A porous titanium dioxide nanometer thin film material based on H2O2 oxidation, its preparation method and application

Abstract

The present invention belongs to the field of catalytic materials, and relates to a preparation method of a catalytic material or a material substrate, in particular to a three-dimensional porous TiO2 nanometer thin film material based on H2O2 oxidation, its preparation method and application. The preparation method of the present invention uses metallic Ti and hydrogen peroxide as raw materials, and directly oxidizes Ti with hydrogen peroxide to obtain a porous TiO2 nanometer thin film material, without using expensive and toxic titanium-containing liquid phases as raw materials, and the cost is relatively low; compared with the traditional anodic oxidation method and sol-gel method, the preparation process is simple, the conditions are controllable, and it is environmentally friendly. The TiO2 of the present invention is anatase TiO2, and its morphology and structure are controllable, and it can be manifested as array shapes such as zero-dimensional quantum dots, one-dimensional nanorod "clusters", three-dimensional nanometer "flowers", and three-dimensional nanosheets. The porous TiO2 nanometer thin film material of the present invention can be used in the catalytic field, especially in the direction of environmental purification, such as electrocatalytic electrode materials and photocatalytic materials. Its performance is stable, safe and environmentally friendly, and it is convenient to recycle, and has good engineering application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic materials, and relates to a preparation method of a photo-electrocatalytic material, in particular to a three-dimensional porous TiO2 nanometer thin film material based on H2O2 oxidation, a preparation method thereof and an application thereof. Background Art

[0002] Titanium dioxide (TiO2) has been widely applied to fields such as organic synthesis, environmental treatment, CO2 reduction, self-cleaning, hydrogen preparation, etc. due to its advantages such as non-toxicity, corrosion resistance and low cost. TiO2 is the most widely used photo- and electro-catalytic material. In order to reduce the economic cost of raw materials and make the catalytic material convenient for recycling and reuse, TiO2 is usually immobilized. The thin film type nanometer material is one of the most main methods for immobilization treatment. Therefore, a series of thin film materials such as TiO2 nanowires, nanorods and nanotubes have emerged successively.

[0003] The main methods for preparing TiO2 include hydrothermal method, sol-gel method, anodic oxidation method, etc. Literature such as "Research Progress on the Preparation and Application of TiO2 Nanorod Arrays by Hydrothermal Method" and "Preparation of Visible Light Responsive TiO2 Double-Layer Nanorod Arrays and Study on Their Photocatalytic Performance" prepared TiO2 nanorod array films by hydrothermal method, which requires low-toxic alcohol / ester-based liquid titanium sources, is irritating to the eyes, respiratory system and skin, requires a high-temperature and high-pressure reaction kettle, and it is difficult to control the decomposition rate of the precursor. The sol-gel method also uses alcohol / ester-based titanium sources as precursors and then conducts film-forming treatment. For example, CN106915770B and CN108607535A use the soft template method for film formation, and CN107986327 uses the hard template method for film formation. However, the template method for film formation requires subsequent high-temperature treatment to remove the template agent, and has large size, small specific surface area, and complex preparation process, and the size depends on the characteristics of the mold; CN105057003B discloses a method for preparing a precursor based on the sol-gel method and preparing a TiO2 nanofilm by electrospinning. This method requires complex equipment with a high-voltage electrostatic device, and subsequent high-temperature treatment is also required to remove the organic carrier; CN104087995B and CN106622247A prepare TiO2 nanofilms by electrodeposition using alcohol / ester-based titanium sources to prepare the precursor; CN1208126C and CN1218634C also use alcohol / ester-based titanium sources as precursors and then dip-coat to prepare TiO2 nanofilms. The films prepared by this method have interface misalignment with the substrate, large surface stress, and unstable structure. The anodic oxidation method is the most commonly used method for preparing TiO2 nanotube array films, such as CN101922044B, CN105817253B, CN106245091B, and the literature "Experimental Factors for Preparing Ordered TiO2 Nanotubes by Anodic Oxidation Method", etc. The electrolyte configuration of this method is relatively complex, the fluoride ion solution is easy to pollute the environment, the electrolysis process releases heat quickly and the temperature control is difficult, the surface stress of the nanotube array film is large, the structure is not stable and easy to fall off. In addition, there are some special methods for preparing TiO2 films, such as the micro-arc oxidation method used in CN101565847B, and the plasma oxidation method used in CN101935819A and CN110499497A. These methods involve complex and high-energy-consuming equipment such as high-voltage electrostatic.

[0004] Therefore, the methods for preparing TiO2 by the above existing technologies have disadvantages such as low safety of titanium sources, difficult control of decomposition rate, complex process of removing template agents or organic carriers at high temperature, and unstable structure. There is an urgent need for a TiO2 preparation method with characteristics such as safe and environmentally friendly substrate, strong controllability of the reaction process, simple equipment, and easy operation to solve the deficiencies of the existing preparation methods. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a three-dimensional porous TiO2 nanometer thin film material based on H2O2 oxidation, its preparation method and application. The TiO2 thin film is formed by oxidizing and etching a pure titanium foil substrate with hydrogen peroxide in a liquid phase environment. The size of the titanium dioxide particles is between 5 nm and 100 nm. The TiO2 nanometer thin film prepared by this method has the characteristics of safe and environmentally friendly substrate, strong controllability, simple equipment, and easy operation. Moreover, its morphology and structure are controllable, presenting array shapes such as zero-dimensional quantum dots, one-dimensional nanorod "clusters" (nanofibers), three-dimensional nanoscale "flowers", three-dimensional nanosheets, and nanofibers, which can enhance the bonding stability between the thin film and the substrate.

[0006] The present invention provides a preparation method of a three-dimensional porous TiO2 nanometer thin film material. The crystal phase of this three-dimensional porous TiO2 nanometer thin film material is anatase titanium dioxide, which can be used in the fields of photocatalysis and electrocatalytic purification. Under certain temperature and pH conditions, H2O2 dissociates into strongly oxidizing particles such as hydrogen peroxide ions (HOO-) and hydroxyl radicals (﹒OH). These particles react with pure Ti to form Ti(OH)4, which is further rapidly hydrolyzed into amorphous TiO2. Part of the Ti(OH)4 is dispersed in the solution in a sol state. At the same time, a large amount of O2 is generated during the decomposition of H2O2. The O2 bubbles are like molds, forming holes of different sizes at positions close to the surface, and then forming a three-dimensional porous nanometer thin film structure. Finally, the obtained nanometer thin film is subjected to high-temperature calcination treatment to obtain anatase TiO2 nanometer thin film.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A preparation method of a porous titanium dioxide nanometer thin film based on H2O2 oxidation, comprising the following steps:

[0008] Step 1: Chemically polish and pre-treat the pure titanium foil;

[0009] Step 2: Measure H2O2 and adjust the pH value of the solution;

[0010] Step 3: Add the pre-treated titanium foil into the above solution, place it in a reaction environment of 30 °C to 100 °C or under high temperature and high pressure conditions, control the reaction time to obtain a sol-like suspension;

[0011] Step 4: Take out the reacted titanium foil and perform ultrasonic treatment;

[0012] Step 5: Rapidly heat up the titanium foil obtained in Step 4 and then naturally cool and anneal it to obtain a structurally stable porous TiO2 nanometer thin film material.

[0013] By adopting the above solution, a further preferred solution is as follows: In step 1, the titanium foil is chemically polished and pretreated with a mixed solution of 5%wt HNO3 and 0.05%wt HF. The pretreated titanium foil is successively ultrasonically cleaned with analytical pure acetone, ethanol, and deionized water for 10 min to 15 min, and then dried with cold air.

[0014] By adopting the above solution, a further preferred solution is as follows: In step 2, the mass fraction of H2O2 is 5% to 30%, and the pH value is between 2 and 11. At the same time, cationic and anionic salt solutions required for adjusting material modification can be added to this solution.

[0015] By adopting the above solution, a further preferred solution is as follows: The high-temperature and high-pressure condition in step 3 is a stainless-steel reactor with a polytetrafluoroethylene liner at 70°C to 180°C, the reaction time is 2 h to 24 h, a light yellow sol-like suspension gradually appears in the solution, and the surface color of the Ti foil changes from light to dark.

[0016] By adopting the above solution, a further preferred solution is as follows: In step 4, the reacted Ti foil is taken out, rinsed 3 to 5 times with deionized water, placed in a 0.05%wt HF aqueous solution for ultrasonic treatment for 10 s to 120 s, then rinsed 2 to 3 times with deionized water, and air-dried naturally.

[0017] By adopting the above solution, a further preferred solution is as follows: In step 4, the reacted Ti foil is taken out, rinsed 3 to 5 times with deionized water, placed in a 0.05%wt HF aqueous solution for ultrasonic treatment for 10 s to 120 s, then rinsed 2 to 3 times with deionized water, and air-dried naturally.

[0018] By adopting the above solution, a further preferred solution is as follows: In step 5, the above titanium foil is placed in a muffle furnace, and under the conditions of room temperature and air atmosphere, it is heated to 450°C to 750°C at a rate of 1 to 2°C / min, held for 3 h to 4 h, and then naturally cooled with the furnace to obtain a three-dimensional porous TiO2 nanometer thin film material with stable structure.

[0019] The porous titanium dioxide nanofilms prepared by adopting the above-mentioned scheme are related to factors such as hydrogen peroxide concentration, pH value, reaction time, reaction temperature, and pressure in terms of their morphological structure and generation rate. The size of the zero-dimensional nano quantum dots on the surface of the prepared TiO2 nanofilm material is 4 nm to 20 nm; the diameter of the one-dimensional nanorods on the surface of the prepared TiO2 nanofilm material is 4 nm to 50 nm; the thickness of the three-dimensional nanosheets on the surface of the prepared TiO2 nanofilm material is 10 nm to 30 nm; the size of the TiO2 quantum dots uniformly distributed on the surface of the three-dimensional nanorod "clusters", nano "flowers", nanosheets, and nanofibers on the surface of the prepared TiO2 nanofilm material is 4 nm to 20 nm. The prepared porous titanium dioxide nanofilms based on H2O2 oxidation are mainly applied in the field of photocatalytic and electrocatalytic degradation of propellant wastewater.

[0020] Due to adopting the above technical scheme, the present invention has the following technical effects:

[0021] (1) The present invention uses pure titanium foil (purity ≥ 99.9%) as the titanium source, and H2O2 with a mass fraction of 5% to 30% and a pH value adjusted between 2 and 11 as the oxidant. In a reaction environment of 30°C to 100°C or under the conditions of a high-temperature and high-pressure reaction kettle, the reaction time is controlled for 2 h to 24 h. At room temperature, it is heated to 450°C to 750°C at a rate of 1 to 2°C / min and kept warm for 3 h to 4 h. The TiO2-based nanofilm material prepared by this method provides a brand-new, low-cost, simple and controllable, safe and environmentally friendly preparation method for the field of photocatalysis and electrocatalysis, and has good prospects for engineering application.

[0022] (2) The preparation method of the TiO2 thin film material of the present invention is closely related to factors such as H2O2 concentration, pH value, reaction time, reaction temperature, and pressure. Any change in the foregoing conditions will affect the morphological structure of the prepared TiO2 thin film material. Therefore, the morphological structure of the TiO2 thin film material obtained by this preparation method is controllable and its performance is stable, and it is easy to reuse. Centrifugal separation is not required during the operation process, and the remaining materials after the reaction are oxygen, water decomposed from hydrogen peroxide, and amorphous titanium dioxide precipitate, which will not cause secondary pollution to the environment.

[0023] (3) The TiO2 thin film material of the present invention is anatase TiO2 and can be used for the preparation of materials or substrate carrier materials in the fields of photocatalysis and electrocatalysis. Description of the Drawings

[0024] Figure 1 Scanning electron microscope (SEM) photograph of zero-dimensional nano quantum dots;

[0025] Figure 2 Scanning electron microscope (SEM) photograph of one-dimensional nanorod "clusters";

[0026] Figure 3 Scanning electron microscope (SEM) photograph of three-dimensional nano "flowers"

[0027] Figure 4 Scanning electron microscope (SEM) photograph of three-dimensional nanosheets

[0028] Figure 5 X-ray electron diffraction (XRD) pattern of TiO2 nanometer thin film material

[0029] Figure 6 Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis) pattern of TiO2 nanometer thin film material

[0030] Figure 7 Water contact angle test photograph of Example 1

[0031] Figure 8 Water contact angle test photograph of Example 2

[0032] Figure 9 Water contact angle test photograph of Example 3

[0033] Figure 10 Water contact angle test photograph of Example 4

[0034] Figure 11 Water contact angle test photograph of Ti foil without hydrogen peroxide treatment

[0035] Figure 12 X-ray electron diffraction (XRD) patterns of MnO2 / TiO2, SnO2 / TiO2, Mn-SnO2 / TiO2 materials and Ti substrate

[0036] Figure 13 Effect of electrocatalytic degradation of unsymmetrical dimethylhydrazine wastewater by titanium dioxide thin film doped with Mn and Sn cations Detailed implementation manners

[0037] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Therefore, the detailed description of the embodiments of the present invention provided below in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] Reference Figures 1-13, The present invention relates to a method for preparing a three-dimensional porous TiO2 nanometer thin film material, which specifically comprises the following steps:

[0039] Step 1: Chemically polish and pre-treat pure titanium foil;

[0040] Step 2: Measure H2O2 and adjust the pH value of the solution;

[0041] Step 3: Add the pre-treated titanium foil into the above solution, place it in a reaction environment of 30°C to 100°C or under high temperature and high pressure conditions, control the reaction time, and obtain a sol-like suspension;

[0042] Step 4: Take out the reacted titanium foil and perform ultrasonic treatment;

[0043] Step 5: Rapidly heat up the titanium foil obtained in Step 4 and then naturally cool and anneal it to obtain a structurally stable porous TiO2 nanometer thin film material.

[0044] Example 1

[0045] Cut pure titanium foil (purity ≥ 99.9%) into 2 cm × 5 cm, chemically polish and pre-treat it with a mixed solution of 5% wt HNO3 and 0.05% wt HF, ultrasonically clean it with acetone, ethanol, and deionized water for 15 min in sequence, and dry it with cold air;

[0046] Measure 50 mL of hydrogen peroxide with a mass fraction of H2O2 of 10%, and adjust the pH value of the solution to 5;

[0047] Place the pre-treated Ti foil into the above solution, and place the reaction system in a reaction environment of 30°C, control the reaction time for 2 h, the solution gradually shows a light yellow sol-like suspension, and the surface color of the Ti foil changes from light to dark;

[0048] Take out the reacted Ti foil, rinse it with deionized water for 3 - 5 times, put it into an aqueous solution of 0.05% wt HF for ultrasonic treatment for 20 s, then rinse it with deionized water for 2 - 3 times, and dry it naturally;

[0049] Place the obtained Ti foil in a muffle furnace, under the conditions of room temperature and air atmosphere, heat it to 450°C at a rate of 1 - 2°C / min, keep it warm for 3 h, and naturally cool and anneal it with the furnace to obtain a structurally stable three-dimensional porous TiO2 nanometer thin film material.

[0050] Figure 1 It is an electron scanning microscope photo of the zero-dimensional nano quantum dots obtained in Example 1. It can be seen from the microscopic morphology diagram of the sample that the microscopic structure on the surface of the TiO2 nanometer thin film material presents as nano quantum dot particles with a particle size of 4 - 10 nm.

[0051] Example 2

[0052] Cut pure titanium foil (purity ≥ 99.9%) into 2 cm × 5 cm, and perform chemical polishing pretreatment with a mixed solution of 5% wt HNO3 and 0.05% wt HF. Ultrasonically clean it with acetone, ethanol, and deionized water for 15 min in sequence, and dry it with cold air;

[0053] Measure 100 mL of hydrogen peroxide with a mass fraction of H2O2 of 20%, and adjust the pH value of the solution to 9;

[0054] Place the pretreated Ti foil into the above solution, and place the reaction system in a reaction environment at 50 °C. Control the reaction time for 12 h. The solution gradually shows a light yellow sol-like suspension, and the surface color of the Ti foil changes from light to dark;

[0055] Take out the reacted Ti foil, rinse it with deionized water for 3 - 5 times, put it into an HF aqueous solution with a concentration of 0.05% wt for ultrasonic treatment for 20 s, then rinse it with deionized water for 2 - 3 times, and dry it naturally;

[0056] Place the obtained Ti foil in a muffle furnace, under the conditions of room temperature and air atmosphere, heat it to 500 °C at a rate of 1 - 2 °C / min, keep it warm for 4 h, and cool it naturally with the furnace to obtain a three-dimensional porous TiO2 nanometer thin film material with stable structure.

[0057] Figure 2 It is the scanning electron microscope photograph of the one-dimensional nanorod "cluster" obtained in Example 2. It can be seen from the microscopic morphology diagram of the sample that the microscopic structure on the surface of the TiO2 nanometer thin film material presents a nanorod "cluster" structure, and the diameter of the nanorods is 20 - 50 nm.

[0058] Example 3

[0059] Cut pure titanium foil (purity ≥ 99.9%) into 2 cm × 5 cm, and perform chemical polishing pretreatment with a mixed solution of 5% wt HNO3 and 0.05% wt HF. Ultrasonically clean it with acetone, ethanol, and deionized water for 15 min in sequence, and dry it with cold air;

[0060] Measure 150 mL of hydrogen peroxide with a mass fraction of H2O2 of 30%, and adjust the pH value of the solution to 7;

[0061] Place the pretreated Ti foil into the above solution, and place the reaction system in a reaction environment at 80 °C. Control the reaction time for 24 h. The solution gradually shows a light yellow sol-like suspension, and the surface color of the Ti foil changes from light to dark;

[0062] Take out the reacted Ti foil, rinse it with deionized water for 3 - 5 times, put it into an HF aqueous solution with a concentration of 0.05% wt for ultrasonic treatment for 20 s, then rinse it with deionized water for 2 - 3 times, and dry it naturally;

[0063] The obtained Ti foil was placed in a muffle furnace. Under the conditions of room temperature and air atmosphere, it was heated to 450 °C at a rate of 1 - 2 °C / min, held for 4 h, and then naturally cooled in the furnace for annealing to obtain a three-dimensional porous TiO2 nanometer thin film material with a stable structure.

[0064] Figure 3 It is the scanning electron microscope photograph of the three-dimensional nano "flowers" obtained in Example 3. It can be seen from the microscopic morphology diagram of the sample that the microscopic structure on the surface of the TiO2 nanometer thin film material presents a nano "flower" - like structure, and nano quantum dots are evenly distributed on the surface of the "flowers", with a particle size of 4 - 20 nm.

[0065] Example 4

[0066] The pure titanium foil (purity ≥ 99.9%) was cut into 2 cm × 5 cm, chemically polished and pretreated with a mixed solution of 5% wt HNO3 and 0.05% wt HF, ultrasonically cleaned with acetone, ethanol, and deionized water for 15 min in sequence, and dried with cold air.

[0067] 200 mL of hydrogen peroxide was measured, with a mass fraction of H2O2 of 20%, and the pH value of the solution was adjusted to 7.

[0068] The pretreated Ti foil was placed into the above solution, poured into the reaction system of a polytetrafluoroethylene high-pressure reaction kettle, and the reaction system was placed in a reaction environment at a constant temperature of 90 °C, controlling the reaction time for 24 h.

[0069] The reacted Ti foil was taken out, rinsed with deionized water for 3 - 5 times, ultrasonically treated in a 0.05% wt HF aqueous solution for 20 s, then rinsed with deionized water for 2 - 3 times, and air-dried naturally.

[0070] The obtained Ti foil was placed in a muffle furnace. Under the conditions of room temperature and air atmosphere, it was heated to 550 °C at a rate of 1 - 2 °C / min, held for 4 h, and then naturally cooled in the furnace for annealing to obtain a three-dimensional porous TiO2 nanometer thin film material with a stable structure.

[0071] Figure 4 It is the scanning electron microscope photograph of the three-dimensional nanosheets obtained in Example 4. It can be seen from the microscopic morphology diagram of the sample that the microscopic structure on the surface of the TiO2 nanometer thin film material presents a nanosheet or nanofiber - like structure, and the thickness of the nanosheets is 6 nm - 30 nm.

[0072] The TiO2 nanometer thin film materials prepared in the above Examples 1 - 4 were subjected to X-ray electron diffraction, ultraviolet - visible diffuse reflection, and water contact angle tests, and the results are as Figures 5-11 shown.

[0073] From Figure 5As can be seen from the X-ray electron diffraction pattern of the TiO2 nanofilm material shown, the diffraction peaks of the samples in Examples 1 to 4 have a good correspondence with TiO2 (COD 96-152-6932) and Ti (COD96-151-2548) in the standard card library, proving that the surface crystal phase composition of the treated film material is mainly TiO2, and the diffraction peak of Ti is the substrate material.

[0074] From Figure 6 As can be seen from the UV-visible diffuse reflection spectrum of the TiO2 nanofilm material shown, compared with the Ti foil without hydrogen peroxide treatment, the absorption of the samples in Examples 1 to 4 in the UV region of 200 nm - 370 nm is significantly enhanced, and the absorption of the sample in Example 4 treated under high temperature and high pressure conditions also increases significantly in the visible light region greater than 380 nm.

[0075] From Figures 7-11 As can be seen from the water contact angle test photos shown, compared with the Ti foil without hydrogen peroxide treatment (i.e., Figure 11 ), the water contact angles of the samples in Examples 1 to 4 are significantly reduced, indicating that the hydrophilic performance of the material is enhanced after hydrogen peroxide treatment.

[0076] Example 5

[0077] Cut the pure titanium foil (purity ≥ 99.9%) into 2 cm × 5 cm, perform chemical polishing pretreatment with a mixed solution of 5% wt HNO3 and 0.05% wt HF, ultrasonically clean with acetone, ethanol, and deionized water for 15 min in sequence, and dry with cold air;

[0078] Measure 200 mL of hydrogen peroxide with a mass fraction of H2O2 of 20%, adjust the pH value of the solution to 7, add 1.0 mmol of manganese sulfate aqueous solution, 1.0 mmol of sodium stannate aqueous solution, and a mixed solution of 1.0 mmol of sodium stannate and 0.2 mmol of manganese sulfate respectively, and stir magnetically for 60 min;

[0079] Place the pretreated Ti foil into the above solution, pour it into the reaction system of a polytetrafluoroethylene high-pressure reaction kettle, and place the reaction system in a constant temperature environment at 90 °C, and control the reaction time for 24 h;

[0080] Take out the reacted Ti foil, rinse it with deionized water for 3 - 5 times, put it into a 0.05% wt HF aqueous solution for ultrasonic treatment for 20 s, then rinse it with deionized water for 2 - 3 times, and dry it naturally;

[0081] The obtained Ti foil was placed in a muffle furnace. Under the conditions of room temperature and air atmosphere, it was heated to 550 °C at a rate of 1-2 °C / min, held for 4 h, and then naturally cooled in the furnace for annealing to obtain a three-dimensional porous TiO2 nanofilm electrode material modified with Mn and Sn, denoted as MnO2 / TiO2, SnO2 / TiO2, and Mn-SnO2 / TiO2 electrodes respectively.

[0082] Using the above three obtained materials as electrocatalytic anodes respectively, with a Pt electrode as the cathode, under the condition of a current density of 30 mA / cm 2 , electrocatalytically degrade 100 mg / L of unsymmetrical dimethylhydrazine wastewater. After 60 min of electrocatalysis, the degradation efficiencies of TiO2 substrate, MnO2 / TiO2, SnO2 / TiO2, and Mn-SnO2 / TiO2 for unsymmetrical dimethylhydrazine wastewater are 79.4%, 60.8%, 99.8%, and 99.97% respectively. Among them, the degradation effect of unsymmetrical dimethylhydrazine reaches 99% when the Mn-SnO2 / TiO2 electrode is electrocatalyzed for 40 min.

[0083] Figure 12 It is the X-ray electron diffraction pattern of the TiO2 substrate and MnO2 / TiO2, SnO2 / TiO2, and Mn-SnO2 / TiO2 electrode materials. It can be seen that the diffraction peaks of the cation-modified TiO2 nanofilm substrate electrode have good correspondence with TiO2 (COD 96-152-6932), Ti (COD 96-151-2548), MnO2 (PDF 30-820), and SnO2 (PDF 01-088-0287) in the standard card library, proving that the main crystal phase composition on the surface of the treated thin film material is TiO2, and the diffraction peak of Ti is the substrate material. And there are also MnO2 and SnO2 crystal phase compositions on the surface of the electrode materials modified with manganese sulfate and sodium stannate cation solutions.

[0084] From Figure 13 the electrocatalytic degradation effect of unsymmetrical dimethylhydrazine wastewater shown, it can be seen that within 60 min, the electrocatalytic degradation efficiency of the TiO2 substrate material treated with hydrogen peroxide for unsymmetrical dimethylhydrazine wastewater reaches 79.4%, indicating that the TiO2 nanofilm material prepared by this method has good electrocatalytic activity.

[0085] The electrocatalytic degradation efficiencies of the modified SnO2 / TiO2 and Mn-SnO2 / TiO2 electrodes for unsymmetrical dimethylhydrazine wastewater are increased to 99.8% and 99.97% respectively, indicating that Sn 4+ cation solution and Mn 2+ , Sn 4+The mixed solution can improve the electrocatalytic activity of the TiO2 substrate material. However, the electrocatalytic degradation efficiency of the MnO2 / TiO2 electrode for unsymmetrical dimethylhydrazine wastewater is reduced to 60.8% because excessive MnO2 will cause the decomposition of the active substance hydrogen peroxide.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and thus cannot limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a porous titanium dioxide nanometer thin film based on H2O2 oxidation, characterized in that It includes the following steps: Step 1: Chemically polish the pure titanium foil for pretreatment; Step 2: Measure H2O2 and adjust the pH value of the solution; Step 3: Add the pretreated titanium foil into the above solution, place it in a reaction environment of 30°C to 100°C or under high temperature and high pressure conditions, control the reaction time to obtain a sol-like suspension; Step 4: Take out the reacted titanium foil and perform ultrasonic treatment; Step 5: Rapidly heat up the titanium foil obtained in Step 4 and then naturally cool and anneal it to obtain a porous TiO2 nanometer thin film material with stable structure; In the said Step 1, chemically polish the titanium foil for pretreatment with a mixed solution of 5%wt HNO3 and 0.05%wt HF, ultrasonically clean the pretreated titanium foil with analytical pure acetone, ethanol, and deionized water for 10 min to 15 min in sequence, and dry it with cold air; In the said Step 2, the mass fraction of H2O2 is 5% to 30%, and the pH value is between 2 and 11; In the said Step 4, put the titanium foil into an HF aqueous solution of 0.05%wt and perform ultrasonic treatment for 10 s to 120 s; In the said Step 5, place the above titanium foil in a muffle furnace, heat it from room temperature to 450°C to 750°C at a rate of 1 to 2°C / min, keep it warm for 3 h to 4 h and then naturally cool; The size of the zero-dimensional nano quantum dots on the surface of the said TiO2 nanometer thin film material is 4 nm to 20 nm; The diameter of the one-dimensional nanorods on the surface of the said TiO2 nanometer thin film material is 4 nm to 50 nm; The thickness of the three-dimensional nanosheets on the surface of the said TiO2 nanometer thin film material is 10 nm to 30 nm; The morphology and structure of the said TiO2 nanometer thin film material present an array shape of zero-dimensional quantum dots, one-dimensional nanorod "clusters", three-dimensional nano "flowers", three-dimensional nanosheets, and nanofibers.

2. According to the preparation method of a porous titanium dioxide nanometer thin film based on H2O2 oxidation as described in Claim 1, the high temperature and high pressure conditions in the said Step 3 are a stainless steel reaction kettle with a polytetrafluoroethylene liner at 70°C to 180°C, and the reaction time is 2 h to 24 h.

3. Application of a porous titanium dioxide nanometer thin film based on H2O2 oxidation prepared by the method according to any one of Claims 1-2 in the treatment of propellant wastewater by photocatalytic and electrocatalytic degradation.

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