WO2 / MoS2 heterojunction piezoelectric catalyst as well as preparation method and application thereof
By loading WO2 quantum dots on the surface of MoS2 nanoparticles, the problem of low separation efficiency of pure-phase MoS2 carriers is solved, and efficient separation of free carriers and rapid degradation of organic pollutants is achieved.
Patent Information
- Application Number
- CN202510417761.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-07-08
AI Technical Summary
The free carrier separation efficiency of pure phase MoS2 is not ideal, which makes its piezoelectric catalytic efficiency difficult to meet practical applications.
The WO2/MoS2 heterojunction piezoelectric catalyst was prepared, and the separation efficiency of free carriers was improved by loading WO2 quantum dots on the surface of MoS2 nanoparticles.
The separation efficiency of free carriers and the degradation performance of organic pollutants are significantly improved, especially the rapid degradation effect of dye pollutants.
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Figure CN120268423A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of piezoelectric catalysts, and in particular, to a WO2 / MoS2 heterojunction piezoelectric catalyst, a preparation method thereof, and an application thereof. Background Art
[0003] With the development of piezoelectronics, the degradation of organic pollutants under dark conditions has become possible by utilizing the piezoelectric effect of semiconductor piezoelectric materials, reducing the dependence on sunlight. In addition, when a semiconductor piezoelectric material is subjected to mechanical external force, opposite polarization charges will be generated on the surface of the semiconductor piezoelectric material, thereby driving the separation of free carriers and achieving the rapid degradation of organic pollutants. Among many piezoelectric materials, MoS2 stands out due to its simple preparation, non-toxicity, stable physical and chemical properties, and relatively high piezoelectric coefficient. However, the free carrier separation efficiency of pure-phase MoS2 is still not ideal, and the free carriers available for participating in the piezoelectric catalytic reaction are relatively low, making its piezoelectric catalytic efficiency difficult to meet practical applications. Summary of the Invention
[0004] The object of the present invention is to provide a WO2 / MoS2 heterojunction piezoelectric catalyst, a preparation method thereof, and an application thereof, which utilize the coupling effect of the polarization electric field generated by the piezoelectric effect and the interfacial electric field of the heterojunction to improve the separation efficiency of free carriers and promote the degradation of dye pollutants.
[0005] To achieve the above object, the present invention provides a WO2 / MoS2 heterojunction piezoelectric catalyst, comprising MoS2 nanoparticles, and WO2 quantum dots are loaded on the surface of the MoS2 nanoparticles.
[0006] Preferably, the mass of the WO2 quantum dots is 1.0% - 10.8% of the total mass of the piezoelectric catalyst.
[0007] The preparation method of the above WO2 / MoS2 heterojunction piezoelectric catalyst comprises the following steps:
[0008] S1. Prepare an aqueous solution of MoS2 nanoparticles and WO2 quantum dots;
[0009] S2. Mix the MoS2 nanoparticles, the aqueous solution of WO2 quantum dots, and deionized water, and perform ultrasonic loading;
[0010] S3. Separate, wash, dry, and pulverize the mixture after ultrasonic loading to obtain the WO2 / MoS2 heterojunction piezoelectric catalyst.
[0011] Preferably, in the S1, the preparation method of the MoS2 nanoparticles comprises:
[0012] S111. Mix sodium molybdate, thioacetamide and deionized water and carry out a hydrothermal reaction;
[0013] S112. After cooling to room temperature, separate, wash, dry and pulverize the hydrothermal reaction product to obtain MoS2 nanoparticle powder.
[0014] Preferably, in S111, the mass ratio of sodium molybdate to thioacetamide is (244.4 - 733.2):(227.7 - 683.0), the temperature of the hydrothermal reaction is 180°C - 200°C, and the heat preservation time is 12h - 24h;
[0015] In S112, the separation is centrifugal separation, the centrifugal speed is 5000rpm - 9000rpm, and the centrifugal time is 1min - 5min; the drying temperature is 50°C - 80°C, and the drying time is 6h - 24h.
[0016] Preferably, in S1, the preparation method of the WO2 quantum dot aqueous solution includes:
[0017] S121. Stir and mix sodium tungstate, L-cysteine and deionized water and carry out a hydrothermal reaction;
[0018] S122. After cooling to room temperature, separate the hydrothermal reaction product to obtain the WO2 quantum dot aqueous solution.
[0019] Preferably, in S121, the mass ratio of sodium tungstate to L-cysteine is (166.6 - 499.8):(122.4 - 367.2), the temperature of the hydrothermal reaction is 190°C - 210°C, the heat preservation time is 20h - 24h, and the stirring speed is 300rpm - 600rpm;
[0020] In S122, the separation is centrifugal separation, the centrifugal speed is 5000rpm - 10000rpm, and the centrifugal time is 5min - 15min.
[0021] Preferably, in S2, the ratio of MoS2 nanoparticles, WO2 quantum dot aqueous solution and deionized water is (30 - 50)mg:(0.5 - 1.5)mL:(1.5 - 0.5)mL; the power of ultrasonic is 100W - 300W, the frequency is 40kHz, and the time is 10min - 30min.
[0022] Preferably, in S3, the separation is centrifugal separation, the centrifugal speed is 5000rpm - 10000rpm, and the centrifugal time is 1min - 5min; the drying temperature is 50°C - 80°C, and the drying time is 6h - 24h.
[0023] The above WO2 / MoS2 heterojunction piezoelectric catalyst is used in piezoelectric catalysis.
[0024] The advantages and positive effects of the WO2 / MoS2 heterojunction piezoelectric catalyst, its preparation method and application according to the present invention are as follows:
[0025] 1. The WO2 / MoS2 heterojunction piezoelectric catalyst has MoS2 nanoparticles as the substrate, on which highly reactive WO2 quantum dots are loaded. By introducing WO2 quantum dots on the surface of the MoS2 piezoelectric catalyst, the number of efficient catalytic active sites is increased, promoting the adsorption and activation of reactants, thus significantly enhancing the generation efficiency of reactive oxygen species.
[0026] 2. The heterojunction interface electric field formed between WO2 and MoS2 has unique advantages. It can effectively drive the separation and migration of free electron-hole pairs. Therefore, compared with the original MoS2, the concentration of free carriers effectively driven by the piezoelectric field and participating in the piezoelectric catalytic reaction in the WO2 / MoS2 heterojunction piezoelectric catalyst is significantly increased, which provides strong support for the rapid degradation of dye pollutants.
[0027] 3. The synergistic effect between the interface electric field of the WO2 / MoS2 heterojunction and the MoS2 piezoelectric field can further promote the efficient separation of free carriers, significantly enhancing the organic pollutant degradation performance of the WO2 / MoS2 heterojunction piezoelectric catalyst.
[0028] 4. The present invention combines the hydrothermal method and the ultrasonic electrostatic assembly technology to efficiently synthesize the WO2 / MoS2 heterostructure piezoelectric catalyst, which not only saves time costs, but also the prepared heterostructure catalyst still retains excellent surface contact characteristics, effectively optimizing the transmission path of free carriers, realizing the efficient separation of free carriers inside MoS2, and significantly improving the efficiency of the piezoelectric catalytic reaction.
[0029] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and examples. Description of the Drawings
[0030] Figure 1 XRD patterns of MoS2, WO2 / MoS2-1, WO2 / MoS2-2, and WO2 / MoS2-3 prepared in Examples 1 to 3 of the present invention;
[0031] Figure 2 SEM images of MoS2 and WO2 / MoS2-1 prepared in Example 1 of the present invention;
[0032] Figure 3 Photocurrent and electrochemical impedance tests of MoS2 and WO2 / MoS2-2 prepared in Example 2 of the present invention;
[0033] Figure 4Degradation diagrams of MoS2, WO2 / MoS2-1, WO2 / MoS2-2, and WO2 / MoS2-3 prepared in Examples 1 to 3 of the present invention for rhodamine B under ultrasonic conditions (300 W, 40 kHz). Detailed implementation manners
[0034] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning derived from the content recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.
[0035] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings.
[0036] A WO2 / MoS2 heterojunction piezoelectric catalyst includes MoS2 nanoparticles, and WO2 quantum dots are loaded on the surface of the MoS2 nanoparticles.
[0037] The mass of the WO2 quantum dots is 1.0% to 10.8% of the total mass of the piezoelectric catalyst, preferably 7.2%.
[0038] The preparation method of the above WO2 / MoS2 heterojunction piezoelectric catalyst includes the following steps:
[0039] S1. Prepare an aqueous solution of MoS2 nanoparticles and WO2 quantum dots.
[0040] The preparation method of the MoS2 nanoparticles includes:
[0041] S111. Mix sodium molybdate, thioacetamide, and deionized water, and carry out a hydrothermal reaction.
[0042] The mass ratio of sodium molybdate to thioacetamide is (244.4 to 733.2):(227.7 to 683.0), preferably (488.8 to 733.2) mg:(455.3 to 683.0) mg, and most preferably 733.2 mg:683.0 mg. The volume of deionized water is 25 to 30 mL, preferably 30 mL.
[0043] Magnetic stirring is carried out during mixing, and the stirring speed is 300 rpm to 600 rpm.
[0044] The temperature of the hydrothermal reaction is 180°C to 200°C, preferably 200°C. The heat preservation time is 12 h to 24 h, more preferably 18 to 24 h, and most preferably 24 h.
[0045] The equipment used for the hydrothermal reaction is a high-pressure reaction kettle with a polytetrafluoroethylene inner lining.
[0046] After cooling to room temperature, the hydrothermal reaction product is separated, washed, dried, and pulverized to obtain MoS2 nanoparticle powder.
[0047] The separation is by centrifugation at a rotational speed of 5000 rpm to 9000 rpm, preferably 8000 rpm. The centrifugation time is 1 min to 5 min, preferably 2 min. The washing is carried out by washing 3 times each with deionized water and ethanol in sequence. The drying temperature is 50 °C to 80 °C, preferably 80 °C; the drying time is 6 h to 24 h, preferably 8 h. The pulverization method is grinding.
[0048] The preparation method of the WO2 quantum dot aqueous solution includes:
[0049] S121. Sodium tungstate, L-cysteine, and deionized water are stirred and mixed for hydrothermal reaction.
[0050] The mass ratio of sodium tungstate to L-cysteine is (166.6 - 499.8) mg : (122.4 - 367.2) mg, preferably (166.6 - 333.2) mg : (122.4 - 244.8) mg, and most preferably 166.6 mg : 122.4 mg.
[0051] The volume of deionized water is 25 - 30 mL, preferably 30 mL.
[0052] The temperature of the hydrothermal reaction is 190 °C to 210 °C, selected as 200 °C. The heat preservation time is 20 h to 24 h, preferably 24 h. The stirring rotational speed is 300 rpm to 600 rpm, preferably 500 rpm; there is no special limitation on the stirring time, and it is only necessary to make the raw materials mix evenly.
[0053] S122. After cooling to room temperature, the hydrothermal reaction product is separated to obtain the WO2 quantum dot aqueous solution.
[0054] The separation is by centrifugation at a rotational speed of 5000 rpm to 10000 rpm, preferably 9000 rpm; the centrifugation time is 5 min to 15 min, preferably 10 min.
[0055] S2. The MoS2 nanoparticles, the WO2 quantum dot aqueous solution, and deionized water are mixed for ultrasonic loading.
[0056] The ratio of MoS2 nanoparticles, the WO2 quantum dot aqueous solution, and deionized water is (30 - 50) mg : (0.5 - 1.5) mL : (1.5 - 0.5) mL, preferably 50 mg : 1.0 mL : 1.0 mL.
[0057] The power of the ultrasound is 100 W to 300 W, preferably 300 W; the frequency is 40 kHz, the time is 10 min to 30 min, preferably 20 - 30 min, and most preferably 20 min.
[0058] S3. Separate, wash, dry and pulverize the mixture after ultrasonic loading to obtain the WO2 / MoS2 heterojunction piezoelectric catalyst.
[0059] The separation is centrifugal separation, the centrifugal speed is 5000 rpm to 10000 rpm, preferably 8000 rpm. The centrifugal time is 1 min to 5 min, preferably 2 min. The washing is to wash 3 times with ethanol. The drying temperature is 50 °C to 80 °C, preferably 60 °C; the drying time is 6 h to 24 h, preferably 6 h. The pulverization method is grinding.
[0060] The above WO2 / MoS2 heterojunction piezoelectric catalyst is applied in piezoelectric catalysis. It is used for piezoelectric catalytic degradation of organic pollutants, and the organic pollutants are dye pollutants, and the dye pollutant is rhodamine B dye. The mass ratio of the WO2 / MoS2 heterojunction piezoelectric catalyst to rhodamine B dye is (10 - 50) mg : (0.25 - 1.0) mg, preferably 10 mg : 0.75 mg. The mass ratio of rhodamine B to water is 0.75 mg : 50 mL.
[0061] Example 1
[0062] Add 733.2 mg of sodium molybdate (purity 99.0%) and 683.0 mg of thioacetamide (purity 99.0%) to 30 mL of deionized water, and stir magnetically at 500 rpm at room temperature for 30 min. Subsequently, pour the solution into a 50 mL polytetrafluoroethylene-lined autoclave, heat to 200 °C, and keep warm for 24 h. After naturally cooling to room temperature, centrifuge the obtained black solid product at 8000 rpm for 2 min, and wash 3 times with deionized water and ethanol respectively. Finally, place the sample in an oven at 80 °C and keep warm for 8 h, and grind to obtain MoS2 powder.
[0063] Add 166.6 mg of sodium tungstate (purity 99.5%) and 122.4 mg of L-cysteine (purity 99.0%) to 30 mL of deionized water, and stir magnetically at 500 rpm at room temperature for 30 min. Subsequently, pour the solution into a 50 mL polytetrafluoroethylene-lined autoclave, heat to 200 °C, and keep warm for 24 h. After naturally cooling to room temperature, centrifuge the obtained solution at 9000 rpm for 10 min to obtain an aqueous solution of WO2 quantum dots.
[0064] 50 mg of MoS2, 0.5 mL of an aqueous solution of WO2 quantum dots, and 1.5 mL of deionized water were added to a 10 mL glass bottle and sonicated in an ultrasonic cleaner at 40 kHz and 300 W for 20 min to obtain a WO2 / MoS2 heterojunction piezoelectric catalyst (denoted as WO2 / MoS2-1).
[0065] Example 2
[0066] The difference between this example and Example 1 is only that the aqueous solution of WO2 quantum dots is 1.0 mL and the deionized water is 1.0 mL, obtaining WO2 / MoS2-2.
[0067] Example 3
[0068] The difference between this example and Example 1 is only that the aqueous solution of WO2 quantum dots is 1.5 mL and the deionized water is 0.5 mL, obtaining WO2 / MoS2-3, and the rest is the same as in Example 1.
[0069] Performance test
[0070] (1) X-ray diffraction (XRD) tests were performed on MoS2, WO2 / MoS2-1, WO2 / MoS2-2, and WO2 / MoS2-3 of Examples 1 to 3 of the present invention, and the results are as Figure 1 shown.
[0071] For the MoS2 sample, the characteristic peaks at 32.2° and 57.0° correspond to the (100) and (110) crystal planes of the 2H-MoS2 standard card (PDF#37-1492). Compared with the 2H-MoS2 standard card, the (002) peak of the MoS2 sample shifts to a higher angle (from 14.4° to 10.8°), which is attributed to the presence of partial 1T-MoS2 in the MoS2 sample, resulting in lattice distortion. For the WO2 / MoS2-1, WO2 / MoS2-2, and WO2 / MoS2-3 samples, a new characteristic peak appears at 26.3°, which matches the (011) crystal plane of the WO2 standard card (PDF#32-1393), indicating that the WO2 quantum dots are successfully loaded on the surface of MoS2 nanoparticles.
[0072] (2) Scanning electron microscopy (SEM) tests were performed on MoS2 and WO2 / MoS2-1 of Example 1 of the present invention, and the results are as Figure 2 shown.
[0073] As can be seen from Figure 2 (a), the microstructure of the MoS2 sample is composed of stacked nanoparticles with a rough surface. The rough surface morphology is expected to expose more odd-layer few-layer MoS2 nanosheets at the edges, thus showing a stronger piezoelectric response. As can be seen from Figure 2As can be seen from (b), since the WO2 quantum dots are relatively small in size, the microscopic morphology of the MoS2 sample does not change significantly after loading WO2 quantum dots.
[0074] (3) The photocurrent and electrochemical impedance tests were carried out on MoS2 and WO2 / MoS2-2 of Example 2 of the present invention on an electrochemical workstation CHI760E, and the results are as Figure 3 shown.
[0075] Compared with the MoS2 sample, the photocurrent of WO2 / MoS2-2 under illumination conditions is significantly increased ( Figure 3 (a)), and the charge transfer impedance is significantly reduced ( Figure 3 (b)), which indicates that the interfacial electric field of the WO2 / MoS2 heterojunction can act as an internal driving force to drive the separation and transport of free carriers, significantly increasing the concentration of free carriers participating in the catalytic reaction, thereby improving the degradation efficiency of organic pollutants.
[0076] (4) The piezoelectric catalytic degradation tests of MoS2, WO2 / MoS2-1, WO2 / MoS2-2 and WO2 / MoS2-3 samples of Examples 1-3 of the present invention on rhodamine B were carried out under ultrasonic conditions (300 W, 40 kHz). The specific experimental process was as follows: The piezoelectric catalytic performance of the samples was evaluated by degrading a 15 mg / L rhodamine B solution; during the experiment, 10 mg of the sample was dispersed in 50 mL of the rhodamine B solution, and stirred for 30 min under dark conditions to eliminate the influence of dye adsorption; then, the degradation experiment was carried out under ultrasonic conditions. Every 10 min, 4 mL of the sample was taken, the supernatant was retained after high-speed centrifugation, and the absorbance of the supernatant was detected. The results are as Figure 4 shown.
[0077] As can be seen from Figure 4 (a), compared with the original MoS2, the WO2 / MoS2 heterojunction piezoelectric catalyst has excellent piezoelectric catalytic degradation activity; after 60 min of ultrasonic irradiation, the degradation rates of MoS2, WO2 / MoS2-1, WO2 / MoS2-2 and WO2 / MoS2-3 samples are 56.2%, 73.8%, 91.0% and 73.5% respectively; among them, WO2 / MoS2-2 has the most excellent piezoelectric catalytic degradation performance.
[0078] As can be seen from Figure 4 (b), the degradation rates of MoS2, WO2 / MoS2-1, WO2 / MoS2-2 and WO2 / MoS2-3 samples are 0.012 min -1 , 0.021 min -1 , 0.042 min -1 and 0.020 min -1; among them, WO2 / MoS2-2 has the fastest piezoelectric catalytic degradation rate.
[0079] Therefore, by using the WO2 / MoS2 heterojunction piezoelectric catalyst, its preparation method and application described in the present invention, the coupling effect of the polarization electric field generated by the piezoelectric effect and the interfacial electric field of the heterojunction is utilized to improve the separation efficiency of free carriers and promote the degradation of dye pollutants.
[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A WO2 / MoS2 heterojunction piezoelectric catalyst, characterized in that: It includes MoS2 nanoparticles, and WO2 quantum dots are loaded on the surface of the MoS2 nanoparticles.
2. The WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 1, wherein: The mass of the WO2 quantum dots is 1.0% - 10.8% of the total mass of the piezoelectric catalyst.
3. A method for preparing the WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 1 or 2, characterized in that, It includes the following steps: S1. Prepare an aqueous solution of MoS2 nanoparticles and WO2 quantum dots; S2. Mix the MoS2 nanoparticles, the aqueous solution of WO2 quantum dots, and deionized water, and perform ultrasonic loading; S3. Separate, wash, dry, and pulverize the mixture after ultrasonic loading to obtain a WO2 / MoS2 heterojunction piezoelectric catalyst.
4. The preparation method of a WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 3, wherein: In S1, the preparation method of the MoS2 nanoparticles includes: S111. Mix sodium molybdate, thioacetamide, and deionized water, and perform a hydrothermal reaction; S112. After cooling to room temperature, separate, wash, dry, and pulverize the hydrothermal reaction product to obtain MoS2 nanoparticle powder.
5. The preparation method of a WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 4, characterized in that: In S111, the mass ratio of sodium molybdate to thioacetamide is (244.4 - 733.2):(227.7 - 683.0), the temperature of the hydrothermal reaction is 180°C - 200°C, and the heat preservation time is 12h - 24h; In S112, the separation is centrifugal separation, the centrifugal rotation speed is 5000rpm - 9000rpm, the centrifugal time is 1min - 5min; the drying temperature is 50°C - 80°C, and the drying time is 6h - 24h.
6. The preparation method of a WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 3, wherein: In S1, the preparation method of the aqueous solution of WO2 quantum dots includes: S121. Stir and mix sodium tungstate, L-cysteine, and deionized water, and perform a hydrothermal reaction; S122. After cooling to room temperature, separate the hydrothermal reaction product to obtain an aqueous solution of WO2 quantum dots.
7. The preparation method of a WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 6, characterized in that: In S121, the mass ratio of sodium tungstate to L-cysteine is (166.6 - 499.8):(122.4 - 367.2), the temperature of the hydrothermal reaction is 190°C - 210°C, the heat preservation time is 20h - 24h, and the stirring rotation speed is 300rpm - 600rpm; In S122, the separation is centrifugal separation, the centrifugal rotation speed is 5000rpm - 10000rpm, and the centrifugal time is 5min - 15min.
8. The preparation method of a WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 3, characterized in that: In S2, the ratio of MoS2 nanoparticles, the aqueous solution of WO2 quantum dots, and deionized water is (30 - 50)mg:(0.5 - 1.5)mL:(1.5 - 0.5)mL; the power of ultrasonic treatment is 100W - 300W, the frequency is 40kHz, and the time is 10min - 30min.
9. The preparation method of a WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 3, characterized in that: In S3, the separation is centrifugal separation, the centrifugal rotation speed is 5000rpm - 10000rpm, the centrifugal time is 1min - 5min; the drying temperature is 50°C - 80°C, and the drying time is 6h - 24h.
10. The application of the WO2 / MoS2 heterojunction piezoelectric catalyst according to claim 1 or 2 in piezoelectric catalysis.