Heterojunction photocatalytic material containing contact interface and composed of mixed crystal type biphase TiO2 and SrTiO3 as well as preparation and application of heterojunction photocatalytic material

Abstract

The invention discloses a heterojunction photocatalytic material containing a contact interface and composed of mixed crystal type biphase T iO2 and SrT iO3, and preparation and application of the heterojunction photocatalytic material. The chemical formula of the heterojunction photocatalytic material is SrT iO3 / T iO2 (A)-T iO2 (R), wherein the mixed crystal type biphase TiO2 is composed of anatase type TiO2 (A) nano particles and rutile type TiO2 (R) nano particles, and the anatase type TiO2 (A) nano particles and the rutile type TiO2 (R) nano particles are connected through damaged sheet-shaped TiO2 (A); wherein the molar ratio of T < iO2 > (A) to T < iO2 > (R) in the mixed crystal type double-phase T < iO2 > is (3-1.5): 1, and the molar ratio of the SrT O3 to the mixed crystal type double-phase T < iO2 > is (1-0.8): 1. The mixed crystal TiO2 and the reduced semiconductor SrT O3 form a heterojunction, efficient electron transfer in the mixed crystal TiO2 can promote transfer of electrons from the TiO2 to the SrT O3, the photocatalytic performance of the material is further improved, and efficient photocatalytic oxidation efficiency is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of photocatalytic materials and wastewater treatment, and specifically relates to a heterojunction photocatalyst composed of a mixed-crystal dual-phase TiO2 and SrTiO3 containing a large number of contact interfaces, and its preparation and application. Background Art

[0002] With the acceleration of industrialization, environmental pollution is becoming increasingly serious, among which the treatment of wastewater containing organic pollutants has become a problem that needs to be solved urgently. Photocatalytic technology has attracted much attention as an efficient and environmentally friendly wastewater treatment method.

[0003] TiO2 is widely used in the field of photocatalysis due to its high stability, low cost, and non-toxicity. Anatase TiO2 has the advantages of high oxidation potential and good photocatalytic activity, while rutile TiO2 has the advantages of narrow band gap and strong conductivity. When they are combined to prepare mixed crystal TiO2, the contact interface between the two has a very high electron transfer efficiency. In addition, SrTiO3, as a reduced semiconductor, can form a SrTiO3 / TiO2S heterojunction when combined with TiO2, which has been proven to effectively promote the separation of photogenerated carriers and significantly improve the photocatalytic performance of the material.

[0004] The synthesis of mixed crystal TiO2 usually adopts the conventional hydrothermal method or calcination method. By adjusting the amount of hydrochloric acid or other additives and the hydrothermal or calcination temperature, mixed crystal TiO2 with anatase and rutile is generated at one time. The mixed crystal TiO2 prepared by this method will have problems such as large single-phase particle size and fewer and uneven two-phase interfaces, resulting in fewer electron transmission paths and limited improvement in photocatalytic performance. Summary of the invention

[0005] The present invention aims to solve the problems mentioned in the above background technology.

[0006] The invention discloses a heterojunction photocatalytic material composed of mixed crystal type dual-phase TiO2 and SrTiO3 with a contact interface, and the chemical formula thereof is SrTiO3 / TiO2(A)-TiO2(R).

[0007] In a specific embodiment, the mixed crystal dual-phase TiO2 is composed of anatase TiO2 (A) nanoparticles and rutile TiO2 (R) nanoparticles, which are connected by broken flaky TiO2 (A).

[0008] In a specific embodiment, the molar ratio of TiO2(A) to TiO2(R) in the mixed crystal dual-phase TiO2 is 3-1.5:1, and the molar ratio of SrTiO3 to the mixed crystal dual-phase TiO2 is 1-0.8:1.

[0009] The method of the present invention for preparing a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface comprises the following steps:

[0010] S1, preparation of amorphous TiO2 nanosheets, uniformly mixing a titanium precursor with anhydrous ethanol, adding cubic salt powder, then vigorously stirring and heating at 60-80°C until the solution is dry, calcining the dried powder in an air atmosphere, and washing the calcined product with deionized water after cooling to dissolve the cubic salt to obtain amorphous TiO2 nanosheets;

[0011] S2, preparation of mixed crystal dual-phase TiO2 (TiO2(A)-TiO2(R)), adding the amorphous TiO2 nanosheets obtained in S1, TiO2(A) and TiO2(R) in a certain proportion into a weak alkaline aqueous solution, stirring for 1-2 hours, transferring to a hydrothermal reactor, hydrothermally treating at 150-170°C for 5-7 days, separating white powder after cooling, and obtaining TiO2(A)-TiO2(R);

[0012] S3, preparation of SrTiO3 / TiO2(A)-TiO2(R), add the precursor of mixed crystal dual-phase TiO2 and Sr into a strong alkaline aqueous solution, stir for 0.5-1h, then add into a hydrothermal kettle, hydrothermally treat at 160-200℃ for 16-30h, separate the white powder and dry it to obtain SrTiO3 / TiO2(A)-TiO2(R).

[0013] In a specific embodiment, in said S1:

[0014] The titanium precursor is tetraethyl titanate, tetraisopropyl titanate or tetrabutyl titanate;

[0015] Cubic salts are inorganic salt compounds whose crystals of KCl, NaCl, and NaNO3 are cubic in structure;

[0016] The mass ratio of titanium precursor, anhydrous ethanol and cubic crystal salt is 1:30:100-300;

[0017] The calcination temperature is 400-500°C and the calcination time is 1-2h.

[0018] In a specific embodiment, in said S2:

[0019] TiO2(A) and TiO2(R) are TiO2 with anatase and rutile structures, with a particle size of 0-60nm;

[0020] The weak base aqueous solution is (C3H7)4NOH and / or NH4F dissolved in deionized water;

[0021] The molar ratio of amorphous TiO2, TiO2(A), and TiO2(R) is 1:5:2-4;

[0022] The molar ratio of the total amount of TiO2, deionized water, and (C3H7)4NOH or NH4F is 1:5:1-1.2.

[0023] In a specific embodiment, in said S3:

[0024] The precursors of Sr are Sr(NO3)2, SrCl2 and their hydrates;

[0025] The strong alkaline aqueous solution is NaOH or KOH dissolved in deionized water;

[0026] The molar ratio of the total amount of TiO2, the precursor of Sr, deionized water, and NaOH or KOH is 1:0.5:600:1-2.

[0027] The invention discloses an application of a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 containing a contact interface, including applying SrTiO3 / TiO2(A)-TiO2(R) photocatalyst to photocatalytically degrade organic pollutant wastewater.

[0028] In a specific embodiment, the photocatalytic material, oxidant and light source as described in any one of claims 1 to 3 are added to wastewater containing organic pollutants, and an oxidation reaction is carried out by photocatalysis.

[0029] In a specific embodiment, the dosage of SrTiO3 / TiO2(A)-TiO2(R) is 0.1‰-0.5‰ of the mass of the wastewater solution;

[0030] Wherein, the oxidant is hydrogen peroxide or persulfate, and the dosage is 1‰-5‰ of the COD concentration of the wastewater;

[0031] Wherein, the light source is a visible light lamp or an ultraviolet light lamp.

[0032] Beneficial Effects

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] 1. The mixed crystal TiO2 is prepared hydrothermally by mixing amorphous TiO2, TiO2(A) and TiO2(R) with a weak alkaline aqueous solution, which can ensure that only amorphous TiO2 is dissolved and recrystallized during hydrothermal treatment. At this time, if the mixing process and the hydrothermal process are well regulated, flaky anatase can be formed and the TiO2(A) and TiO2(R) particles can be connected to form a mixed crystal TiO2 with a large number of contact flaky interfaces. The flaky interfaces are good electron transfer paths.

[0035] 2. Compared with the traditional hydrothermal method, the mixed crystal TiO2 prepared by this method has the advantages of adjustable single-phase particle size and proportion, flaky connection interface and relatively controllable proportion, which greatly improves the photocatalytic performance.

[0036] 3. Mixed crystal TiO2 and reduced semiconductor SrTiO3 form a heterojunction. The efficient electron transfer inside the mixed crystal TiO2 will promote the transfer of electrons from TiO2 to SrTiO3, further improving the photocatalytic performance of the material and achieving efficient photocatalytic oxidation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a TEM image of SrTiO3 / TiO2(A)-TiO2(R) in the present invention;

[0038] Figure 2 is a TEM image of TiO2(A)-TiO2(R) in the present invention;

[0039] Figure 3 This is a diagram showing the COD removal of glucose simulated wastewater by photocatalytic material in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "counterclockwise", "clockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection, it can be a direct connection, it can be an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Example 1

[0044] The invention discloses a heterojunction photocatalytic material composed of mixed crystal type dual-phase TiO2 and SrTiO3 with a contact interface, and the chemical formula thereof is SrTiO3 / TiO2(A)-TiO2(R).

[0045] Among them, the mixed crystal dual-phase TiO2 is composed of anatase TiO2 (A) nanoparticles and rutile TiO2 (R) nanoparticles, which are connected by broken flaky TiO2 (A).

[0046] Among them, the molar ratio of TiO2(A) to TiO2(R) in the mixed crystal dual-phase TiO2 is 3-1.5:1, and the molar ratio of SrTiO3 to the mixed crystal dual-phase TiO2 is 1-0.8:1.

[0047] Example 2

[0048] This embodiment provides a method for preparing a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface, comprising the following steps:

[0049] S1, preparation of amorphous TiO2 nanosheets, 1g of tetrabutyl titanate and 30g of anhydrous ethanol were uniformly mixed, and then 300g of KCl powder was added, followed by vigorous stirring and heating at 70°C until the solution was dry. The dried powder was calcined at 400°C in an air atmosphere for 1h, and after cooling, the calcined product was fully washed with deionized water to dissolve the cubic salt to obtain amorphous TiO2 nanosheets;

[0050] S2, preparation of mixed crystal dual-phase TiO2 (TiO2(A)-TiO2(R)), add 0.5g of amorphous TiO2 nanosheets obtained from S1, 2.5g of commercially available TiO2(A) of about 30nm and 1g of TiO2(R) into 9ml of mixed aqueous solution containing 3.6g of (C3H7)4NOH and 0.37g of NH4F, stir well for 1h and transfer to a hydrothermal autoclave, and hydrothermally treat at 170℃ for 6 days. After cooling, separate the white powder to obtain TiO2(A)-TiO2(R);

[0051] S3, preparation of SrTiO3 / TiO2(A)-TiO2(R), add 0.5g mixed crystal dual-phase TiO2 and 1.32g Sr(NO3)2 into 70g aqueous solution containing 0.5g NaOH, stir for 0.5h and then add into a hydrothermal kettle, hydrothermally treat at 160℃ for 20h, separate the white powder and dry to obtain SrTiO3 / TiO2(A)-TiO2(R).

[0052] Result analysis:

[0053] The SrTiO3 / TiO2(A)-TiO2(R) powder obtained above was characterized by TEM. The results are as follows Figure 1 As shown, the material is a cluster structure composed of particles with a size of 30 nm.

[0054] The TiO2(A)-TiO2(R) powders obtained above were characterized by TEM. The results are as follows Figure 2 As shown, the material has a lamellar interface (in the yellow circle) connecting two particles.

[0055] Example 3

[0056] This embodiment provides a photocatalytic process for degrading phenol simulated wastewater.

[0057] 1L of glucose simulated wastewater with a COD concentration of 3000mg / L was prepared, 0.5g of the catalytic material obtained in Example 1 was added and ultrasonically mixed, then transferred to a photocatalytic device, 15ml of a 30% hydrogen peroxide solution was added, the ultraviolet light power was set to 40W, the total reaction time was 2h, and samples were taken every 30min during the process to test the COD concentration. The results are as follows: Figure 3 shown.

[0058] Comparative Example 1

[0059] This comparative example provides a photocatalytic process for degrading glucose simulated wastewater.

[0060] The photocatalytic process was carried out in accordance with Example 2, except that the catalytic material used was TiO2 (P25). Figure 3 As shown, it is shown that the material obtained in Example 1 has better COD degradation performance.

[0061] Comparative Example 2

[0062] This comparative example provides a photocatalytic process for degrading glucose simulated wastewater.

[0063] The photocatalytic process is similar to that of Example 2, except that the catalytic material used is the catalyst prepared in step S3 using P25 as the raw material, which is recorded as SrTiO3 / TiO2 (P25). Figure 3As shown, it is shown that the material obtained in Example 1 has better COD degradation performance.

[0064] Example 4

[0065] The present embodiment provides an application of a heterojunction photocatalytic material composed of a mixed-crystal dual-phase TiO2 and SrTiO3 with a contact interface, including applying the SrTiO3 / TiO2(A)-TiO2(R) photocatalyst to photocatalytic degradation of organic pollutant wastewater.

[0066] The photocatalytic material, oxidant and light source of Example 1 are added to wastewater containing organic pollutants, and an oxidation reaction is carried out by photocatalysis.

[0067] Wherein, the dosage of SrTiO3 / TiO2(A)-TiO2(R) is 0.1‰-0.5‰ of the mass of the wastewater solution;

[0068] Wherein, the oxidant is hydrogen peroxide or persulfate, and the dosage is 1‰-5‰ of the COD concentration of the wastewater;

[0069] Wherein, the light source is a visible light lamp or an ultraviolet light lamp.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface, wherein the chemical formula is SrTiO3 / TiO2(A)-TiO2(R).

2. The heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface as claimed in claim 1, characterized in that: Mixed-crystal dual-phase TiO2 consists of anatase TiO2 (A) nanoparticles and rutile TiO2 (R) nanoparticles, which are connected by broken flake TiO2 (A).

3. The heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface as claimed in claim 1 or 2, characterized in that: The molar ratio of TiO2(A) to TiO2(R) in the mixed crystal dual-phase TiO2 is 3-1.5:1, and the molar ratio of SrTiO3 to the mixed crystal dual-phase TiO2 is 1-0.8:

1.

4. A method for preparing a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 containing a contact interface as described in any one of claims 1 to 3, characterized in that: The following steps are involved: S1, preparation of amorphous TiO2 nanosheets, uniformly mixing a titanium precursor with anhydrous ethanol, adding cubic salt powder, then vigorously stirring and heating at 60-80°C until the solution is dry, calcining the dried powder in an air atmosphere, and washing the calcined product with deionized water after cooling to dissolve the cubic salt to obtain amorphous TiO2 nanosheets; S2, preparation of mixed crystal dual-phase TiO2 (TiO2(A)-TiO2(R)), adding the amorphous TiO2 nanosheets obtained in S1, TiO2(A) and TiO2(R) in a certain proportion into a weak alkaline aqueous solution, stirring for 1-2 hours, transferring to a hydrothermal reactor, hydrothermally treating at 150-170°C for 5-7 days, separating white powder after cooling, and obtaining TiO2(A)-TiO2(R); S3, preparation of SrTiO3 / TiO2(A)-TiO2(R), add the precursor of mixed crystal dual-phase TiO2 and Sr into a strong alkaline aqueous solution, stir for 0.5-1h, then add into a hydrothermal kettle, hydrothermally treat at 160-200℃ for 16-30h, separate the white powder and dry it to obtain SrTiO3 / TiO2(A)-TiO2(R).

5. The method for preparing a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface as claimed in claim 4, characterized in that: In said S1: The titanium precursor is tetraethyl titanate, tetraisopropyl titanate or tetrabutyl titanate; Cubic salts are inorganic salt compounds whose crystals of KCl, NaCl, and NaNO3 are cubic in structure; The mass ratio of titanium precursor, anhydrous ethanol and cubic crystal salt is 1:30:100-300; The calcination temperature is 400-500°C and the calcination time is 1-2h.

6. The method for preparing a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface as claimed in claim 4, characterized in that: In said S2: TiO2(A) and TiO2(R) are TiO2 with anatase and rutile structures, with a particle size of 0-60nm; The weak base aqueous solution is (C3H7)4NOH and / or NH4F dissolved in deionized water; The molar ratio of amorphous TiO2, TiO2(A), and TiO2(R) is 1:5:2-4; The molar ratio of the total amount of TiO2, deionized water, and (C3H7)4NOH or NH4F is 1:5:1-1.

2.

7. The method for preparing a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a large number of contact interfaces as claimed in claim 4, characterized in that: In the S3: The precursors of Sr are Sr(NO3)2, SrCl2 and their hydrates; The strong alkaline aqueous solution is NaOH or KOH dissolved in deionized water; The molar ratio of the total amount of TiO2, the precursor of Sr, deionized water, and NaOH or KOH is 1:0.5:600:1-2.

8. Application of a heterojunction photocatalytic material composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface, characterized in that: The SrTiO3 / TiO2(A)-TiO2(R) photocatalyst was applied to photocatalytic degradation of organic pollutants in wastewater.

9. The use of a heterojunction photocatalytic material composed of a mixed crystal dual-phase TiO2 and SrTiO3 containing a contact interface as claimed in claim 8, characterized in that: The photocatalytic material, oxidant and light source as described in any one of claims 1 to 3 are added to wastewater containing organic pollutants to perform an oxidation reaction using photocatalysis.

10. The use of a heterojunction photocatalyst composed of mixed crystal dual-phase TiO2 and SrTiO3 with a contact interface as claimed in claim 9, characterized in that: in, The dosage of SrTiO3 / TiO2(A)-TiO2(R) is 0.1‰-0.5‰ of the mass of the wastewater solution; Wherein, the oxidant is hydrogen peroxide or persulfate, and the dosage is 1‰-5‰ of the COD concentration of the wastewater; Wherein, the light source is a visible light lamp or an ultraviolet light lamp.

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