MXene / Bi2O2S composite photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses an MXene / Bi2O2S composite photocatalyst as well as a preparation method and application thereof, and belongs to the technical field of novel materials for environmental catalysis. The preparation method of the MXene / Bi2O2S composite photocatalyst comprises the following steps: uniformly mixing Bi (NO3) 3.5 H2O, thiourea and LiOH.H2O, adding MXene, and carrying out a hydrothermal reaction, so as to obtain the MXene / Bi2O2S composite photocatalyst. The MXene / Bi2O2S composite photocatalyst prepared by the preparation method disclosed by the invention can be used for photocatalytic reduction of CO2 into CH4 and CO in a full-spectrum irradiation and high-purity CO2 reaction system.

Description

Technical Field

[0001] The present invention belongs to the technical field of new environmental catalytic materials, and in particular relates to a MXene / Bi2O2S composite photocatalyst and a preparation method and application thereof. Background Art

[0002] Photocatalytic technology has received great attention in recent years due to its wide applications in environmental pollutant degradation and clean energy production. Among them, clean energy production, such as catalytic reduction of carbon dioxide to carbon monoxide and / or methane, is a major technology for preparing clean energy. Traditional photocatalyst materials, such as titanium dioxide (TiO2), although have good photocatalytic performance, can only absorb ultraviolet light due to their wide band gap, resulting in low utilization efficiency under sunlight. In addition, photogenerated electron-hole pairs are easy to recombine, which also limits their photocatalytic efficiency. MXene is an emerging class of two-dimensional materials that can be used as photocatalysts. However, a single material has limitations when used as a photocatalyst, resulting in poor photocatalytic activity and stability.

[0003] In order to further improve the redox potential of photocatalysts and improve the efficiency of redox reactions, those skilled in the art have been actively exploring. For example, it is an important direction to use two-dimensional layered materials and other compounds with catalytic effects to prepare composite photocatalysts. The invention is called an ultra-thin BiOI / Mxene 2D / 2D heterojunction photocatalyst and its preparation method and application (publication number CN116603549A), which discloses a catalyst for photocatalytic carbon dioxide reduction, wherein the ultra-thin BiOI / Mxene 2D / 2D heterojunction photocatalyst is prepared by ultrasonic stripping method. The ultra-thin BiOI nanosheets are in situ grown on the surface of the ultra-thin Ti3C2 nanosheets. It has been experimentally verified that in a pure carbon dioxide atmosphere, the catalyst is excellent in catalyzing the directional reduction of carbon dioxide to carbon monoxide, but cannot catalyze the directional reduction of carbon dioxide to methane. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a MXene / Bi2O2S composite photocatalyst and a preparation method and application thereof.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] A method for preparing a MXene / Bi2O2S composite photocatalyst comprises performing a hydrothermal reaction to obtain the MXene / Bi2O2S composite photocatalyst.

[0008] Preferably, the mass ratio of Bi(NO3)3·5H2O, thiourea and LiOH·H2O is 1.9403:0.1522:12.

[0009] Preferably, the mass ratio of Bi(NO3)3·5H2O to MXene is 1.9403:(0.01-0.08). For example, the mass ratio of the molar mass of Bi(NO3)3·5H2O to MXene is 1.9403:0.01, 1.9403:0.02, 1.9403:0.04 or 1.9403:0.08.

[0010] Preferably, the mass ratio of Bi(NO3)3·5H2O to MXene is 1.9403:(0.01-0.04).

[0011] More preferably, the mass ratio of Bi(NO3)3·5H2O to MXene is 1.9403:0.02 g.

[0012] Preferably, the temperature of the hydrothermal reaction is 200° C. and the time is 72 h.

[0013] More preferably, the preparation method of the MXene / Bi2O2S composite photocatalyst is:

[0014] (1) 1.9403 g (0.004 mol) of Bi(NO3)3·5H2O, 0.1522 g (0.002 mol) of thiourea and 12 g of LiOH·H2O were added to 60 mL of deionized water and stirred thoroughly to obtain a solution, and then 0.02 g of MXene was added to the above solution and stirred thoroughly to obtain a mixed solution;

[0015] (2) transferring the mixed solution prepared in step (1) into a hydrothermal reaction kettle, performing a hydrothermal reaction at 200° C. for 72 h, and obtaining a brown-black precipitate after cooling;

[0016] (3) The brown-black precipitate prepared in step (2) is washed and dried to obtain a MXene / Bi2O2S composite photocatalyst.

[0017] Bismuth-based oxygen-based layered materials have been widely studied in the field of catalysis because of their suitable energy band width. Among them, Bi2O2S is an orthorhombic crystal layered structure with a Pnnm space group, with a band gap of about 1.5 eV, and has the characteristics of carrier separation, high transmission efficiency and long carrier lifetime. However, Bi2O2S is mainly used in ferroelectrics, thermoelectrics, optoelectronic devices and supercapacitors, and there is little research in the field of photocatalysis. Based on the advantages of Bi2O2S and MXene, the present invention creatively provides a photocatalyst of Bi2O2S and MXene composite, which is expected to overcome the limitations of a single material. By combining MXene with the Bi2O2S photocatalyst, the present invention can improve the separation efficiency of photogenerated carriers of the composite photocatalyst, thereby enhancing the overall photocatalytic performance, so that the composite photocatalyst has more efficient photocatalytic activity and stronger stability. This composite photocatalyst has potential application prospects in the fields of environmental photocatalytic energy conversion.

[0018] The second technical solution of the present invention:

[0019] The present invention also provides a MXene / Bi2O2S composite photocatalyst prepared according to the above preparation method.

[0020] The third technical solution of the present invention:

[0021] The present invention also provides application of the MXene / Bi2O2S composite photocatalyst in photocatalytic energy conversion.

[0022] Preferably, the MXene / Bi2O2S composite photocatalyst is used for photocatalytic conversion of CO2 into CH4 and CO.

[0023] The MXene / Bi2O2S composite photocatalyst prepared by the present invention can photocatalytically reduce CO2 to CH4 and CO in a full-spectrum irradiation and high-purity CO2 reaction system.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] (1) The MXene / Bi2O2S composite photocatalyst of the present invention is prepared by hydrothermal synthesis by uniformly stirring Bi(NO3)3·5H2O, thiourea, LiOH·H2O and MXene. It has high operability and can realize mass production of the composite photocatalyst through a relatively simple process, which provides convenience for industrial application and helps to reduce production costs.

[0026] (2) Compared with single Bi2O2S or MXene materials, the MXene / Bi2O2S composite photocatalyst prepared by the present invention has a higher separation efficiency of photogenerated electrons and holes, reducing the recombination of electron-hole pairs.

[0027] (3) The MXene / Bi2O2S composite photocatalyst prepared in the present invention has good performance and cycle stability in photocatalytic reduction of CO2 to CH4 and CO in a full-spectrum irradiation and high-purity CO2 reaction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 X-ray diffraction patterns of the MXene / Bi2O2S composite photocatalysts prepared in Examples 1 to 4 of the present invention, wherein 0.5% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 1, 1.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 2, 2.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 3, and 4.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 4;

[0030] Figure 2 This is the XPS full scan of the MXene / Bi2O2S composite photocatalyst prepared in Example 2 of the present invention;

[0031] Figure 3 The photocatalytic CO2 reduction effect diagram of the MXene / Bi2O2S composite photocatalyst and Bi2O2S photocatalyst prepared in Examples 1 to 4 of the present invention in a full-spectrum irradiation, high-purity CO2 reaction system, wherein 0.5% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 1, 1.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 2, 2.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 3, and 4.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 4;

[0032] Figure 4 The transient fluorescence spectra of the MXene / Bi2O2S composite photocatalysts and Bi2O2S photocatalysts prepared in Examples 1 to 4, wherein 0.5% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 1, 1.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 2, 2.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 3, and 4.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 4;

[0033] Figure 5 This is a photocatalytic CO2 reduction cycle experimental effect diagram of the MXene / Bi2O2S composite photocatalyst prepared in Example 2 of the present invention;

[0034] Figure 6 This is the XRD pattern of the MXene / Bi2O2S composite photocatalyst prepared in Example 2 of the present invention before and after five cycles of reaction. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] All raw materials used in the embodiments of the present invention are purchased from commercial sources. As an example, MXene is purchased from Wuhan Xuanyiyuan Technology Co., Ltd.

[0041] The technical solution of the present invention is further illustrated by the following embodiments.

[0042] Example 1

[0043] A method for preparing a MXene / Bi2O2S composite photocatalyst:

[0044] (1) 1.9403 g (0.004 mol) of Bi(NO3)3·5H2O, 0.1522 g (0.002 mol) of thiourea and 12 g of LiOH·H2O were added to 60 mL of deionized water and stirred thoroughly to obtain a solution, and then 0.01 g of MXene was added to the above solution and stirred thoroughly to obtain a mixed solution;

[0045] (2) transferring the mixed solution prepared in step (1) into a hydrothermal reaction kettle, performing a hydrothermal reaction at 200° C. for 72 h, and obtaining a brown-black precipitate after cooling;

[0046] (3) The brown-black precipitate prepared in step (2) was washed and dried to obtain a MXene / Bi2O2S composite photocatalyst (labeled as 0.5% MBOS).

[0047] Example 2

[0048] The same as Example 1, except that the mass of MXene in step (1) is 0.02 g, and a MXene / Bi2O2S composite photocatalyst (labeled as 1.0% MBOS) is obtained.

[0049] Example 3

[0050] The same as Example 1, except that the mass of MXene in step (1) is 0.04 g, and a MXene / Bi2O2S composite photocatalyst (labeled as 2.0% MBOS) is obtained.

[0051] Example 4

[0052] The same as Example 1, except that the mass of MXene in step (1) is 0.08 g, and a MXene / Bi2O2S composite photocatalyst (labeled as 4.0% MBOS) is obtained.

[0053] Comparative Example 1

[0054] Preparation of Bi2O2S: The same as Example 1, except that no MXene is added in step (1), and a Bi2O2S photocatalyst is obtained.

[0055] The X-ray diffraction patterns of the MXene / Bi2O2S composite photocatalysts prepared in Examples 1 to 4 are shown in Figure 1 ; Figure 10.5% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 1, 1.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 2, 2.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 3, and 4.0% MBOS is the MXene / Bi2O2S composite photocatalyst prepared in Example 4. Figure 1 It can be seen that due to the small amount of MXene added in Examples 1-4, the XRD diffraction peak position of the prepared MXene / Bi2O2S composite photocatalyst corresponds to the standard peak position of Bi2O2S (PDF: 34-1493). Due to the small amount of MXene added, the XRD diffraction peak of MXene is not shown in the XRD. However, from the XPS full scan of the 1.0% MBOS composite photocatalyst prepared in Example 2 ( Figure 2 ), it can be clearly observed that the Ti element in MXene exists in the composite catalyst, proving that MXene and Bi2O2S are successfully composited.

[0056] Effect Example 1

[0057] The performance of the MXene / Bi2O2S composite photocatalysts prepared in Examples 1 to 4 in photocatalytic reduction of CO2 to CH4 and CO in a full spectrum irradiation, high purity CO2 reaction system was measured and compared with the catalytic performance of the Bi2O2S photocatalyst. Figure 2 .

[0058] The specific operating steps of the above-mentioned photocatalyst photocatalytic CO2 reduction performance test are as follows:

[0059] Ultrasonic dispersion of 30 mg of the photocatalyst to be tested was placed on a glass culture dish with a diameter of 5 cm. The culture dish was placed on the upper layer of a reactor with a volume of 200 mL and a quartz glass window. 1.2 g of anhydrous Na2CO3 was added to the bottom and the reactor was sealed. The air in the reactor was evacuated with a vacuum pump, and nitrogen was introduced to completely remove the residual air. After confirming that there was no air in the reactor, 2 mL of H2SO4 (concentrated sulfuric acid (18.4 mol / L) and water in a volume ratio of 1:1) was injected into the reactor. After Na2CO3 and H2SO4 completely reacted to generate CO2 gas, the light source was turned on for photocatalytic CO2 reduction reaction. The products generated by the photocatalytic reaction and their contents were analyzed by gas chromatography.

[0060] from Figure 3It can be seen that compared with the Bi2O2S photocatalyst, the MXene / Bi2O2S composite photocatalysts prepared in Examples 1 to 4 of the present invention have significantly enhanced photocatalytic CO2 reduction to CH4 and CO performance in a full-spectrum irradiation, high-purity CO2 reaction system. Among them, the 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention has the highest photocatalytic CO2 reduction reaction activity.

[0061] from Figure 4 It can be seen that compared with the Bi2O2S photocatalyst, the fluorescence spectrum peak intensity of the MXene / Bi2O2S composite photocatalyst prepared in Examples 1 to 4 of the present invention is significantly reduced. Among them, the 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention has the lowest fluorescence spectrum peak. This shows that the recombination of electrons and holes in the MXene / Bi2O2S composite photocatalyst can be significantly suppressed. The 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention has the highest photogenerated carrier separation efficiency, which is beneficial to improving its photocatalytic CO2 reduction performance.

[0062] from Figure 5 It can be seen that the 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention has a good effect in photocatalytic reduction of CO2 to CH4 and CO in the cycle experiment, and the effect is still stable after five cycles. This proves that the 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention has high cycle stability. Figure 6 It can be seen that the XRD pattern of the 1.0% MBOS composite photocatalyst before and after the reaction has no obvious change, which further proves that the 1.0% MBOS composite photocatalyst prepared in Example 2 has good chemical stability.

[0063] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A MXene / Bi 2 O 2 Preparation method of S composite photocatalyst, It is characterized in that The following steps are involved: Bi(NO 3 ) 3 ·5H 2 O, thiourea and LiOH·H 2 O is mixed, MXene is added, and a hydrothermal reaction is performed to obtain the MXene / Bi 2 O 2 S composite photocatalyst.

2. MXene / Bi according to claim 1 2 O 2 Preparation method of S composite photocatalyst, It is characterized in that The Bi(NO 3 ) 3 ·5H 2 O, thiourea and LiOH·H 2 The mass ratio of O is 1.9403:0.1522:

12.

3. MXene / Bi according to claim 1 2 O 2 Preparation method of S composite photocatalyst, It is characterized in that The Bi(NO 3 ) 3 ·5H 2 The mass ratio of O to MXene is 1.9403:(0.01-0.08).

4. MXene / Bi according to claim 3 2 O 2 Preparation method of S composite photocatalyst, It is characterized in that The Bi(NO 3 ) 3 ·5H 2 The mass ratio of O to MXene is 1.9403:(0.01-0.04).

5. MXene / Bi according to claim 4 2 O 2 Preparation method of S composite photocatalyst, It is characterized in that Bi(NO 3 ) 3 ·5H 2 The mass ratio of O to MXene is 1.9403:0.

02.

6. MXene / Bi according to claim 1 2 O 2 Preparation method of S composite photocatalyst, It is characterized in that The temperature of the hydrothermal reaction is 200° C. and the time is 72 hours.

7. A MXene / Bi 2 O 2 S composite photocatalyst, It is characterized in that Prepared according to the preparation method according to any one of claims 1 to 6.

8. MXene / Bi according to claim 7 2 O 2 Application of S composite photocatalyst in photocatalytic energy conversion.

9. The use according to claim 8, It is characterized in that The MXene / Bi 2 O 2 S composite photocatalyst for photocatalytic CO 2 Convert to CH 4 and CO.

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