A MXene / Bi2O2S composite photocatalyst and its preparation method and application

Abstract

The present invention discloses a MXene / Bi 2 O 2 S composite photocatalyst and its preparation method and application belong to the technical field of new environmental catalytic materials. 2 O 2 The preparation method of the composite photocatalyst comprises the following steps: 3 ) 3 ·5H 2 O, thiourea and LiOH·H 2 After mixing evenly, MXene is added to carry out hydrothermal reaction to obtain the MXene / Bi 2 O 2 S composite photocatalyst. MXene / Bi prepared by the present invention 2 O 2 S composite photocatalyst under full spectrum irradiation and high purity CO 2 In the reaction system, CO 2 Photocatalytic reduction to CH 4 and CO.

Description

Technical Field

[0001] The present invention belongs to the technical field of new environmental catalytic materials, and in particular relates to a MXene / Bi 2 O 2 S composite photocatalyst and its preparation method and application. Background Art

[0002] Photocatalytic technology has received great attention in recent years due to its wide application 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 (TiO 2 ), although it has good photocatalytic performance, it can only absorb ultraviolet light due to its wide band gap, resulting in low utilization efficiency under sunlight. In addition, the photogenerated electron-hole pairs are easy to recombine, which also limits its 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, technicians in this field have been actively exploring. For example, the use of two-dimensional layered materials and other compounds with catalytic effects to prepare composite photocatalysts is an important direction. The invention is titled "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 exfoliation. 3 C 2 Nanosheets, in ultrathin Ti 3 C 2 The nanosheets are composed of BiOI ultra-thin nanosheets grown in situ on the surface. Experimental verification shows that in a pure carbon dioxide atmosphere, the catalyst performs well 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 / Bi 2 O 2 S composite photocatalyst and its preparation method and application.

[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 MXene / Bi 2 O 2 The preparation method of the composite photocatalyst of MXene / Bi is carried out by hydrothermal reaction to obtain the 2 O 2 S composite photocatalyst.

[0008] Preferably, the Bi(NO 3 ) 3 ·5H 2 O, thiourea and LiOH·H 2 The mass ratio of O is 1.9403:0.1522:12.

[0009] Preferably, the Bi(NO 3 ) 3 ·5H 2 The mass ratio of O to MXene is 1.9403:(0.01-0.08). 3 ) 3 ·5H 2 The molar mass ratio of O to MXene is 1.9403:0.01, 1.9403:0.02, 1.9403:0.04 or 1.9403:0.08.

[0010] Preferably, the Bi(NO 3 ) 3 ·5H 2 The mass ratio of O to MXene is 1.9403:(0.01-0.04).

[0011] More preferably, the Bi(NO 3 ) 3 ·5H 2 The mass ratio of O 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 MXene / Bi 2 O 2 The preparation method of S composite photocatalyst is:

[0014] (1) Weigh 1.9403 g (0.004 mol) of Bi(NO 3 ) 3 ·5H 2 O, 0.1522 g (0.002 mol) of thiourea and 12 g of LiOH·H 2O was added into 60 mL of deionized water and stirred thoroughly to obtain a solution, and then 0.02 g of MXene was added into the above solution and stirred thoroughly to obtain a mixed solution;

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

[0016] (3) Wash and dry the brown-black precipitate prepared in step (2) to obtain MXene / Bi 2 O 2 S composite photocatalyst.

[0017] Bismuth-based oxide layered materials have been widely studied in the field of catalysis because of their suitable energy band width. 2 O 2 S is an orthorhombic layered structure with a Pnnm space group, a band gap of about 1.5 eV, and has the characteristics of high carrier separation, high transmission efficiency, and long carrier lifetime. 2 O 2 S is mainly used in ferroelectric, thermoelectric, optoelectronic devices and supercapacitors, and there is little research in the field of photocatalysis. 2 O 2 The advantages of S and MXene provide a creative way to 2 O 2 The photocatalyst composited with S and MXene is expected to overcome the limitations of a single material. 2 O 2 The S photocatalyst composite can improve the separation efficiency of the photogenerated carriers of the composite photocatalyst, thereby enhancing the overall photocatalytic performance, making the composite photocatalyst have 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 / Bi prepared according to the above preparation method 2 O 2 S composite photocatalyst.

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

[0021] The present invention also provides the MXene / Bi 2 O 2 Application of S composite photocatalyst in photocatalytic energy conversion.

[0022] Preferably, the MXene / Bi2 O 2 S composite photocatalyst for photocatalytic CO 2 Convert to CH 4 and CO.

[0023] MXene / Bi prepared by the present invention 2 O 2 S composite photocatalyst under full spectrum irradiation and high purity CO 2 In the reaction system, CO 2 Photocatalytic reduction to CH 4 and CO.

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

[0025] (1) MXene / Bi of the present invention 2 O 2 S composite photocatalyst using Bi(NO 3 ) 3 ·5H 2 O, thiourea and LiOH·H 2 O and MXene are evenly stirred and then hydrothermally synthesized, which has high operability and can achieve mass production of composite photocatalysts through a relatively simple process, providing convenience for industrial applications and helping to reduce production costs.

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

[0027] (3) MXene / Bi prepared by the present invention 2 O 2 S composite photocatalyst under full spectrum irradiation and high purity CO 2 In the reaction system, it has good photocatalytic CO 2 Reduction to CH 4 and CO performance and cycle stability. 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 MXene / Bi prepared in Examples 1 to 4 of the present invention 2 O2 X-ray diffraction pattern of S composite photocatalyst, where 0.5% MBOS is MXene / Bi prepared in Example 1 2 O 2 S composite photocatalyst, 1.0% MBOS is MXene / Bi prepared in Example 2 2 O 2 S composite photocatalyst, 2.0% MBOS is MXene / Bi prepared in Example 3 2 O 2 S composite photocatalyst, 4.0% MBOS is MXene / Bi prepared in Example 4 2 O 2 S composite photocatalyst;

[0030] Figure 2 MXene / Bi prepared in Example 2 of the present invention 2 O 2 XPS full scan of S composite photocatalyst;

[0031] Figure 3 MXene / Bi prepared in Examples 1 to 4 of the present invention 2 O 2 S composite photocatalyst and Bi 2 O 2 S photocatalyst under full spectrum irradiation, high purity CO 2 Photocatalytic CO 2 Reduction effect diagram, where 0.5% MBOS is MXene / Bi prepared in Example 1 2 O 2 S composite photocatalyst, 1.0% MBOS is MXene / Bi prepared in Example 2 2 O 2 S composite photocatalyst, 2.0% MBOS is MXene / Bi prepared in Example 3 2 O 2 S composite photocatalyst, 4.0% MBOS is MXene / Bi prepared in Example 4 2 O 2 S composite photocatalyst;

[0032] Figure 4 MXene / Bi prepared in Examples 1 to 4 2 O 2 S composite photocatalyst and Bi 2 O 2 Transient fluorescence spectrum of S photocatalyst, where 0.5% MBOS is MXene / Bi prepared in Example 1 2 O 2S composite photocatalyst, 1.0% MBOS is MXene / Bi prepared in Example 2 2 O 2 S composite photocatalyst, 2.0% MBOS is MXene / Bi prepared in Example 3 2 O 2 S composite photocatalyst, 4.0% MBOS is MXene / Bi prepared in Example 4 2 O 2 S composite photocatalyst;

[0033] Figure 5 MXene / Bi prepared in Example 2 of the present invention 2 O 2 Photocatalytic CO catalysis of S composite photocatalyst 2 Reduction cycle experiment effect diagram;

[0034] Figure 6 MXene / Bi prepared in Example 2 of the present invention 2 O 2 XRD patterns of S composite photocatalyst 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 MXene / Bi 2 O 2 Preparation method of S composite photocatalyst:

[0044] (1) Weigh 1.9403 g (0.004 mol) of Bi(NO 3 ) 3 ·5H 2 O, 0.1522 g (0.002 mol) of thiourea and 12 g of LiOH·H 2 O was added into 60 mL of deionized water and stirred thoroughly to obtain a solution, and then 0.01 g of MXene was added into the above solution and stirred thoroughly to obtain a mixed solution;

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

[0046] (3) Wash and dry the brown-black precipitate prepared in step (2) to obtain MXene / Bi 2 O 2 S composite photocatalyst (labeled as 0.5% MBOS).

[0047] Example 2

[0048] Same as Example 1, except that the mass of MXene in step (1) is 0.02 g, and the obtained MXene / Bi 2 O 2 S composite photocatalyst (labeled as 1.0% MBOS).

[0049] Example 3

[0050] Same as Example 1, except that the mass of MXene in step (1) is 0.04 g, and the obtained MXene / Bi 2 O 2 S composite photocatalyst (labeled as 2.0% MBOS).

[0051] Example 4

[0052] Same as Example 1, except that the mass of MXene in step (1) is 0.08 g, and the obtained MXene / Bi 2 O 2 S composite photocatalyst (labeled as 4.0% MBOS).

[0053] Comparative Example 1

[0054] Bi 2 O 2 Preparation of S: Same as Example 1, except that MXene is not added in step (1) to obtain Bi 2 O 2 S photocatalyst.

[0055] MXene / Bi prepared in Examples 1 to 4 2 O 2 The X-ray diffraction pattern of S composite photocatalyst is shown in Figure 1 ; Figure 1 0.5% MBOS is MXene / Bi prepared in Example 1 2 O 2 S composite photocatalyst, 1.0% MBOS is MXene / Bi prepared in Example 2 2 O 2 S composite photocatalyst, 2.0% MBOS is MXene / Bi prepared in Example 3 2 O 2 S composite photocatalyst, 4.0% MBOS is MXene / Bi prepared in Example 4 2 O 2 S composite photocatalyst. Figure 1 As can be seen from the figure, since the mass of MXene added in Examples 1-4 is relatively small, the prepared MXene / Bi 2 O 2 The XRD diffraction peak position of S composite photocatalyst and Bi 2 O 2 S (PDF: 34-1493) standard peak position. 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 Bi 2 O 2 S successfully reunited.

[0056] Effect Example 1

[0057] Determination of MXene / Bi prepared in Examples 1 to 4 2 O 2 S composite photocatalyst under full spectrum irradiation and high purity CO 2 Photocatalytic CO 2 Reduction to CH 4 and CO performance, and with Bi 2 O 2 The catalytic performance of S photocatalyst is compared. Figure 2 .

[0058] The above-mentioned photocatalyst photocatalyzes CO 2 The specific steps for restoring performance test are as follows:

[0059] 30 mg of the photocatalyst to be tested was ultrasonically dispersed on a glass culture dish with a diameter of 5 cm. The culture dish was placed on the upper layer of a 200 mL reactor with a quartz glass window. 1.2 g of anhydrous Na 2 CO 3 The reactor was then sealed. The air in the reactor was evacuated using 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 H 2 SO 4 (The volume ratio of concentrated sulfuric acid (18.4 mol / L) and water is 1:1). 2 CO 3 With H 2 SO 4 Complete reaction produces CO 2 After the gas is generated, the light source is turned on to photocatalyze CO 2 Reduction reaction. The products generated by the photocatalytic reaction and their contents were analyzed by gas chromatography.

[0060] from Figure 3 It can be seen that compared with Bi 2 O 2 S photocatalyst, MXene / Bi prepared in Examples 1 to 4 of the present invention 2 O 2 S composite photocatalyst under full spectrum irradiation and high purity CO 2 In the reaction system, the photocatalytic CO 2 Reduction to CH 4and CO performance. Among them, the 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention has the highest photocatalytic CO 2 Reduction reaction activity.

[0061] from Figure 4 It can be seen that compared with Bi 2 O 2 S photocatalyst, MXene / Bi prepared in Examples 1 to 4 of the present invention 2 O 2 The fluorescence spectrum peak intensity of the S composite photocatalyst 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 MXene / Bi 2 O 2 The recombination of electrons and holes in the S 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 CO 2 Restore performance.

[0062] from Figure 5 It can be seen that the 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention photocatalytically reduces CO in the cycle experiment. 2 CH 4 The effects of 1.0% MBOS composite photocatalyst prepared in Example 2 of the present invention are relatively good, and the effects are still stable after five cycles. 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 method for preparing a MXene / Bi2O2S composite photocatalyst, characterized in that: The following steps are involved: Bi(NO3)3·5H2O, thiourea and LiOH·H2O are mixed, MXene is added, and a hydrothermal reaction is performed to obtain the MXene / Bi2O2S composite photocatalyst; The mass ratio of Bi(NO3)3·5H2O to MXene is 1.9403:(0.01-0.04); The temperature of the hydrothermal reaction is 200°C and the time is 72h; The MXene / Bi2O2S composite photocatalyst is used for photocatalytic conversion of CO2 into CH4 and CO.

2. The method for preparing the MXene / Bi2O2S composite photocatalyst according to claim 1, characterized in that: The mass ratio of Bi(NO3)3·5H2O, thiourea and LiOH·H2O is 1.9403:0.1522:

12.

3. The method for preparing the MXene / Bi2O2S composite photocatalyst according to claim 1, characterized in that: The mass ratio of Bi(NO3)3·5H2O to MXene is 1.9403∶0.

02.

4. A MXene / Bi2O2S composite photocatalyst, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 3.

5. The use of the MXene / Bi2O2S composite photocatalyst according to claim 4 in photocatalytic energy conversion, characterized in that: The MXene / Bi2O2S composite photocatalyst is used for photocatalytic conversion of CO2 into CH4 and CO.

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