TiO2-Fe2o3 ordered hierarchical structure nanorod array and preparation method and application thereof

Abstract

The application discloses TiO2-Fe2O3 ordered hierarchical structure nanorod arrays, a preparation method and application thereof, and belongs to the field of materials and environmental protection technology. A rutile TiO2 film is mixed with a precursor I, a first-time hydrothermal growth reaction obtains TiO2 primary nanorod arrays, the TiO2 primary nanorod arrays are mixed with a precursor II, a second-time hydrothermal growth reaction is carried out, drying and annealing are carried out, and the TiO2-Fe2O3 ordered hierarchical structure nanorod arrays are obtained. The precursor I is a NaCl saturated aqueous solution of TiCl3. The precursor II is a NaNO3 saturated aqueous solution of FeCl3. The TiO2-Fe2O3 ordered hierarchical structure nanorod arrays have good research potential in the application promotion in the field of actual wastewater advanced treatment and practical application prospects under sunlight.

Description

Technical Field

[0001] This invention belongs to the fields of materials and environmental protection technology, and in particular relates to a TiO2-Fe2O3 ordered hierarchical structure nanorod array, its preparation method and application. Background Technology

[0002] Photocatalytic water purification technology is a novel advanced water treatment method based on the unique valence band structure of semiconductor materials. Semiconductor materials have a certain band gap. When irradiated with photons of energy greater than the semiconductor band gap, electrons in the material structure absorb the photons and jump from the valence band to the conduction band, generating electron-hole pairs. Toxic metal ions in wastewater can be reduced by reducing electrons; the more negative the redox potential of the conduction band and the higher the conduction band energy, the stronger the reducing power. Similarly, organic matter in wastewater can be oxidized into water and carbon dioxide by oxidizing holes; the more positive the redox potential of the valence band and the stronger the oxidizing power.

[0003] TiO2, due to its inherent photochemical stability and resistance to photocorrosion, has become the most widely used and iconic semiconductor material in the field of photocatalysis. The recent emergence of nanomaterial synthesis and application technologies has brought tremendous opportunities and challenges to the research of photocatalytic materials. One-dimensional TiO2 nanostructures combine the characteristics of nanomaterials with the inherent properties of TiO2, achieving both high-efficiency photocatalysis and low cost in the field of heterogeneous catalysis, making it the most representative and promising photocatalyst in the field. Currently, in laboratory simulations and actual production and domestic water purification, the most widely used and frequently applied TiO2 granular photocatalyst is P25 (Degussa). Powdered TiO2 can increase the specific surface area of ​​the catalyst, thereby improving wastewater purification efficiency. However, when using semiconductor particles for wastewater treatment, due to the small particle size, the catalyst is easily lost in aqueous solutions, difficult to recover, and suffers significant loss of active ingredients, making long-term reuse impossible.

[0004] Patent 201010548151.2 relates to a novel ordered secondary structure TiO2 nanorod catalyst. This catalytic material is a transparent substrate supported catalyst, which makes up for the problem that particulate nano TiO2 materials are not easy 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 transport of photogenerated charge carriers, thus effectively improving the efficiency of photocatalytic degradation of wastewater.

[0005] The two homopolymers of TiO2, anatase and rutile, have band gaps of 3.2 eV and 3.0 eV, respectively, corresponding to absorption spectral band boundary wavelengths of 387.5 nm and 413.3 nm. Only ultraviolet light with energy higher than the boundary wavelength can excite TiO2 to generate charge carriers, which can then participate in the mineralization and degradation of pollutants. Because TiO2 catalysts have very low utilization rates of solar energy and cannot effectively respond to as much of the full spectrum of light, large-scale industrial applications of TiO2 catalysts face cost and logistical obstacles. Summary of the Invention

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

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

[0008] A method for preparing an ordered hierarchical structured TiO2-Fe2O3 nanorod array involves mixing a rutile TiO2 film with precursor I, followed by a first hydrothermal growth reaction to obtain a TiO2 primary nanorod array. The TiO2 primary nanorod array is then mixed with precursor II, followed by a second hydrothermal growth reaction, and finally dried and annealed to obtain the ordered hierarchical structured TiO2-Fe2O3 nanorod array. Precursor I is a saturated aqueous solution of TiCl3 in NaCl, and precursor II is a saturated aqueous solution of FeCl3 in NaNO3.

[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 precursor I is 1.30.

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

[0012] More preferably, the FeCl3 concentration in 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] This invention achieves simple composite synthesis of different semiconductor materials using methods different from catalyst sensitization and composite processes. The specific principle of the preparation process for the TiO2-Fe2O3 ordered hierarchical nanorod array material provided by this invention is as follows: Maintaining the band gap of each monomer essentially unchanged, and starting from the perspective of spectral response range changes, using the basic semiconductor monomer as a primary structural template, other semiconductor materials are introduced to perform simple composite synthesis between dissimilar monomers. The dissimilar materials mutually "fill the gaps" during growth, achieving effective absorption of light energy in their respective spectral response bands, expanding the overall spectral response range of the simple composite material (TiO2-Fe2O3), and improving the catalyst's utilization rate of the full spectrum of natural light energy.

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

[0017] The second technical solution provided by this invention

[0018] An ordered hierarchical structured nanorod array of TiO2-Fe2O3 prepared by the above method.

[0019] The third technical solution provided by this invention

[0020] Application of the above-mentioned TiO2-Fe2O3 ordered hierarchical nanorod array in the photocatalytic degradation of methylene blue.

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

[0022] When using semiconductor TiO2-Fe2O3 material with an ordered hierarchical nanorod array structure for wastewater treatment, this invention solves the problems of easy loss of TiO2 powder catalysts in solution, large loss of active ingredients, and difficulty in recycling and reuse, since it is a supported catalyst. It achieves controllable and effective recovery of the catalyst, allowing the material to be used for a long time and reducing water treatment costs.

[0023] This invention addresses the problem of insufficient photocatalytic capacity of ordinary TiO2 photocatalysts with uncontrollable structural growth when using TiO2 photocatalysts with ordinary primary nanorod arrays in wastewater degradation processes. This is achieved by improving the pH and morphology of TiO2 primary structure growth and introducing an ordered hierarchical structure of heteromorphic Fe2O3.

[0024] This invention improves TiO2 nanorod primary array materials with photocatalytic properties by introducing a narrow bandgap, low-energy conduction band Fe2O3 ordered array structure and a TiO2-Fe2O3 ordered hierarchical structure preparation process. This yields a cross-shaped secondary structure nanorod array material with good morphology and high photocatalytic activity. This overcomes the disadvantages of TiO2 primary nanorod arrays in photocatalytic reactions, which have a wide bandgap and can only absorb high-energy ultraviolet light. It expands the spectral response range of semiconductor TiO2 primary nanorod arrays and improves the energy utilization rate in the visible light region of natural sunlight.

[0025] The TiO2-Fe2O3 ordered hierarchical nanorod array provided by this invention has good research potential and practical application prospects under sunlight conditions in the field of advanced wastewater treatment. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The diagrams show a comparison of the photoexcitation principles of TiO2-Fe2O3 composite modification and TiO2-Fe2O3 ordered hierarchical structure, where (a) is a schematic diagram of the photoexcitation principle of TiO2-Fe2O3 composite modification and (b) is a schematic diagram of the photoexcitation principle 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, 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, and (f) pH is 2.00.

[0031] Figure 5 (a) is a SEM morphology characterization image of the first-order nanorod array TNAs in Example 3, and (b) is a SEM morphology characterization image of the TFeAs-1 prepared in Example 3.

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

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

[0034] Figure 8 Degradation curves of methylene blue for 1 hour using TFeAs-1 (Example 3), TFeAs-2 (Example 5), and P25 Degussa particles under ultraviolet enhanced wavelength (250nm-380nm) light source irradiation;

[0035] Figure 9 The curves showing the comparison of the degradation effects of TFeAs-1 in Example 3, TNAs in Example 3, TFeAs-3 in Example 5, and TTNAs in Patent 201010548151.2 on methylene blue under visible light irradiation (400nm-780nm) conditions. Detailed Implementation

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

[0037] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0038] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0039] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

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

[0041] The room temperature in this invention refers to 25±2℃.

[0042] All raw materials required for the embodiments of this invention were obtained through purchase.

[0043] This invention discloses a method for preparing a TiO2-Fe2O3 ordered hierarchical nanorod array. The material is prepared using a TiO2 primary nanorod array as the base material via a hydrothermal process. In this material, the photocatalyst TiO2 is immobilized on a pretreated quartz glass substrate, exhibiting an irregularly shaped ordered hierarchical nanorod array structure. The specific morphology of this structure can be synergistically controlled by the pH values ​​of the two precursor solutions used in catalyst preparation. Compared to TiO2 with a primary nanorod array structure, this structure has a larger specific surface area, which is beneficial for improving the absorption and utilization rate of light energy and enhancing the contact adsorption of harmful substances in water, thus achieving deep water purification. Furthermore, this TiO2-Fe2O3 ordered hierarchical nanorod array is a supported photocatalyst that can be repeatedly recycled, significantly improving the utilization rate of the photocatalyst and effectively reducing the cost of wastewater treatment. It also purifies water without affecting other parts of the body. This study aims to prevent secondary pollution of the environment. Most importantly, based on the properties of semiconductor TiO2 and Fe2O3 monomers, and employing a simple composite mechanism, a TiO2-Fe2O3 (TFeAs) ordered hierarchical structure material was prepared on a transparent quartz substrate. While maintaining the single-crystal morphology of each monomer, a growth mode was achieved where Fe2O3 and TiO2 monomers mutually "fill gaps," increasing the specific surface area of ​​the simple composite catalyst. This effectively leverages the absorption response advantages of the two synthesized monomers to their respective effective light irradiation bands, achieving full utilization of the entire light spectrum and enhancing the catalytic efficiency of TiO2-based photocatalytic water purification materials and their potential for practical application under sunlight conditions.

[0044] This invention provides a method for preparing an ordered hierarchical structured TiO2-Fe2O3 nanorod array, comprising the following steps:

[0045] 1) Tetrabutyl titanate, diethanolamine and ethanol are mixed and then added to the dropwise solution. The mixture is stirred and mixed, and then aged to obtain the sizing solution. The dropwise solution is composed of water, ethanol and concentrated hydrochloric acid.

[0046] 2) The spin coating solution obtained in step 1) is coated onto the substrate, dried and heat-treated to obtain a rutile TiO2 film on the substrate surface;

[0047] 3) The rutile TiO2 film obtained in step 2) is mixed with precursor I and reacted at 190°C. After the reaction is complete, a TiO2 primary nanorod array is obtained. 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) The TiO2 primary nanorod array obtained in step 3) is mixed with precursor II and reacted at 130°C. After the reaction is completed, it is dried and annealed to obtain the TiO2-Fe2O3 ordered hierarchical 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 dropwise solution, the rate of addition is 5-7 mL / min, preferably 5 mL / min; in the dropwise solution, 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 step of stirring and mixing, the stirring time is 15-45 min, preferably 0.5 hours; in the step of aging, the time is 20-24 hours, preferably 20 hours.

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

[0051] In step 3), the concentration of TiCl3 in the saturated NaCl aqueous solution is 0.05 mol / L; the pH value is 0.25-1.50, preferably 1.30; in the reaction step, the temperature is 190℃ and the time is 3h, and 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, and the pH value is 1.00-2.10, preferably 1.40. In the reaction step, the temperature is 130℃ and the time is 5h. The reaction in this step is a hydrothermal growth reaction. The subsequent treatment step after the reaction is to dry at room temperature and anneal in a muffle furnace at 400℃ for 1h.

[0053] This invention also provides an ordered hierarchical structured TiO2-Fe2O3 nanorod array (TFeAs) prepared by the above method, and its application in the preparation of photocatalytic water purification materials. In this nanorod array, each TiO2-Fe2O3 cross-shaped hierarchical nanorod has a diameter of 80-200 nm and a length of 600-2200 nm.

[0054] Figure 1 The diagrams show a comparison between the photoexcitation principles of TiO2-Fe2O3 composite modified catalyst and the photoexcitation principle of TiO2-Fe2O3 ordered hierarchical structure. (a) shows the photoexcitation principle of TiO2-Fe2O3 composite modified catalyst, which shows that after photoexcitation, 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) shows the photoexcitation principle of TiO2-Fe2O3 ordered hierarchical structure, which shows that after photoexcitation, photogenerated electrons and holes in TiO2 and Fe2O3 migrate and transport within their respective energy bands without mutual jumps or transfers.

[0055] Example 1

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

[0057] 1) Tetrabutyl titanate, diethanolamine and ethanol were mixed in a molar ratio of 1:1:4 and added to a dropping solution (composed of 1.7 mL water, 34 mL ethanol and 0.31 mL concentrated hydrochloric acid with a mass percentage concentration of 37%) at a rate of 5 mL / min. The mixture was stirred and mixed for 0.5 h and aged for 20 h to obtain a light yellow sizing solution.

[0058] 2) The spin coating solution obtained in step 1) was coated onto a cleaned quartz glass substrate using a spin coating method (rotation speed of 3000 r / min and rotation radius of 2.5 cm). After drying at 95°C for 0.5 h, it was 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) was mixed with precursor I and hydrothermally grown at 190℃ for 3 hours. After the reaction was complete, a TiO2 primary nanorod array was obtained. Precursor I was a saturated aqueous solution of TiCl3 in NaCl with a concentration of 0.05 mol / L. The pH value was adjusted to 0.25, 0.50, 1.00, 1.10, 1.20, 1.30, 1.40 and 1.50 by NaOH solution, and then hydrothermally grown at 190℃. After 3 hours, the reaction was complete, yielding TiO2 primary nanorod arrays grown in different pH environments, designated as 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), respectively. Figure 2 The SEM morphology of the TiO2 primary nanorod arrays (TNAs) prepared in this embodiment is characterized by growth 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 morphology of the TiO2 primary nanorod arrays (TNAs) prepared in this embodiment, grown in different pH environments of precursor I, is shown in the figures: (a) TNAs-4, (b) TNAs-5, (c) TNAs-6, (d) TNAs-7, and (e) TNAs-8. Figure 2 and Figure 3 As can be seen, 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 embodiment, different Fe2O3 ordered nanorod arrays (FeAs) were prepared by adjusting the pH of precursor II:

[0062] Precursor II (FeCl3 in NaNO3 saturated aqueous solution) with a concentration of 0.15 mol / L was prepared, 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 array FeAs was prepared by hydrothermal growth at 130℃ for 5 hours. The SEM morphology characterization of the Fe2O3 nanorod array is shown in the figure. Figure 4 Among them, (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, and (f) pH is 2.00. Figure 4As can be seen, the pH of precursor II affects the morphology of the final Fe2O3 ordered hierarchical nanorod array. When the pH is too low, the nanorods do not grow completely, are not upright, and have a low density. When pH = 1.30, the aspect ratio and density of the nanorods are optimal. When pH > 1.40, the nanorods become thicker, begin to grow randomly, and the proportion of rod-shaped morphology decreases. When the pH is too high, the morphology changes and becomes spherical.

[0063] Example 3: A method for preparing an ordered hierarchical structured TiO2-Fe2O3 nanorod array

[0064] 1) Tetrabutyl titanate, diethanolamine and ethanol were mixed in a molar ratio of 1:1:4 and added to a dropping solution (composed of 1.7 mL water, 34 mL ethanol and 0.31 mL concentrated hydrochloric acid with a mass percentage concentration of 37%) at a rate of 5 mL / min. The mixture was stirred and mixed for 0.5 h and aged for 20 h to obtain a light yellow sizing solution.

[0065] 2) The spin coating solution obtained in step 1) was coated onto a cleaned quartz glass substrate using a spin coating method (rotation speed of 3000 r / min and rotation radius of 2.5 cm). After drying at 95°C for 0.5 h, it was 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 TiCl3 in NaCl with a concentration of 0.05 mol / L and a pH of 0.25) and hydrothermally grown at 190℃ for 3 h. After the reaction was completed, a TiO2 primary nanorod array was obtained, denoted as TNAs-1.

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

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

[0069] Example 4: Preparation of TiO2-Fe2O3 ordered hierarchical nanorod arrays

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

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

[0072] Example 5: Preparation of TiO2-Fe2O3 ordered hierarchical nanorod arrays (TFeAs-3)

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

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

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

[0076] The TiO2 primary nanorod arrays, TiO2-Fe2O3 ordered hierarchical nanorods, and α-Fe2O3 in Examples 3-5 were characterized by XRD, and the results are shown in the figure. Figure 7 , Figure 7 (a) shows the XRD characterization results of TNAs in Examples 3 and 5; (b) shows the XRD characterization results of FeAs (i.e., α-Fe2O3) (obtained by preparing Fe2O3 separately on the substrate and then detecting it); (c) shows the XRD characterization results of TFeAs-1; and (d) shows the XRD characterization results of TFeAs-2 (different pH values ​​of the precursor only affect the morphology and not the XRD results, so the XRD characterization results of the two are consistent); the XRD characterization of the TiO2 primary nanorod array obtained in step 3) of Example 3 is consistent with... Figure 7 In (a), the characteristic peaks are in the same position and have similar peak intensity ratios, both belonging to rutile TiO2. The XRD characterization results of the TiO2-Fe2O3 ordered hierarchical structure nanorods prepared in Example 4 show that TiO2 is rutile crystal form and Fe2O3 is α-Fe2O3.

[0077] Application Trial

[0078] 1. Photocatalytic degradation of p-methylene blue solution

[0079] The TiO2-Fe2O3 ordered hierarchical structured nanorod arrays and internationally used P25 (Degussa) particles prepared in Examples 3 and 4 above were used as catalysts. Both catalysts were irradiated with an ultraviolet enhanced wavelength (250nm-380nm) light source to determine the photocatalytic degradation effect of the two catalysts on methylene blue solution.

[0080] The entire reaction was carried out in a dark room, with the temperature controlled within the range of 25-30℃. The reaction cycle was 1 hour. A 300UV ultraviolet lamp (purchased from Beijing Bofeilai Co., Ltd.) was used to irradiate vertically from above the cylindrical main reactor. Below the main reactor was a gas chamber with an air flow rate of 5L / min. The concentration of the methylene blue solution was 0.2g / L, and the amount added was 200mL. The amount of catalyst added was 0.004g / L.

[0081] The degradation rate of methylene blue is calculated using the following formula:

[0082]

[0083] Where C0 is the initial concentration of methylene blue (0.2 g / L), and C is the concentration of methylene blue after degradation.

[0084] The degradation rate of the obtained methylene blue is as follows: Figure 8 As shown. By Figure 8 It can be seen that, within a 1-hour degradation period, the TiO2-Fe2O3 ordered hierarchical nanorod arrays obtained in Examples 3 and 5 of this invention, labeled as TFeAs-1 and TFeAs-3, exhibit significant degradation advantages in photocatalytic degradation compared to the internationally used P25 (Degussa) particulate catalyst (referred to as P25).

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

[0086] Using the TiO2-Fe2O3 ordered hierarchical structured nanorod arrays prepared in Examples 3 and 5 above, the TiO2 primary nanorod array (TNAs-6) obtained in step 3) of Example 1 as catalysts, and the ordered secondary structured TiO2 nanorod array (TiO2-TiO2) prepared in Example 1 of Patent 201010548151.2 as catalysts, the photocatalytic degradation effect of the above four types of catalysts on methylene blue solution was measured by adjusting the light irradiation band to the visible band (400nm-780nm).

[0087] The entire reaction was carried out in a dark room at room temperature, with a reaction cycle of 1 hour. A 300 UV intensifier lamp (purchased from Beijing Bofeilai Co., Ltd.) was used to irradiate vertically from above the cylindrical main reactor. Below the main reactor was a gas chamber with an air flow rate of 5 L / min. The concentration of the methylene blue solution was 0.2 g / L, the amount added was 200 ml, and the amount of catalyst added was 0.004 g / L.

[0088] The degradation rate of the obtained methylene blue is as follows: Figure 9 As shown in the figure, within a 1-hour degradation period, the arrays obtained in Examples 3 and 5 of this invention, labeled TFeAs-1 and TFeAs-3, exhibit significant degradation advantages in photocatalytic degradation compared to 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 methylene blue in the visible band is: 93.4% (TFeAs-3) > 92.7% (TFeAs-1) > 40.7% (TTNAs) > 34.3% (TNAs). This result shows that the TiO2-Fe2O3 ordered hierarchical nanorod array provided by the present invention can effectively improve the utilization rate of the catalyst to the energy of the full spectrum light source and increase the degradation efficiency of organic matter.

[0090] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A TiO2-Fe2O3 ordered hierarchical nanorod array, characterized in that, The TiO2-Fe2O3 ordered hierarchical nanorod array is a cross-shaped secondary structure nanorod array material. The preparation method of the TiO2-Fe2O3 ordered hierarchical nanorod array includes the following steps: mixing a rutile TiO2 film with precursor I, performing a first hydrothermal growth reaction to obtain a TiO2 primary nanorod array; mixing the TiO2 primary nanorod array with precursor II, performing a second hydrothermal growth reaction, and drying and annealing to obtain the TiO2-Fe2O3 ordered hierarchical nanorod array; wherein precursor I is a TiCl3 NaCl saturated aqueous solution; and precursor II is a FeCl3 NaNO3 saturated aqueous solution. The concentration of TiCl3 in precursor I is 0.05 mol / L, and the pH is 0.25-1.50; the concentration of FeCl3 in precursor II is 0.15 mol / L, and the pH is 1.

4. The temperature for the second hydrothermal growth reaction was 130°C, and the time was 5 hours.

2. The TiO2-Fe2O3 ordered hierarchical nanorod array according to claim 1, characterized in that, The annealing temperature is 400℃ and the time is 1 hour.

3. The application of the TiO2-Fe2O3 ordered hierarchical nanorod array as described in claim 1 or 2 in the preparation of photocatalytic water purification materials.

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