Bismuth oxychloride-based heterojunction photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a bismuth oxychloride-based heterojunction photocatalyst as well as a preparation method and application thereof, and belongs to the technical field of photocatalysis. According to the invention, bismuth oxychloride and sulfur indium zinc are compounded, so that antibiotic pollutants in a water body are removed, and at the same time, the antibiotic is used as a hole sacrificial agent to realize high-efficiency hydrogen production. The bismuth oxychloride-based heterojunction photocatalyst obtained by the invention is high in photon-generated carrier separation and transmission efficiency, good in photocatalytic activity and good in stability, can effectively remove antibiotic pollutants in a water body, and can also take the antibiotic pollutants as a hole sacrificial agent to realize efficient hydrogen production; the dual effects of environment-friendly decontamination and new energy obtaining are achieved, and the green and environment-friendly concept is met. The preparation method is simple to operate, low in cost and wide in application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalysis, and relates to a bismuth oxychloride-based heterojunction photocatalyst and a preparation method thereof, as well as an application of the catalyst in removing antibiotic pollutants in water while efficiently producing hydrogen. Background Art

[0002] In recent years, with the widespread use of antibiotics, antibiotic residues such as ofloxacin in water pose a serious threat to the ecological environment and human health. Traditional water treatment methods are difficult to effectively remove these antibiotics, and photocatalytic technology has attracted much attention as a green and efficient method. Bismuth oxychloride, as a potential photocatalytic material, provides a possibility for solving the above problems. When photocatalytically degrading antibiotics, bismuth oxychloride is usually required to be compounded with other materials to improve the photocatalytic degradation ability. CN110639563A discloses a ternary composite Z-type photocatalyst of bismuth oxychloride / silver / silver ferrite, which is based on bismuth oxychloride as a carrier, which is coated with silver ferrite, and silver ferrite is loaded with silver element, making full use of the performance of bismuth oxychloride, silver ferrite and silver element, and achieving a better antibiotic wastewater treatment effect. However, the photocatalyst needs to use precious metal silver, which is costly. CN115990494A discloses a bismuth-bismuth oxychloride-bismuth oxyiodide composite photocatalyst, which combines bismuth, bismuth oxychloride and bismuth oxyiodide at the same time. Compared with single bismuth oxychloride and single bismuth oxyiodide, it has a better effect in degrading antibiotics. However, the dangerous chemical sodium borohydride needs to be used to reduce bismuth during the preparation process.

[0003] Photocatalytic hydrogen production from water is a method of directly decomposing water to produce hydrogen using solar energy, which has attracted more and more attention. Common photocatalysts for photocatalytic hydrogen production from water include tantalates, niobates, titanates and polysulfides. CN115282986B discloses a two-dimensional sulfur-indium zinc photocatalyst with doping-vacancy dual sites, its preparation method and application, which uses a hydrothermal method to prepare a ZnIn2O3 photocatalyst. 2 S 4 The noble metal single atom is doped into ZIS, and the introduction of the noble metal single atom will generate S vacancies in ZIS, forming a doping-vacancy dual-site structure. 2 S 4 When producing hydrogen by photolysis of water, triethanolamine (TEOA) needs to be added as a hole scavenger. By consuming photogenerated holes, it can significantly inhibit charge recombination and extend the electron lifetime, thereby improving the efficiency of hydrogen generation.

[0004] There is currently no report on the use of bismuth oxychloride in combination with indium zinc sulfide to efficiently produce hydrogen while removing antibiotic pollutants from water using antibiotics as sacrificial agents. Summary of the invention

[0005] The purpose of the present invention is to provide a bismuth oxychloride-based heterojunction photocatalyst and its preparation method and application, by compounding bismuth oxychloride with indium zinc sulfide, using antibiotics as hole sacrificial agents, and efficiently producing hydrogen while removing antibiotic pollutants in water. The bismuth oxychloride-based heterojunction photocatalyst obtained by the present invention has high separation and transmission efficiency of photogenerated carriers, good photocatalytic activity and good stability. The purpose of the present invention is achieved by the following specific technical solutions.

[0006] A bismuth oxychloride-based heterojunction photocatalyst, wherein the photocatalyst is composited by indium zinc sulfide and bismuth oxychloride to form a Z-type heterojunction structure.

[0007] The method for preparing the above-mentioned bismuth oxychloride-based heterojunction photocatalyst comprises the following steps: S1. Dissolve the zinc source, indium source and sulfur source in a solvent to form a mixed solution. S2, adding bismuth oxychloride powder to the mixed solution of step S1, fully dispersing to form a mixture; S3, heating and stirring the mixture of step S2 to fully react, separating the solid and the liquid after the reaction, washing the solid with an organic solvent and then drying to obtain a bismuth oxychloride-based heterojunction photocatalyst product.

[0008] Furthermore, in step S1, the zinc source is selected from one or more of zinc chloride, zinc sulfate, zinc nitrate, zinc gluconate and zinc acetate, preferably zinc chloride; the indium source is selected from one or more of indium trichloride, indium nitrate and indium sulfate, preferably indium trichloride; the sulfur source is thioacetamide (TAA), sodium sulfide or thiourea, preferably thioacetamide; the solvent is ethylene glycol, ethanol, glycerol or water, preferably ethylene glycol.

[0009] Furthermore, in step S1, the molar ratio of zinc, indium and sulfur elements in the zinc source, indium source and sulfur source is 1: (1.8-2.2): (3.6-4.4), and the zinc ion concentration in the mixed solution is 0.001-0.015 mol / L.

[0010] Furthermore, the method for sufficient dispersion in step S2 is ultrasonic dispersion.

[0011] Furthermore, in step S2, the reaction temperature is 70-90° C., and the reaction time is 1-3 hours.

[0012] Furthermore, the solid-liquid separation method in step S3 is centrifugal separation, and the organic solvent is one or two selected from ethanol and methanol.

[0013] The above-mentioned bismuth oxychloride-based heterojunction photocatalyst is used to remove antibiotic pollutants in water bodies, and photolyzes water to produce hydrogen while removing antibiotic pollutants in water bodies.

[0014] Further, the antibiotic is one or more of ofloxacin, levofloxacin and ciprofloxacin. When photocatalytic water splitting for hydrogen production, the antibiotic is used as a hole sacrificial agent, and no other hole sacrificial agent needs to be added.

[0015] The present invention has the following beneficial technical effects: A novel bismuth oxychloride-based heterojunction photocatalyst is obtained in the present invention, which forms a Z-type heterojunction, has high separation and transport efficiency of photo-generated carriers, good photocatalytic activity, and good stability. The novel bismuth oxychloride-based heterojunction photocatalyst obtained in the present invention can effectively remove antibiotic pollutants in water, and at the same time, the antibiotic pollutants can be used as hole sacrificial agents to achieve efficient hydrogen production, realizing the dual effects of environmental protection decontamination and obtaining new energy, which conforms to the concept of green environmental protection. The preparation method of the present invention is simple in operation, low in cost, and has broad application prospects. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the action mechanism of the bismuth oxychloride-based heterojunction photocatalyst of the present invention.

[0017] Figure 2 is the XRD pattern of the samples of Examples 1-4.

[0018] Figure 3 is the SEM image of the sample of Example 1.

[0019] Figure 4 is the effect diagram of ofloxacin removal and hydrogen production of the sample of Example 1.

[0020] Figure 5 is the hydrogen production effect diagram of the samples of Examples 1-4. Detailed Embodiments

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Example 1

[0022] Prepare a bismuth oxychloride-based heterojunction photocatalyst, including the following steps: S1: Add 0.040 g of ZnCl 2 , 0.088 g of InCl 3 and 0.060 g of TAA to 34 mL of ethylene glycol to obtain a mixed solution.

[0023] S2: Add 0.3 g of BiOCl powder to the above mixed solution and ultrasonically disperse for 30 minutes to obtain a mixture.

[0024] S3: Place the above mixture in a water bath at 80 °C and stir for 2 hours; centrifuge 6 times with ethanol and dry at 40 °C for 12 h to obtain bismuth oxychloride-based heterojunction photocatalyst powder, and the sample is denoted as ZIN / BiOCl-34. Example 2

[0025] Change the addition amount of ethylene glycol in step S1 of Example 1 to 68 mL, keep other conditions the same, and the sample is denoted as ZIN / BiOCl-34. Example 3

[0026] Change the addition amount of ethylene glycol in step S1 of Example 1 to 85 mL, keep other conditions the same, and the sample is denoted as ZIN / BiOCl-85. Example 4

[0027] Change the addition amount of ethylene glycol in step S1 of Example 1 to 170 mL, keep other conditions the same, and the sample is denoted as ZIN / BiOCl-170. Example 5

[0028] Prepare bismuth oxychloride-based heterojunction photocatalyst, including the following steps: S1: Add appropriate amounts of zinc acetate dihydrate, indium nitrate hexahydrate and sodium sulfide to deionized water, and then add ethylene glycol to obtain a mixed solution.

[0029] S2: Add appropriate amount of BiOCl powder to the above mixed solution and ultrasonically disperse for 30 minutes to obtain a mixture.

[0030] S3: Place the above mixture in a water bath at 80 °C and stir for 2 hours; centrifuge 6 times with ethanol and dry at 40 °C for 12 h to obtain bismuth oxychloride-based heterojunction photocatalyst powder, and the sample is denoted as ZIN / BiOCl. Example 6

[0031] Prepare bismuth oxychloride-based heterojunction photocatalyst, including the following steps: S1: Use deionized water and ethanol as solvents, add appropriate amounts of Zn(CH 3 COO) 2 ·2H 2 O, InCl 3 and TAA, and then add ethylene glycol to obtain a mixed solution.

[0032] S2: Add appropriate amount of BiOCl powder to the above mixed solution and ultrasonically disperse for 30 minutes to obtain a mixture.

[0033] S3: Place the above mixture in a water bath at 80 °C and stir for 2 hours; centrifuge 6 times with ethanol and dry at 40 °C for 12 h to obtain bismuth oxychloride-based heterojunction photocatalyst powder, and the sample is denoted as ZIN / BiOCl. Example 7

[0034] To prepare a bismuth oxychloride-based heterojunction photocatalyst, the following steps are included: S1: Disperse an appropriate amount of Zn(NO 3 ) 2 ·6H 2 O, In(NO) 3 ·5H 2 O and thiourea in deionized water, and then add ethylene glycol to obtain a mixed solution.

[0035] S2: Add an appropriate amount of BiOCl powder to the above mixed solution and ultrasonically disperse for 30 minutes to obtain a mixture.

[0036] S3: Place the above mixture in a water bath at 80 °C and stir for 2 hours; centrifuge 6 times with ethanol and dry at 40 °C for 12 h to obtain a bismuth oxychloride-based heterojunction photocatalyst powder, and the sample is denoted as ZIN / BiOCl. Example 8

[0037] To prepare a bismuth oxychloride-based heterojunction photocatalyst, the following steps are included: S1: Use deionized water and ethanol as solvents, add an appropriate amount of zinc nitrate hexahydrate, indium chloride and TAA, and then add ethylene glycol to obtain a mixed solution.

[0038] S2: Add an appropriate amount of BiOCl powder to the above mixed solution and ultrasonically disperse for 30 minutes to obtain a mixture.

[0039] S3: Place the above mixture in a water bath at 80 °C and stir for 2 hours; centrifuge 6 times with ethanol and dry at 40 °C for 12 h to obtain a bismuth oxychloride-based heterojunction photocatalyst powder, and the sample is denoted as ZIN / BiOCl. Example 9

[0040] To prepare a bismuth oxychloride-based heterojunction photocatalyst, the following steps are included: S1: Dissolve Zn(NO 3 ) 2 ·6H 2 O and In(NO) 3 ·5H 2 O and TAA in deionized water, and then add ethylene glycol to obtain a mixed solution.

[0041] S2: Add an appropriate amount of BiOCl powder to the above mixed solution and ultrasonically disperse for 30 minutes to obtain a mixture.

[0042] S3: Place the above mixture in a water bath at 80 °C and stir for 2 hours; centrifuge 6 times with ethanol and dry at 40 °C for 12 h to obtain the bismuth oxychloride-based heterojunction photocatalyst powder, and the sample is denoted as ZIN / BiOCl. Example 10

[0043] Perform XRD characterization on the samples obtained in Examples 1-4, and the results are as Figure 2 shown. The figure shows that the characteristic peaks of ZnIn 2 S 4 coexist with those of BiOCl, confirming the formation of the heterojunction. Perform SEM characterization on the sample obtained in Example 1, and the results are as Figure 3 shown. The sample has a nano-sheet structure and a large specific surface area, which is beneficial to the photocatalytic reaction. Example 11

[0044] Perform the experiment of photocatalytic hydrogen production while removing ofloxacin on the sample obtained in Example 1.

[0045] Add the photocatalyst prepared in Example 1 to an aqueous solution containing ascorbic acid, isopropanol, L-histidine, sodium oxalate and ofloxacin (simulating sewage water body). The volume of the aqueous solution is 30 mL, the concentrations of ascorbic acid, isopropanol, L-histidine and sodium oxalate are 5 mM, the concentration of ofloxacin is 50 mg / L, and the addition amount of the photocatalyst is 200 mg. Turn on the stirrer and perform a dark reaction for 0.5 h; irradiate with a xenon lamp in the full wavelength range. Take liquid samples at regular intervals, determine the ofloxacin concentration by measuring the absorbance, and determine the hydrogen production rate by a gas chromatograph. The results are as Figure 4 shown. It can be seen that the sample obtained in Example 1 can efficiently produce hydrogen while removing ofloxacin pollutants. Example 12

[0046] Perform the photocatalytic hydrogen production experiment on the samples obtained in Examples 1-4.

[0047] Replace ofloxacin in Example 11 with triethanolamine, and perform the photocatalytic hydrogen production experiment on the samples obtained in Examples 1-4 respectively under the same other conditions. Compare the hydrogen production rate results with those in Example 11, and the results are as Figure 5 shown. It can be seen that ofloxacin as a hole sacrificial agent has a better hydrogen production effect than triethanolamine, and no other hole sacrificial agent needs to be added when photocatalytic hydrogen production while removing antibiotic pollutants; the hydrogen production effect of the sample in Example 1 is better than that of other examples.

[0048] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. The protection scope of the present invention is defined by the claims and their equivalent technical solutions.

Claims

1. A bismuth oxychloride-based heterojunction photocatalyst, characterized in that: The photocatalyst is composed of indium zinc sulfide and bismuth oxychloride to form a Z-type heterojunction structure.

2. The method for preparing a bismuth oxychloride-based heterojunction photocatalyst according to claim 1, characterized in that: The following steps are involved: S1. Dissolve the zinc source, indium source and sulfur source in a solvent to form a mixed solution. S2, adding bismuth oxychloride powder to the mixed solution of step S1, fully dispersing to form a mixture; S3, heating and stirring the mixture of step S2 to fully react, separating the solid and the liquid after the reaction, washing the solid with an organic solvent and then drying to obtain a bismuth oxychloride-based heterojunction photocatalyst product.

3. The preparation method according to claim 2, characterized in that: In step S1, the zinc source is selected from one or more of zinc chloride, zinc sulfate, zinc nitrate, zinc gluconate and zinc acetate, the indium source is selected from one or more of indium trichloride, indium nitrate and indium sulfate, the sulfur source is thioacetamide, sodium sulfide or thiourea, and the solvent is ethylene glycol, ethanol, glycerol or water.

4. The preparation method according to claim 3, characterized in that: In step S1, the zinc source is zinc chloride, the indium source is indium trichloride, the sulfur source is thioacetamide, and the solvent is ethylene glycol.

5. The preparation method according to claim 2, characterized in that: In step S1, the molar ratio of zinc, indium and sulfur elements in the zinc source, indium source and sulfur source is 1: (1.8-2.2): (3.6-4.4), and the zinc ion concentration in the mixed solution is 0.001-0.015 mol / L.

6. The preparation method according to claim 2, characterized in that: The method for sufficient dispersion in step S2 is ultrasonic dispersion.

7. The preparation method according to claim 2, characterized in that: In step S2, the reaction temperature is 70-90° C., and the reaction time is 1-3 hours.

8. The preparation method according to claim 2, characterized in that: The solid-liquid separation method in step S3 is centrifugal separation, and the organic solvent is one or two selected from ethanol and methanol.

9. The use of the bismuth oxychloride-based heterojunction photocatalyst in removing antibiotic pollutants in water according to claim 1, characterized in that: Photolysis of water to produce hydrogen while removing antibiotic pollutants from water bodies.

10. The use according to claim 9, characterized in that: The antibiotic is one or more of ofloxacin, levofloxacin and ciprofloxacin, and the antibiotic is used as a hole sacrificial agent when photolysis of water is used to produce hydrogen.

Images