Preparation method and application of bismuth tantalate quantum dot-modified indium zinc sulfide microsphere S-type heterojunction photocatalyst

Abstract

The invention relates to an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots, wherein the S-type heterojunction of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots is composed of the (200) diffraction crystal plane of indium zinc sulfide and the (102) diffraction crystal plane of bismuth tantalate quantum dots. Preparation method: bismuth tantalate quantum dots are added during the solvent thermal growth process of indium zinc sulfide microspheres, and after secondary solvent thermal, the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots is obtained. Application of the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots in photocatalytic treatment of chromium-containing wastewater. Application of the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots in photocatalytic treatment of chromium-containing wastewater for hydrogen production. Beneficial effects are as follows: the bismuth tantalate / indium zinc sulfide S-type heterojunction photocatalyst has excellent photocatalytic performance, and due to the formation of the S-type heterojunction, it has stronger light absorption capacity and higher carrier separation efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalysis, and in particular to a preparation method and application of a bismuth tantalate quantum dot-modified indium zinc sulfide microsphere S-type heterojunction photocatalyst. Background Art

[0002] The rapid generation of heavy metal wastewater in the process of industrialization and urbanization has exceeded the self-purification capacity of natural water bodies; excessive discharge of chromium-containing wastewater has also caused damage to the water environment and the survival of various aquatic plants and animals, thus affecting human health and development. In nature, chromium is mainly Cr(VI) and Cr(III), and the toxicity of Cr(VI) is much greater than that of Cr(III).

[0003] At present, the main methods for treating chromium-containing wastewater are: electrolytic reduction, chemical precipitation, ion exchange, biofilm, photocatalysis, etc. There are precedents for photocatalytic treatment of chromium-containing wastewater. The main advantage is that Cr(VI) is directly reduced to Cr(III) by photogenerated electrons without the need for external energy. However, Ti or Pt-based catalysts are often used, which are costly and complex to prepare. They are difficult to promote on a large scale and are currently only in the laboratory stage.

[0004] As a secondary energy source, hydrogen energy has the advantages of high energy density and only produces water as a combustion product. It is considered to be one of the best candidates to replace traditional fossil energy. The water decomposition reaction to produce hydrogen and the Cr(VI) reduction reaction in wastewater share the same liquid phase carrier. If clean hydrogen energy can be obtained while treating chromium-containing wastewater, it will achieve the effect of killing two birds with one stone.

[0005] Therefore, in summary, we propose a bismuth tantalate quantum dot-modified indium zinc sulfide microsphere S-type heterojunction photocatalyst that can produce clean hydrogen while treating chromium-containing wastewater. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method and application of an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, so as to solve the problems of high cost of photocatalytic treatment of chromium-containing wastewater and low efficiency of single indium zinc sulfide microspheres and bismuth tantalate quantum dot catalysts in the above-mentioned background technology.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, wherein the S-type heterojunction of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is composed of the (200) diffraction crystal plane of indium zinc sulfide and the (102) diffraction crystal plane of bismuth tantalate quantum dots.

[0008] The beneficial effects of the present invention are as follows: the bismuth tantalate / indium zinc sulfide S-type heterojunction photocatalyst has excellent photocatalytic performance, and due to the formation of the S-type heterojunction, it has stronger light absorption capacity and higher carrier separation efficiency.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, in the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, the bismuth tantalate quantum dots are evenly attached to the surface of indium zinc sulfide microspheres, forming a closely contacted 0D / 3D heterojunction structure.

[0011] Based on the above technical scheme, the present invention also provides a method for preparing an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, wherein bismuth tantalate quantum dots are added during the solvothermal growth process of indium zinc sulfide microspheres, and after secondary solvothermal growth, an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is obtained.

[0012] The above further beneficial effect is that the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots can be prepared by a simple solvothermal method, and the synthesis process is simple, low-cost and high-efficiency.

[0013] Furthermore, the mass fraction of bismuth tantalate quantum dots in the sulfur indium zinc microsphere S-type heterojunction photocatalyst modified with bismuth tantalate quantum dots is 10% to 40%.

[0014] The above further beneficial effect is: by changing Cd 0.5 Zn 0.5 By adjusting the ratio of S and Nb2O5, photocatalysts with different mass ratios can be obtained.

[0015] Further, the specific preparation steps of sulfur indium zinc microspheres are as follows:

[0016] Zinc acetate dihydrate, indium chloride tetrahydrate, ultrapure water and ethanol are mixed, and thiourea is added to carry out hydrothermal reaction at a temperature of 120°C-200°C for 16h-24h to obtain a yellow precipitate, which is sulfur-indium zinc microspheres.

[0017] Furthermore, the temperature is 160°C and the time is 20h.

[0018] Further, the specific preparation steps of bismuth tantalate quantum dots are as follows:

[0019] B1. Mix bismuth nitrate pentahydrate, tantalum chloride, ethanol, acetic acid and benzyl alcohol to obtain a milky white solution;

[0020] B2. Potassium hydroxide is added dropwise to the milky white solution obtained in B1 to undergo a hydrothermal reaction to obtain a light yellow precipitate, which is bismuth tantalate quantum dots.

[0021] Furthermore, the specific preparation steps of the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots are as follows:

[0022] C1. Dispersing the indium zinc sulfide microspheres in ethanol and acetic acid, and adding bismuth nitrate pentahydrate, tantalum chloride and benzyl alcohol to obtain a light yellow suspension;

[0023] C2. Potassium hydroxide is added dropwise to the light yellow suspension obtained in C1 to undergo a hydrothermal reaction to obtain a light yellow precipitate, which is the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots.

[0024] Furthermore, the hydrothermal reaction temperature is 200°C-250°C, and the time is 16h-24h.

[0025] Furthermore, the hydrothermal reaction temperature was 230°C and the time was 20 h.

[0026] Based on the above technical solution, the present invention also provides an application of an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots in the photocatalytic treatment of chromium-containing wastewater.

[0027] The above further beneficial effects are: in situ X-ray photoelectron spectroscopy analysis proves that the photocatalyst is an S-type heterojunction photocatalyst; the photocatalytic performance test results show that, using light as energy, the photocatalyst can reduce Cr(VI) to less toxic Cr(III) with an efficiency of more than 95%, and the degradation rate is still more than 90% after five cycles, proving that the S-type heterojunction photocatalyst has excellent activity and stability under visible light irradiation, and is an efficient, green and safe environmental purification technology.

[0028] Based on the above technical solution, the present invention also provides an application of an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots in the photocatalytic treatment of chromium-containing wastewater to produce hydrogen.

[0029] The above method has the further beneficial effect of producing hydrogen while treating chromium-containing wastewater, with an average hydrogen production rate of about twice that of single ZnIn2S4. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 X-ray diffraction patterns of Bi3TaO7 QDs, ZnIn2S4 MFs and a series of Bi3TaO7@ZnIn2S4 samples;

[0031] Figure 2 Scanning electron microscope and transmission electron microscope images of 20% Bi3TaO7@ZnIn2S4;

[0032] Figure 3 In-situ X-ray photoelectron spectra of Bi3TaO7, ZnIn2S4 and 20% Bi3TaO7@ZnIn2S4 samples;

[0033] Figure 4The photocatalytic reduction effect diagram of Cr(VI) of Bi3TaO7, ZnIn2S4 and a series of Bi3TaO7@ZnIn2S4 samples;

[0034] Figure 5 This is a diagram of the photocatalytic hydrogen production effect of Bi3TaO7, ZnIn2S4 and a series of Bi3TaO7@ZnIn2S4 samples. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0036] Example 1

[0037] A bismuth tantalate quantum dot-modified indium zinc sulfide microsphere S-type heterojunction photocatalyst, wherein the bismuth tantalate quantum dot-modified indium zinc sulfide microsphere S-type heterojunction is composed of a (200) diffraction crystal plane of indium zinc sulfide and a (102) diffraction crystal plane of the bismuth tantalate quantum dot;

[0038] Among them, the bismuth tantalate quantum dots in the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots are evenly attached to the surface of indium zinc sulfide microspheres, forming a closely contacted 0D / 3D heterojunction structure.

[0039] The preparation method of the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots comprises the following specific steps:

[0040] Preparation of indium zinc sulfide microspheres:

[0041] A1, dissolve 0.175 g zinc acetate dihydrate and 0.469 g indium chloride tetrahydrate in a mixed solution of 30 mL ultrapure water and 30 mL ethanol, stir continuously for 30 minutes, add 0.49 g thiourea, and perform hydrothermal reaction at 160°C for 20 hours to obtain a yellow precipitate;

[0042] A2, washing and drying the yellow precipitate obtained in A1 in sequence to obtain sulfur indium zinc microspheres;

[0043] Preparation of bismuth tantalate quantum dots modified indium zinc sulfide microspheres S-type heterojunction photocatalyst:

[0044] C1, disperse 4.5 g of the sulfur indium zinc microspheres obtained in A2 into a mixed solution of 25 mL of ethanol and 5 mL of acetic acid, dissolve 1.374 g of bismuth nitrate pentahydrate and 0.358 g of tantalum chloride, dissolve 20 mL of benzyl alcohol in the mixed solution, and stir vigorously to obtain a light yellow suspension;

[0045] C2. Add 7 mol / L potassium hydroxide solution to the light yellow suspension obtained in C1 until the pH is 10.2, stir vigorously for 30 minutes, and hydrothermally react at 230°C for 20 hours to obtain a light yellow precipitate, which is the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, marked as 10% Bi3TaO7@ZnIn2S4.

[0046] in,

[0047] The method for preparing bismuth tantalate quantum dots is as follows:

[0048] B1, dissolve 1.374 g of bismuth nitrate pentahydrate and 0.358 g of tantalum chloride in a mixed solution of 25 mL of ethanol and 5 mL of acetic acid, dissolve 20 mL of benzyl alcohol in the mixed solution, and stir vigorously to obtain a milky white solution;

[0049] B2, add 7 mol / L potassium hydroxide solution dropwise to the milky white solution obtained in B1 until the pH is 10.2, stir vigorously for 30 minutes, and hydrothermally react at 230°C for 20 hours to obtain a light yellow precipitate;

[0050] B3, washing and drying the light yellow precipitate obtained in B2 in sequence to obtain bismuth tantalate quantum dots.

[0051] Example 2

[0052] The difference between this embodiment and embodiment 1 is that the mass of the sulfur indium zinc microspheres in C1 is replaced by 4g, 4.5g, and the others remain unchanged. The obtained target product is marked as 20% Bi3TaO7@ZnIn2S4.

[0053] Example 3

[0054] The difference between this embodiment and embodiment 1 is that the mass of the sulfur indium zinc microspheres in C1 is replaced by 3 g, while the others remain unchanged. The obtained target product is marked as 40% Bi3TaO7@ZnIn2S4.

[0055] The present invention can obtain composite photocatalysts with different mass ratios by changing the ratio of Bi3TaO7 QDs and ZnIn2S4 MFs. In-situ X-ray photoelectron spectroscopy analysis proves that the composite photocatalyst is an S-type heterojunction photocatalyst.

[0056] The photocatalytic performance test results show that the photocatalyst can effectively reduce Cr(VI) in wastewater with an efficiency of more than 95%, and the degradation rate is still more than 90% after five cycles, proving that the S-type heterojunction photocatalyst has excellent activity and stability under visible light irradiation;

[0057] While treating chromium-containing wastewater, hydrogen can be produced, and its average hydrogen production rate is about twice that of single ZnIn2S4. The catalyst is simple to prepare and has low cost.

[0058] from Figure 1 It can be seen that the crystal phase structure and composition of the synthesized Bi3TaO7 and ZnIn2S4 and Bi3TaO7@ZnIn2S4 photocatalysts with different ratios were characterized by X-ray diffraction analysis method;

[0059] In the XRD spectrum of the photocatalyst sample, with the increase of Bi3TaO7 QDs dosage, the characteristic peak intensity of Bi3TaO7 in the Bi3TaO7@ZnIn2S4 composite photocatalyst gradually increases. Among them, the characteristic peaks of Bi3TaO7 and ZnIn2S4 can be observed in the XRD diffraction spectrum of 40% Bi3TaO7@ZnIn2S4. The typical characteristic peaks correspond to the (200) diffraction crystal plane of zinc indium sulfide and the (102) diffraction crystal plane of bismuth tantalate quantum dots. It is preliminarily determined that the photocatalyst has good crystallinity and possesses the common properties of the two monomers.

[0060] from Figure 2 From the scanning electron microscope image in a), we can see that ZnIn2S4 exhibits a typical microspherical morphology, with a large number of nanoparticles of different dimensions attached to the surface, which are Bi3TaO7 quantum dots. Figure 2 The transmission electron microscopy image in b) clearly shows the heterojunction interface of the two monomers, the (200) diffraction crystal plane of indium zinc sulfide and the (102) diffraction crystal plane of bismuth tantalate quantum dots, confirming the formation of the heterojunction photocatalyst.

[0061] from Figure 3 It can be seen that the S 2p orbital binding energy of 20% Bi3TaO7@ZnIn2S4 shifts toward the high binding energy direction compared with ZnIn2S4, and shifts toward the low binding energy direction under UV irradiation; similarly, the Bi 4f orbital binding energy of 20% Bi3TaO7@ZnIn2S4 shifts toward the low binding energy direction compared with Bi3TaO7, and shifts toward the high binding energy direction under UV irradiation. Bi3TaO7 and ZnIn2S4 and 20% Bi3TaO7@ZnIn2S4 show opposite charge transfer paths under UV irradiation. This result indicates that the photogenerated electrons shift from Bi3TaO7 to ZnIn2S4 during hybridization, constructing an S-type electron transfer path that stabilizes the electron flow direction and generates a built-in electric field on the heterojunction interface. This built-in electric field helps Bi3TaO7@ZnIn2S4 and effectively separates the charge carriers.

[0062] Combination Figure 2 and Figure 3 It can be confirmed that the bismuth tantalate quantum dots modified indium zinc sulfide microsphere composite photocatalyst is an S-type heterojunction photocatalyst.

[0063] Figure 4 This is a photocatalytic reduction of Cr(VI) effect diagram of Bi3TaO7, ZnIn2S4 and their series Bi3TaO7@ZnIn2S4 samples under visible light irradiation. It can be seen from the figure that compared with monomers Bi3TaO7 and ZnIn2S4, the series Bi3TaO7@ZnIn2S4 catalysts all exhibit photocatalytic reduction of Cr(VI) activity better than the monomers. Among them, the 20% Bi3TaO7@ZnIn2S4 sample has the best photocatalytic reduction of Cr(VI) activity compared with the 10% Bi3TaO7@ZnIn2S4 and 40% Bi3TaO7@ZnIn2S4 samples. After 120 minutes of visible light irradiation, more than 95% of the ciprofloxacin molecules were effectively degraded.

[0064] Bi3TaO7@ZnIn2S4 photocatalyst can decompose water to produce hydrogen while photocatalytically reducing Cr(VI). Figure 5 As shown in the figure, the five lines from top to bottom represent ZB20, ZB40, ZB10, ZnIn2S4 and Bi3TaO7 respectively. The average hydrogen production rate of the 20% Bi3TaO7@ZnIn2S4 sample under visible light irradiation reaches 13.6 μmol g -1 h -1 .

[0065] The present invention uses photocatalytic technology: using light as energy, Cr(VI) can be reduced to low-toxic Cr(III), which is an efficient, green and safe technology for treating heavy metal-containing wastewater. A bismuth tantalate quantum dot-modified sulfur indium zinc microsphere S-type heterojunction fiber photocatalyst for treating chromium-containing wastewater and generating hydrogen energy is prepared by a simple secondary solvothermal method. It has a simple synthesis process and low cost. The bismuth tantalate quantum dot-modified sulfur indium zinc microsphere S-type heterojunction fiber photocatalyst has excellent photocatalytic performance due to the formation of the S-type heterojunction, which has stronger light absorption capacity and higher carrier separation efficiency.

[0066] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An application of an S-type heterojunction photocatalyst of bismuth tantalate quantum dots modified indium zinc sulfide microspheres, characterized in that: The S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is applied to the photocatalytic treatment of chromium-containing wastewater, and Cr(VI) is reduced to Cr(III) using light as energy. The S-type heterojunction of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is composed of the (200) diffraction crystal plane of indium zinc sulfide and the (102) diffraction crystal plane of bismuth tantalate quantum dots. The mass fraction of bismuth tantalate quantum dots in the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is 10% to 40%.

2. The use according to claim 1, characterized in that: In the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, bismuth tantalate quantum dots are evenly attached to the surface of indium zinc sulfide microspheres, forming a closely contacted 0D / 3D heterojunction structure.

3. The use according to claim 1, characterized in that: The specific preparation steps of sulfur indium zinc microspheres are as follows: Zinc acetate dihydrate, indium chloride tetrahydrate, ultrapure water and ethanol are mixed, and thiourea is added to carry out hydrothermal reaction at a temperature of 120°C-200°C for 16h-24h to obtain a yellow precipitate, which is sulfur-indium-zinc microspheres.

4. The use according to claim 3, characterized in that: The specific preparation steps of the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified by bismuth tantalate quantum dots are as follows: C1. Dispersing the indium zinc sulfide microspheres in ethanol and acetic acid, and adding bismuth nitrate pentahydrate, tantalum chloride and benzyl alcohol to obtain a light yellow suspension; C2. Potassium hydroxide is added dropwise to the light yellow suspension obtained in C1 to undergo a hydrothermal reaction to obtain a light yellow precipitate, which is the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots.

5. The use according to claim 4, characterized in that: The hydrothermal reaction temperature is 200°C-250°C, and the reaction time is 16h-24h.

6. An application of an S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots, characterized in that: The S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is applied to the photocatalytic treatment of chromium-containing wastewater to produce hydrogen, and Cr(VI) is reduced to Cr(III) using light as energy. The S-type heterojunction of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is composed of the (200) diffraction crystal plane of indium zinc sulfide and the (102) diffraction crystal plane of bismuth tantalate quantum dots. The mass fraction of bismuth tantalate quantum dots in the S-type heterojunction photocatalyst of indium zinc sulfide microspheres modified with bismuth tantalate quantum dots is 10% to 40%.

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