One-step preparation of two-dimensional BiOxSy material and application of two-dimensional BiOxSy material in gas sensor
By using the one-step ultrasonic treatment method in solid-liquid systems, the problems of high detection limit and low room temperature sensitivity of bismuth-based materials for nitrogen dioxide sensors are solved, and the NO2 gas with high sensitivity and low detection limit are achieved Sensitive sensor.
Patent Information
- Application Number
- CN202411549072.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-01
- Publication Date
- 2025-02-14
AI Technical Summary
When existing bismuth-based materials are used in nitrogen dioxide sensors, the detection limit is high and the sensitivity is low at room temperature, which cannot meet the market's requirements for reliable detection of NO2.
Two-dimensional BiOxSy materials were prepared by a one-step method using ultrasonic treatment in a solid-liquid system, adjusting their oxygen-sulfur ratio to improve the electronic structure and thus improving the gas-sensitive response.
Under room temperature and violet excitation conditions, the prepared gas-sensitive sensor has the highest gas-sensitive response and the lowest detection limit, the best gas-sensitive response to NO2, with good repeatability and recovery.
Smart Images
Figure CN119430278A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of gas sensors, in particular to a two-dimensional BiO x S y One-step preparation of materials and their application in gas sensors. Background Art
[0002] NO 2 Gas is an important source of environmental pollution, which seriously harms human health and hinders the sustainable development of society. 2 Sensors are of great significance for environmental monitoring and human health protection. 2 The existing detection equipment has problems such as high operating temperature, low response signal, slow response speed and poor detection signal stability, which cannot meet the market demand for NO 2 To achieve the requirement of reliable detection. For example, various gas sensors based on conductors and semiconductors have been widely studied. Most of the more mature gas sensors based on metal oxides need to work in high temperature environments. Bismuth-based materials are also a type of gas-sensitive material that can be used to prepare nitrogen dioxide sensors. The existing reported nitrogen dioxide sensors made of bismuth-based materials have high detection limits and low sensitivity at room temperature. Summary of the invention
[0003] In view of the problems that the existing bismuth-based materials have high detection limits and low sensitivity at room temperature when used in nitrogen dioxide sensors, the present invention provides a one-step method for preparing two-dimensional BiO x S y Materials methods and their application in nitrogen dioxide sensors.
[0004] The present invention provides a one-step method for preparing two-dimensional BiO x S y The materials and methods are as follows:
[0005] First, bismuth metal particles with a particle size of 1-3 mm are dispersed in Na 2 S solution to form a dispersion, keep the dispersion at 80-90°C for 1-3 hours under bath ultrasound, and then centrifuge at a speed of 3000-4000 rpm to remove the precipitate; centrifuge the obtained supernatant at a speed of 10000-13000 rpm for 30 minutes to obtain the exfoliated two-dimensional BiO x S y Nanosheets. Two-dimensional BiO obtained by exfoliation x S y The nanosheets were further washed several times in ethanol solution.
[0006] Among them, the Na 2S solution is composed of Na 2 S·9H 2 O is dissolved in ethanol solution.
[0007] Preferably, in Na 2 In S solution, Na 2 S·9H 2 The concentration of O is 0.1-0.5 mol / L.
[0008] Preferably, the ethanol solution is an ethanol aqueous solution in which ethanol accounts for 25% by volume.
[0009] Preferably, in the dispersion, the amount of metallic bismuth added is 2 Add 0.1-0.15 g of metallic bismuth to the S solution.
[0010] The two-dimensional BiO prepared by the above method x S y Nanosheets are mainly used to prepare gas sensors. Especially for the preparation of NO 2 Gas sensor for concentration. x S y The nanosheets are dispersed in an ethanol solution, and then the dispersion is dropped on the interdigital electrodes to produce a gas sensor.
[0011] Compared with the prior art, the present invention is beneficial in that:
[0012] (1) The present invention provides a one-step method for synthesizing two-dimensional bismuth oxysulfide by ultrasonic treatment in a solid-liquid system. The principle of the method is that when solid bismuth is ultrasonically treated in a pure water environment, an extremely thin oxyhydroxide layer is formed on the bismuth surface by reacting with oxygen and water molecules; the introduction of dissolved hydrogen sulfide helps to convert bismuth oxyhydroxide into sulfide. Importantly, the lattice mismatch between the surface layer and the interior of pure bismuth allows the exfoliation of two-dimensional bismuth oxyhydroxide and sulfide nanosheets. By adjusting the oxygen-sulfur ratio in the two-dimensional bismuth oxysulfide, its electronic structure, including the band gap, work function and energy band position, can be effectively adjusted, greatly improving its application in photoelectric gas detection.
[0013] (2) Using two-dimensional BiO x S y The gas sensor prepared by the nanosheet has the highest gas sensitive response under room temperature and violet light excitation conditions; compared with the reported bismuth compound-based NO 2 Compared with other common gases, this gas sensor has the lowest detection limit for NO 2 It has the best gas sensitive response with good repeatability and recoverability.
[0014] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 The BiO prepared in Example 1 0.61 S 0.94 Characterization images of the nanosheets, where (a) is an AFM image, (b) is a TEM image with the corresponding EDS mapping, (c) is a HRTEM image with the corresponding FFT pattern, and (d) is an XPS spectrum of the Bi 4f region.
[0016] Figure 2 BiO 0.61 S 0.94 Gas sensor performance test diagram. (a) shows the performance of 100ppb NO under different light conditions. 2 (b) is the sensor response to different NO under violet light irradiation. 2 Dynamic gas response of NO concentration, (c) 250 ppb NO under violet light activation at room temperature 2 (d) is the repeatability of the sensor, and (d) is the selectivity of the sensor to different gas types. DETAILED DESCRIPTION
[0017] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0018] Example 1
[0019] A method for preparing two-dimensional BiO 0.61 S 0.94 The materials and methods are as follows:
[0020] First, 5 g of metallic bismuth particles with an average particle size of 2 mm were dispersed in 40 ml of Na 2 S solution to obtain a dispersion; the Na 2 S solution is composed of Na 2 S·9H 2 O is dissolved in ethanol solution, Na 2 The S concentration is 0.1 mol / L, and the ethanol solution is an ethanol aqueous solution with an ethanol volume ratio of 25%. Then, the dispersion is kept in a bath ultrasonic bath at 80-90°C for 2 hours; then, the dispersion is centrifuged in a centrifuge at a speed of 4000 rpm for 30 minutes to separate the precipitate; the supernatant obtained by centrifugation is further centrifuged at a speed of 12000 rpm for 30 minutes, and BiO is obtained by high-speed centrifugal stripping. 0.61 S 0.94The nanosheets were washed with ethanol solution for three times, and the clean nanosheets were collected for subsequent material characterization and gas sensing tests.
[0021] The BiO prepared in Example 1 0.61 S 0.94 The nanosheets were characterized and tested for gas sensing as follows:
[0022] (1) The product prepared in Example 1 was characterized by atomic force microscopy. Figure 1 As shown in (a), it can be seen that the thickness of the nanosheet is 2.657 nm, which indicates that the preparation method of the present invention successfully exfoliates the two-dimensional material. Figure 1 (b) is a TEM image with corresponding EDS mapping of Example 1. Through TEM and corresponding EDS characterization and analysis, it was found that Bi, O, and S elements existed in the nanosheets and were evenly distributed, proving that the S element had been successfully introduced. Figure 1 (c) is a HRTEM image with corresponding FFT mode of Example 1. HRTEM and corresponding FET show that the lattice spacing is 0.28nm, which may be due to the replacement of some O atoms by S atoms to increase the lattice spacing. In addition, XPS spectrum analysis was also performed on the product of Example 1 to reveal the chemical composition of bismuth oxysulfide. The results are shown in FIG. Figure 1 (d) The peaks at 160.52 and 161.80 eV are attributed to the S2p of the S-Bi bond. 3 / 2 and S2p 1 / 2 The peaks at 158.04 and 163.32 eV are attributed to the Bi 4f 7 / 2 and Bi 4f 5 / 2 The peaks at 158.66 and 164.0 eV correspond to the Bi 4f 7 / 2 and Bi 4f 5 / 2 The peak area ratio of Bi-S to Bi-O is 1:0.6, which proves that in 0.1 mol / L Na 2 The bismuth oxysulfide compound synthesized in S is BiO 0.61 S 0.94 .
[0023] (2) Gas sensor test:
[0024] The two-dimensional BiO prepared in Example 1 0.61 S 0.94 Dispersed in 25% ethanol aqueous solution to obtain a dispersion in which the two-dimensional BiO x S y The concentration was 0.02 mg / mL; then 40 μL of the dispersion was dripped onto the interdigital electrodes with a spacing of 10 μm at 45 °C to prepare BiO 0.61 S 0.94Gas sensor. Gas sensing measurements were performed at room temperature and under violet light with a wavelength of 405 nm. The resistance of the sensor was measured using a Tektronix DMM 4040 digital multimeter. The total gas flow rate into the chamber was maintained at 200 standard cubic centimeters per minute (sccm) and was controlled by a high-precision mass flow controller. The gas-sensitive response was defined as (R 0 -R g ) / R g × 100%, where R 0 and R g Represents the device in N 2 The resistance in the balance gas and analysis gas is shown in the test results. Figure 2 . Figure 2 (a) shows BiO 0.61 S 0.94 NO gas sensor under different lighting environments 2 Gas sensor resistance curve. In a dark environment without any light, the base resistance is the highest among all sensors, the gas response is 39.2%, and the recovery is incomplete. When light is introduced into the environment, due to the photoexcitation of carriers and NO 2 The sensor's base resistance decreases and fully recovers after photodesorption of the molecules. The sensor has the best gas response under violet light (149.1%) compared to blue light (89.8%) and ultraviolet light (26.7%). The reduction in gas response in ultraviolet light may be due to the excessive carrier density suppressing the exciton lifetime and, more importantly, the high light energy leads to an acceleration of the photodesorption rate, which results in NO 2 The effective adsorption of molecules is reduced.
[0025] The present invention further studies BiO 0.61 S 0.94 Gas sensing performance of gas sensors under room temperature violet light irradiation, such as Figure 2 As shown in (b), for 10, 50, 100, 150, 200 and 250 ppb NO 2 The dynamic gas responses of 17.4%, 60.6%, 149.1%, 181.0%, 199.4% and 212.0% were achieved at 200 ℃ and 100 ℃ respectively, and the response amplitudes were well consistent with the classical Langmuir isotherm model. 2 Compared with gas sensors, BiO 0.61 S 0.94 The gas sensor has the lowest detection limit. Figure 2 (c) shows BiO 0.61 S 0.94 Gas sensor for 250ppb NO 2 Repeatability under room temperature violet light irradiation. After five consecutive test cycles, the change in the gas response amplitude is negligible, indicating that BiO0.61 S 0.94 The gas sensor has good repeatability. 0.61 S 0.94 The selectivity test results of gas sensors for various common gases are as follows: Figure 2 (d) As shown. It can be concluded that the BiO 0.61 S 0.94 Gas sensor for 250ppb NO 2 The response is at least to 50 ppm H 2 S, 50ppm SO 2 , 500ppm CO, 1% H 2 , 0.1% CO 2 and 1% CH 4 This shows that BiO 0.61 S 0.94 Gas sensor for NO 2 This may be due to the excellent selectivity of NO 2 In BiO 0.61 S 0.94 The affinity on the surface is stronger, NO 2 Molecules and BiO 0.61 S 0.94 The electronic band positions of the two are well matched, which shows that the BiO 0.61 S 0.94 Gas sensor can be used to selectively detect low concentrations of NO 2 .
[0026] In summary, the present invention obtains two-dimensional BiO by a one-step method of ultrasonic treatment in a solid-liquid reaction system. x S y Nanosheets, and two-dimensional BiO x S y Gas sensor. It has the highest gas sensitive response under room temperature and violet light excitation conditions. Compared with the reported bismuth compound-based NO 2 Compared with other common gases, this gas sensor has the lowest detection limit for NO 2 It has the best gas sensitive response with good repeatability and recoverability.
[0027] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.
Claims
1. A method for preparing two-dimensional BiO x S y A method of material, characterized in that The method is prepared by a one-step method. Bismuth metal particles are dispersed in a Na2S solution to form a dispersion. The dispersion is kept at 80-90°C for 1-3 hours in a bath type ultrasonic bath. The dispersion is then centrifuged to remove the precipitate. The obtained supernatant is centrifuged at a speed of 10000-13000 rpm for 30 minutes to obtain the exfoliated two-dimensional BiO x S y Nanosheets.
2. Preparation of two-dimensional BiO as claimed in claim 1 x S y A method of material, characterized in that The Na2S solution is prepared by dissolving Na2S·9H2O in an ethanol solution.
3. Preparation of two-dimensional BiO as claimed in claim 2 x S y A method of material, characterized in that In the Na2S solution, the concentration of Na2S·9H2O is 0.1-0.5 mol / L.
4. Preparation of two-dimensional BiO as claimed in claim 2 x S y A method of material, characterized in that The ethanol solution is an ethanol aqueous solution in which ethanol accounts for 25% by volume.
5. The method for preparing two-dimensional BiO as claimed in claim 1 x S y A method of material, characterized in that The particle size of the metal bismuth particles is 1-3 mm.
6. Preparation of two-dimensional BiO as claimed in claim 5 x S y A method of material, characterized in that In the dispersion, the amount of metallic bismuth added is 0.1 to 0.15 g of metallic bismuth per 1 mL of Na2S solution.
7. The method for preparing two-dimensional BiO as claimed in claim 1 x S y A method of material, characterized in that Exfoliated 2D BiO x S y The nanosheets were further washed in ethanol solution.
8. A two-dimensional BiO x S y Material, characterized in that Prepared by the preparation method according to any one of claims 1 to 7.
9. A two-dimensional BiO x S y The application of the material is characterized by Used to prepare gas sensors.
10. A two-dimensional BiO x S y The application of the material is characterized by For the preparation of gas sensors for detecting NO2 concentration, two-dimensional BiO x S y The nanosheets are dispersed in an ethanol solution, and the obtained dispersion is dropped on the interdigital electrodes to obtain a gas sensor.