Preparation method of bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial and application thereof

Abstract

The application relates to a preparation method and application of a bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial. The application aims to solve the problems of low sensitivity and long recovery time of an existing Bi2S3 material in NO2 detection at room temperature. The application adopts a simple hydrothermal synthesis method to prepare a Bi2S3 / MoS2 composite nanomaterial by taking sodium molybdate, bismuth nitrate pentahydrate and thiourea as main raw materials. In the prepared Bi2S3 / MoS2 composite nanomaterial, Bi2S3 is in a nanowire structure, MoS2 is in a nanosheet structure, and the two structures are in close contact to form a composite material. The NO2 gas sensor prepared based on the composite nanomaterial has the characteristics of high sensitivity, fast response and room temperature operation, and the application can be applied to the field of gas sensors.

Description

Technical Field

[0001] This invention relates to a method for preparing bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials and their applications. Background Technology

[0002] Bi₂S₃ nanomaterials possess excellent physicochemical properties, such as high carrier mobility (~10⁻⁶). 3 cm 2 V -1 s -1 With its adjustable band structure (1.3–1.7 eV), it has been widely used in photocatalysis, gas sensing, energy storage, medical and environmental protection fields.

[0003] The structural characteristics of Bi2S3 materials significantly influence their functional properties. For example, fabricating characteristic structures such as nanowires, nanorods, and hierarchical structures can effectively improve their performance. Currently, Bi2S3 can be used as a gas-sensitive material to detect NO2 at room temperature, but its low sensitivity and long recovery time limit its application in the field of NO2 sensing. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low sensitivity and long recovery time of existing Bi2S3 materials when detecting NO2 at room temperature, and to provide a method for preparing bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials and their applications.

[0005] This invention discloses a method for preparing bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials, which comprises the following steps:

[0006] 1. Add Bi(NO3)3·5H2O to deionized water, stir, then add Na2MoO4, continue stirring, then add thiourea, and continue stirring to obtain the reaction solution; the mass-volume ratio of Bi(NO3)3·5H2O, Na2MoO4, thiourea and deionized water is (40-80)mg:(10-50)mg:(110-150)mg:40mL;

[0007] II. Hydrothermal reaction: Transfer the reaction solution to a reaction vessel and react at 180-220℃ for 19-29 hours to obtain the reaction product;

[0008] 3. Cleaning: Centrifuge the reaction product, then clean the solid phase obtained by centrifugation, and then vacuum dry to obtain composite nanomaterials.

[0009] This invention relates to the application of bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials as gas-sensitive materials for NO2 gas sensors.

[0010] Constructing heterojunctions is a major method for improving the functional properties of materials. Layered MoS2 nanomaterials possess high specific surface area, narrow band gap, and excellent optoelectronic properties. Therefore, this invention constructs a Bi2S3 / MoS2 heterojunction to enhance NO2 sensitivity.

[0011] The beneficial effects of this invention are:

[0012] (1) The preparation method involved in this invention has the advantages of being simple, having high yield, good reproducibility, and low environmental pollution;

[0013] (2) The novel Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial of the present invention can effectively reduce material agglomeration, and the proportion of MoS2 in the composite nanomaterial can be adjusted by changing the amount of Na2MoO4 added in the reaction solution.

[0014] (3) A novel Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial of the present invention can effectively improve the NO2 sensitivity performance at room temperature. The gas sensor prepared therefrom exhibits excellent NO2 sensitivity performance at room temperature, with a measurement range of 50 ppb to 10 ppm;

[0015] (4) The response time of the Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial to 1ppm NO2 is 13-15s, and the recovery time is 29s. The calculated sensitivity of the Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial sensor is 21.3. Attached Figure Description

[0016] Figure 1 SEM image of the Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial prepared in Example 1;

[0017] Figure 2 The energy spectrum of the Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial prepared in Example 1 is shown below.

[0018] Figure 3 The image shows the XRD pattern of the Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial prepared in Example 1.

[0019] Figure 4 SEM images of the Bi2S3 nanowire nanomaterials prepared in Example 1 for comparison;

[0020] Figure 5 The image shows the dynamic test curve of NO2 concentration at 1 ppm obtained from the gas sensor prepared in Example 2.

[0021] Figure 6 To compare the dynamic test curve of NO2 concentration at 1 ppm prepared by the gas sensor in Example 2;

[0022] Figure 7 This is the dynamic test curve of NO2 concentration of the gas sensor obtained in Example 2. Detailed Implementation

[0023] Specific Implementation Method 1: This implementation method describes a method for preparing a bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial, which is carried out according to the following steps:

[0024] 1. Add Bi(NO3)3·5H2O to deionized water, stir, then add Na2MoO4, continue stirring, then add thiourea, and continue stirring to obtain the reaction solution; the mass-volume ratio of Bi(NO3)3·5H2O, Na2MoO4, thiourea and deionized water is (40-80)mg:(10-50)mg:(110-150)mg:40mL;

[0025] II. Hydrothermal reaction: Transfer the reaction solution to a reaction vessel and react at 180-220℃ for 19-29 hours to obtain the reaction product;

[0026] 3. Cleaning: Centrifuge the reaction product, then clean the solid phase obtained by centrifugation, and then vacuum dry to obtain composite nanomaterials.

[0027] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the stirring rate in step one is 1000 rpm. Everything else is the same as in Specific Implementation Method One.

[0028] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: in step 1, Bi(NO3)3·5H2O is added to deionized water and stirred for 30 minutes. Everything else is the same as in Specific Implementation Method 1 or 2.

[0029] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: after adding Na2MoO4 in step one, stirring continues for 30 minutes. Everything else is the same as in Specific Implementation Methods One to Three.

[0030] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: thiourea is added in step one, and stirring is continued for 60 minutes. Everything else is the same as in Specific Implementation Methods One to Four.

[0031] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step three, cleaning refers to sequentially cleaning with anhydrous ethanol and deionized water, with the number of cleaning cycles being ≥3. Everything else is the same as in Specific Implementation Methods One to Five.

[0032] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that step three involves vacuum drying at 40-80℃ for 12 hours. Everything else is the same as in Specific Implementation Methods One to Six.

[0033] Specific Implementation Method 8: This implementation method describes the application of bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials as gas-sensitive materials for NO2 gas sensors.

[0034] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the preparation method of the bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial as the gas-sensitive material for a NO2 gas sensor is as follows:

[0035] Bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials were dispersed in deionized water to obtain a dispersion of the composite nanomaterials. This dispersion was then coated onto interdigitated electrodes to form a NO2 gas-sensitive film. The film was then vacuum-dried at 60°C for 2 hours to obtain an NO2 gas sensor based on the Bi2S3 nanowires / MoS2 nanosheets composite nanomaterials. Other procedures are the same as in Specific Embodiment Eight.

[0036] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Eight or Nine in that the concentration of the dispersion is 1 mg / mL. Everything else is the same as in Specific Implementation Methods Eight or Nine.

[0037] The following experiments were conducted to verify the beneficial effects of the present invention:

[0038] Example 1 This example describes a method for preparing Bi2S3 nanowire / MoS2 nanosheet composite nanomaterials, which is carried out according to the following steps:

[0039] I. Preparation of reaction solution: Add 60 mg of Bi(NO3)3·5H2O to 40 mL of deionized water and stir at 1000 rpm for 30 minutes; then add 30 mg of Na2MoO4 and stir for another 30 minutes; then add 140 mg of thiourea and continue stirring for 60 minutes to form the reaction solution.

[0040] II. Hydrothermal reaction: Transfer the reaction solution from step one to a 100mL reactor and react at 210℃ for 24 hours.

[0041] 3. Cleaning: Centrifuge the reaction product from step 2, then wash the solid obtained by centrifugation with ethanol 3 times and deionized water 3 times, and then vacuum dry at 60°C for 12 hours to obtain composite nanomaterials.

[0042] Comparative Example 1: A method for preparing Bi2S3 nanowires is carried out according to the following steps:

[0043] I. Preparation of reaction solution: Add 60 mg of Bi(NO3)3·5H2O to 40 mL of deionized water and stir at 1000 rpm for 30 minutes; then add 140 mg of thiourea and continue stirring for 60 minutes to form the reaction solution.

[0044] II. Hydrothermal reaction: Transfer the reaction solution from step one to a 100mL reactor and react at 210℃ for 24 hours.

[0045] 3. Cleaning: Centrifuge the reaction product obtained in step 2, then wash the solid obtained by centrifugation with ethanol 3 times and deionized water 3 times. The precipitate is vacuum dried at 60°C for 12 hours to obtain Bi2S3 nanowires.

[0046] The Bi₂S₃ nanowire / MoS₂ nanosheet composite nanomaterial prepared in Example 1 was observed using scanning electron microscopy. Figure 1 As shown, from Figure 1 As can be seen, the prepared composite nanomaterial consists of Bi₂S₃ nanowires and MoS₂ nanosheets. The Bi₂S₃ nanowires are approximately 50 nm in diameter and 800 nm in length. The Bi₂S₃ nanowires are attached to the surface of the MoS₂ nanosheets, forming a compact heterostructure. The energy dispersive spectroscopy (EDS) spectrum of the composite nanomaterial is shown below. Figure 2 As shown, from Figure 2 As can be seen from the image, the prepared composite nanomaterial is composed of Bi, S, and Mo elements, proving the successful preparation of the composite nanomaterial. The XRD pattern of the composite nanomaterial is shown below. Figure 3 As shown, from Figure 3 As can be seen, the prepared Bi2S3 conforms to the JCPDS NO.17-0320 standard card, and the prepared MoS2 nanosheets conform to the JCPDS NO.037-1492 standard card.

[0047] Scanning electron microscopy was performed on the Bi2S3 nanowires prepared in Comparative Example 1, as shown in the following figures. Figure 4 As shown, from Figure 4 As can be seen, the prepared Bi2S3 nanomaterials exhibit a nanowire structure, which is the same as the Bi2S3 structure in the composite material. Figure 4 No MoS2 nanosheet structure was observed.

[0048] Example 2: The Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial prepared in Example 1 was used as a sensitive material for an NO2 gas sensor, as detailed below:

[0049] 10 mg of Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial was ultrasonically dispersed in 10 mL of deionized water to form a sensitive solution with a concentration of 1 mg / mL. 10 μL of the solution was coated onto an interdigital electrode (7 × 14 mm) to form a gas-sensitive film. The film was then vacuum dried at 60 °C to obtain a NO2 gas sensor based on Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial.

[0050] Comparative Example 2: The Bi2S3 nanowire nanomaterials prepared in Comparative Example 1 were used as a sensitive material for an NO2 gas sensor, as detailed below:

[0051] 10 mg of Bi2S3 nanowire material was ultrasonically dispersed in 10 mL of deionized water to form a solution with a concentration of 1 mg / mL. 10 μL of the solution was coated onto an interdigital electrode (7 × 14 mm) to form a gas-sensitive film. The film was then vacuum dried at 60 °C to obtain a NO2 gas sensor based on Bi2S3 nanowires.

[0052] The gas sensors prepared in Example 2 and Comparative Example 2 were tested for NO2 sensitivity at a concentration of 1 ppm. Figure 5 The figure shows the dynamic test curve of NO2 concentration at room temperature using a Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial sensor; Figure 6 The figure shows the dynamic test curve of NO2 concentration at room temperature using a Bi2S3 nanowire nanomaterial sensor. From... Figure 5 The response time of the Bi₂S₃ nanowire / MoS₂ nanosheet composite nanomaterial to a 1 ppm NO₂ concentration is 13–15 s, and the recovery time is 29 s. The calculated sensitivity of the Bi₂S₃ nanowire / MoS₂ nanosheet composite nanomaterial sensor is 21.3. Figure 6 The response time of Bi₂S₃ nanowire nanomaterials to 1 ppm NO₂ concentration is 20–21 s, and the recovery time is 131–133 s. The calculated sensitivity of the Bi₂S₃ nanowire nanomaterial sensor is 9.5. Comparison with experimental structures shows that the addition of MoS₂ nanosheets significantly improves the NO₂ sensitivity of Bi₂S₃ nanowires.

[0053] The dynamic NO2 sensing characteristics of the Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial sensor prepared in Example 2 were detected, and the results were as follows: Figure 7The NO2 concentration dynamic test curve is shown. This Bi2S3 nanowire / MoS2 nanosheet composite nanomaterial sensor features high sensitivity and room temperature operation, enabling NO2 detection in the concentration range of 50 ppb to 10 ppm. Gas sensors based on Bi2S3 nanowire / MoS2 nanosheet composite nanomaterials have promising application prospects.

Claims

1. A method for preparing a bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial, characterized in that... The preparation method is carried out according to the following steps:

1. Add Bi(NO3)3•5H2O to deionized water, stir for 30 min, then add Na2MoO4, stir for another 30 min, then add thiourea, and stir for another 60 min to obtain the reaction solution; the mass-volume ratio of Bi(NO3)3•5H2O, Na2MoO4, thiourea and deionized water is (40-80) mg: (10-50) mg: (110-150) mg: 40 mL; II. Hydrothermal reaction: Transfer the reaction solution to a reaction vessel and react at 180-220℃ for 19-29 hours to obtain the reaction product; 3. Cleaning: Centrifuge the reaction product, then clean the solid phase obtained by centrifugation, and then vacuum dry to obtain composite nanomaterials.

2. The method for preparing a bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial according to claim 1, characterized in that... The stirring speed in step one is 1000 rpm.

3. The method for preparing a bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial according to claim 1, characterized in that... The cleaning process in step three refers to washing with anhydrous ethanol and deionized water in sequence, with the number of cleaning cycles being ≥3.

4. The method for preparing a bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial according to claim 1, characterized in that... Step 3 involves vacuum drying at 40-80℃ for 12 hours.

5. The application of the bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial prepared as described in claim 1 as a gas-sensitive material for NO2 gas sensors.

6. The application according to claim 5, characterized in that... The preparation method of bismuth trisulfide nanowires / molybdenum disulfide nanosheets composite nanomaterials as gas-sensitive materials for NO2 gas sensors is as follows: The bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial was dispersed in deionized water to obtain a dispersion of the composite nanomaterial. The dispersion of the composite nanomaterial was coated onto an interdigitated electrode to form a NO2 gas sensitive film on the interdigitated electrode. Then, it was vacuum dried at 60°C for 2 h to obtain an NO2 gas sensor based on the bismuth trisulfide nanowire / molybdenum disulfide nanosheet composite nanomaterial.

7. The application according to claim 5, characterized in that... The concentration of the dispersion is 1 mg / mL.

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