Preparation method of phosphorane room-temperature gas-sensitive material, product and application of phosphorane room-temperature gas-sensitive material

Abstract

The invention discloses a preparation method of a phosphorane room-temperature gas-sensitive material, which comprises the following steps: respectively adding Bi (NO3) 3.5 H2O and Na2MoO4. 2H2O into ethylene glycol, stirring until the Bi (NO3) 3.5 H2O and the Na2MoO4. 2H2O are completely dissolved, mixing the two solutions, and adding isopropanol to prepare a mixed solution; and transferring the obtained mixed solution into a high-pressure reaction kettle, carrying out solvothermal reaction at 160 DEG C for 15 hours, naturally cooling to room temperature after the reaction is finished, centrifuging, washing and freeze-drying to obtain the gas-sensitive material. The gas-sensitive material prepared by the method has good morphology and structure, and the successful preparation of the special litchi-shaped structure improves the electronic characteristics of the material and effectively enhances the gas-sensitive performance of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of gas-sensitive materials, and in particular relates to a method for preparing a phosphine room-temperature gas-sensitive material. Background Art

[0002] Phosphine (PH3) is a colorless, odorless, highly toxic, and flammable gas. In recent years, it has been widely used not only in agricultural storage fumigation and chemical synthesis, but also in the manufacture of semiconductor devices. However, to date, no satisfactory ppm-level PH3 detection technology has been developed. Metal oxide semiconductors (MOS) have attracted widespread attention due to their excellent performance and are being widely studied and applied in gas sensors.

[0003] The test tube method remains the most commonly used method for PH3 detection, with all the disadvantages of a manual procedure. Monitoring PH3 concentrations during fumigation is essential to confirm that the treatment is adequate to achieve the desired insect control, but such monitoring can be relatively expensive and labor-intensive.

[0004] In recent years, several materials have been studied for PH3 sensing, but they all work at 300℃ and above, which poses a great safety hazard. Bi2MoO6 has been studied for ppb-level H2S, NH3 and other volatile organic compounds (VOCs) detection due to its unique physical and chemical properties.

[0005] At present, many methods have been explored to enhance the gas sensing performance of Bi2MoO6. According to the research, Bi2MoO6 with different morphologies has different gas sensing performance at different working temperatures. By controlling the synthetic morphology of Bi2MoO6 nanomaterials, such as nanosheets, hollow spheres, etc., the flower-like Bi2MoO6 microsphere structure based on in-situ deposition can be used to selectively detect low-concentration H2S gas at 100°C; the solvent-thermal synthesis of yolk-shell Bi2MoO6 microspheres exhibits excellent sensing performance for ppm-level isopropanol at 270°C.

[0006] However, there is no research report on the use of Bi2MoO6 gas-sensitive materials for detecting PH3 at room temperature. Summary of the invention

[0007] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0008] In view of the above-mentioned and / or existing problems in the prior art in the preparation of bimetallic oxide gas-sensitive materials, the present invention is proposed and used.

[0009] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a phosphine room temperature gas-sensitive material, comprising the following steps: Bi(NO3)3·5H2O and Na2MoO4·2H2O were added to two beakers containing ethylene glycol respectively, and after stirring until completely dissolved, the two solutions were mixed and isopropanol was added to prepare a mixed solution; The obtained mixed solution was transferred into a high-pressure reactor, and then subjected to solvent thermal reaction at 160° C. for 15 h. After the reaction was completed, the solution was naturally cooled to room temperature, centrifuged, washed, and freeze-dried to obtain the gas-sensitive material.

[0010] As a preferred solution of the method for preparing the phosphine room temperature gas-sensitive material in the present invention, the molar ratio of Bi(NO3)3·5H2O to Na2MoO4·2H2O is 2:1.

[0011] As a preferred scheme for the preparation method of the phosphine room temperature gas-sensitive material in the present invention, Bi(NO3)3·5H2O and Na2MoO4·2H2O are respectively added into two beakers containing ethylene glycol, wherein the ratio of ethylene glycol to Bi(NO3)3·5H2O is 10mL:1.940g, and the ratio of ethylene glycol to Na2MoO4·2H2O is 10mL:0.484g.

[0012] As a preferred solution of the method for preparing the phosphine room temperature gas-sensitive material in the present invention, the volume ratio of ethylene glycol to isopropanol is 20%-40%.

[0013] As a preferred embodiment of the method for preparing the phosphine room temperature gas-sensitive material in the present invention, the freeze drying refers to drying in a cold dryer for not less than 48 hours.

[0014] Another object of the present invention is that, in the product prepared by the preparation method, the gas-sensitive material is a sphere with a core-shell structure, and the diameter thereof is between 1 and 2 μm.

[0015] As a preferred solution of the product of the present invention, the outer shell of the sphere is in the shape of a lychee-shaped outer shell, and the core is formed by the accumulation of small spheres with a diameter of 50-100 nm.

[0016] Another object of the present invention is to use the product in preparing phosphine room temperature gas sensor.

[0017] As a preferred solution of the application described in the present invention, it includes: The product is added with a proper amount of deionized water and ground into a paste, and then the paste is coated on the surface of the gas sensor substrate to form a film with uniform thickness, and dried and aged at 60-80° C. for 24 hours to form a gas-sensitive coating to obtain a gas-sensitive element.

[0018] Compared with the prior art, the present invention has the following beneficial effects: the gas-sensitive material prepared by the present invention has good morphology and structure, and the successful preparation of the special litchi-shaped structure improves the electronic properties of the material and effectively enhances its gas-sensitive performance; the preparation of the present invention is simple and safe, low in cost, and high in practicality, filling the gap in the research on the use of a solvent thermal method to prepare litchi-shaped Bi2MoO6 as a room-temperature sensing gas-sensitive material for phosphine; the gas-sensitive element exhibits good gas-sensitive performance to phosphine gas at room temperature, has high selectivity and stability to phosphine, and a response value of 11.4% to 0.15 ppm phosphine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 This is the XRD spectrum of the Bi2MoO6 material subjected to solvothermal reaction at 160°C for 15h in an embodiment of the present invention.

[0020] Figure 2 This is the SEM morphology of the Bi2MoO6 material subjected to solvothermal reaction at 160°C for 15h in an embodiment of the present invention.

[0021] Figure 3 This is a high-magnification SEM morphology image of Bi2MoO6 particles with different structures in the embodiments of the present invention.

[0022] Figure 4 This is the response curve of the Bi2MoO6 sensor in the embodiment of the present invention to phosphine concentration of 0.15-4.5ppm under 60%RH and room temperature conditions.

[0023] Figure 5 This is a test result diagram of the response repeatability and long-term stability of the Bi2MoO6 sensor to phosphine in an embodiment of the present invention.

[0024] Figure 6 This is a comparison chart of the sensitivity of the Bi2MoO6 sensor Bi2MoO6 in an embodiment of the present invention to potential interfering gases (such as NH3, H2S, CO2, CO, C2H4 and C2H6O) at specific concentrations at 60%RH and room temperature.

[0025] Figure 7 This is a comparison chart of the selectivity of samples S1, S2, S3, S4, S5, and S6 in the embodiments of the present invention to interfering gases (NH3, H2S, CO2, CO, and C2H4) at 60% RH and room temperature.

[0026] Figure 8 This is a comparison chart of the response tests of samples S1, S2, S3, S4, S5, and S6 in the embodiments of the present invention at 60% RH and room temperature to 1.2 ppm PH3 every 2 weeks. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0030] The commercial sources of Bi(NO3)3·5H2O, Na2MoO4·2H2O, ethylene glycol and isopropanol raw materials are shown in the following table.

[0031] Example 1 The method for preparing the phosphine room temperature gas-sensitive material of the present invention comprises the following steps: At room temperature, 1.940 g Bi(NO3)3·5H2O and 0.484 g Na2MoO4·2H2O were added into two beakers containing 10 ml ethylene glycol at a molar mass ratio of 2:1, respectively, and stirred magnetically until completely dissolved. After mixing the two solutions, 60 ml isopropanol was added, and magnetic stirring was performed for 40 min to form a uniform mixed solution. The obtained solution was transferred into a high-pressure reactor and subjected to solvent thermal reaction at 160° C. for 15 h. After the reaction was completed, the solution was naturally cooled to room temperature, centrifuged, washed, and freeze-dried to obtain the litchi-shaped Bi2MoO6 gas-sensitive material.

[0032] The gas-sensitive material is used in the preparation of phosphine room-temperature gas-sensitive elements. Specifically, the gas-sensitive material is added to deionized water and ground into a paste, and then the paste is coated on the surface of the gas sensor substrate (the surface of which is printed with Pt Al2O3 interdigital electrodes, purchased from Wuhan Huachuang Ruike Technology Co., Ltd.) to form a thin film with uniform thickness, and the film is dried and aged at 60-80°C for 24 hours to obtain the gas-sensitive element.

[0033] XRD and SEM tests were performed on Bi2MoO6 gas-sensitive materials, such as Figure 1 , Figure 2 As shown, the results show that it is indeed a lychee-like structure, and the prepared nanomaterial does not contain other components, indicating that the gas-sensitive material with a lychee-like special structure can be successfully prepared through this embodiment.

[0034] Two gas sensors were prepared using two gas-sensitive materials. Phosphine with a concentration of 0.15-4.5 ppm was introduced into the two gas sensors by adjusting the flowmeter. The continuous response curve of the gas sensors to phosphine at 60% RH and room temperature was measured. Figure 4 As shown in the figure, it can be seen that the two sensors show consistent response trends to the changing concentration of PH3 gas. The response change to 0.15 ppm PH3 is clearly discernible, and there is a good linear relationship between the response value and the concentration. The R of the linear fitting of the two is 2 =0.9992.

[0035] The response repeatability and long-term stability of phosphine were tested. The flowmeter was adjusted to introduce 0.3 and 0.6 ppm phosphine, and the response of the above sensor was measured at 60% RH and room temperature. Figure 5 As shown in the figure, it can be seen that in the continuous periodic concentration changes, the litchi-like Bi2MoO6 exhibits stable repetitive characteristics to PH3. In the long-term test with an interval of 1 week, the results show that the litchi-like Bi2MoO6 still maintains a certain sensitivity to PH3 after several weeks, and the maximum response attenuation within 10 weeks is less than 10%.

[0036] By adjusting the flowmeter to introduce 5 ppm of different types of gases, the selectivity of the above sensor to phosphine was measured at 60% RH and room temperature.

[0037] from Figure 6 It can be seen that the sensitivity of litchi-like Bi2MoO6 to potential interfering gases (such as NH3, H2S, CO2, CO, C2H4 and C2H6O) at specific concentrations at 60%RH and room temperature. Although litchi-like Bi2MoO6 shows the best response to PH3, it still shows a certain cross-sensitivity to these potential interfering gases.

[0038] Example 2 Reference Figure 3 , Figure 7 and Figure 8 The difference between this embodiment and embodiment 1 is that it further proves the performance of the gas sensor prepared by the present invention by means of experimental verification.

[0039] At room temperature, 6 parts of 1.940g Bi(NO3)3·5H2O and 0.484g Na2MoO4·2H2O were added to 6 parts of corresponding ethylene glycol solvents at a molar mass ratio of 2:1, stirred until completely dissolved, and then the two solutions were mixed and the corresponding parts of isopropanol were added. The ratios of the 6 parts of ethylene glycol and isopropanol solvents were 0:8, 1:7, 2:6, 4:4, 6:2 and 8:0, respectively, to prepare a mixed solution, and the total volume of each part of ethylene glycol solvent and isopropanol solvent was 80ml; The obtained solution was transferred into a high-pressure reactor and subjected to solvent thermal reaction at 160°C for 15 hours. After the reaction, it was naturally cooled to room temperature, centrifuged, washed, and freeze-dried to obtain the lychee-shaped Bi2MoO6 gas-sensitive material, which were respectively recorded as samples S1, S2, S3, S4, S5, and S6.

[0040] like Figure 3 As shown, (a)-(f) are SEM morphology images of microspheres obtained when the ethylene glycol:isopropanol solvent ratio is 0:8, 1:7, 2:6, 4:4, 6:2 and 8:0, respectively.

[0041] When isopropanol was used as the sole solvent, uniform and smooth crystalline nanoparticles of S1 were observed. After a small amount of ethylene glycol was added to S2, these crystalline nanoparticles aggregated into nanospheres, indicating that EG was the main growth complexing agent for the spherical structure. When the ratio of ethylene glycol to isopropanol was 2:6 and 4:4, the described lychee-like Bi2MoO6 structure could be observed in S3 and S4. However, with further increase of ethylene glycol, the lychee-like structure disappeared in S5 and transformed into nanospheres composed of flaky particles, indicating that sufficient isopropanol was required as the driving force for the growth of crystalline particles. However, when ethylene glycol was used as the sole solvent, the SEM image of S6 showed a morphology with a large number of dispersed structures.

[0042] The gas-sensitive material is used in the preparation of a phosphine room-temperature gas-sensitive element. Specifically, the gas-sensitive material is added to deionized water and ground into a paste. The paste is then applied to the surface of a gas sensor substrate and completely covers the platinum electrode to form a thin film of uniform thickness. The film is dried and aged at 60-80° C. for 24 hours to obtain a gas-sensitive element.

[0043] Phosphine with a concentration of 1 ppm was introduced by adjusting the flowmeter, and the response of the sensor was measured under the conditions of 60% RH and room temperature.

[0044] Table 1 Response of Bi2MoO6 nanoparticles prepared with different solvent ratios to 1 ppm phosphine at 60% RH and room temperature The responses of Bi2MoO6 nanomaterials with different structures obtained by different solvent ratios in Table 1 to 1ppm phosphine at 60%RH and room temperature show that bismuth molybdate materials with different structures all respond to phosphine. It should be noted that the gas-sensitive response of Bi2MoO6 with litchi-like structure is significantly higher than that of Bi2MoO6 with other structures.

[0045] This indicates that the lychee-like structure sample S3 synthesized when the volume ratio of ethylene glycol to isopropanol is 2:6 (between 20% and 40%) is the best embodiment for use as a room temperature gas-sensitive detection material for phosphine. Figure 7 As shown in the figure, it can be seen that among the six materials, S3 can distinguish gases at the same concentration more clearly. The energy band width of Bi2MoO6 under the lychee-like morphology is about 2.61eV, which improves the electronic properties of the material. In addition, the response values ​​of S1, S2 and S6 are too small, and S4 and S5 are not obvious enough to distinguish different gases. Figure 8 As shown in the figure, it can be seen that in the response test of 1.2 ppm PH3 at intervals of 2 weeks, S3 always maintains less attenuation over time, and S4 and S5 have obvious response attenuation after the 5th week and the 3rd week respectively. The response values ​​of S1, S2 and S6 are disturbed by errors, and the test is stopped after 5 weeks.

[0046] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a phosphine room temperature gas-sensitive material, characterized in that: The following steps are included: Bi(NO3)3·5H2O and Na2MoO4·2H2O were added to two beakers containing ethylene glycol respectively, and after stirring until completely dissolved, the two solutions were mixed and isopropanol was added to prepare a mixed solution; The obtained mixed solution was transferred into a high-pressure reactor, and then subjected to solvent thermal reaction at 160° C. for 15 h. After the reaction was completed, the solution was naturally cooled to room temperature, centrifuged, washed, and freeze-dried to obtain the gas-sensitive material.

2. The method for preparing the phosphine room temperature gas-sensitive material according to claim 1, characterized in that: The molar ratio of Bi(NO3)3·5H2O and Na2MoO4·2H2O is 2:

1.

3. The method for preparing the phosphine room temperature gas-sensitive material according to claim 2, characterized in that: Bi(NO3)3·5H2O and Na2MoO4·2H2O were added into two beakers containing ethylene glycol respectively, wherein the ratio of ethylene glycol to Bi(NO3)3·5H2O was 10mL:1.940g, and the ratio of ethylene glycol to Na2MoO4·2H2O was 10mL:0.484g.

4. The method for preparing the phosphine room temperature gas-sensitive material according to claim 3, characterized in that: The volume ratio of the ethylene glycol to the isopropanol is 20%-40%.

5. The method for preparing the phosphine room temperature gas-sensitive material according to claim 1, characterized in that: The freeze drying refers to drying in a cold dryer for not less than 48 hours.

6. The product prepared by the preparation method according to claim 4, characterized in that: The gas-sensitive material is a sphere with a core-shell structure and a diameter between 1 and 2 μm.

7. The product according to claim 6, characterized in that: The shell of the sphere is in the shape of a lychee shell, and the core is formed by the accumulation of small spheres with a diameter of 50-100 nm.

8. Use of the product as claimed in claim 7 in the preparation of phosphine room temperature gas sensor.

9. The use according to claim 8, characterized in that: The method comprises the steps of adding an appropriate amount of deionized water to the product and grinding the product to form a paste, then coating the paste on the surface of a gas sensor substrate to form a film with uniform thickness, drying at 60-80° C. and aging for 24 hours to form a gas-sensitive coating to obtain a gas-sensitive element.

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