Method for modifying Fe-MoS2 photocatalyst through low-temperature plasma

Abstract

The invention discloses a preparation method of a low-temperature plasma modified iron-molybdenum disulfide (Fe-MoS2) photocatalyst, which comprises the following steps: uniformly spreading a to-be-modified Fe-MoS2 photocatalyst in a low-temperature plasma modification device, taking air as a gas medium in the reaction process, turning on a plasma power supply, adjusting the discharge power, and carrying out low-temperature plasma modification on the Fe-MoS2 photocatalyst to obtain the low-temperature plasma modified Fe-MoS2 photocatalyst. And carrying out photocatalyst modification treatment at normal temperature and normal pressure. After low-temperature plasma modification is conducted for a period of time, a power source is turned off, the photocatalyst is collected after being cooled to the room temperature, and the modified Fe-MoS2 photocatalyst is obtained and used for the photocatalytic treatment technology of degradation-resistant organic wastewater. The photocatalyst disclosed by the invention is prepared by taking Fe-MoS2 as a basic material and using a low-temperature plasma modification method; the reaction is carried out at normal temperature and normal pressure, and secondary pollution is avoided by taking air as a medium; the method has the advantages of simple process and low comprehensive treatment cost. The modified photocatalyst has the advantages of high catalytic activity, strong stability, excellent electronic performance, excellent degradation effect and wide application.

Description

Technical Field

[0001] This invention relates to the field of photocatalyst preparation technology, specifically to a method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst. Background Technology

[0002] Fe-MoS2, as a novel photocatalytic material, has shown broad application prospects in the field of organic pollutant degradation due to its unique layered structure, suitable band gap width, and excellent electron transport performance. It can not only generate highly oxidizing active species through photocatalysis, but also achieve Fenton-like reactions to synergistically degrade pollutants by leveraging the valence state cycle of Fe, making it widely used in the treatment of recalcitrant antibiotic wastewater. However, Fe-MoS2 photocatalysts have some drawbacks: firstly, the strong van der Waals forces and high stacking density between MoS2 layers lead to insufficient exposure of active sites; secondly, Fe elements are easily dissolved from the crystal lattice, causing secondary pollution and reducing the photocatalyst's cycling stability; and thirdly, the high recombination rate of photogenerated electron-hole pairs limits further improvement in photocatalytic efficiency. These problems seriously affect the application effect of Fe-MoS2 in practical water treatment.

[0003] To further enhance the photocatalytic performance of Fe-MoS2, existing technologies employ modification methods such as elemental doping, morphology control, and semiconductor composites. However, these methods generally suffer from low reaction efficiency, complex processes, and the potential for secondary pollution. Low-temperature plasma modification technology, as an environmentally friendly polymerization technique, offers advantages such as mild reaction conditions, high controllability, and no secondary pollution. Dielectric barrier discharge, a type of low-temperature plasma technology, can achieve stable discharge at room temperature and pressure without requiring harsh conditions such as vacuuming, effectively optimizing the surface structure and electronic properties of photocatalytic materials. Summary of the Invention

[0004] To address the problems of insufficient active sites, Fe element leakage, high recombination rate of photogenerated carriers, and complex modification processes in existing Fe-MoS2 photocatalysts, this invention provides a method for preparing Fe-MoS2 photocatalysts by low-temperature plasma modification. This method is simple, environmentally friendly, and efficient, and can significantly improve the catalytic performance and stability of Fe-MoS2.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0007] (1) Fe-MoS2 pretreatment: Fe-MoS2 powder is evenly spread on the quartz medium plate in the low-temperature plasma modification device to ensure uniform sample thickness;

[0008] (2) Low-temperature plasma modification of Fe-MoS2: Using air as the discharge medium, the discharge power supply is turned on, the discharge power and modification time are adjusted, and low-temperature plasma modification treatment is carried out at room temperature and pressure.

[0009] (3) Post-processing of Fe-MoS2 modification: After the modification is completed, the power is turned off and the sample is collected after cooling to room temperature to obtain the modified Fe-MoS2 photocatalyst.

[0010] Furthermore, the low-temperature plasma modification device is a dielectric barrier discharge device. The discharge is powered by a high-frequency AC power supply, a microsecond pulse power supply, or a nanosecond pulse power supply.

[0011] Furthermore, the Fe-MoS2 involved in the modification in step (1) is prepared by hydrothermal synthesis, wherein the molar ratio of Fe to Mo is 0.03, the hydrothermal synthesis conditions are reaction at 200℃ for 24h, vacuum drying at 60℃ for 12h, and finally grinding to obtain Fe-MoS2 material.

[0012] Furthermore, in step (1), the dielectric material is a quartz glass plate with a thickness of 2 mm; the electrode sheet is an iron electrode or a copper electrode.

[0013] Furthermore, the discharge power in step (2) is 30-70W. Preferably, the discharge power in step (2) is 50-60W.

[0014] Furthermore, the modification time in step (2) is 1 to 10 minutes. Preferably, the modification time in step (2) is 3 to 5 minutes.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Structural optimization enhances catalytic activity: High-energy particle bombardment by low-temperature plasma loosens the interlayer stacking of Fe-MoS2, significantly increasing the specific surface area. At the same time, it induces the generation of S vacancies and nanoparticle attachment, exposing more active sites and promoting reactant adsorption and electron transfer.

[0017] 2. Inhibit Fe leakage and enhance stability: During the modification process, a FeOOH passivation layer is formed on the surface of Fe-MoS2, which effectively restricts the dissolution of Fe elements and reduces the leakage by 47.8%; the cycle stability is significantly better than that of the unmodified sample.

[0018] 3. Improve electronic performance and reduce recombination rate: Low-temperature plasma modification introduces MoO3 and MoS2 to form a pn heterojunction. At the same time, surface defect sites can capture photogenerated carriers, significantly reducing the electron-hole recombination rate, increasing photocurrent density, and reducing charge transfer impedance.

[0019] 4. The process is environmentally friendly, simple and efficient: the reaction is carried out at normal temperature and pressure, without the need for vacuum or high temperature and high pressure conditions, and uses air as the medium, so there is no secondary pollution; the process is simple and the overall treatment cost is low. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the tetracycline removal rate of Fe-MoS2 after five cycles in this invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in further detail below with reference to specific examples.

[0022] The numerical ranges in this invention should be understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended, meaning that they include but are not limited to.

[0024] Unless otherwise specified, the experimental methods used in this invention are all conventional methods.

[0025] Unless otherwise specified, all materials and reagents used in this invention can be purchased or synthesized by known methods.

[0026] The Fe-MoS2 used in this invention was prepared by hydrothermal synthesis: 14.2 mg of FeCl3·6H2O was accurately weighed as a dopant and dissolved in 10 mL of deionized water; 0.3089 g of (NH4)6Mo7O was also prepared. 24• 4H₂O and 0.4662 g CH₄N₂S were dissolved in 20 mL of deionized water and stirred continuously at 500 rpm for 10 min at room temperature, followed by sonication for 30 min until completely dissolved. The mixed solution was added dropwise to FeCl₃ solution on a magnetic stirrer, mixed thoroughly, and sonicated for 30 min before being transferred to a high-pressure reactor and hydrothermally treated at 200 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain a black precipitate. The precipitate was vacuum dried at 60 °C for 12 h and finally ground to obtain Fe-MoS₂ material.

[0027] In the quantitative experiments of this invention, each experiment was repeated three times, and the average value of the results was taken.

[0028] Example 1

[0029] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0030] (1) Fe-MoS2 pretreatment: Fe-MoS2 powder is evenly spread on the quartz medium plate in the low-temperature plasma modification device to ensure uniform sample thickness;

[0031] (2) Low-temperature plasma modification of Fe-MoS2: Using air as the discharge medium, the discharge power supply is turned on, the discharge power is 50W, and low-temperature plasma modification treatment is carried out at room temperature and pressure for 5min.

[0032] (3) Post-processing of Fe-MoS2 modification: After the modification is completed, the power is turned off and the sample is collected after cooling to room temperature to obtain the modified Fe-MoS2 photocatalyst.

[0033] Tetracycline degradation test: 75 mg / L of the modified Fe-MoS2 photocatalyst was added to 100 mL of a 20 mg / L tetracycline solution. The pH of the solution was adjusted to 5.53, and the mixture was stirred in the dark for 40 min to reach adsorption equilibrium. Then, 3 mM H2O2 was added, and the solution was irradiated with a 300 W xenon lamp (wavelength 400–1100 nm) for 40 min. The test results showed that the tetracycline removal rate was 88.7%.

[0034] Example 2

[0035] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0036] The discharge power was adjusted to 50W, and the low-temperature plasma modification treatment was carried out for 3 minutes. Other conditions were the same as in Example 1.

[0037] Tetracycline degradation test: The removal rate of tetracycline can reach 87.1%.

[0038] Example 3

[0039] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0040] The discharge power was adjusted to 60W, and the low-temperature plasma modification treatment was carried out for 3 minutes. Other conditions were the same as in Example 1.

[0041] Tetracycline degradation test: The removal rate of tetracycline can reach 87.1%.

[0042] Example 4

[0043] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0044] The discharge power was adjusted to 60W, the modification time was set to 5min, and other conditions were the same as in Example 1.

[0045] Tetracycline degradation test: The removal rate of tetracycline can reach 90.3%.

[0046] Example 5

[0047] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0048] Adjust the discharge power to 60W and set the modification time to 5min.

[0049] Catalyst recycling: After each catalytic test, the Fe-MoS2 catalyst is recovered using a vacuum filter, washed three times with deionized water, and then dried in a vacuum drying oven for later use.

[0050] Tetracycline degradation test: Other conditions were the same as in Example 1. The tetracycline removal rate is shown in Appendix. Figure 1 .

[0051] Example 6

[0052] A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst includes the following steps:

[0053] Adjust the discharge power to 60W and set the modification time to 5min.

[0054] Tetracycline degradation test: The solution pH was 4, and other conditions were the same as in Example 1. The removal rate of tetracycline reached 86.7%.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a low-temperature plasma-modified Fe-MoS2 photocatalyst, characterized in that, Includes the following steps: (1) Fe-MoS2 pretreatment: Fe-MoS2 powder is evenly spread on the quartz medium plate in the low-temperature plasma modification device to ensure uniform sample thickness; (2) Low-temperature plasma modification of Fe-MoS2: Using air as the discharge medium, the discharge power supply is turned on, the discharge power and modification time are adjusted, and low-temperature plasma modification treatment is carried out at room temperature and pressure. (3) Post-processing of Fe-MoS2 modification: After the modification is completed, the power is turned off and the sample is collected after cooling to room temperature to obtain the modified Fe-MoS2 photocatalyst.

2. The preparation method of the low-temperature plasma-modified Fe-MoS2 photocatalyst according to claim 1, characterized in that, The Fe-MoS2 in step (1) is prepared by hydrothermal synthesis, wherein the molar ratio of Fe to Mo is 0.03, the hydrothermal synthesis conditions are reaction at 200℃ for 24h, vacuum drying at 60℃ for 12h, and finally grinding to obtain Fe-MoS2 material.

3. The preparation method of the low-temperature plasma-modified Fe-MoS2 photocatalyst according to claim 1, characterized in that, The low-temperature plasma modification device is a dielectric barrier discharge device.

4. The preparation method of the low-temperature plasma-modified Fe-MoS2 photocatalyst according to claim 1, characterized in that, In step (1), the dielectric material is a quartz glass plate with a thickness of 2 mm; the electrode sheet is an iron or copper electrode.

5. The method for preparing the low-temperature plasma-modified Fe-MoS2 photocatalyst according to claim 1, characterized in that, The discharge power in step (2) is 30-70W.

6. The method for preparing the low-temperature plasma-modified Fe-MoS2 photocatalyst according to claim 1, characterized in that, The modification time in step (2) is 1-10 min.

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