO2 photocatalysts having poor degradation capabilities for organic dye wastewater and being non-recyclable. The method includes: 1. micro-arc oxidation treatment; 2. microwave hydrothermal treatment; 3. ion deposition exchange treatment; and 4. de-crystallization treatment. The present invention is used to in situ construct a wide-band visible / ultraviolet dual heterostructure of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide on a titanium surface.

Description

Technical Field

[0001] The present invention relates to a method for constructing a double heterostructure. Background Art

[0002] Currently, commonly used photocatalysts are difficult to recycle or have low recovery rates during wastewater treatment. Furthermore, TiO2-based catalysts, typically nanomaterials, are mixed with wastewater and degrade it under light. Therefore, it's difficult to separate the catalyst from the wastewater for reuse and to reduce wastewater treatment costs. Furthermore, pure TiO2, due to its wide energy band gap, can only absorb light in the ultraviolet range, and its high rate of photogenerated electron-hole recombination significantly impacts the photocatalytic performance. Summary of the Invention

[0003] The present invention aims to solve the problem that existing TiO2 photocatalysts have poor degradation ability for organic dye wastewater and cannot be recycled and reused, and further provides a method for in situ construction of wide-band wavelength visible / ultraviolet light titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructures on titanium surface.

[0004] A method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface is carried out in the following steps:

[0005] 1. Micro-arc oxidation treatment:

[0006] The titanium plate with the oxide layer removed is placed in an electrolyte, with the titanium plate with the oxide layer removed serving as an anode and a stainless steel plate serving as a cathode, and micro-arc oxidation is performed in a pulse constant current mode under the conditions of a current of 0.2A to 2.0A, a pulse frequency of 600Hz to 1000Hz, a duty cycle of 4% to 20%, and an electrolyte temperature of 20°C to 30°C to obtain a titanium plate treated with micro-arc oxidation;

[0007] The electrolyte consists of phosphate, fluoride salt, alkali solution and deionized water;

[0008] 2. Microwave hydrothermal treatment:

[0009] The titanium plate treated by micro-arc oxidation is immersed in an alkaline solution for microwave hydrothermal treatment to obtain a titanium plate treated by microwave hydrothermal treatment;

[0010] 3. Ion deposition exchange treatment:

[0011] ① Immerse the titanium plate after microwave hydrothermal treatment in tungstate solution, take it out and immerse it in hydrochloric acid, and finally wash it;

[0012] ② Repeat step 3① 5 to 20 times, and then dry to obtain the titanium plate after ion deposition exchange;

[0013] 4. De-crystallization treatment:

[0014] The titanium plate after ion deposition exchange is placed in a muffle furnace and de-crystallized under air atmosphere, thereby completing the in-situ construction of a wide-band wavelength visible / ultraviolet light titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructure on the titanium surface.

[0015] The beneficial effects of the present invention are:

[0016] The present invention aims to in situ prepare titanium dioxide / sodium titanate and / titanium dioxide@tungsten trioxide dual structures on the surface of titanium plate with excellent photocatalytic effect in the visible and ultraviolet wavelength range. A porous coating is prepared on the surface of titanium plate by micro-arc oxidation technology, and then microwave hydrothermal treatment is performed to form a large number of sodium titanate nanowires (Na + +TiO2+OH - ―Na 0.23 TiO2) provides more active sites for the subsequent deposition of tungstate ions; then it is transformed into a composite structure of titanate and tungstate through ion deposition exchange technology, and after de-crystallization, it is transformed into a TiO2 / WO3 heterogeneous structure; at the same time, the process parameters of ion exchange are controlled to retain the structure of sodium titanate nanowires to form TiO2 / Na 0.23 TiO2 heterogeneous structure is used to achieve high catalytic performance under wide-range visible / ultraviolet wavelengths, solving the problems of low photocatalytic degradation rate and difficult recycling of existing TiO2-based photocatalysts.

[0017] The sample treated by the present invention was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After the sample treated by the present invention was tested by XRD diffraction, TiO2, Na 0.23 TiO2 and WO3 phases. Scanning electron microscopy revealed the formation of a large number of titanium dioxide @ sodium titanate and / or titanium dioxide @ tungsten trioxide dual heterostructures on the surface. Furthermore, transmission electron microscopy images revealed a good coupling relationship between the WO3 particles and the TiO2 nanorods. The photocatalytic activity of the surface of the sample treated by the present invention was characterized by placing it in a methylene blue solution and irradiating it with a xenon lamp. The degradation rate of the organic dye reached over 86% in the fifth cycle. After five cycles of cyclic testing, no significant changes in the heterostructure were observed in the scanning electron microscopy images, indicating that the sample obtained by the present invention possesses stable, long-term degradation performance.

[0018] Appendix

[0019] Figure 1 This is a scanning electron microscope image of the titanium dioxide / sodium titanate heterostructure constructed in situ on the titanium surface in step 2 of Example 1;

[0020] Figure 2 The EDS spectrum of the wide-band wavelength visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures constructed in situ on the titanium surface in Example 1;

[0021] Figure 3 This is the XRD pattern of the wide-band visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide dual heterostructures constructed in situ on the titanium surface in Example 1. A is the anatase peak, B is the titanium peak, C is the rutile peak, D is the tungsten oxide peak, and E is the sodium titanate peak.

[0022] Figure 4 This is a scanning electron microscope image of the in-situ construction of wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructures on the titanium surface in Example 1;

[0023] Figure 5 This is a transmission electron microscopy image of the titanium dioxide @ tungsten trioxide heterostructure in the in-situ construction of wide-band wavelength visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures on the titanium surface in Example 1;

[0024] Figure 6 Graph showing the fifth cycle photocatalytic degradation rate of the titanium plate treated with micro-arc oxidation prepared in step 1 of Example 1 and the titanium surface in situ constructed with wide-band wavelength visible / ultraviolet light using a dual heterostructure of titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide prepared in step 4;

[0025] Figure 7 This is a scanning photo of the in-situ construction of wide-range wavelength visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures on the titanium surface in Example 1 after five cycles of cyclic testing. DETAILED DESCRIPTION

[0026] Specific embodiment 1: This embodiment is a method for in-situ construction of a wide-band wavelength visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructure on a titanium surface, which is carried out in the following steps:

[0027] 1. Micro-arc oxidation treatment:

[0028] The titanium plate with the oxide layer removed is placed in an electrolyte, with the titanium plate with the oxide layer removed serving as an anode and a stainless steel plate serving as a cathode, and micro-arc oxidation is performed in a pulse constant current mode under the conditions of a current of 0.2A to 2.0A, a pulse frequency of 600Hz to 1000Hz, a duty cycle of 4% to 20%, and an electrolyte temperature of 20°C to 30°C to obtain a titanium plate treated with micro-arc oxidation;

[0029] The electrolyte consists of phosphate, fluoride salt, alkali solution and deionized water;

[0030] 2. Microwave hydrothermal treatment:

[0031] The titanium plate treated by micro-arc oxidation is immersed in an alkaline solution for microwave hydrothermal treatment to obtain a titanium plate treated by microwave hydrothermal treatment;

[0032] 3. Ion deposition exchange treatment:

[0033] ① Immerse the titanium plate after microwave hydrothermal treatment in tungstate solution, take it out and immerse it in hydrochloric acid, and finally wash it;

[0034] ② Repeat step 3① 5 to 20 times, and then dry to obtain the titanium plate after ion deposition exchange;

[0035] 4. De-crystallization treatment:

[0036] The titanium plate after ion deposition exchange is placed in a muffle furnace and de-crystallized under air atmosphere, thereby completing the in-situ construction of a wide-band wavelength visible / ultraviolet light titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructure on the titanium surface.

[0037] This embodiment constructs a heterostructure to solve the problem of high recombination rate of TiO2 photogenerated electron-hole pairs and promotes the separation of electron-hole pairs. At the same time, the Z-type heterostructure not only separates the photogenerated electrons and holes, but also makes the oxidation potential of the photogenerated holes more negative and the reduction potential of the photogenerated electrons more positive, thereby achieving a wide range of light absorption spectrum. 0.23 The energy band structures of TiO2, WO3, and TiO2 are well matched, exhibiting good coupling, and combined with the specific flower-like morphology of this embodiment, a titanium dioxide / sodium titanate and titanium dioxide@tungsten trioxide dual heterostructure with excellent photocatalytic effects in the visible and ultraviolet wavelength ranges is achieved.

[0038] The beneficial effects of this embodiment are:

[0039] This embodiment aims to in situ prepare titanium dioxide / sodium titanate and / titanium dioxide@tungsten trioxide dual structures on the surface of titanium plate with excellent photocatalytic effect in the visible and ultraviolet wavelength range. A porous coating is prepared on the surface of titanium plate by micro-arc oxidation technology, and then microwave hydrothermal treatment is performed to form a large number of sodium titanate nanowires (Na + +TiO2+OH - ―Na 0.23 TiO2) provides more active sites for the subsequent deposition of tungstate ions; then it is transformed into a composite structure of titanate and tungstate through ion deposition exchange technology, and after de-crystallization, it is transformed into a TiO2 / WO3 heterogeneous structure; at the same time, the process parameters of ion exchange are controlled to retain the structure of sodium titanate nanowires to form TiO2 / Na 0.23TiO2 heterogeneous structure is used to achieve high catalytic performance under wide-range visible / ultraviolet wavelengths, solving the problems of low photocatalytic degradation rate and difficult recycling of existing TiO2-based photocatalysts.

[0040] The sample treated by this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After the sample treated by this embodiment was tested by XRD diffraction, TiO2, Na 0.23 TiO2 and WO3 phases. Scanning electron microscopy revealed that a large number of titanium dioxide @ sodium titanate and / or titanium dioxide @ tungsten trioxide dual heterostructures were formed on the surface. Furthermore, transmission electron microscopy images revealed that the WO3 particles were well coupled with the TiO2 nanorods. The photocatalytic properties of the surface of the sample treated in this embodiment were characterized by placing it in a methylene blue solution and irradiating it with a xenon lamp. The degradation rate of the organic dye reached over 86% in the fifth cycle. After five cycles of cycling tests, no significant changes were observed in the heterostructures shown in the scanning electron microscopy images, indicating that the sample obtained in this embodiment possesses stable, long-term degradation performance.

[0041] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the titanium plate described in step 1 is titanium, titanium alloy, titanium-based medium entropy alloy or titanium-based high entropy alloy. Other aspects are the same as specific embodiment 1.

[0042] Specific embodiment 3: This embodiment differs from either specific embodiment 1 or 2 in that the titanium plate described in step 1 is an HCP-Ti medium-entropy alloy or high-entropy alloy, a BCC-Ti medium-entropy alloy or high-entropy alloy, a BCC medium-entropy alloy or high-entropy alloy, or a BCC and HCP dual-phase medium-entropy alloy or high-entropy alloy. Other embodiments are the same as specific embodiments 1 or 2.

[0043] Specific embodiment 4: This embodiment differs from Specific embodiments 1 to 3 in that the electrolyte described in step 1 is composed of sodium hexametaphosphate, sodium fluoride, sodium hydroxide, and deionized water, with the concentration of sodium hexametaphosphate being 5 g / L to 20 g / L, the concentration of sodium fluoride being 2 g / L to 15 g / L, and the concentration of sodium hydroxide being 2 g / L to 10 g / L. Other embodiments are the same as Specific embodiments 1 to 3.

[0044] Specific embodiment 5: This embodiment differs from Specific embodiments 1 to 4 in that in step 1, micro-arc oxidation is performed for 5 to 40 minutes under the conditions of a current of 0.2 A to 2.0 A, a pulse frequency of 600 Hz to 1000 Hz, a duty cycle of 4% to 20%, and an electrolyte temperature of 20° C. to 30° C. The rest is the same as Specific embodiments 1 to 4.

[0045] Specific embodiment 6: This embodiment differs from Specific embodiments 1 to 5 in that the alkali solution in step 2 is sodium hydroxide solution, ammonia solution, or potassium hydroxide solution; and the concentration of the alkali solution in step 2 is 0.5 mol / L to 5 mol / L. Other aspects are the same as Specific embodiments 1 to 5.

[0046] Specific embodiment 7: This embodiment differs from Specific embodiments 1 to 6 in that, in step 2, the titanium plate after micro-arc oxidation treatment is immersed in an alkaline solution and subjected to microwave hydrothermal treatment at a power of 400W to 1000W and a temperature of 60°C to 200°C for 1 to 6 hours. Other steps are the same as Specific embodiments 1 to 6.

[0047] Specific embodiment 8: This embodiment differs from Specific embodiments 1 to 7 in that: the tungstate solution described in step 3 (1) is a sodium tungstate solution or a potassium tungstate solution; the concentration of the tungstate solution described in step 3 (1) is 0.1 mol / L to 2.0 mol / L; and the concentration of the hydrochloric acid described in step 3 (1) is 6 mol / L to 12 mol / L. Other aspects are the same as Specific embodiments 1 to 7.

[0048] Specific embodiment 9: This embodiment differs from Specific embodiments 1 to 8 in that in step 3 (1), the titanium plate after microwave hydrothermal treatment is immersed in a tungstate solution at a temperature of 20°C to 37°C for 20 to 60 minutes, then removed and immersed in hydrochloric acid at a temperature of 40°C to 80°C for 10 to 30 seconds. Other steps are the same as Specific embodiments 1 to 8.

[0049] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that in step 4, the decrystallization treatment is performed in an air atmosphere at a temperature of 300° C. to 800° C. for 1 to 8 hours. Other aspects are the same as specific embodiments 1 to 9.

[0050] The following examples are used to verify the beneficial effects of the present invention:

[0051] Example 1:

[0052] A method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface is carried out in the following steps:

[0053] 1. Micro-arc oxidation treatment:

[0054] A titanium plate with its oxide layer removed was placed in an electrolyte, with the titanium plate with its oxide layer removed as the anode and the stainless steel plate as the cathode. Micro-arc oxidation was performed for 10 minutes in a pulse constant current mode at a current of 1.2 A, a pulse frequency of 600 Hz, a duty cycle of 8%, and an electrolyte temperature of 20°C to obtain a titanium plate treated with micro-arc oxidation, namely A / R-TiO2.

[0055] The electrolyte is composed of sodium hexametaphosphate, sodium fluoride, sodium hydroxide and deionized water, wherein the concentration of sodium hexametaphosphate is 10 g / L, the concentration of sodium fluoride is 4 g / L, and the concentration of sodium hydroxide is 4 g / L;

[0056] The titanium plate is HCP+BCC type titanium niobium zirconium tin;

[0057] 2. Microwave hydrothermal treatment:

[0058] The titanium plate treated with micro-arc oxidation was immersed in alkaline solution and subjected to microwave hydrothermal treatment at a power of 800 W and a temperature of 200°C for 2 h to obtain a titanium plate treated with microwave hydrothermal treatment, i.e., a titanium dioxide / sodium titanate heterostructure constructed in situ on the titanium surface;

[0059] The alkali solution is a sodium hydroxide solution; the concentration of the alkali solution is 3 mol / L;

[0060] 3. Ion deposition exchange treatment:

[0061] ① Immerse the titanium plate after microwave hydrothermal treatment in tungstate solution at 25°C for 30 minutes, then take it out and immerse it in hydrochloric acid at 50°C for 30 seconds, and finally wash it with deionized water;

[0062] The tungstate solution is a sodium tungstate solution; the concentration of the tungstate solution is 0.5 mol / L; the concentration of the hydrochloric acid is 12 mol / L;

[0063] ② Repeat step 3① 10 times, and then dry to obtain the titanium plate after ion deposition exchange;

[0064] 4. De-crystallization treatment:

[0065] The titanium plate after ion deposition exchange was placed in a muffle furnace and decrystallized for 5 hours in an air atmosphere at 600°C to obtain a titanium plate with a surface in-situ constructed wide-band wavelength visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructure.

[0066] Figure 1This is a scanning electron microscope image of the titanium dioxide / sodium titanate heterostructure constructed in situ on the titanium surface in step 2 of Example 1. As can be seen from the image, a large number of abundant clusters of titanium dioxide / sodium titanate composite structures are formed on the titanium surface, and the sodium titanate nanowires have a diameter of approximately 50 nm and a length of approximately 200 nm.

[0067] Figure 2 This is the EDS spectrum of the in-situ construction of wide-band wavelength visible / ultraviolet light titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide dual heterostructures on the titanium surface in Example 1; as can be seen from the figure, tungsten element was successfully introduced into the sample, and the composition mainly consists of W, Ti, O and Na elements.

[0068] Figure 3 This is the XRD spectrum of the wide-band visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide dual heterostructures constructed in situ on the titanium surface in Example 1. A is the anatase peak, B is the titanium peak, C is the rutile peak, D is the tungsten oxide peak, and E is the sodium titanate peak. As can be seen from the figure, TiO2, WO3 phase and Na 0.23 TiO2 phase.

[0069] Figure 4 This is a scanning electron microscope image of the in-situ construction of wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructures on the titanium surface in Example 1; Figure 5 This is a transmission electron micrograph of the titanium dioxide @ tungsten trioxide heterostructure in the in situ construction of wide-band wavelength visible / ultraviolet titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures on the titanium surface in Example 1. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, transmission electron micrographs show that the WO3 particles have a good coupling relationship with the TiO2 nanorods.

[0070] A 6 mm × 6 mm titanium plate with a dual heterostructure of titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide, constructed in situ on the surface with wide-band visible / ultraviolet light, was placed in 10 mL of a 10 mg / mL methylene blue solution. Prior to illumination, the solution and catalyst were magnetically stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium. The methylene blue solution was then irradiated under a 300 W xenon lamp, positioned 25 cm above the solution surface. Five cycles were repeated, each lasting 2 hours. After each cycle, the sample was removed, cleaned, and then reinserted for testing. Concentration measurements were taken every 30 minutes using a UV-visible spectrometer. After each measurement, the probe solution was returned to the photocatalytic reactor. MB has a maximum absorbance at 664 nm, which was used as the wavelength for monitoring MB degradation. Figure 6This is a graph of the fifth cycle photocatalytic degradation rate of the titanium plate after micro-arc oxidation treatment prepared in step 1 of Example 1 and the titanium surface prepared in step 4, which is in situ constructed with wide-band wavelength visible / ultraviolet light titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructures. Figure 7 This is a scanning electron micrograph of the titanium surface in situ construction of a wide-band visible / UV dual heterostructure of titanium dioxide, sodium titanate, and titanium dioxide, tungsten trioxide after five cycles of testing. Under xenon lamp irradiation, the degradation rate of the organic dye reached 87% in the first cycle and 86.2% in the fifth cycle. After five cycles of testing, no significant changes in the heterostructure were observed in the scanning electron micrograph, demonstrating the stable, long-term degradation performance of the resulting sample.

[0071] Example 2: This example differs from Example 1 in that in step 1, micro-arc oxidation is performed for 10 minutes under the conditions of a current of 1.5 A, a pulse frequency of 600 Hz, a duty cycle of 8%, and an electrolyte temperature of 20° C. Other steps are the same as in Example 1.

[0072] The sample treated in this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After XRD diffraction test, TiO2, WO3 phase and Na phase were detected on the sample surface. 0.23 TiO2 phase. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, according to transmission electron microscopy photos, WO3 particles have a good coupling relationship with TiO2 nanorods. The photocatalytic ability of the sample surface treated in this embodiment is characterized. The test method is the same as that in Example 1. A sample with a size of 6mm×6mm is placed in a methylene blue solution. Under the irradiation of a xenon lamp, the degradation rate of the organic dye reaches 90% in the first cycle and 88% in the fifth cycle. After 5 cycles of cyclic testing, the heterostructure on the scanning electron microscopy photo has not changed significantly, indicating that the obtained sample has stable and long-term degradation performance.

[0073] Example 3: This example differs from Example 1 in that the concentration of the alkali solution in step 2 is 5 mol / L. Other steps are the same as Example 1.

[0074] The sample treated in this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After XRD diffraction test, TiO2, WO3 phase and Na phase were detected on the sample surface. 0.23TiO2 phase. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, according to the transmission electron microscopy photos, it can be seen that WO3 particles have a good coupling relationship with TiO2 nanorods. The photocatalytic ability of the sample surface treated in this embodiment is characterized. The test method is the same as that in Example 1. A sample with a size of 6mm×6mm is placed in a methylene blue solution. Under the irradiation of a xenon lamp, the degradation rate of the organic dye reaches 91% in the first cycle and 90% in the fifth cycle. After 5 cycles of cyclic testing, the heterostructure on the scanning electron microscopy photos has not undergone obvious changes, indicating that the obtained sample has stable and long-term degradation performance.

[0075] Example 4: This example differs from Example 1 in that the concentration of the tungstate solution in step 3① is 1 mol / L. Other steps are the same as Example 1.

[0076] The sample treated in this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After XRD diffraction test, TiO2, WO3 phase and Na phase were detected on the sample surface. 0.23 TiO2 phase. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, according to transmission electron microscopy photos, WO3 particles have a good coupling relationship with TiO2 nanorods. The photocatalytic ability of the sample surface treated in this embodiment is characterized. The test method is the same as that in Example 1. A sample with a size of 6mm×6mm is placed in a methylene blue solution. Under the irradiation of a xenon lamp, the degradation rate of the organic dye reaches 93% in the first cycle and 92% in the fifth cycle. After 5 cycles of cyclic testing, the heterostructure on the scanning electron microscopy photo has not changed significantly, indicating that the obtained sample has stable and long-term degradation performance.

[0077] Example 5: This example differs from Example 1 in that the concentration of hydrochloric acid in step 3① is 8 mol / L. Other steps are the same as Example 1.

[0078] The sample treated in this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After XRD diffraction test, TiO2, WO3 phase and Na phase were detected on the sample surface. 0.23TiO2 phase. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, according to transmission electron microscopy photos, WO3 particles have a good coupling relationship with TiO2 nanorods. The photocatalytic ability of the sample surface treated in this embodiment is characterized. The test method is the same as that in Example 1. A sample with a size of 6mm×6mm is placed in a methylene blue solution. Under the irradiation of a xenon lamp, the degradation rate of the organic dye reaches 88% in the first cycle and 86% in the fifth cycle. After 5 cycles of cyclic testing, the heterostructure on the scanning electron microscopy photo has not changed significantly, indicating that the obtained sample has stable and long-term degradation performance.

[0079] Example 6: This example differs from Example 1 in that step 4 involves de-crystallization in an air atmosphere at a temperature of 800° C. The rest is the same as Example 1.

[0080] The sample treated in this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After XRD diffraction test, TiO2, WO3 phase and Na phase were detected on the sample surface. 0.23 TiO2 phase. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, according to the transmission electron microscopy photos, it can be seen that WO3 particles have a good coupling relationship with TiO2 nanorods. The photocatalytic ability of the sample surface treated in this embodiment is characterized. The test method is the same as that in Example 1. A sample with a size of 6mm×6mm is placed in a methylene blue solution. Under the irradiation of a xenon lamp, the degradation rate of the organic dye reaches 92% in the first cycle and 90% in the fifth cycle. After 5 cycles of cyclic testing, the heterostructure on the scanning electron microscopy photos has not undergone obvious changes, indicating that the obtained sample has stable and long-term degradation performance.

[0081] Example 7: This example differs from Example 1 in that the de-crystallization treatment in step 4 is performed for 8 hours. Other aspects are the same as Example 1.

[0082] The sample treated in this embodiment was tested by EDS spectrum. Tungsten was successfully introduced into the sample. The composition mainly consisted of W, Ti, O and Na. After XRD diffraction test, TiO2, WO3 phase and Na phase were detected on the sample surface. 0.23TiO2 phase. Scanning electron microscopy shows that a large number of titanium dioxide @ sodium titanate and titanium dioxide @ tungsten trioxide double heterostructures are formed on the surface. In addition, according to transmission electron microscopy photos, WO3 particles have a good coupling relationship with TiO2 nanorods. The photocatalytic ability of the sample surface treated in this embodiment is characterized. The test method is the same as that in Example 1. A sample with a size of 6mm×6mm is placed in a methylene blue solution. Under the irradiation of a xenon lamp, the degradation rate of the organic dye reaches 95% in the first cycle and 92% in the fifth cycle. After five cycles of cyclic testing, the heterostructure on the scanning electron microscopy photo has not changed significantly, indicating that the obtained sample has stable and long-term degradation performance.

Claims

1. A method for in-situ construction of wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructures on titanium surface, characterized in that It is carried out in the following steps:

1. Micro-arc oxidation treatment: The titanium plate with the oxide layer removed is placed in an electrolyte, with the titanium plate with the oxide layer removed as the anode and the stainless steel plate as the cathode, and micro-arc oxidation is performed in a pulse constant current mode under the conditions of a current of 0.2A-2.0A, a pulse frequency of 600Hz-1000Hz, a duty cycle of 4%-20%, and an electrolyte temperature of 20°C-30°C to obtain a titanium plate treated with micro-arc oxidation; The electrolyte is composed of sodium hexametaphosphate, sodium fluoride, sodium hydroxide and deionized water, wherein the concentration of sodium hexametaphosphate is 5g / L~20g / L, the concentration of sodium fluoride is 2g / L~15g / L, and the concentration of sodium hydroxide is 2g / L~10g / L; 2. Microwave hydrothermal treatment: The titanium plate treated by micro-arc oxidation is immersed in an alkaline solution for microwave hydrothermal treatment to obtain a titanium plate treated by microwave hydrothermal treatment; 3. Ion deposition exchange treatment: ① Immerse the titanium plate after microwave hydrothermal treatment in tungstate solution, take it out and immerse it in hydrochloric acid, and finally wash it; The tungstate solution is a sodium tungstate solution or a potassium tungstate solution; ② Repeat step 3① for 5 to 20 times, and then dry to obtain the titanium plate after ion deposition exchange; 4. De-crystallization treatment: The titanium plate after ion deposition exchange is placed in a muffle furnace and de-crystallized under air atmosphere, thereby completing the in-situ construction of a wide-band wavelength visible / ultraviolet light titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide dual heterostructure on the titanium surface.

2. The method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that The titanium plate described in step 1 is titanium, titanium alloy, titanium-based medium entropy alloy or titanium-based high entropy alloy.

3. The method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that The titanium plate described in step 1 is an HCP-Ti type medium entropy alloy or high entropy alloy, a BCC-Ti type medium entropy alloy or high entropy alloy, a BCC type medium entropy alloy or high entropy alloy, or a BCC and HCP dual-phase medium entropy alloy or high entropy alloy.

4. The method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that In step 1, micro-arc oxidation is performed for 5 min to 40 min under the conditions of a current of 0.2 A to 2.0 A, a pulse frequency of 600 Hz to 1000 Hz, a duty cycle of 4% to 20%, and an electrolyte temperature of 20° C. to 30° C.

5. The method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that The alkali solution in step 2 is sodium hydroxide solution, ammonia solution or potassium hydroxide solution; the concentration of the alkali solution in step 2 is 0.5 mol / L~5 mol / L.

6. The method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that In step 2, the titanium plate treated with micro-arc oxidation is immersed in an alkaline solution and subjected to microwave hydrothermal treatment for 1 h to 6 h at a power of 400 W to 1000 W and a temperature of 60° C. to 200° C.

7. The method for in-situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that The concentration of the tungstate solution in step 3① is 0.1mol / L~2.0mol / L; the concentration of the hydrochloric acid in step 3① is 6mol / L~12mol / L.

8. The method of in situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that In step 3①, the titanium plate after microwave hydrothermal treatment is immersed in a tungstate solution at a temperature of 20°C to 37°C for 20min to 60min, and then taken out and immersed in hydrochloric acid at a temperature of 40°C to 80°C for 10s to 30s.

9. The method of in situ construction of a wide-band visible / ultraviolet titanium dioxide@sodium titanate and titanium dioxide@tungsten trioxide double heterostructure on a titanium surface according to claim 1, characterized in that In step 4, de-crystallization treatment is performed in an air atmosphere at a temperature of 300° C. to 800° C. for 1 hour to 8 hours.

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