Bi2O2CO3 / CuBi2O4 composite photocatalyst and preparation method thereof

Abstract

The invention discloses a Bi2O2CO3 / CuBi2O4 composite photocatalyst and a preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst. According to the method, in-situ growth of a Bi2O2CO3 nanosheet on a CuBi2O4 nanorod is realized through regulation and control of a solvent, and the Bi2O2CO3 / CuBi2O4 composite photocatalyst is obtained. According to the invention, the organic solvent is adopted as a carbon source, so that conversion from CuBi2O4 to Bi2O2CO3 can be realized, construction of a two-dimensional nanosheet composite one-dimensional nanorod can also be realized, charge transfer is enhanced, and the specific surface area of the catalyst is increased. The Bi2O2CO3 / CuBi2O4 composite photocatalyst disclosed by the invention is used for photocatalytic degradation of 20 mg / L of tetracycline hydrochloride (TC) and shows excellent catalytic performance, and the removal rate of the TC within 60 minutes reaches 85% or above.

Description

Technical Field

[0001] The present invention relates to a Bi2O2CO3 / CuBi2O4 composite photocatalyst and a preparation method thereof, belonging to the technical field of nanomaterial preparation. Background Art

[0002] With the development of the industrial and pharmaceutical industries, a large amount of heavy metal- and antibiotic-containing wastewater enters the environment, posing a major threat to human health. Traditional pollution removal methods, including adsorption, flocculation, filtration, and biological treatment, all have the disadvantages of incomplete pollutant removal and high material consumption. Photocatalytic technology using sunlight as energy and semiconductor catalysts as carriers is currently widely used in the fields of organic pollutant mineralization and heavy metal ion removal.

[0003] Bismuth-based semiconductors represented by Bi2S3, Bi2O3, BiVO4, Bi2WO6, and BiOX (X = Cl, Br, I) have shown excellent performance in the field of photocatalysis due to their unique layer structure and electronic configuration, and have become an important class of photocatalytic materials. As a typical "Sillén" phase semiconductor, the crystal structure of Bi2O2CO3 consists of alternating (Bi2O2) 2+ and CO3 2- layers. The inherent layered structure promotes the generation of an internal electric field, which is beneficial to the separation of photo-generated carriers. However, the wide bandgap (~3.3 eV) of Bi2O2CO3 makes it only respond to ultraviolet light, thus hindering the utilization of solar energy. To address the scientific problem of weak light response, it has been found that element doping of semiconductors can enhance the light absorption characteristics of semiconductors. Wu C. et al. constructed Br-doped Bi2O2CO3 and then in-situ reduced and deposited Bi nanoparticles on the surface of Bi2O2CO3 for the photocatalytic degradation of tetracycline. Among them, Br doping adjusted the energy level structure of Bi2O2CO3, making its bandgap narrower and having an obvious absorption enhancement in the visible light region. According to the crystal structure of Bi2O2CO3 and DFT calculations, it was shown that I - could partially replace CO3 2- in Bi2O2CO3, thereby narrowing its bandgap. Based on this, Zai J. et al. prepared I-doped rose-like Bi2O2CO3 microspheres by hydrothermal method. Photoelectrochemical tests and DFT calculations showed that I - formed an intermediate energy level in the forbidden band of Bi2O2CO3. Catalytic experiments showed that the I-doped Bi2O2CO3 microspheres could completely degrade rhodamine B within 6 min under visible light (λ>400 nm) irradiation, and about 90% of hexavalent chromium could be reduced after 25 min.

[0004] In recent years, by coupling with other semiconductors, especially narrow-bandgap semiconductors, to construct heterojunctions, the light absorption characteristics can be enhanced, providing a larger specific surface area and more active sites, and improving the photocatalytic activity of Bi2O2CO3. Zhang R. et al. considered the high specific surface area and porous structure of metal-organic frameworks (MOFs), and introduced the porous n-type semiconductor MIL-125(Ti) into Bi2O2CO3 by a solvothermal method, self-assembling a hierarchical tandem heterophotocatalytic composite material with a nanoflower-like structure to solve the problem of antibiotic pollution. The tight binding of MIL-125(Ti) nanoparticles and Bi2O2CO3 nanosheets promoted the charge transfer and separation under light irradiation. In the photocatalytic degradation experiment, the concentration of tetracycline was 20 mg / L, and the composite photocatalyst could achieve 92.2% degradation of tetracycline within 60 min. Among narrow-bandgap semiconductors, CuBi2O4 is considered a very promising candidate material due to its strong response to visible light and matched energy band structure. So far, many studies have reported that CuBi2O4 composite materials exhibit good photocatalytic activity under visible light by constructing heterojunctions. Zhang L. et al. prepared a novel 0D / 1D CuBi2O4@WO3 nanofiber-membrane photocatalyst by an electrospinning method. During the high-voltage electrospinning process, the CuBi2O4 microspheres disintegrated, and CuBi2O4 nanoparticles were simultaneously formed on the WO3 nanofibers, thus constructing a well-dispersed CuBi2O4@WO3 nanoheterojunction. The CuBi2O4@WO3 composite photocatalyst exhibited excellent photocatalytic activity in the photocatalytic degradation of antibiotics in environmental remediation, and its photocatalytic activity for degrading tetracycline was 8.1 times and 3.6 times that of WO3 nanofibers and pure CuBi2O4 microspheres, respectively.

[0005] The above modification methods are all based on Bi2O2CO3 and other bismuth-based carriers for modification, and only doping and compounding are carried out, which cannot effectively regulate the morphology and achieve in-situ compounding. Summary of the Invention

[0006] The purpose of the present invention is to provide an in-situ Bi2O2CO3 / CuBi2O4 composite photocatalyst with excellent catalytic performance and its preparation method, which solves the above technical problems existing in the prior art.

[0007] The technical solution to achieve the purpose of the present invention is as follows:

[0008] A preparation method of a Bi2O2CO3 / CuBi2O4 composite photocatalyst, comprising the following steps:

[0009] Step 1: Stir and disperse bismuth nitrate and copper nitrate in 0.25 mol / L sodium hydroxide solution, conduct hydrothermal reaction at 160 - 180 °C, control the pH to be 6 - 7.5 until the reaction ends, cool naturally, and then obtain one-dimensional CuBi2O4 nanorods after centrifugation, washing, and drying.

[0010] Step 2: Disperse the one-dimensional CuBi2O4 nanorods in water, add acetone / ethanol, stir and mix evenly, then conduct solvothermal reaction at 160 - 180 °C, control the pH to be 6 - 7.5 until the reaction ends, cool naturally, and then obtain a three-dimensional Bi2O2CO3 / CuBi2O4 composite photocatalyst after centrifugation, washing, and drying.

[0011] Further, in Step 1, the mass concentration of bismuth nitrate is 25 mg / mL, and the mass concentration of copper nitrate is 10 mg / mL.

[0012] Further, in Step 1, the magnetic stirring time of bismuth nitrate and copper nitrate in sodium hydroxide solution is more than 3 h, and the hydrothermal reaction time is more than 24 h.

[0013] Further, in Step 1, the centrifugation rate is 9000 r / min, and the drying temperature is 60 - 80 °C.

[0014] Further, in Step 2, the ratio of CuBi2O4 to the organic solvent is 100 mg:1 mL.

[0015] Further, in Step 2, the volume concentration of acetone or ethanol is 0.038 mL / mL.

[0016] Further, in Step 2, the mixing time of CuBi2O4 with ethanol or acetone solution is more than 0.5 h.

[0017] Further, in Step 2, the solvothermal reaction time is more than 24 h, the centrifugation rate is 9000 r / min, and the drying temperature is 60 - 80 °C.

[0018] Further, it is applied in photocatalytic degradation of organic dyes and removal of heavy metal ions.

[0019] Further, the Bi2O2CO3 / CuBi2O4 composite photocatalyst is composed of multiple groups of one-dimensional CuBi2O4 nanorods, which are bonded by Bi2O2CO3 particles and form a three-dimensional spatial structure.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] (1) For the wide-bandgap Bi2O2CO3 coupled with the narrow-bandgap CuBi2O4 semiconductor, a composite heterojunction catalyst is constructed to enhance the specific surface area and carrier separation. This three-dimensional Bi2O2CO3 / CuBi2O4 composite material has a three-dimensional network structure. It is a composite material with the properties of both materials, having high mechanical strength and stability, being able to withstand high temperatures and pressures, and being suitable for catalysts used in high-temperature environments.

[0022] (2) The acetone / ethanol provided in the preparation method can be used both as a solvent and as a reactant. Compared with traditional polyvinylpyrrolidone, it cannot form a solution and pure water needs to be used as a solvent for dissolution, reducing the amount of reactants used. Moreover, in terms of cost, the preparation cost of acetone / ethanol is less than 1 / 20 of the cost of polyvinylpyrrolidone, that is, the industrial production process has stronger economic benefits.

[0023] (3) Directly using a simple organic solvent as the carbon source and CuBi2O4 as the Bi source to directly synthesize the composite catalyst in-situ, enhancing the interfacial contact.

[0024] (4) The Bi2O2CO3 / CuBi2O4 composite photocatalyst is used for photocatalytic degradation of 20 mg / L tetracycline hydrochloride; it shows excellent catalytic performance, and the degradation rate reaches more than 85% in 60 min. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0026] Figure 1 It is the synthesis route diagram of the preparation method of the present invention.

[0027] Figure 2 It is the XRD diffraction pattern of the materials prepared in Example 1, Example 2, Example 3 and Comparative Example 1.

[0028] Figure 3 Scanning electron micrographs of the CuBi2O4 nanorods, Bi2O2CO3 nanosheets and Bi2O2CO3 / CuBi2O4 composite photocatalyst prepared in Example 1, Example 2, Example 3 and Comparative Example 1.

[0029] Figure 4 It is the line graph of the photocatalytic degradation performance of tetracycline of the CuBi2O4 nanorods, Bi2O2CO3 nanosheets and Bi2O2CO3 / CuBi2O4 composite photocatalyst prepared in Example 1, Example 2, Example 3 and Comparative Example 1.

[0030] Figure 5It is the UV spectrum of the photocatalytic degradation liquid of the Bi2O2CO3 / CuBi2O4 composite material (acetone) prepared in Example 2.

[0031] Figure 6 It is the UV spectrum of the photocatalytic degradation liquid of the Bi2O2CO3 / CuBi2O4 composite material (ethanol) prepared in Example 3. Specific embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. 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.

[0033] Figure 1 It is the synthesis mechanism diagram of the preparation method of the present invention. Weigh a certain amount of bismuth nitrate and copper nitrate, disperse them in a sodium oxide solution and stir and mix. Then transfer them to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. After centrifugation, washing and drying, CuBi2O4 nanorod materials are obtained. Subsequently, the CuBi2O4 nanorods are dispersed in deionized water, ethanol or acetone is added, and stirred at room temperature. Then transfer them to a polytetrafluoroethylene reaction kettle for solvothermal reaction. After centrifugation, washing and drying, a three-dimensional Bi2O2CO3 / CuBi2O4 composite photocatalyst is obtained.

[0034] Example 1

[0035] In step A1, 5 mmol of Bi(NO3)3·5H2O and 3.2 mmol of Cu(NO3)2·3H2O are put into 21.75 mmol of a sodium hydroxide solution with a concentration of 0.25 mol / L and stirred on a magnetic stirrer for 3 h.

[0036] A2, the obtained solution is transferred to a 100 mL polytetrafluoroethylene reaction kettle, and hydrothermal reaction is carried out at 160-180 °C for 24 h. Control the pH to 6-7.5 until the reaction ends, take it out and cool naturally to obtain sample 1.

[0037] A3, the obtained sample 1 is centrifuged, washed and dried at 60 °C to prepare one-dimensional CuBi2O4 nanorods.

[0038] Example 2

[0039] In step B1, 200 mg of the one-dimensional CuBi2O4 nanorods obtained in step one of Example 1 are dispersed in 50 mL of deionized water and ultrasonically dispersed for 30 min to obtain solution 1.

[0040] B2, 2 mL of acetone is quantitatively added to the obtained solution 1 and stirred for 0.5 h to obtain solution 2.

[0041] B3, the resulting solution 2 was transferred to a 100 mL polytetrafluoroethylene reaction kettle. After stirring and mixing evenly, a solvothermal reaction was carried out at 160 - 180 °C for 24 h under hydrothermal conditions. The reaction was terminated under the condition of controlling the pH value to be 6 - 7.5. After taking it out and naturally cooling, sample 2 was obtained;

[0042] B4, the obtained sample 2 was centrifuged and washed, and then dried in an oven at 60 °C for 12 h to prepare a three-dimensional Bi2O2CO3 / CuBi2O4 composite material.

[0043] Example 3

[0044] In step 1, one-dimensional CuBi2O4 nanorods were obtained using the same part as in Example 1.

[0045] In step 2, B1, 200 mg of the one-dimensional CuBi2O4 nanorods obtained in step 1 were dispersed in 50 mL of deionized water and ultrasonically dispersed for 30 min to obtain solution 1;

[0046] B2, 2 mL of ethanol was quantitatively added to the resulting solution 1 and stirred for 0.5 h to obtain solution 2;

[0047] B3, the resulting solution 2 was transferred to a 100 mL polytetrafluoroethylene reaction kettle and hydrothermally treated for 24 h. The reaction was terminated under the condition of controlling the pH value to be 6 - 7.5. After taking it out and naturally cooling, a sample was obtained;

[0048] B4, the obtained sample was centrifuged and washed, and then dried in an oven at 60 °C for 12 h to prepare a three-dimensional Bi2O2CO3 / CuBi2O4 composite material.

[0049] Measurement of the photocatalytic performance of the three-dimensional Bi2O2CO3 / CuBi2O4 composite photocatalyst:

[0050] 20 mg of the Bi2O2CO3 / CuBi2O4 composite material was dispersed in 50 mL of a 20 mg / L tetracycline hydrochloride solution and stirred in the dark for 1 h to obtain a suspension;

[0051] The resulting suspension was irradiated under a 300 W xenon lamp (λ > 420 nm), and 3 mL of the liquid was taken every 10 minutes;

[0052] The resulting liquid sample was centrifuged at 9000 r / min for 1 min to remove the catalyst, and liquid 1 was obtained;

[0053] The centrifuged liquid 1 was detected by an ultraviolet-visible spectrophotometer to evaluate the photocatalytic performance.

[0054] Comparative Example 1

[0055] First step: Disperse 200 mg of CuBi2O4 nanorods in 50 mL of deionized water and ultrasonically disperse for 30 min;

[0056] Second step: Quantitatively add 10 mL of acetone to the solution obtained in the first step and stir for 0.5 h;

[0057] Third step: Transfer the solution obtained in the second step to a 100 mL polytetrafluoroethylene reaction kettle, hydrothermal react for 24 h, and take it out to cool naturally;

[0058] Fourth step: Centrifuge and wash the sample obtained in the third step, dry it in an oven at 60 °C for 12 h to obtain the Bi2O2CO3 material.

[0059] Comparative example 2

[0060] First step: Disperse 20 mg of CuBi2O4 material in 50 mL of 20 mg / L tetracycline hydrochloride solution and stir in the dark for 1 h;

[0061] Second step: Place the suspension obtained in the first step under illumination of a 300 W xenon lamp (λ>420 nm), and take 3 mL of liquid every 10 minutes;

[0062] Third step: Centrifuge the liquid sample obtained in the second step at 9000 r / min for 1 min to remove the catalyst;

[0063] Fourth step: Detect the centrifuged liquid obtained in the third step with a UV-visible spectrophotometer to evaluate the photocatalytic performance.

[0064] Comparative example 3

[0065] First step: Disperse 20 mg of Bi2O2CO3 material in 50 mL of 20 mg / L tetracycline hydrochloride solution and stir in the dark for 1 h;

[0066] Second step: Place the suspension obtained in the first step under illumination of a 300 W xenon lamp (λ>420 nm), and take 3 mL of liquid every 10 minutes;

[0067] Third step: Centrifuge the liquid sample obtained in the second step at 9000 r / min for 1 min to remove the catalyst;

[0068] Fourth step: Detect the centrifuged liquid obtained in the third step with a UV-visible spectrophotometer to evaluate the photocatalytic performance.

[0069] Figure 2XRD diffraction patterns of the materials prepared in Example 1, Example 2, Example 3 and Comparative Example 1. In the figure, the characteristic diffraction peaks of CuBi2O4 and Bi2O2CO3 correspond to Example 1 and Comparative Example 1 respectively. Among them, the diffraction peaks of the XRD pattern of Example 1 at 20.8°, 27.9°, 33.2° and 46.6° present the (200), (211), (310) and (411) crystal planes of CuBi2O4 respectively; the diffraction peaks of the XRD pattern of Comparative Example 1 at 12.9°, 23.9°, 26.0°, 30.3°, 32.7° and 42.3° present the (002), (011), (004), (013), (110) and (114) crystal planes of Bi2O2CO3 respectively. Further analyzing the XRD patterns of Example 2 and Example 3, the characteristic diffraction peaks of CuBi2O4 and Bi2O2CO3 both appear, indicating the in-situ synthesis of Bi2O2CO3 / CuBi2O4 composite materials by organic solvents.

[0070] Figure 3 Scanning electron microscope images of the materials prepared in Example 1, Example 2, Example 3 and Comparative Example 1. (a) is the prepared CuBi2O4 nanorod material, (b) is the prepared Bi2O2CO3 nanosheet material, (c) is the Bi2O2CO3 / CuBi2O4 composite material induced by acetone solution, and (d) is the Bi2O2CO3 / CuBi2O4 composite material induced by ethanol solution. By comparing Figure (a) and Figure (b), it can be found that increasing the amount of organic solvent used can completely convert CuBi2O4 into Bi2O2CO3. It can be observed from Figures (c) and (d) that an appropriate amount of organic solvent input can synthesize a photocatalytic material composed of Bi2O2CO3 nanosheets and CuBi2O4 nanorods.

[0071] Figure 4 Line charts showing the photocatalytic degradation of tetracycline over time for the materials prepared in Example 1, Example 2, Example 3 and Comparative Example 1. It can be seen from the figure that the degradation rate of 20 mg / L hydrochloric acid tetracycline in 50 mL degraded by 20 mg of the Bi2O2CO3 / CuBi2O4 composite material (acetone) prepared in Example 2 reached more than 94.6% within 60 min; the degradation rate of 20 mg / L hydrochloric acid tetracycline in 50 mL degraded by 20 mg of the Bi2O2CO3 / CuBi2O4 composite material (ethanol) prepared in Example 3 reached more than 86.8% within 60 min; both had higher photocatalytic activities than the materials prepared in Example 1 and Comparative Example 1.

[0072] Figure 5It is the photocatalytic degradation liquid ultraviolet spectrum of the Bi2O2CO3 / CuBi2O4 composite material (acetone) prepared in Example 2. As can be seen from the figure, as the illumination time increases, the substances in the solution are gradually mineralized and decomposed, and the intensity of the ultraviolet spectral characteristic peaks between 350 - 400 nm gradually decreases.

[0073] Figure 6 It is the photocatalytic degradation liquid ultraviolet spectrum of the Bi2O2CO3 / CuBi2O4 composite material (ethanol) prepared in Example 3. As can be seen from the figure, as the illumination time increases, the substances in the solution are gradually mineralized and decomposed, and the intensity of the ultraviolet spectral characteristic peaks between 350 - 400 nm gradually decreases.

[0074] At the same time, for the acetone / ethanol provided in the preparation method of the present application, it can not only be used as a solvent but also participate as a reactant, and can also reduce costs and improve cost - effectiveness. Compared with traditional polyvinylpyrrolidone, it cannot form a solution and requires pure water as a solvent for dissolution, reducing the amount of reactants used. And in terms of cost, the preparation cost of acetone / ethanol is less than 1 / 20 of the cost of polyvinylpyrrolidone. That is, the industrial production link has stronger economic benefits.

[0075] In summary, by simply adding an organic solvent to the CuBi2O4 suspension under hydrothermal reaction conditions, a Bi2O2CO3 / CuBi2O4 composite material with excellent photocatalytic performance can be obtained, which will provide a potential new photocatalyst and a new method for preparing composite photocatalysts for the purification of environmental pollutants. The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above - mentioned embodiments. What is described in the above - mentioned embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A preparation method of a Bi2O2CO3 / CuBi2O4 composite photocatalyst, characterized in that, It includes the following steps: Step 1: Stir and disperse bismuth nitrate and copper nitrate in a 0.25 mol / L sodium hydroxide solution, conduct a hydrothermal reaction at 160 - 180 °C, control the pH to be 6 - 7.5 until the reaction ends, cool naturally, and then after centrifugation, washing, and drying, obtain one-dimensional CuBi2O4 nanorods; Step 2: Disperse the one-dimensional CuBi2O4 nanorods in water, add acetone / ethanol, stir and mix evenly, conduct a solvothermal reaction at 160 - 180 °C, control the pH to be 6 - 7.5 until the reaction ends, cool naturally, and then after centrifugation, washing, and drying, obtain a three-dimensional Bi2O2CO3 / CuBi2O4 composite photocatalyst.

2. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, characterized in that, In Step 1, the mass concentration of the bismuth nitrate is 25 mg / mL, and the mass concentration of the copper nitrate is 10 mg / mL.

3. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, characterized in that, In Step 1, the magnetic stirring time of the bismuth nitrate and copper nitrate in the sodium hydroxide solution is more than 3 h, and the hydrothermal reaction is more than 24 h.

4. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, characterized in that, In Step 1, the centrifugation rate is 9000 r / min, and the drying temperature is 60 - 80 °C.

5. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, wherein, In Step 2, the ratio of the CuBi2O4 to the organic solvent is 100 mg:1 mL.

6. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, characterized in that, In Step 2, the volume concentration of the acetone or ethanol is 0.038 mL / mL.

7. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, wherein In Step 2, the mixing time of the CuBi2O4 with the ethanol or acetone solution is more than 0.5 h.

8. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to claim 1, characterized in that, In Step 2, the solvothermal reaction time is more than 24 h, the centrifugation rate is 9000 r / min, and the drying temperature is 60 - 80 °C.

9. The preparation method of the Bi2O2CO3 / CuBi2O4 composite photocatalyst according to any one of claims 1 to 8, characterized in that, Applications in photocatalytic degradation of organic dyes and removal of heavy metal ions.

10. A Bi2O2CO3 / CuBi2O4 composite photocatalyst, characterized in that, The Bi2O2CO3 / CuBi2O4 composite photocatalyst is composed of multiple groups of one-dimensional CuBi2O4 nanorods, which are bonded by Bi2O2CO3 particles and form a three-dimensional spatial structure.

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