Amorphous photocatalyst based on H2O2 etching of MnIn2S4 ultrathin nanosheets and its method

Abstract

The application belongs to the field of catalysts, and particularly relates to an amorphous structure photocatalyst based on H2O2 etching MnIn2S4 ultrathin nanosheets and a method thereof. The catalyst is synthesized by a solvothermal method, and the prepared photocatalyst is an ultrathin nanosheet with a thickness of about 2 nm; H2O2 is used to etch MnIn2S4, MnSO4 is generated and dissolved in water, part of Mn atoms are removed, and an InOS5 disordered structure is formed. The ultrathin nanosheet is beneficial to improving the catalytic efficiency of photocatalytic reduction of carbon dioxide, the photocatalytic CO2 reduction performance of the catalyst is improved by about 3.8 times, and the photocatalytic NO3 ‑ reduction performance is improved by about 2.6 times.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically relating to an amorphous photocatalyst formed by etching MnIn2S4 ultrathin nanosheets with H2O2 and its method. Background Technology

[0002] Due to rapid technological and industrial development, energy demand is enormous. Fossil fuels remain the primary global energy source, but unfortunately, they are non-renewable energy sources and cause significant environmental damage due to the high carbon dioxide emissions during combustion. Photocatalytically converting carbon dioxide into useful compounds or fuels, such as carbon monoxide, methane, and formic acid, is an attractive approach to addressing the energy crisis and environmental problems. However, while many catalysts have been developed for the photocatalytic reduction of carbon dioxide, most suffer from insufficient active sites, low photocatalytic activity, and photogenerated carrier recombination. Therefore, it is necessary to design photocatalysts with more CO2 reduction sites at the atomic level.

[0003] Ultrathin two-dimensional (2D) materials have attracted widespread attention as a novel type of photocatalyst. Ultrathin structures possess a large specific surface area and numerous active sites, which is beneficial for adsorbing reactant molecules. Their thickness can be controlled at the nanometer scale or even thinner, effectively shortening the migration distance of photogenerated electrons and holes from the bulk phase to the material surface, thereby reducing the possibility of photogenerated electron-hole recombination in the bulk phase. Besides the advantages of MnIn2S4 ultrathin nanosheets as ultrathin materials, they have also attracted attention due to their beneficial electronic states, band gap, tunable morphology, and satisfactory stability. However, in numerous studies on MnIn2S4 ultrathin nanosheets, their photocatalytic performance remains unsatisfactory due to their high carrier recombination rate and insufficient surface active sites. Therefore, in recent years, [the text abruptly ends here, likely due to an incomplete sentence or missing information]. x In2S y Etching removed some Mn and a small amount of S from the MnIn2S4 ultrathin nanosheets, forming an amorphous InOS5 structure that adsorbed more NO3. - CO2 participates in photocatalytic reduction reactions. Summary of the Invention

[0004] The purpose of this invention is to provide an amorphous photocatalyst and its method based on H2O2 etching of MnIn2S4 ultrathin nanosheets.

[0005] Based on the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for forming an amorphous photocatalyst based on H2O2 etching of MnIn2S4 ultrathin nanosheets, comprising the following steps:

[0007] (1) MnIn2S4 ultrathin nanosheet catalyst was prepared by solvothermal method;

[0008] (2) The obtained MnIn2S4 was reacted with hydrogen peroxide under ultrasound for 20s to 40s, deionized water was added and centrifuged immediately, and dried to obtain an amorphous photocatalyst.

[0009] Preferably, the MnIn2S4 ultrathin nanosheet catalyst is prepared by solvothermal methods, and the specific steps are as follows:

[0010] S1. Dissolve MnCl2, In(NO3)3 and polyvinylpyrrolidone in a mixed solvent of deionized water and anhydrous ethanol, stir until the solution is clear, and add thioacetamide to the solution.

[0011] S2 The solution obtained from S1 was solvothermally reacted at 180±5℃ for 24h. The resulting product was centrifuged, washed and dried to obtain MnIn2S4 ultrathin nanosheet catalyst.

[0012] The molar ratio of MnCl2:In(NO3)3:thioacetamide is 0.25:0.5:2.

[0013] The volume ratio of deionized water to anhydrous ethanol in the mixed solvent is 1:1.

[0014] Preferably, 1 ml of hydrogen peroxide is added for every 25 mg of MnIn2S4.

[0015] Preferably, the volume ratio of hydrogen peroxide to deionized water is 1:9.

[0016] The optimal drying temperature is 60-80℃.

[0017] Preferably, the obtained photocatalyst has a thickness of 2 nm and has an amorphous structure.

[0018] Preferably, the obtained MnIn2S4 is reacted with hydrogen peroxide under ultrasound for 40 s.

[0019] In a second aspect, the present invention provides an amorphous photocatalyst prepared by the method described in the first aspect.

[0020] Thirdly, the present invention provides the use of the amorphous photocatalyst prepared by the method described in the first aspect in photocatalytic nitrate reduction and photocatalytic CO2 reduction.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] The photocatalyst of this invention is produced by etching MnIn2S4 ultrathin nanosheets with hydrogen peroxide using H2O2. This generates MnSO4, which reacts to remove the Mn atoms bonded to In on the MnIn2S4 ultrathin nanosheets, forming an amorphous InSO5 structure. This exposes more active sites, allowing for the adsorption of more CO2 molecules and NO3. - Furthermore, by shortening the migration distance of photogenerated electrons and holes from the bulk phase to the material surface through the ultrathin thickness of the nanomaterial, the possibility of photogenerated electron-hole recombination in the bulk phase is reduced, thereby improving photocatalytic performance. This catalyst is synthesized via a solvothermal method, which features mild reaction conditions and simple operation. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0024] Figure 1 It is the prepared MnIn2S4(a) and Mn x In2S y (b) XRD of TEM images of ultrathin nanosheets. Figure 2 These are TEM images of MnIn2S4 ultrathin nanosheets, where a: 200 nm, b: 100 nm.

[0025] Figure 3 It is Mn x In2S y TEM images of ultrathin nanosheets, where a: 200 nm, b: 100 nm.

[0026] Figure 4 It is the prepared MnIn2S4(a) and Mn x In2S y (b) HRTEM image of ultrathin nanosheets.

[0027] Figure 5 It is the prepared MnIn2S4(a) and Mn x In2S y (b) Mn 2p spectrum of ultrathin nanosheets.

[0028] Figure 6 It is the prepared MnIn2S4(a) and Mn x In2S y (b) S2p spectrum of ultrathin nanosheets.

[0029] Figure 7 It is the prepared MnIn2S4(a) and Mn x In2S y (b) XPS full spectrum of ultrathin nanosheets.

[0030] Figure 8 It is Mn x In2S y HAADF-STEM and EDS elemental mapping images of ultrathin nanosheets, where (a) 100nm (b) 20nm (c) 5nm (d) 1nm HAADF-STEM image, (e) EDS elemental mapping image.

[0031] Figure 9 It is the preparation of MnIn2S4, Mn x In2S y and Mn x In2S y -1 Photocatalytic reduction performance of ultrathin nanosheets, where (a) MnIn2S4, Mn x In2S y and Mn x In2S y -1 Photocatalytic reduction of NO3 by ultrathin nanosheets - Performance diagram, (b) MnIn2S4, Mn x In2S y Photocatalytic reduction performance of CO2 on ultrathin nanosheets. Detailed Implementation

[0032] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0034] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0035] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0036] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0037] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0038] Example 1

[0039] 0.25 mmol MnCl2, 0.5 mmol In(NO3)3, and 0.2 g PVP (average molar wt 40000) were weighed and dissolved in 15 mL deionized water and 15 mL anhydrous ethanol. After vigorous stirring and further stirring for 10 minutes, 2 mmol thioacetamide was added to the above solution. The solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 180 °C for 24 hours. The product was centrifuged, washed three times with deionized water and three times with anhydrous ethanol, and dried in a forced-air drying oven at 60 °C to obtain the MnIn2S4 ultrathin nanosheet catalyst.

[0040] Example 2

[0041] Weigh 25 mg of the MnIn2S4 catalyst prepared in Example 1 into a beaker, add 1 mL of H2O2, sonicate for 40 s, add 9 mL of deionized water, and centrifuge the resulting product immediately. Finally, dry at 60 °C and name it MnIn2S4. x In2S y .

[0042] Example 3

[0043] Weigh 25 mg of the MnIn2S4 catalyst prepared in Example 1 into a beaker, add 1 mL of H2O2, sonicate for 20 s, add 9 mL of deionized water, and centrifuge the resulting product immediately. Finally, dry at 60 °C and name it MnIn2S4. x In2S y -1.

[0044] Figure 1 For MnIn2S4 and Mn x In2S y XRD patterns of ultrathin nanosheets, Figure 1 Figure a corresponds to the MnIn2S4 conforming standard card JCPDS NO.31-0594.

[0045] Figure 2 These are TEM images of MnIn2S4 ultrathin nanosheets. Figure 2 It can be seen that MnIn2S4 nanosheets were successfully synthesized.

[0046] Figure 3 It is Mn x In2S y TEM image of ultrathin nanosheets. Ultrathin nanosheets were successfully synthesized.

[0047] Figure 4 It is the preparation of MnIn2S4 and Mn x In2S y HRTEM image of the ultrathin nanosheets. The MnIn2S4 ultrathin nanosheets show a planar spacing of 0.317 nm, which matches well with the (311) plane of the standard card.

[0048] Figure 5 It is the preparation of MnIn2S4 and Mn x In2S y Mn 2p spectra of ultrathin nanosheets. x In2S y The Mn 2p spectrum of ultrathin nanosheets differs significantly from that of MnIn2S4. x In2S y The ultrathin nanosheets have a very low Mn content, which proves that MnIn2S4 may have lost some Mn through the etching reaction of H2O2, possibly forming MnSO4 material that dissolves in water.

[0049] Figure 6 It is the preparation of MnIn2S4 and Mn x In2S y S2p spectra of ultrathin nanosheets. The characteristic S2p peaks of the MnIn2S4 atomic layers are 158.95 eV and 160.24 eV, respectively, while those of Mn... x In2S y The S2p characteristic peaks of the ultrathin nanosheets are 163.29 eV and 168.77 eV, respectively. This result also proves that H2O2 also etched away a small portion of the S in MnIn2S4.

[0050] Figure 7It is the preparation of MnIn2S4 and Mn x In2S y XPS full spectrum of ultrathin nanosheets. The full spectrum shows that Mn... x In2S y The ultrathin nanosheets have fewer Mn peaks than MnIn2S4, consistent with the Mn 2p spectrum results. Due to their extremely low content, they were not detected in the full spectrum.

[0051] Figure 8 It is Mn x In2S y Aberration-corrected electron microscopy and elemental mapping of ultrathin nanosheets, from Figure 8 The ab result further confirms that the material still maintains its ultrathin morphology after H2O2 etching, while the cd result reveals the Mn content. x In2S y The amorphous structure is shown. The mapping plot further confirms the XPS results.

[0052] Figure 9 It is the preparation of MnIn2S4, Mn x In2S y and Mn x In2S y -1 Photocatalytic reduction performance of ultrathin nanosheets for carbon dioxide and photocatalytic reduction of NO3 - ,from Figure 9 As can be seen, the amorphous photocatalyst based on H2O2 etching of MnIn2S4 ultrathin nanosheets prepared in this invention increases the CO yield by approximately 3.8 times compared to the original MnIn2S4 ultrathin nanosheets. The NH3 yield also increases by approximately 2.6 times compared to the original MnIn2S4 ultrathin nanosheets.

[0053] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for forming an amorphous photocatalyst based on H2O2 etching of MnIn2S4 ultrathin nanosheets, characterized in that, Includes the following steps: (1) MnIn2S4 ultrathin nanosheet catalyst was prepared by solvothermal method; (2) The obtained MnIn2S4 was reacted with hydrogen peroxide under ultrasound for 20s~40s, deionized water was added and centrifuged immediately, and dried to obtain an amorphous photocatalyst.

2. The method as described in claim 1, characterized in that, The MnIn2S4 ultrathin nanosheet catalyst was prepared by solvothermal methods, and the specific steps are as follows: S1. Dissolve MnCl2, In(NO3)3 and polyvinylpyrrolidone in a mixed solvent of deionized water and anhydrous ethanol, stir until the solution is clear, and add thioacetamide to the solution. S2 The solution obtained from S1 was solvothermally reacted at 180±5℃ for 24h. The resulting product was centrifuged, washed and dried to obtain MnIn2S4 ultrathin nanosheet catalyst. The molar ratio of MnCl2:In(NO3)3:thioacetamide is 0.25:0.5:

2. The volume ratio of deionized water to anhydrous ethanol in the mixed solvent is 1:

1.

3. The method as described in claim 1, characterized in that, Add 1 mL of hydrogen peroxide for every 25 mg of MnIn2S4.

4. The method as described in claim 1, characterized in that, The volume ratio of hydrogen peroxide to deionized water is 1:

9.

5. The method as described in claim 1, characterized in that, The drying temperature is 60-80℃.

6. The method as described in claim 1, characterized in that, The obtained MnIn2S4 was reacted with hydrogen peroxide under sonication for 40 s.

7. The amorphous photocatalyst prepared by the method according to any one of claims 1-6.

8. The amorphous photocatalyst as described in claim 7, characterized in that, The photocatalyst is 2 nm thick and has an amorphous structure.

9. The use of the amorphous photocatalyst prepared by the method according to any one of claims 1-6 in the photocatalytic reduction of nitrate.

10. Use of the amorphous photocatalyst prepared by the method of any one of claims 1-6 in photocatalytic CO2 reduction.

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