TiO2-Fe2O3 ordered hierarchical structure nanorod array as well as preparation method and application thereof

Abstract

The invention discloses a TiO2-Fe2O3 ordered hierarchical structure nanorod array and a preparation method and application thereof, and belongs to the technical field of materials and environmental protection, a rutile type TiO2 film and a precursor I are mixed, a first hydrothermal growth reaction is performed to obtain a TiO2 first-level nanorod array, the TiO2 first-level nanorod array and a precursor II are mixed, a hydrothermal growth reaction is performed again, and drying and annealing are performed to obtain the TiO2-Fe2O3 ordered hierarchical structure nanorod array. The precursor I is a NaCl saturated aqueous solution of TiCl3, and the precursor II is a NaCl saturated aqueous solution of TiCl3; and the precursor II is a NaNO3 saturated aqueous solution of FeCl3. The TiO2-Fe2O3 ordered hierarchical structure nanorod array provided by the invention has good research potential and practical application prospect under a sun illumination condition in application and popularization in the field of practical wastewater advanced treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of materials and environmental protection, and particularly relates to a TiO2-Fe2O3 ordered hierarchical structure nanorod array and a preparation method and application thereof. Background Art

[0002] Photocatalytic water purification technology is a new deep water treatment method based on the special valence band structure characteristics of semiconductor materials. Semiconductor materials have a certain width of band gap. When irradiated by photons with energy greater than the semiconductor band gap width, electrons in the material structure absorb photons and jump from the valence band to the conduction band to generate electron-hole pairs. Toxic metal ions in sewage can be reduced by reducing electrons. The more negative the oxidation-reduction potential of the conduction band, the higher the conduction band energy and the stronger the reducing ability. Organic matter in sewage can be oxidized into water and carbon dioxide by oxidizing holes. The more positive the oxidation-reduction potential of the valence band, the stronger the oxidizing ability.

[0003] TiO2 has become the most widely used iconic semiconductor material in the field of photocatalysis due to its own advantages such as photochemical stability and light corrosion resistance. The emergence of nanomaterial synthesis and application technology in recent years has brought great opportunities and challenges to the research of photocatalytic materials. The one-dimensional TiO2 nanostructure combines the characteristics of nanomaterials and TiO2 itself, achieving the goal of high-efficiency photocatalysis and low cost in the field of multiphase catalysis, and becoming the most representative and promising photocatalyst in the field of photocatalysis. At present, the most widely used and frequently used TiO2 particle photocatalyst in laboratory simulation experiments and actual production and living water treatment at home and abroad is P25 (Degussa). Powdered TiO2 can increase the specific surface area of ​​the catalyst, thereby improving the efficiency of sewage purification. However, when using semiconductor particles for sewage treatment, due to the small particles, the catalyst is easy to lose in the aqueous solution, difficult to recover, and the active component loss is large, and it cannot be reused for a long time.

[0004] Patent 201010548151.2 involves a new type of ordered secondary structure TiO2 nanorod catalyst. This catalytic material is a transparent substrate-loaded catalyst, which makes up for the problem that granular nano-TiO2 materials are difficult to recover after dispersion. At the same time, due to its internal single crystal structure and unique one-dimensional substrate secondary growth hierarchical structure, it increases the specific surface area while ensuring the efficient and effective separation and transmission of photogenerated carriers, thereby effectively improving the efficiency of photocatalytic degradation of wastewater.

[0005] The bandgap widths of the two isomorphous variants of TiO2, anatase and rutile, are 3.2eV and 3.0eV respectively, and the corresponding absorption spectrum band edge wavelengths are 387.5nm and 413.3nm. Only ultraviolet light with energy higher than the light energy corresponding to the edge wavelength can excite TiO2 to generate carriers, and then participate in the mineralization and degradation reaction of pollutants. Since TiO2 catalysts have a very low utilization rate of natural solar energy and cannot achieve as much effective response to full-spectrum illumination as possible, TiO2 catalysts have cost issues and conditional barriers to large-scale industrial practical applications. Summary of the invention

[0006] The purpose of the present invention is to provide a TiO2-Fe2O3 ordered hierarchical structure nanorod array and its preparation method and application, so as to solve the problems existing in the above-mentioned prior art.

[0007] One of the technical solutions provided by the present invention:

[0008] A method for preparing a TiO2-Fe2O3 ordered hierarchical structure nanorod array comprises the following steps: mixing a rutile TiO2 film with a precursor I, performing a first hydrothermal growth reaction to obtain a TiO2 primary nanorod array, mixing the TiO2 primary nanorod array with a precursor II, performing a second hydrothermal growth reaction, and drying and annealing to obtain the TiO2-Fe2O3 ordered hierarchical structure nanorod array, wherein the precursor I is a saturated NaCl aqueous solution of TiCl3; and the precursor II is a saturated NaNO3 aqueous solution of FeCl3.

[0009] Preferably, the concentration of TiCl3 in the precursor I is 0.05 mol / L and the pH is 0.25-1.50.

[0010] More preferably, the pH of TiCl3 in the precursor I is 1.30.

[0011] Preferably, the concentration of FeCl3 in the precursor II is 0.10-0.20 mol / L, and the pH is 1.00-2.10.

[0012] More preferably, the concentration of FeCl3 in the precursor II is 0.15 mol / L and the pH is 1.4.

[0013] Preferably, the temperature of the second hydrothermal growth reaction is 130° C. and the time is 5 hours.

[0014] More preferably, the annealing temperature is 400° C. and the time is 1 hour.

[0015] The present invention adopts a method different from catalyst sensitization and compounding by simply compounding different semiconductor materials. The specific principle of the preparation process of the TiO2-Fe2O3 ordered hierarchical structure nanorod array material provided by the present invention is as follows: the bandgap width of each original monomer is kept basically unchanged, and from the perspective of the change of the spectral response range, the basic semiconductor monomer is used as the primary structure template, and other semiconductor materials are introduced to perform simple composite synthesis between heterogeneous monomers, and the heterogeneous materials "grow in gaps" with each other to achieve effective absorption of light energy in their respective spectral response bands, expand the overall spectral response range of the simple composite material (TiO2-Fe2O3), and improve the utilization rate of the catalyst for the full spectrum energy of natural light.

[0016] In the method for preparing TiO2-Fe2O3 ordered hierarchical structure nanorod array provided by the present invention, TiO2 primary nanorod array is used as the basic material. The material is prepared by a hydrothermal process and has the characteristics of controllable microstructure orientation, uniform diameter distribution, specific morphology that can be regulated by pH, and neat overall structure.

[0017] The second technical solution provided by the present invention

[0018] A TiO2-Fe2O3 ordered hierarchical structure nanorod array prepared by the above preparation method.

[0019] The third technical solution provided by the present invention

[0020] An application of the TiO2-Fe2O3 ordered hierarchical structure nanorod array in photocatalytic degradation of methyl blue.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] When the present invention uses a semiconductor TiO2-Fe2O3 material with an ordered hierarchical nanorod array structure for sewage treatment, since it is a solid-supported catalyst, it solves the problems of TiO2 powder catalysts being easily lost in the solution, causing a large loss of active ingredients and being difficult to recover and reuse, thereby achieving controllable and effective recovery of the catalyst, allowing the material to be used for a long time and reducing water treatment costs.

[0023] The present invention solves the problem of insufficient photocatalytic ability of the catalyst itself due to uncontrollable structural growth of ordinary TiO2 photocatalysts with primary nanorod array structures when preparing a novel photocatalytic material TiO2-Fe2O3 ordered hierarchical structure nanorod array by controlling the pH value of the TiO2 primary structure growth and improving the morphology and introducing an irregular Fe2O3 ordered hierarchical structure during wastewater degradation.

[0024] The present invention improves the TiO2 nanorod primary array material with photocatalytic properties, introduces a Fe2O3 ordered array structure with a narrow bandgap and a low-energy conduction band and a preparation process of a TiO2-Fe2O3 ordered hierarchical structure, and obtains a cross-shaped secondary structure nanorod array material with good morphology and high photocatalytic activity, which makes up for the disadvantages of the TiO2 primary nanorod array in the photocatalytic reaction that it has a wide bandgap and can only absorb high-energy ultraviolet light, expands the spectral response range of the semiconductor TiO2 primary nanorod array, and improves the utilization rate of the energy in the visible light region of natural sunlight.

[0025] The TiO2-Fe2O3 ordered hierarchical structure nanorod array provided by the present invention has good research potential and practical application prospects under sunlight conditions in the application and promotion of the actual wastewater deep treatment field. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 Schematic diagram comparing the principle of light excitation of TiO2-Fe2O3 composite modification and light excitation of TiO2-Fe2O3 ordered hierarchical structure, where (a) is a schematic diagram of the principle of light excitation of TiO2-Fe2O3 composite modification, and (b) is a schematic diagram of the principle of light excitation of TiO2-Fe2O3 ordered hierarchical structure;

[0028] Figure 2 SEM morphology characterization of TiO2 primary nanorod arrays (TNAs) grown in different precursor I pH environments, where (a) is TNAs-1, (b) is TNAs-2, and (c) is TNAs-3;

[0029] Figure 3 SEM morphology characterization of TiO2 primary nanorod arrays (TNAs) grown in different precursor I pH environments, where (a) is TNAs-4, (b) is TNAs-5, (c) is TNAs-6, (d) is TNAs-7, and (e) is TNAs-8;

[0030] Figure 4 SEM morphology characterization of Fe2O3 ordered nanorod arrays (FeAs) grown in different precursor solution pH environments, including (a) pH 1.10, (b) pH 1.20, (c) pH 1.30, (d) pH 1.40, (e) pH 1.50, and (f) pH 2.00;

[0031] Figure 5 (a) is a SEM morphology characterization picture of the primary nanorod array TNAs in Example 3, and (b) is a SEM morphology characterization picture of TFeAs-1 prepared in Example 3;

[0032] Figure 6 (a) is the SEM morphology characterization of the TiO2-Fe2O3 ordered hierarchical structure nanorods of Example 4, and (b) is the SEM morphology characterization of the TiO2-Fe2O3 ordered hierarchical structure nanorods of Example 5;

[0033] Figure 7 XRD characterization of TiO2-Fe2O3 ordered hierarchical structure nanorods (TFeAs), TNAs and FeAs in Examples 3 and 5, where (a) is TNAs, (b) is FeAs, (c) is TFeAs-1, and (d) is TFeAs-3;

[0034] Figure 8 The degradation curve of methyl blue in 1h period of TFeAs-1 of Example 3 and TFeAs-2 of Example 5 and P25 international general particles (Degussa) under irradiation of ultraviolet enhanced band (250nm-380nm) light source;

[0035] Fig. 9 It is a comparison curve of the degradation effect of TFeAs-1 in Example 3, TNAs in Example 3, TFeAs-3 in Example 5 and TTNAs in Patent 201010548151.2 on methyl blue under visible light (400nm-780nm) irradiation conditions. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0038] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0039] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0040] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0041] The room temperature in the present invention refers to 25±2°C.

[0042] The raw materials required for the embodiments of the present invention are all purchased.

[0043] The present invention discloses a method for preparing a TiO2-Fe2O3 ordered hierarchical structure nanorod array. The material is prepared by a hydrothermal process using a TiO2 primary nanorod array as a basic material. In the material, the photocatalyst TiO2 is immobilized on a pretreated quartz glass substrate and has a special-shaped ordered hierarchical nanorod array structure. The specific morphology of the structure can be coordinated and regulated by the pH values ​​of two precursor solutions for preparing the catalyst. Compared with TiO2 with a primary nanorod array structure, the specific surface area is larger, which is beneficial to improving the absorption and utilization rate of light energy, improving the contact and adsorption of harmful substances to be degraded in the water body, and achieving the purpose of deep purification of the water body. At the same time, the TiO2-Fe2O3 ordered hierarchical structure nanorod array is a solid-supported photocatalyst, which can be recycled and reused many times, greatly improving the utilization rate of the photocatalyst, effectively reducing the cost of sewage treatment, and purifying water without any damage to the water. Secondary pollution to the environment; most importantly, based on the properties of semiconductor TiO2 and Fe2O3 monomers, a simple composite mechanism is adopted to study and prepare TiO2-Fe2O3 (TFeAs) ordered hierarchical structure materials on a transparent quartz substrate. On the basis of maintaining the single crystal morphology of each monomer, the growth mode of Fe2O3 and TiO2 monomers is realized to "fill the gap" with each other, thereby increasing the specific surface area of ​​the simple composite catalyst, effectively exerting the absorption response advantages of the two synthetic monomers to the light energy of their respective effective illumination bands, realizing the full utilization of the full spectrum of light energy, and improving the catalytic efficiency of TiO2 photocatalytic water purification materials and the potential for practical application under sunlight conditions.

[0044] The present invention provides a method for preparing a TiO2-Fe2O3 ordered hierarchical structure nanorod array, comprising the following steps:

[0045] 1) After tetrabutyl titanate, diethanolamine and ethanol are mixed, a dropping liquid is added, stirred and mixed, and aged to obtain a spinning liquid; the dropping liquid is composed of water, ethanol and concentrated hydrochloric acid;

[0046] 2) coating the spinning solution obtained in step 1) on a substrate, drying and heat treating the substrate to obtain a rutile TiO2 film on the substrate surface;

[0047] 3) mixing the rutile TiO2 film obtained in step 2) with a precursor I, reacting at 190° C. to obtain a TiO2 primary nanorod array after the reaction is completed; the precursor I is a saturated aqueous solution of TiCl3 in NaCl, and the pH value of the precursor I is 0.25-1.50;

[0048] 4) Mixing the TiO2 primary nanorod array obtained in step 3) with precursor II, reacting at 130°C, and after the reaction is completed, drying and annealing are performed to obtain the TiO2-Fe2O3 ordered hierarchical structure nanorod array (TFeAs); the precursor II is a saturated aqueous solution of FeCl3 and NaNO3, and the pH value of the precursor II is 1.00-2.10.

[0049] In step 1), the molar ratio of tetrabutyl titanate, diethanolamine and ethanol is 1:1:4; in the step of adding the droplet, the rate of adding the droplet is 5-7 mL / min, preferably 5 mL / min; in the droplet, the volume ratio of water, ethanol and concentrated hydrochloric acid is 1.7 mL:34 mL:0.31 mL, and the mass percentage concentration of the concentrated hydrochloric acid is 37%; in the stirring and mixing step, the stirring time is 15-45 min, preferably 0.5 hour; in the aging step, the time is 20-24 hours, preferably 20 hours.

[0050] The coating method of step 2) is a spin coating method, in which the rotation speed is 2800-3000r / min, preferably 3000r / min, and the rotation radius is 2.5cm; in the drying step, the temperature is 90-100°C, preferably 95°C, and the time is 10-30min, preferably 0.5h; in the heat treatment step, the temperature is 750-850°C, preferably 800°C, and the time is 15-20min, preferably 15min; the thickness of the rutile TiO2 film is 200nm; the substrate is a quartz glass sheet. In actual operation, this step can be repeated according to the desired thickness of the rutile TiO2 film to obtain the desired film thickness.

[0051] In step 3), the concentration of TiCl3 in the saturated aqueous solution of NaCl is 0.05 mol / l; the pH value is 0.25-1.50, preferably 1.30; in the reaction step, the temperature is 190°C and the time is 3h. The reaction in this step is a hydrothermal growth reaction.

[0052] In step 4), the concentration of FeCl3 in the saturated aqueous solution of NaNO3 is 0.10-0.20 mol / l, preferably 0.15 mol / l, the pH value is 1.00-2.10, preferably the pH value is 1.40, in the reaction step, the temperature is 130°C, and the time is 5h; the reaction in this step is a hydrothermal growth reaction; the subsequent treatment step after the reaction is completed is drying at room temperature and annealing in a muffle furnace at 400°C for 1h.

[0053] The present invention also provides a TiO2-Fe2O3 ordered hierarchical nanorod array (TFeAs) prepared by the above method, and the use of the array in preparing a photocatalytic water purification material. In the nanorod array, each TiO2-Fe2O3 cross-shaped hierarchical nanorod has a diameter of 80-200nm and a length of 600-2200nm.

[0054] Figure 1 Figure 1 is a schematic diagram comparing the principle of photoexcitation of TiO2-Fe2O3 composite modification and photoexcitation of TiO2-Fe2O3 ordered hierarchical structure. (a) is a schematic diagram of the principle of photoexcitation of TiO2-Fe2O3 composite modification. It can be seen that for TiO2-Fe2O3 composite modified catalyst, after light excitation, electrons jump from the conduction band of TiO2 to the conduction band of Fe2O3, and photogenerated holes transfer from the valence band of Fe2O3 to the valence band of TiO2. (b) is a schematic diagram of the principle of photoexcitation of TiO2-Fe2O3 ordered hierarchical structure. It can be seen that for TiO2-Fe2O3 ordered hierarchical structure catalyst, after light excitation, the photogenerated electrons and holes of TiO2 and Fe2O3 migrate and transmit within their respective energy bands without mutual transition and transfer.

[0055] Example 1

[0056] In this example, different TiO2 ordered nanorod arrays (TNAs) were prepared by adjusting the pH of precursor I:

[0057] 1) Tetrabutyl titanate, diethanolamine and ethanol were mixed at a molar ratio of 1:1:4, and a droplet (composed of 1.7 mL of water, 34 mL of ethanol and 0.31 mL of concentrated hydrochloric acid with a mass percentage concentration of 37%) was added at a rate of 5 mL / min, and the mixture was stirred for 0.5 h. After aging for 20 h, a light yellow spinning solution was obtained;

[0058] 2) The spinning solution obtained in step 1) was coated on a cleaned quartz glass substrate by spin coating (rotation speed of 3000 r / min, rotation radius of 2.5 cm), dried at 95° C. for 0.5 h, and heat treated at 800° C. for 15 min to obtain a rutile TiO2 film with a thickness of 200 nm on the substrate surface;

[0059] 3) The rutile TiO2 film obtained in step 2) is mixed with precursor I, and the mixture is subjected to a hydrothermal growth reaction at 190°C for 3 hours. After the reaction is completed, a TiO2 primary nanorod array is obtained; wherein precursor I is a saturated aqueous solution of NaCl with a concentration of 0.05 mol / L TiCl3, and the pH values ​​are adjusted to 0.25, 0.50, 1.00, 1.10, 1.20, 1.30, 1.40 and 1.50 respectively by using a NaOH solution, and then the mixture is subjected to a hydrothermal growth reaction at 190°C for 3 hours. After 3 h, the reaction was completed and TiO2 primary nanorod arrays grown in different pH environments were obtained, which were respectively named TNAs-1 (pH = 0.25), TNAs-2 (pH = 0.50), TNAs-3 (pH = 1.00), TNAs-4 (pH = 1.10), TNAs-5 (pH = 1.20), TNAs-6 (pH = 1.30), TNAs-7 (pH = 1.40) and TNAs-8 (pH = 1.50). Figure 2 The SEM morphology characterization of the TiO2 primary nanorod arrays (TNAs) prepared in this example grown in different pH environments of precursor I, where (a) is TNAs-1, (b) is TNAs-2, and (c) is TNAs-3. Figure 3 The SEM images of TiO2 primary nanorod arrays (TNAs) prepared in this example grown in different pH environments of precursor I are shown in Figure 1, where (a) is TNAs-4, (b) is TNAs-5, (c) is TNAs-6, (d) is TNAs-7, and (e) is TNAs-8. Figure 2 and Figure 3 It can be seen that as the pH of precursor I gradually increases, the diameter of the prepared TNAs decreases and the growth density decreases.

[0060] Example 2

[0061] In this example, different Fe2O3 ordered nanorod arrays (FeAs) were prepared by adjusting the pH of precursor II:

[0062] The precursor II (saturated aqueous solution of FeCl3 in NaNO3) was prepared with a concentration of 0.15 mol / L, and the pH values ​​of the solution were adjusted to 1.10, 1.20, 1.30, 1.40, 1.50 and 2.00, respectively. The Fe2O3 nanorod arrays were prepared by hydrothermal growth reaction at 130°C for 5 hours. The SEM morphology of FeAs is shown in Figure 4 , where (a) pH is 1.10, (b) pH is 1.20, (c) pH is 1.30, (d) pH is 1.40, (e) pH is 1.50, (f) pH is 2.00, from Figure 4It can be seen that the pH of precursor II affects the morphology of the final Fe2O3 ordered hierarchical structure nanorod array. When the pH is too low, the nanorods are not fully grown, not upright, and have a low density. When pH = 1.30, the aspect ratio and density of the nanorods are optimal. After pH>1.40, the nanorods become thicker and begin to grow disorderly, and the proportion of rod-like morphology decreases. When the pH is too high, the morphology changes and becomes spherical.

[0063] Example 3 A method for preparing a TiO2-Fe2O3 ordered hierarchical structure nanorod array

[0064] 1) Tetrabutyl titanate, diethanolamine and ethanol were mixed at a molar ratio of 1:1:4, and a droplet (composed of 1.7 mL of water, 34 mL of ethanol and 0.31 mL of concentrated hydrochloric acid with a mass percentage concentration of 37%) was added at a rate of 5 mL / min, and the mixture was stirred for 0.5 h. After aging for 20 h, a light yellow spinning solution was obtained;

[0065] 2) The spinning solution obtained in step 1) was coated on a cleaned quartz glass substrate by spin coating (rotation speed of 3000 r / min, rotation radius of 2.5 cm), dried at 95° C. for 0.5 h, and heat treated at 800° C. for 15 min to obtain a rutile TiO2 film with a thickness of 200 nm on the substrate surface;

[0066] 3) The rutile TiO2 film obtained in step 2) was mixed with precursor I (a saturated aqueous solution of NaCl with a concentration of 0.05 mol / L TiCl3 and a pH value of 0.25), and hydrothermally grown at 190°C for 3 h. After the reaction was completed, a TiO2 primary nanorod array was obtained, which was recorded as TNAs-1;

[0067] 4) The TiO2 primary nanorod array obtained in step 3) was mixed with precursor II (a saturated aqueous solution of NaNO3 with a concentration of 0.15 mol / L of FeCl3 and a pH value of 2.05), and the mixture was hydrothermally grown at 130°C for 5 h. After the reaction was completed, the mixture was repeatedly rinsed with deionized water, dried naturally, and annealed in a muffle furnace at 400°C for 1 h to obtain a TiO2-Fe2O3 ordered hierarchical structure nanorod array, which was recorded as TFeAs-1.

[0068] Figure 5 The TiO2 primary nanorod array prepared in step 3) of this embodiment has a neat structure and uniform diameter distribution, and its SEM morphology is as follows: Figure 5 As shown in (a), Figure 5 (a) It can be seen that in the primary nanorod array, the diameter of each nanorod is 80-90nm and the length is 1800-1900nm; the SEM morphology of the TiO2-Fe2O3 ordered hierarchical structure nanorod array (TFeAs-1) prepared in this example is as follows Figure 5 As shown in (b), Figure 5 (b) It can be seen that at the active sites of the TiO2 primary nanorod array (diameter 90-100nm, length 1800-2000nm), secondary microsphere granular Fe2O3 grows, and the diameter of each Fe2O3 nanosphere particle is 55-65nm, which is the Fe2O3 secondary nanosphere particle array (TiO2-Fe2O3).

[0069] Example 4 Preparation of TiO2-Fe2O3 Ordered Hierarchical Structure Nanorod Array

[0070] The TNAs-6 prepared in Example 1 was mixed with a precursor II (a saturated aqueous solution of NaNO3 with a concentration of 0.15 mol / l of FeCl3 and a pH value of 1.30), and subjected to a hydrothermal growth reaction at 130°C for 5 h. After the reaction was completed, the mixture was repeatedly rinsed with deionized water, dried naturally, and annealed in a muffle furnace at 400°C for 1 h to obtain an ordered hierarchical structured TiO2-Fe2O3 nanorod array, denoted as TFeAs-2.

[0071] The TiO2 primary nanorod array prepared in step 3) of this embodiment has a uniform diameter distribution and a large aspect ratio. Its SEM morphology is shown in the figure below. Figure 3 (c) shows that Figure 3 (c) It can be seen that in the primary nanorod array, each nanorod has a diameter of 20-30 nm and a length of 1300-1400 nm. The SEM morphology of TFeAs-2 prepared in this example is as follows Figure 6 As shown in (a), Figure 6 (a) It can be seen that a new cross-shaped rod-shaped ordered hierarchical structure TiO2-Fe2O3 grows at the active sites of the TiO2 primary nanorod array (diameter 90-100nm, length 1800-2000nm), and the diameter of each TiO2-Fe2O3 cross-shaped hierarchical nanorod is 80-200nm and the length is 600-2200nm.

[0072] Example 5 Preparation of TiO2-Fe2O3 Ordered Hierarchical Structure Nanorod Array (TFeAs-3)

[0073] The TNAs-6 prepared in Example 1 was mixed with a precursor II (a saturated aqueous solution of NaNO3 with a concentration of 0.15 mol / L FeCl3 and a pH value of 1.40), and a hydrothermal growth reaction was carried out at 130°C for 5 h. After the reaction was completed, the mixture was repeatedly rinsed with deionized water, dried naturally, and annealed in a muffle furnace at 400°C for 1 h to obtain a TiO2-Fe2O3 ordered hierarchical structure nanorod array (TFeAs-3).

[0074] The TiO2 primary nanorod array prepared in step 3) of this embodiment has uniform diameter distribution and large aspect ratio. Its SEM morphology is as follows: Figure 3 (c) shows that Figure 3 (c) It can be seen that in the primary nanorod array, the diameter of each nanorod is 20-30 nm and the length is 1300-1400 nm.

[0075] The SEM morphology of the TiO2-Fe2O3 ordered hierarchical structure nanorod array (TFeAs-3) prepared in this example is as follows Figure 6 As shown in (b), Figure 6 (b) It can be seen that at the active sites of the TiO2 primary nanorod array (diameter 90-100nm, length 1800-2000nm), a new cross-shaped rod-shaped ordered hierarchical structure TiO2-Fe2O3 grows, and the diameter of each TiO2-Fe2O3 cross-shaped hierarchical nanorod is 180-200nm and the length is 600-1800nm.

[0076] XRD characterization was performed on the TiO2 primary nanorod arrays, TiO2-Fe2O3 ordered hierarchical nanorods and α-Fe2O3 in Examples 3-5, respectively. The test results are shown in Figure 7 , Figure 7 (a) is the XRD characterization result of TNAs in Examples 3 and 5, (b) is the XRD characterization result of FeAs (i.e., α-Fe2O3) (obtained by preparing Fe2O3 alone on a substrate for detection), (c) is the XRD characterization result of TFeAs-1, and (d) is the XRD characterization result of TFeAs-2 (different pH values ​​of the precursors only affect the morphology but not the XRD results, so the XRD characterization results of the two are consistent); the XRD characterization of the TiO2 primary nanorod arrays obtained in step 3) of Example 3 is consistent with Figure 7 In (a), the characteristic peak positions are the same and the peak intensity ratios are similar, both of which belong to rutile TiO2. The XRD characterization results of the TiO2-Fe2O3 ordered hierarchical structure nanorods prepared in Example 4 show that TiO2 is rutile and Fe2O3 is α-Fe2O3.

[0077] Application test

[0078] 1. Photocatalytic degradation of methyl blue solution

[0079] The TiO2-Fe2O3 ordered hierarchical structure nanorod arrays prepared in Examples 3 and 4 and the internationally used P25 (Degussa) particles were used as catalysts and irradiated with an ultraviolet enhanced band (250nm-380nm) light source to measure the photocatalytic degradation effects of the two catalysts on methyl blue solution.

[0080] The whole reaction process was carried out in a dark room, the temperature range was controlled at 25-30°C, the reaction cycle was 1h, a 300UV ultraviolet enhanced lamp (purchased from Beijing Bofeilai Co., Ltd.) was irradiated vertically from above the cylindrical main reactor, there was an air chamber below the main reactor, the air flow rate was 5L / min, the concentration of methyl blue solution was 0.2g / L, the amount added was 200mL, and the catalyst dosage was 0.004g / L.

[0081] The degradation rate of methyl blue was calculated according to the following formula:

[0082]

[0083] Wherein, C0 is the initial concentration of methyl blue, 0.2 g / L, and C is the concentration of methyl blue after degradation.

[0084] The degradation rate of methyl blue was Figure 8 As shown. Figure 8 It can be seen that within the 1-hour degradation period, the TiO2-Fe2O3 ordered hierarchical structure nanorod arrays obtained in Examples 3 and 5 of the present invention, marked as TFeAs-1 and TFeAs-3, have obvious degradation advantages in photocatalytic degradation compared with the internationally used P25 (Degussa) particle catalyst (referred to as P25):

[0085] The degradation rate of methyl blue in the ultraviolet enhanced band is: 96.4% (TFeAs-2)>96.1% (TFeAs-1)>72.1% (P25); this result shows that the TiO2-Fe2O3 ordered hierarchical structure nanorod array provided by the present invention can effectively improve the utilization rate of the catalyst to the energy of the light source and improve the degradation efficiency of organic matter.

[0086] The TiO2-Fe2O3 ordered hierarchical structure nanorod arrays prepared in the above Examples 3 and 5, the TiO2 primary nanorod array (TNAs-6) obtained in step 3) of Example 1 were used as catalysts, and the ordered secondary structure TiO2 nanorod array (TiO2-TiO2) prepared in Example 1 of Patent 201010548151.2 was used as a catalyst. The illumination band was adjusted to the visible band (400nm-780nm), and the photocatalytic degradation effects of the above four types of catalysts on methyl blue solution were measured.

[0087] The whole reaction process was carried out in a dark room at room temperature. The reaction period was 1 h. A 300UV ultraviolet enhanced lamp (purchased from Beijing Bofeilai Co., Ltd.) was vertically irradiated from above the cylindrical main reactor. There was an air chamber below the main reactor. The air flow rate was 5 L / min. The concentration of the methyl blue solution was 0.2 g / L, the amount added was 200 ml, and the catalyst dosage was 0.004 g / L.

[0088] The degradation rate of methyl blue was Fig. 9 As shown in the figure, within the 1h degradation period, the arrays obtained in Examples 3 and 5 of the present invention, marked as TFeAs-1 and TFeAs-3, have obvious degradation advantages in photocatalytic degradation compared with the TiO2 primary nanorod array obtained in step 3) of Example 1 as a catalyst TNAs and the ordered secondary structure TiO2 nanorod array (TiO2-TiO2) TTNAs prepared in Example 1 of Patent 201010548151.2:

[0089] The degradation rate of methyl blue in the visible band is: 93.4% (TFeAs-3)>92.7% (TFeAs-1)>40.7% (TTNAs)>34.3% (TNAs); the results show that the TiO2-Fe2O3 ordered hierarchical structure nanorod array provided by the present invention can effectively improve the utilization rate of the catalyst for the energy of the full spectrum light source and increase the degradation efficiency of organic matter.

[0090] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a TiO2-Fe2O3 ordered hierarchical structure nanorod array, characterized in that: The rutile TiO2 film is mixed with the precursor I, and the first hydrothermal growth reaction is performed to obtain the TiO2 primary nanorod array. The TiO2 primary nanorod array is mixed with the precursor II, and the hydrothermal growth reaction is performed again. The mixture is dried and annealed to obtain the TiO2-Fe2O3 ordered hierarchical structure nanorod array. The precursor I is a saturated NaCl aqueous solution of TiCl3; the precursor II is a saturated NaNO3 aqueous solution of FeCl3.

2. The preparation method according to claim 1, characterized in that: The concentration of TiCl3 in the precursor I is 0.05 mol / L, and the pH is 0.25-1.

50.

3. The preparation method according to claim 2, characterized in that: The pH of TiCl3 in the precursor I is 1.

30.

4. The preparation method according to claim 1, characterized in that: The concentration of FeCl3 in the precursor II is 0.10-0.20 mol / L, and the pH is 1.00-2.

10.

5. The preparation method according to claim 4, characterized in that: The concentration of FeCl3 in the precursor II is 0.15 mol / L and the pH is 1.

4.

6. The preparation method according to claim 1, characterized in that: The temperature of the second hydrothermal growth reaction is 130° C. and the time is 5 hours.

7. The preparation method according to claim 1, characterized in that: The annealing temperature is 400° C. and the annealing time is 1 h.

8. A TiO2-Fe2O3 ordered hierarchical structure nanorod array prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the TiO2-Fe2O3 ordered hierarchical structure nanorod array according to claim 8 in the preparation of photocatalytic water purification materials.

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