A phosphine gas monitoring device and a method for preparing a phosphine sensor

Abstract

The application provides a phosphine gas monitoring device and a phosphine sensor preparation method, which comprises a drum type TENG, an AC / DC conversion unit, a voltage control unit, a micro control unit, a PH3 sensor and a display unit connected in sequence; the drum type TENG stores electric energy in the voltage control unit through the AC / DC conversion unit, when the voltage reaches a set threshold value, the voltage control unit delivers electric energy to the micro control unit, the micro control unit controls the PH3 sensor to collect the PH3 gas concentration, and then the data is uploaded to the display module through a wireless communication module. The technical scheme of the application overcomes the problem that the prior art lacks a phosphine gas monitoring device with high sensitivity, strong environmental adaptability and sustainability.

Description

Technical Field

[0001] This invention relates to the field of gas monitoring, specifically to a phosphine gas monitoring device and a method for preparing a phosphine sensor. Background Technology

[0002] In the industrial sector, especially in outdoor pipeline systems that are prevalent throughout factory areas, real-time and accurate monitoring of phosphine (PH3) gas is a crucial safety and environmental requirement.

[0003] Traditional gas monitoring equipment is often bulky, inconvenient to install, and consumes a lot of power, making it difficult to adapt to the complex and diverse outdoor pipeline environments. The emergence of high-performance miniaturized sensors has perfectly solved this problem. However, the widespread distributed PH3 gas monitoring nodes and wireless transmission modules require a large number of batteries, increasing maintenance costs and causing environmental problems such as battery pollution. Therefore, distributed self-powered systems have emerged in recent years. Triboelectric nanogenerators (TENGs), based on the synergistic mechanism of contact electrification and electrostatic induction, can efficiently output electrical energy under slight mechanical disturbances, possessing significant advantages such as low starting threshold, simple structure, low cost, and flexible material selection.

[0004] In recent years, the development of gas-sensitive materials has provided more innovative solutions for industrial pH3 monitoring. With the development of nanotechnology, the functional modification of gas-sensitive materials has become an important way to improve the performance of gas sensors. By adjusting the surface properties, particle size, crystal structure, and functional groups of materials, researchers can significantly improve the response, sensitivity, and selectivity of gas-sensitive materials to pH3. Among these, metal-organic frameworks (MOFs) have become a promising choice due to their large specific surface area, highly ordered pore structure, and abundant active sites. However, the insulating properties of ZIF-8 alone severely limit its electron transport efficiency and sensitivity to pH3. At the same time, the aforementioned advantages of ZIF-8 allow it to be better functionalized and compounded with other materials to further enhance its sensitivity and selectivity to pH3. For example, doping with highly conductive polymers such as carbon nanotubes, graphene, or polyaniline (PANI). Among them, the protonated nitrogen groups (-NH) on the PANI chain... + / -N + =) It is expected to connect with open zinc sites (Zn) in the ZIF-8 framework. 2+These materials form dual active adsorption centers. This cascade effect, from electronic structure modulation to interfacial chemical enhancement, enables the composite material to achieve a leapfrog breakthrough in sensing performance while maintaining its high specific surface area advantage. Furthermore, the semiconductor-type pH3 sensor prepared based on these functionalized materials exhibits lower power consumption and can be better integrated with data acquisition and transmission technologies, supporting large-scale distributed monitoring. However, the reasons for the performance optimization brought about by this functionalization modification mechanism and the effectiveness of the integrated monitoring method in practical environments require further investigation. Therefore, exploring the functionalization modification mechanism of gas-sensitive materials and rigorously evaluating the stability and monitoring performance of this method during long-term operation in practical environments, in order to develop cost-effective industrial field pH3 monitoring devices, has become a research focus.

[0005] Therefore, there is a need for a phosphine gas monitoring device and a method for preparing a phosphine sensor that has high sensitivity, good environmental adaptability and sustainability. Summary of the Invention

[0006] The main objective of this invention is to provide a phosphine gas monitoring device and a method for preparing a phosphine sensor, in order to solve the problem of the lack of phosphine gas monitoring devices with high sensitivity, strong environmental adaptability and sustainability in the prior art.

[0007] To achieve the above objectives, the present invention provides a phosphine gas monitoring device, comprising: a drum-type TENG, an AC / DC conversion unit, a voltage control unit, a microcontroller unit, a PH3 sensor, and a display unit connected in sequence; the drum-type TENG stores electrical energy in the voltage control unit through the AC / DC conversion unit; when the voltage reaches a set threshold, the voltage control unit supplies electrical energy to the microcontroller unit; the microcontroller unit controls the PH3 sensor to collect the PH3 gas concentration; and then the data is uploaded to the display module through a wireless communication module.

[0008] Furthermore, the drum-type TENG includes: a barrel-shaped outer shell, a stator, a rotor, a rotating rod, and fan blades. The fan blades are fixedly connected to one end of the rotating rod, and the fan blades rotate coaxially with the rotor. The stator is located on the inner wall of the barrel-shaped outer shell, and the rotor is located inside the barrel-shaped outer shell, rotating relative to the stator.

[0009] Furthermore, the rotor includes: flexible blades, multiple flexible blades are connected to each other on one side and integrally formed to form rotating blades, the rotating blades have through holes in the middle, the rotating rod passes through the rotating blades through the through holes, and the rotating blades are fixed on the rotating rods; the stator includes multiple conductive films, multiple conductive films are uniformly covered on the inner wall of the barrel-shaped shell, and the positive and negative electrode conductive films alternately cover the inner wall of the barrel-shaped shell.

[0010] Furthermore, the flexible blades are made of fluoropropylene (FEP) films, and the conductive films are made of Cu electrode films; there are four FEP films and eight Cu electrode films.

[0011] This invention also provides a method for preparing a phosphine sensor, specifically including the following steps:

[0012] S1, Prepare granular ZIF-8.

[0013] S2, to prepare particulate polyaniline.

[0014] S3, introduce polyaniline (PANI) monomer and prepare particulate ZIF-8 / PANI composite material through chemical oxidative polymerization.

[0015] S4. The ZIF-8 / PANI solution is uniformly dropped onto the pre-prepared interdigitated electrode to form a gas sensing film. The sensing film is then completely solidified to obtain the phosphine sensor.

[0016] Furthermore, step S1 specifically includes the following steps:

[0017] S1.1 Dissolve 0.5–2.0 g of zinc nitrate hexahydrate Zn(NO3)2·6H2O in 50–100 mL of deionized water to form a zinc nitrate solution; weigh 3.0–8.0 g of 2-methylimidazole and dissolve it in 10–30 mL of deionized water to obtain an imidazole solution.

[0018] S1.2, slowly add zinc nitrate solution to 2-methylimidazole solution, mix and continue stirring for 2–10 minutes to ensure uniform reaction of solution.

[0019] S1.3, the solvent and unreacted substances are removed by centrifugation, the product is washed with methanol, and finally dried at 40–80℃ for 4–12 hours to obtain granular ZIF-8 powder.

[0020] Furthermore, step S2 specifically includes the following steps:

[0021] S2.1, Dissolve 1.0–3.0 g of aniline in 20–50 mL of deionized water and add 1–5 mL of hydrochloric acid to form an aniline solution.

[0022] S2.2, Dissolve 0.2–1.0 g of ammonium persulfate (APS) in 10–30 mL of deionized water to obtain an ammonium persulfate solution.

[0023] S2.3, mix aniline solution with ammonium persulfate solution and stir magnetically at room temperature for 1–4 hours. When the color of the solution gradually changes from black to dark green, it indicates that the polymerization reaction is complete.

[0024] Furthermore, step S3 specifically includes the following steps:

[0025] S3.1 Weigh 0.5–2.0 g of zinc nitrate hexahydrate Zn(NO3)2·6H2O, dissolve it in 50–100 mL of deionized water to obtain a zinc nitrate solution. Weigh 1.0–3.0 g of aniline and dissolve it in 20–50 mL of deionized water to form an aniline solution. Add 1–5 mL of hydrochloric acid to adjust the acidity of the solution to form a mixed aniline solution.

[0026] S3.2, add the aniline solution to the zinc nitrate solution and stir thoroughly to form a homogeneous solution. Add ammonium persulfate (APS) as an oxidant. Dissolve 0.2–1.0 g of APS in 10–30 mL of deionized water to obtain an ammonium persulfate solution. Slowly add the ammonium persulfate solution dropwise to the aniline mixed solution. Aniline forms a polyaniline solution through oxidative polymerization under acidic conditions. Dissolve 3.0–8.0 g of 2-methylimidazole in 10–30 mL of deionized water and add it to the polyaniline solution. 2-methylimidazole reacts with the zinc source to form ZIF-8 crystals. As the reaction continues, the color of the solution changes from light to dark green, indicating that the polymerization reaction of polyaniline is complete.

[0027] S3.3, unreacted monomers and excess ammonium persulfate are removed by centrifugation, and the product is washed with methanol to remove impurities.

[0028] S3.4, the ZIF-8 / PANI composite material is transferred to a drying oven and dried at 40–80°C for 4–12 hours to obtain granular ZIF-8 / PANI composite material.

[0029] Furthermore, step S4 specifically includes the following steps:

[0030] S4.1 Dissolve ZIF-8 / PANI in deionized water; place the solution on a magnetic stirrer and stir thoroughly to ensure complete dissolution.

[0031] S4.2, uniformly drop the solution onto the pre-prepared interdigitated electrode (IDE) to form a gas sensing film; the spin coating time during drop addition is 30–90 s to ensure uniform film layer.

[0032] S4.3 Place the coated sensor film sample into a vacuum drying oven and vacuum dry it at 40-80℃ for 2-6 hours until the sensor film is completely cured, and finally obtain the ZIF-8 / PANI gas sensor.

[0033] The present invention has the following beneficial effects:

[0034] Given the limitations of existing research, this invention develops a long-term stable pH3 concentration monitoring instrument based on functionalized ZIF-8 / PANI gas-sensitive materials, aiming to monitor the gas phase pH3 concentration in industrial settings in real time. This invention synthesizes a composite ZIF-8 / PANI material with surface functionalization effects using in-situ polymerization, which serves as the gas-sensitive material for the pH3 sensor. Compared to single materials, the ZIF-8 / PANI composite material obtained through in-situ polymerization exhibits multiple synergistic effects at the surface, electronic, and mechanical levels, significantly improving the sensor's accuracy, selectivity, and long-term stability. This is supported by experimental testing and first-principles calculations. In terms of application verification, this invention first uses MEMS patch technology to encapsulate the ZIF-8 / PANI pH3 sensor under constant temperature and humidity, fabricating a fixed pH3 concentration monitoring instrument. Real-time acquisition and stable transmission of pH3 concentration data are achieved through bus communication. The instrument has undergone over 180 days of actual testing, verifying its stability in real-world environments. This innovative application not only promotes the intelligent and networked development of industrial pH3 monitoring systems but also significantly expands the coverage and flexibility of pH3 concentration monitoring, providing reliable technical support for industrial environmental protection. This invention designs an integrated energy system for self-driven pH3 gas monitoring based on a triboelectric nanogenerator (TENG) and a novel "energy storage and release-dynamic allocation" energy storage mechanism. By optimizing the TENG design, ideal electrical output characteristics are achieved. Combined with an energy management strategy, the system overcomes the low-frequency and fluctuating characteristics of wind-driven TENGs, efficiently converting intermittent electrical energy generated by irregular wind energy input into the TENG into a stable low-voltage DC output, which is then stored in a capacitor. When the stored energy reaches a set threshold, it is released in a concentrated manner, providing the complete energy required for the sensor and wireless communication module to operate, achieving self-triggered data acquisition and transmission. Long-term environmental testing for six months has demonstrated the system's stability and practicality. The overall design is simple and highly scalable, and can be further integrated with a cloud communication module for remote, large-scale monitoring and management, providing a new path and technical support for low-cost, green, and sustainable intelligent environmental monitoring systems. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0036] Figure 1A structural diagram of the roller-type TENG of the present invention is shown.

[0037] Figure 2 A COMSOL simulation diagram of the power generation performance of the drum-type TENG of the present invention is shown.

[0038] Figure 3 The advantages of TENG in the rotational speed frequency domain under common surface wind speed drive are shown.

[0039] Figure 4 The SEM image of PANI is shown.

[0040] Figure 5 The SEM image of ZIF-8 at the 500nm scale is shown.

[0041] Figure 6 The SEM image of ZIF-8 at the 50nm scale is shown.

[0042] Figure 7 SEM images of the ZIF-8 / PANI nanocomposite are shown.

[0043] Figure 8 HRTEM images of the ZIF-8 / PANI nanocomposite at the 0.5 μm scale are shown.

[0044] Figure 9 HRTEM images of ZIF-8 / PANI nanocomposites at the 100 nm scale are shown.

[0045] Figure 10 HRTEM images of ZIF-8 / PANI nanocomposites at the 5 nm scale are shown.

[0046] Figure 11 The EDX elemental mapping of the ZIF-8 / PANI nanocomposite is shown.

[0047] Figure 12 The XRD patterns of ZIF-8, PANI, and ZIF-8 / PANI are shown.

[0048] Figure 13 XPS spectra of C in the ZIF-8 / PANI nanocomposite are shown.

[0049] Figure 14 XPS spectra of nitrogen in ZIF-8 / PANI nanocomposites are shown.

[0050] Figure 15 XPS spectra of Zn in ZIF-8 / PANI nanocomposite material are shown.

[0051] Figure 16 XPS spectra of the ZIF-8 / PANI nanocomposite material are shown.

[0052] Figure 17 The resistance values ​​of the ZIF-8 and ZIF-8 / PANI sensors are shown under different concentrations of pH 3.

[0053] Figure 18 The resistance values ​​of the PANI sensor are shown under different concentrations of pH 3.

[0054] Figure 19 The response values ​​of ZIF-8, PANI, and ZIF-8 / PANI sensors to different concentrations of PH3 are shown.

[0055] Figure 20 The fitted curves of the response values ​​of ZIF-8, PANI and ZIF-8 / PANI sensors to PH3 and PH3 concentration are shown.

[0056] Figure 21 The effect of spin coating time on the response of the ZIF-8 / PANI sensor is shown.

[0057] Figure 22 The response recovery times of the ZIF-8, PANI, and ZIF-8 / PANI sensors to 10 ppm PH3 are shown.

[0058] Figure 23 The response curve of the ZIF-8 / PANI sensor to relative humidity is shown.

[0059] Figure 24 The baseline resistance of the ZIF-8 / PANI detector at 0 ppm is shown at different temperatures.

[0060] Figure 25 The PH3 response curves of the ZIF-8 / PANI sensor at different concentrations are shown.

[0061] Figure 26 The response change of the ZIF-8 / PANI sensor under an ambient condition of 4 ppm is shown.

[0062] Figure 27 The deviation in the long-term stability of the ZIF-8 / PANI sensor is shown.

[0063] Figure 28 The response of the ZIF-8 / PANI sensor to different gases at a concentration of 3 ppm is shown.

[0064] Figure 29 The charge density of PANI is shown.

[0065] Figure 30 The charge density of ZIF-8 is shown.

[0066] Figure 31 The charge density of ZIF-8 / PANI is shown.

[0067] Figure 32 The total density state TDOS curves of three materials, PANI, ZIF-8, and ZIF-8 / PANI, are shown.

[0068] Figure 33 The TDOS diagrams of ZIF-8 / PANI material before and after adsorption of PH3 molecules are shown.

[0069] Figure 34 The projected density state (PDOS) diagram of ZIF-8 / PANI adsorbed PH3 molecules is shown.

[0070] Figure 35 The sensing mechanism of PH3 by the p / n heterojunction composed of ZIF-8 / PANI composite material is shown.

[0071] The reference numerals in the above figures are:

[0072] 10. Barrel-shaped outer casing; 20. Stator; 30. Rotor; 40. Rotating rod; 50. Fan blade. Detailed Implementation

[0073] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0074] Example 1

[0075] like Figure 1 The phosphine gas monitoring device shown is characterized by comprising: a drum-type TENG, an AC / DC conversion unit, a voltage control unit, a microcontroller unit, a PH3 sensor, and a display unit connected in sequence; the drum-type TENG stores electrical energy in the voltage control unit through the AC / DC conversion unit; when the voltage reaches a set threshold, the voltage control unit supplies electrical energy to the microcontroller unit; the microcontroller unit controls the PH3 sensor to collect the PH3 gas concentration; and then the data is uploaded to the display module through a wireless communication module.

[0076] Specifically, such as Figure 1As shown, the drum-type TENG includes: a barrel-shaped outer shell 10, a stator 20, a rotor 30, a rotating rod 40, and a fan blade 50. The fan blade is fixedly connected to one end of the rotating rod, and the fan blade rotates coaxially with the rotor. The stator is located on the inner wall of the barrel-shaped outer shell, and the rotor is located inside the barrel-shaped outer shell, rotating relative to the stator.

[0077] Specifically, the rotor includes: flexible blades, multiple flexible blades are connected to each other on one side and integrally formed to form rotating blades, the rotating blades have through holes in the middle, the rotating rod passes through the rotating blades through the through holes, and the rotating blades are fixed on the rotating rods; the stator includes multiple conductive films, multiple conductive films are uniformly covered on the inner wall of the barrel-shaped shell, and the positive and negative electrode conductive films alternately cover the inner wall of the barrel-shaped shell.

[0078] Specifically, the flexible blades are made of fluoropropylene (FEP) films, and the conductive films are made of Cu electrode films; there are four FEP films and eight Cu electrode films.

[0079] This invention uses fluoropropylene (FEP) and copper (Cu) as the friction materials for a triboelectric generator (TENG). The roller-type TENG comprises four flexible FEP blades and eight Cu electrodes. The roller-type TENG adopts an independent structure, and its working principle is based on triboelectric charging and electrostatic induction. Its energy conversion is driven by the sliding relative motion between the FEP film and the Cu electrodes. The roller-type TENG has a diameter and length of 10 cm and is made of acrylic. Scanning electron microscopy (SEM) images show that the FEP film surface has high smoothness, which helps to increase the actual contact area during friction, thereby improving the surface charge generation efficiency. The TENG's operating mechanism includes four distinct stages. In the first stage, the rotating FEP film rests on electrode A, which is very close to electrode B. Through electrostatic induction, an equal amount of positive charge accumulates on the surface of electrode A. Therefore, the TENG system maintains static equilibrium, and no current flows through the external circuit. In the second stage, as the FEP film transitions from electrode A to electrode B, the overlap area between the FEP film and electrode A decreases. This reduction in overlap creates a potential difference between electrodes A and B, facilitating the migration of positive charges from electrode A to B through the external circuit, thus generating current. The third stage then occurs when the FEP film and electrode B completely overlap, causing all positive charges to accumulate on the surface of electrode B, marking the climax of the first half of the power generation cycle. The roller-type TENG again reaches a static equilibrium state, with no current flowing in the external circuit. The final stage begins when the FEP film moves in the reverse direction from electrode B to electrode A, generating a reverse current in the system. The overlap between the FEP film and electrode A marks the completion of the entire power generation cycle. To visualize the continuous change in electric field strength, a finite element simulation of this process, COMSOL, was developed. Figure 2 As shown. In the initial stage, the FEP blade completely overlaps with the electrode, resulting in a minimum electric field strength, as... Figure 2 (i) When the FEP rotates toward the midpoint between the two electrodes, the accumulated charge on the two electrodes is equal, resulting in the maximum electric field strength. Figure 2 (ii). As the FEP rotates further, the electric field strength gradually weakens, as... Figure 2 (iii). After the FEP completely covers the second electrode, the electric field strength reaches its lowest point, marking the completion of one cycle, as shown. Figure 2 (iv). To further investigate the relationship between wind speed and TENG rotation speed, this invention uses a fan (ZT-3 Test Bench) to drive the TENG fan blades. The TENG's advantageous rotational speed frequency domain is as follows: Figure 3 As shown.

[0080] Example 2

[0081] A method for preparing a phosphine sensor specifically includes the following steps:

[0082] S1, Prepare granular ZIF-8.

[0083] S2, to prepare particulate polyaniline.

[0084] S3, introduce polyaniline (PANI) monomer and prepare particulate ZIF-8 / PANI composite material through chemical oxidative polymerization.

[0085] S4. The ZIF-8 / PANI solution is uniformly dropped onto the pre-prepared interdigitated electrode to form a gas sensing film. The sensing film is then completely solidified to obtain the phosphine sensor.

[0086] Specifically, step S1 includes the following steps:

[0087] S1.1 Dissolve 0.5–2.0 g of zinc nitrate hexahydrate Zn(NO3)2·6H2O in 50–100 mL of deionized water to form a zinc nitrate solution; weigh 3.0–8.0 g of 2-methylimidazole and dissolve it in 10–30 mL of deionized water to obtain an imidazole solution.

[0088] S1.2, slowly add zinc nitrate solution to 2-methylimidazole solution. During the reaction, the solution quickly turns milky white, indicating that ZIF-8 has begun to form. After mixing, continue stirring for 2–10 minutes to ensure uniform reaction of the solution.

[0089] S1.3, the solvent and unreacted substances are removed by centrifugation, the product is washed with methanol, and finally dried at 40–80℃ for 4–12 hours to obtain granular ZIF-8 powder.

[0090] Specifically, step S2 includes the following steps:

[0091] S2.1, Dissolve 1.0–3.0 g of aniline in 20–50 mL of deionized water and add 1–5 mL of hydrochloric acid to form an aniline solution.

[0092] S2.2, Dissolve 0.2–1.0 g of ammonium persulfate (APS) in 10–30 mL of deionized water to obtain an ammonium persulfate solution.

[0093] S2.3, mix aniline solution with ammonium persulfate solution and stir magnetically at room temperature for 1–4 hours. During this process, aniline will form polyaniline through chemical oxidation polymerization. When the color of the solution gradually changes from black to dark green, it indicates that the polymerization reaction is complete.

[0094] Specifically, step S3 includes the following steps:

[0095] S3.1 Weigh 0.5–2.0 g of zinc nitrate hexahydrate Zn(NO3)2·6H2O, dissolve it in 50–100 mL of deionized water to obtain a zinc nitrate solution. Weigh 1.0–3.0 g of aniline and dissolve it in 20–50 mL of deionized water to form an aniline solution. Add 1–5 mL of hydrochloric acid to adjust the acidity of the solution to form a mixed aniline solution.

[0096] In step S3.2, the aniline solution is added to the zinc nitrate solution and thoroughly stirred to form a homogeneous solution. Ammonium persulfate (APS) is added as an oxidant; 0.2–1.0 g of APS is dissolved in 10–30 mL of deionized water to obtain an ammonium persulfate solution. The ammonium persulfate solution is slowly added dropwise to the aniline mixture. The reaction system immediately undergoes chemical polymerization, with aniline forming a polyaniline solution through oxidative polymerization in an acidic environment. 3.0–8.0 g of 2-methylimidazole is dissolved in 10–30 mL of deionized water and added to the polyaniline solution. 2-methylimidazole reacts with the zinc source to form ZIF-8 crystals. Due to the presence of the aniline monomer, polyaniline forms a conductive polymer layer on the surface of the ZIF-8 crystals and is tightly bonded to the ZIF-8 structure. The reaction continues for approximately 2 hours, and the solution color changes from light to dark green, indicating that the polymerization of polyaniline is complete.

[0097] S3.3, unreacted monomers and excess ammonium persulfate are removed by centrifugation, and the product is washed multiple times with methanol to remove impurities.

[0098] S3.4, the ZIF-8 / PANI composite material is transferred to a drying oven and dried at 40–80°C for 4–12 hours to obtain granular ZIF-8 / PANI composite material.

[0099] Specifically, step S4 includes the following steps:

[0100] S4.1 Dissolve ZIF-8 / PANI in deionized water; place the solution on a magnetic stirrer and stir thoroughly for 10 minutes to ensure complete dissolution.

[0101] S4.2, the solution is uniformly dropped onto the pre-prepared interdigitated electrode (IDE) to form a gas sensing film; to ensure the uniformity of the film layer, the spin coating time during dropping is 30–90 s.

[0102] S4.3 Place the coated sensor film sample into a vacuum drying oven and vacuum dry it at 40-80℃ for 2-6 hours until the sensor film is completely cured, and finally obtain the ZIF-8 / PANI gas sensor.

[0103] Specifically, the PH3 sensor is encapsulated by precisely soldering the prepared phosphine sensor onto a dedicated housing base. Then, an automated dispensing process is used to evenly apply epoxy sealant along the perimeter of the housing. After the cap is assembled using an airtight sealing device, a 4-hour constant-temperature curing process is performed to ensure the structural integrity and airtight bond strength between the housing and the cap. The encapsulated product uses a standard pin design, allowing for direct insertion into a printed circuit board for rapid installation.

[0104] Based on a modular design concept, the PH3 sensor probe uses a spring-loaded contact interface to achieve electrical connection with the main control board. The PH3 sensor module's protection system employs a three-tiered composite structure: an inner layer with a silicone buffer membrane to resist mechanical impact; a middle layer with a polytetrafluoroethylene (PTFE) microporous breathable membrane for waterproofing and dustproofing; and an outer layer with a 316L stainless steel sintered filter (5μm pore size) at the detection port, effectively blocking dust particles while maintaining efficient diffusion of gas molecules. This design balances adaptability to harsh environments with high detection response sensitivity.

[0105] Specifically, the ZIF-8 / PANI testing instrument features a die-cast aluminum alloy explosion-proof housing and an internal double-layer printed circuit board stacked architecture: the top layer houses a high-precision signal conditioning module with temperature compensation circuitry, while the bottom layer contains a 32-bit MCU and a 24-bit high-precision digital-to-analog converter module to digitize sensor signals. After assembly, the embedded system program is programmed, and the long-term operational stability of the equipment is verified through a 72-hour continuous aging test.

[0106] The surface morphology of PANI, ZIF-8, and ZIF-8 / PANI composite material was characterized in detail using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 4SEM images of PANI are shown, revealing that PANI forms a highly discontinuous layered deposition structure based on the fibrous and porous nature of the base film. The polyaniline particles exhibit a relatively regular distribution, forming an interwoven network with a certain degree of porosity. The particle size is approximately 200 nm, and this structural feature provides a good supporting framework for subsequent composite materials. Figure 5 and Figure 6 The images show SEM images of ZIF-8 at different magnifications. These images verify the unique rhombic dodecahedral particle structure of ZIF-8, with particle sizes mainly concentrated between 200-500 nm. This size range not only endows ZIF-8 with a large specific surface area but also enables it to exhibit excellent performance during adsorption, especially for PH3. This morphology and structure of ZIF-8 makes it a candidate material with high adsorption potential, particularly suitable for applications such as gas sensors. In the ZIF-8 / PANI composite material, the PANI particle network is uniformly attached to the surface of the ZIF-8 particles, such as... Figure 7 As shown. Figure 11 An elemental mapping of the ZIF-8 / PANI composite material is presented, showing the uniform distribution of C, N, and Zn, further demonstrating the successful synthesis of the ZIF-8 / PANI composite material. Furthermore, TEM characterization of the morphology of the ZIF-8 / PANI composite material revealed that it retains the typical granular structure of ZIF-8 particles, such as... Figure 8 and Figure 9 As shown. Figure 10 As shown, the HRTEM images reveal a clear lattice spacing with a d value of approximately 925 Å, which corresponds to the (200) plane of PANI, indicating that the nanocomposite has high crystallinity. These characterization results demonstrate that the ZIF-8 / PANI composite not only maintains good structural features in morphology but also exhibits excellent orderliness in its crystal structure, providing a foundation for its outstanding performance in the field of PH3 sensing.

[0107] XRD patterns of ZIF-8, PANI, and ZIF-8 / PANI samples were obtained using an X-ray diffractometer under Cu Kα radiation (λ=1.5418Å), as shown below. Figure 12As shown. Typical peaks of PANI were identified at 2θ = 20.4° and 25.4° on PANI powder, attributed to the (020) and (200) crystal planes, which are parallel and perpendicular to the PANI molecular chains, respectively (JCPDS No. 53–1718). XRD provides information on the phase and structure of the synthesized ZIF-8, confirming its cubic phase (JCPDS# 62-1030). The prepared ZIF-8 exhibited diffraction peaks at 2θ = 7.19, 10.25, 12.58, 14.55, 16.32, 17.88, 19.38, 21.99, 24.35, 25.48, 26.54, 29.51, 30.48, 31.37, 32.26, 34.8, and 36.4, corresponding to the crystal planes (1 1 0), (2 0 0), (2 1 1), (2 2 0), (3 1 0), (2 2 2), (3 2 1), (4 1 1), (3 3 2), (4 22), (4 3 1), (4 4 0), (4 3 3), (4 4 2), (6 1 1), (6 2 2), and (4 4 4). The absence of additional peaks indicates that the synthesized material is pure. The grain size was calculated using the Debye-Scherrer formula, as shown in Equation (1):

[0108] D=Kλ / βcosθ (1);

[0109] Where D = grain size, K = 0.9 is the form factor, θ = Bragg angle; λ = 1.54 Å is the X-ray wavelength, and β = full width at half maximum (FWHM). The crystallite size of ZIF-8 synthesized according to the Debye-Scherrer equation is ~52 nm. The maximum diffraction peak in the plane is used in the Debye-Scherrer formula to calculate the grain size. The X-ray diffraction pattern of ZIF-8 / PANI contains all the diffraction peaks of pure ZIF-8 and pure PANI, further confirming the existence of ZIF-8 and PANI.

[0110] XPS characterization was performed to further analyze the elemental composition of the ZIF-8 / PANI composite material. Figure 13 The C1s XPS spectrum shown reveals three main chemical states of carbon. Three significant peaks appear at 288.6 eV, 286.7 eV, and 284.8 eV, which can be attributed to C=C (graphitic carbon), CN (carbon-nitrogen single bond), and CC (carbon-carbon) bonds, respectively. This detailed peak position analysis helps to further confirm the structural integrity and fidelity of the ZIF-8 framework. Figure 14The N1s spectrum also showed three distinct peaks at 398.0 eV, 400.2 eV, and 402.5 eV, corresponding to nitrogen atoms in the CN functional group, the imine-like structure (C=N), and the positively charged structure (-N+-), respectively. These different chemical environments of nitrogen further validated the typical coordination environment around the zinc ion and the chemical composition of PANI, and demonstrated the effective binding of the imidazole ester linker to the metal center in the MOF structure. Figure 15 The Zn 2p spectrum shows distinct peaks at binding energies of 1020.9 eV and 1044.0 eV, belonging to the electronic states of Zn 2p 3 / 2 and Zn 2p 1 / 2, respectively, confirming the presence of zinc in the ZIF-8 structure. Finally, Figure 16 The overall XPS spectrum of the ZIF-8 / PANI composite material clearly shows the peaks corresponding to N, C, and Zn, further proving the successful synthesis of the composite material. These XPS results indicate that the changes in the chemical state and the bonding mode of each element during the composite process of ZIF-8 and PANI are as expected, supporting the rationality of the composite material structure and the success of the synthesis.

[0111] The sensitivity of three pH 3 detectors—ZIF-8, PANI, and ZIF-8 / PANI—was tested using a dynamic gas mixing system to generate a pH 3 concentration gradient from 0.2 ppm to 5 ppm. The detectors have a base resistance. The resistance changes when the pH3 concentration is different. The resistance gradually stabilizes. The change in resistance reflects the gas concentration. The sensor's response to PH3... Defined as:

[0112] (2).

[0113] During testing, the instrument is first placed in a sealed gas chamber, and a fixed concentration of pH 3 is introduced. After obtaining the corresponding resistance value, the pH 3 in the chamber is returned to 0 ppm to restore its initial resistance. Once the resistance is restored, the instrument is exposed to a new pH 3 concentration for testing. Figure 17 and Figure 18As shown, the resistance changes of pH3 detectors based on pure ZIF-8, PANI, and ZIF-8 / PANI composite materials at different pH3 concentrations are illustrated. At 0 ppm pH3, the base resistances of single ZIF-8 and PANI are 7.1 MΩ and 40.2 kΩ, respectively, gradually decreasing and increasing with increasing pH3 concentration. It can be seen that although the single ZIF-8 sensor has a certain response to pH3, its base resistance is too high, which is detrimental to the development of downstream data acquisition devices. With PANI doping, the base resistance of the ZIF-8 / PANI composite material is significantly reduced, exhibiting better conductivity. To better quantify and compare the performance of the instruments, Figure 19 The instrument's response under a pH 3 concentration gradient was demonstrated. The ZIF-8 / PANI detection instrument exhibited a higher response than the ZIF-8 and PANI elemental pH 3 detection instruments. This further demonstrates the synergistic effect between the composite materials in improving the phosphine sensing performance. Furthermore, the fitting of the instrument's response curve shows that its response increases with increasing pH 3 concentration, as... Figure 20 As shown. Their fitting equations are expressed as Y=35.1*X 0.62 Y = 24.4 * X 0.43 and Y=7.4*X 0.71 Their fitting coefficients R² are all above 0.9, indicating high accuracy of the fitting equations and providing a good foundation for the design of data acquisition software. To obtain optimal sensing performance, this invention investigated the effect of spin-coating time of ZIF-8 / PANI material onto interdigital electrodes on the sensor response. The response of the ZIF-8 / PANI sensor was tested at a pH concentration of 5 ppm with spin-coating times ranging from 20 to 100 s. Experimental results show that the sensor response first increases and then decreases with increasing spin-coating time, reaching its maximum at 60 s. This may be because the composite material binds more fully to the pH molecules with increasing film thickness; however, further increases in thickness beyond a certain point affect the fit between the interdigital electrode and the sensitive material, making the sensor less sensitive to changes in resistance. Therefore, this invention uses a spin-coating time of 60 s as the default parameter for other experiments. Figure 21 . Figure 22The response / recovery curves of three sensors at 10 ppm pH 3 are presented. Response time is defined as the time required for the response value to increase to 90% of the steady-state response value, and recovery time is the time required for the steady-state response value to decrease to 10%. Their response times are 29.1 s, 25.5 s, and 18.7 s, respectively, and their recovery times are 33.3 s, 27.2 s, and 17 s, respectively. The results show that the ZIF-8 / PANI sensor has the shortest response / recovery time, which is 10.4 / 16.3 s shorter than the pure ZIF-8 and 6.8 / 10.2 s shorter than the PANI sensors. In summary, Table 1 summarizes the sensing performance of the ZIF-8 / PANI sensor and compares it with previously published work. The results show that the ZIF-8 / PANI sensor has certain advantages in terms of response value, response / recovery time, and detection range.

[0114] Table 1. Performance comparison between the sensor proposed in this invention and existing PH3 sensors.

[0115]

[0116] To further verify the stability of the ZIF-8 / PANI testing instrument, this invention explored the effects of changes in ambient temperature and humidity on the instrument's response. This invention tested the instrument's response changes within a relative humidity range of 0% to 97% RH, such as... Figure 23 As shown. The humidity environment tested was simulated using different saturated hydrochloric acid solutions; the specific configuration process is detailed in the Methods section. The results show that the instrument's response increases linearly with increasing humidity, with the fitted curve being Y = 0.99 + 0.043 * X. The above tests guided the anti-interference design of the instrument during the sealing process. Next, as... Figure 24 As shown, the resistance of the instrument increases linearly when the temperature rises from 19℃ to 31℃, indicating that reasonable temperature fluctuations at room temperature have little effect on it. Figure 24 The fitted curve is: Y = 0.99286*X + 531.5, R0 2 =0.99789; Furthermore, in actual testing, based on the temperature and humidity influence curve and the calibration of the data acquisition algorithm, more accurate phosphine concentration data can be obtained. Further, the instrument was set to concentrations of 1 ppm, 2 ppm, and 4 ppm respectively. Figure 25 The instruments demonstrated good repeatability and consistency, validating the mass production potential of the gas-sensitive thin film preparation method and encapsulation technology. To ensure long-term use of the encapsulated instruments, long-term stability tests were conducted on five instruments under a pH of 4 ppm. Figure 26As shown, the response of five instruments to pH 3 concentration was tested before and after 60 days. The results show that the response deviation of the five ZIF-8 / PANI sensors remained within 1% after sixty days, demonstrating good long-term stability. Figure 27 As shown. Finally, the selectivity and detection mechanism of the ZIF-8 / PANI PH3 detector were analyzed. Figure 28 As shown, when the instrument is placed in different gas environments at 3 ppm, the ZIF-8 / PANI sensor exhibits a significantly higher response to PH3 than to other gases, indicating excellent PH3 selectivity. This is attributed to the synergistic effect of the ZIF-8 / PANI composite material. Compared to ZIF-8 alone, PANI demonstrates better chemoselectivity. Through surface modification or alteration, the composite material can selectively adsorb PH3 molecules, thereby reducing interference from other gases. This improves the instrument's response accuracy to the target gas, a fact verified by simulations.

[0117] To further verify the feasibility of ZIF-8 / PANI composite material as a pH3-sensitive material, this invention employed density functional theory (DFT) for geometric optimization calculations. Through these calculations, the performance of ZIF-8, PANI, and ZIF-8 / PANI in the pH3 adsorption process was analyzed.

[0118] The geometry optimization results provide molecular models related to PH3 adsorption for ZIF-8, PANI, and ZIF-8 / PANI. Figure 29 , Figure 30 and Figure 31 Charge density diagrams of PANI, ZIF-8, and ZIF-8 / PANI after PH3 adsorption are shown. Analysis indicates that the charge transfer phenomenon is more significant in the ZIF-8 / PANI system compared to PANI and ZIF-8 alone. This reflects a stronger interaction between the composite material and PH3, thus endowing ZIF-8 / PANI with a stronger PH3 adsorption capacity. The adsorption energy of the materials is calculated using the following formula:

[0119] (3);

[0120] in, It is the energy of the entire system. It refers to the energy of ZIF-8, PANI, and ZIF-8 / PANI molecules.

[0121] Table 2 summarizes the adsorption energies of each material. The adsorption energy of ZIF-8 / PANI is -0.7761 eV, significantly higher than that of PANI (0.0793 eV) and ZIF-8 (0.7136 eV). This result indicates that the ZIF-8 / PANI composite material has a stronger PH3 adsorption capacity than PANI and ZIF-8 alone. Increased adsorption energy generally means that the material can more effectively capture PH3 molecules; therefore, ZIF-8 / PANI exhibits higher sensitivity in PH3 sensor applications.

[0122] Table 2 Simulation parameters of PH3 adsorption by three materials: ZIF-8, PANI, and ZIF-8 / PANI.

[0123]

[0124] Figure 32 The image also shows the total density states (TDOS) curves of different materials before and after ZIF-8 / PANI adsorption of PH3. Figure 33 The projected density states (PDOS) plots of ZIF-8 / PANI after PH3 adsorption are shown. Analyzing these plots can provide further insight into the changes in the electronic structure of the material. Figure 32 The TDOS analysis showed that the electron density curve of ZIF-8 / PANI shifted compared to ZIF-8 due to the doping effect of PANI. This indicates that PANI significantly modulates the electronic structure of ZIF-8, thereby improving the electronic conductivity of the composite material and enhancing its adsorption capacity for PH3 and its sensing performance. After PH3 adsorption, as... Figure 33 As shown, the TDOS curves of ZIF-8 / PANI exhibit slight enhancements at multiple locations. This enhancement is mainly due to the strong interaction between PH3 molecules and the material surface, further verifying the strong adsorption performance of ZIF-8 / PANI for PH3. Furthermore, as... Figure 34 As shown, PDOS analysis revealed the electronic hybridization between PH3 molecules and the ZIF-8 / PANI composite material. Specifically, significant overlap peaks were observed in multiple orbitals at -19.5 eV, -11.9 eV, -7.0 eV, -4.7 eV, and 2.3 eV, indicating strong interactions between the N 1s, H 1s, C 1s, and Zn 2p orbitals. This hybridization enhances the interaction between PH3 molecules and ZIF-8 / PANI, thereby improving the material's PH3 adsorption capacity. These calculation results provide strong theoretical support for the application of ZIF-8 / PANI in PH3 sensors, demonstrating its potential in the field of gas sensors.

[0125] The PH3 sensing mechanism mainly originates from the synergistic effect of binary nanomaterials. The PH3 sensing mechanism of the PANI / ZIF-8 composite material can be explained by the pn heterojunction it constructs and the synergistic effect of the two materials.

[0126] When PANI is combined with ZIF-8, the introduction of ZIF-8 not only enhances the specific surface area of ​​the material and increases the adsorption sites for PH3, but also further improves the sensing performance of the material due to the pn heterojunction formed by PANI and ZIF-8. Figure 35 As shown, ZIF-8 typically exhibits n-type semiconductor properties, which, combined with the p-type characteristics of PANI, forms a pn heterojunction. When PH3 molecules contact the composite material, the reaction between the PANI surface and PH3 leads to the consumption of electrons in the PANI, while ZIF-8, through its electronic structure, further promotes charge distribution and transport, increasing the material's PH3 response. Furthermore, the synergistic effect of the PANI / ZIF-8 composite material further amplifies this charge transfer process, making the composite material exhibit a stronger PH3 response than PANI or ZIF-8 materials alone.

[0127] In summary, the superior performance of the PANI / ZIF-8 composite material in pH3 sensing is attributed to the formation of the pn heterojunction and the synergistic effect of the two materials in adsorption and electron transfer. The composite material not only responds rapidly at low pH3 concentrations but also enhances detection sensitivity and accuracy through signal amplification mechanisms, thus providing superior pH3 sensing performance compared to the single material. The doping of ZIF-8 with PANI not only modulates the electronic structure of the material but also enhances the interaction between pH3 molecules and the material, thereby improving the adsorption efficiency and sensing performance of pH3.

[0128] Example 3

[0129] The preparation method of ZIF-8 / PANI composite material specifically includes the following steps:

[0130] First, granular ZIF-8 was prepared. 1.0 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in 80 mL of deionized water to form a zinc nitrate solution. Simultaneously, 6.0 g of 2-methylimidazole was weighed and dissolved in 20 mL of deionized water to obtain an imidazole solution. The zinc nitrate solution was slowly added to the 2-methylimidazole solution. During the reaction, the solution rapidly turned milky white, indicating the start of ZIF-8 formation. After mixing, stirring was continued for 5 minutes to ensure uniform reaction. Then, the solvent and unreacted substances were removed by centrifugation, and the product was washed with methanol. Finally, it was dried overnight at 60°C to obtain granular ZIF-8 powder.

[0131] Next, granular polyaniline (PANI) was prepared. First, 2.0 g of aniline was dissolved in 30 mL of deionized water, and 3 mL of hydrochloric acid was added to form an acidic solution. Then, 0.5 g of ammonium persulfate (APS) was dissolved in 20 mL of deionized water to obtain an ammonium persulfate solution. The aniline solution and the ammonium persulfate solution were mixed and magnetically stirred at room temperature for 2 hours. During this process, aniline will form polyaniline through a chemical oxidative polymerization reaction, and the color of the solution will gradually change from black to dark green, indicating the completion of the polymerization reaction.

[0132] Finally, to prepare granular ZIF-8 / PANI composite materials, this invention introduces polyaniline (PANI) monomers into the ZIF-8 synthesis process, achieving the composite through chemical oxidative polymerization. First, 1.0 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) is weighed and dissolved in 80 mL of deionized water to obtain a zinc nitrate solution. Then, 2.0 g of aniline is weighed and dissolved in 30 mL of deionized water to form an aniline solution, and 3 mL of hydrochloric acid is added to adjust the acidity. Next, the aniline solution is added to the zinc nitrate solution and thoroughly stirred to form a homogeneous solution. Based on this, ammonium persulfate (APS) is added as an oxidant; 0.5 g of APS is dissolved in 20 mL of deionized water to obtain an ammonium persulfate solution. The ammonium persulfate solution is slowly added dropwise to the above mixed solution, and the reaction system immediately undergoes chemical polymerization, with aniline forming polyaniline through oxidative polymerization in an acidic environment. Simultaneously, 6.0 g of 2-methylimidazole was dissolved in 20 mL of deionized water and added to the above mixed solution. The 2-methylimidazole reacted with the zinc source to form ZIF-8 crystals. Due to the presence of aniline monomer, polyaniline formed a conductive polymer layer on the surface of the ZIF-8 crystals and tightly bonded to the ZIF-8 structure. The reaction continued for about 2 hours, and the color of the solution changed from light to dark green, indicating that the polymerization reaction of polyaniline was basically complete. Next, unreacted monomers and excess ammonium persulfate were removed by centrifugation, and the product was washed multiple times with methanol to remove impurities. Finally, the ZIF-8 / PANI composite material was transferred to a drying oven and dried overnight at 60°C to obtain granular ZIF-8 / PANI composite material. Through this method, ZIF-8 and polyaniline were chemically polymerized during the synthesis process to form a granular composite material with excellent conductivity and adsorption properties. The surface of this composite material has the high specific surface area of ​​ZIF-8 and the conductivity of polyaniline.

[0133] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a phosphine sensor for use in a phosphine gas monitoring device, characterized in that, Specifically, the steps include the following: S1, Preparation of granular ZIF-8; S2, to prepare granular polyaniline; S3, introduce polyaniline PANI monomer and prepare particulate ZIF-8 / PANI composite material by chemical oxidative polymerization; S4. The ZIF-8 / PANI solution is uniformly dropped onto the pre-prepared interdigitated electrode to form a gas sensing film. The sensing film is then completely solidified to obtain the phosphine sensor. The phosphine gas monitoring device includes: a drum-type TENG, an AC / DC conversion unit, a voltage control unit, a microcontroller unit, a PH3 sensor, and a display unit connected in sequence; the drum-type TENG stores electrical energy in the voltage control unit through the AC / DC conversion unit. When the voltage reaches a set threshold, the voltage control unit supplies electrical energy to the microcontroller unit, which controls the PH3 sensor to collect the PH3 gas concentration, and then uploads the data to the display unit through a wireless communication module.

2. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 1, characterized in that, The drum-type TENG includes: a barrel-shaped outer shell, a stator, a rotor, a rotating rod, and fan blades. The fan blades are fixedly connected to one end of the rotating rod, and the fan blades rotate coaxially with the rotor. The stator is located on the inner wall of the barrel-shaped outer shell, and the rotor is located inside the barrel-shaped outer shell, rotating relative to the stator.

3. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 2, characterized in that, The rotor includes: The flexible blades are interconnected on one side and integrally formed into a rotating blade. The rotating blade has a through hole in the middle. The rotating rod passes through the through hole of the rotating blade and is fixed on the rotating rod. The stator includes multiple conductive films. The multiple conductive films are uniformly covered on the inner wall of the barrel-shaped shell, and the positive and negative electrode conductive films alternately cover the inner wall of the barrel-shaped shell.

4. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 3, characterized in that, The flexible blades are made of fluoropropylene (FEP) film, and the conductive film is made of Cu electrode film; there are four FEP films and eight Cu electrode films.

5. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 1, characterized in that, Step S1 specifically includes the following steps: S1.1 Dissolve 0.5–2.0 g of zinc nitrate hexahydrate Zn(NO3)2·6H2O in 50–100 mL of deionized water to form a zinc nitrate solution; weigh 3.0–8.0 g of 2-methylimidazole and dissolve it in 10–30 mL of deionized water to obtain a 2-methylimidazole solution. S1.2, Slowly add zinc nitrate solution to 2-methylimidazole solution, mix and continue stirring for 2–10 minutes to ensure uniform reaction of solution; S1.3, the solvent and unreacted substances are removed by centrifugation, the product is washed with methanol, and finally dried at 40–80℃ for 4–12 hours to obtain granular ZIF-8 powder.

6. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 1, characterized in that, Step S2 specifically includes the following steps: S2.1, Dissolve 1.0–3.0 g of aniline in 20–50 mL of deionized water, and add 1–5 mL of hydrochloric acid to form an aniline hydrochloride solution; S2.2, Dissolve 0.2–1.0 g of ammonium persulfate (APS) in 10–30 mL of deionized water to obtain an ammonium persulfate solution; S2.3, mix aniline hydrochloride solution with ammonium persulfate solution and stir magnetically at room temperature for 1–4 hours. When the color of the solution gradually changes from black to dark green, it indicates that the polymerization reaction is complete.

7. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 1, characterized in that, Step S3 specifically includes the following steps: S3.1 Weigh 0.5–2.0 g of zinc nitrate hexahydrate Zn(NO3)2·6H2O, dissolve it in 50–100 mL of deionized water to obtain a zinc nitrate solution, weigh 1.0–3.0 g of aniline and dissolve it in 20–50 mL of deionized water to form an aniline solution, and add 1–5 mL of hydrochloric acid to adjust the acidity of the solution to form a mixed aniline solution; S3.2, the aniline mixed solution is added to the zinc nitrate solution and stirred thoroughly to form a homogeneous first mixed solution. Ammonium persulfate (APS) is added as an oxidant; 0.2–1.0 g of APS is dissolved in 10–30 mL of deionized water to obtain an ammonium persulfate solution. The ammonium persulfate solution is slowly added dropwise to the first mixed solution. Aniline undergoes oxidative polymerization under acidic conditions to form a polyaniline solution. 3.0–8.0 g of 2-methylimidazole is dissolved in 10–30 mL of deionized water and added to the polyaniline solution. 2-methylimidazole reacts with the zinc source to form ZIF-8 crystals. As the reaction continues, the color of the solution changes from light to dark green, indicating that the polymerization reaction of polyaniline is complete. S3.3, remove unreacted monomers and excess ammonium persulfate by centrifugation, and wash the product with methanol to remove impurities; S3.4, the ZIF-8 / PANI composite material is transferred to a drying oven and dried at 40–80°C for 4–12 hours to obtain granular ZIF-8 / PANI composite material.

8. The method for preparing a phosphine sensor for use in a phosphine gas monitoring device according to claim 1, characterized in that, Step S4 specifically includes the following steps: S4.1, Dissolve ZIF-8 / PANI in deionized water; place the solution on a magnetic stirrer and stir thoroughly to ensure complete dissolution; S4.2, uniformly drop the solution onto the pre-prepared interdigitated electrode (IDE) to form a gas sensing film; the spin coating time during drop addition is 30–90 s to ensure uniform film layer; S4.3 Place the coated sensor film sample into a vacuum drying oven and vacuum dry it at 40-80℃ for 2-6 hours until the sensor film is completely cured, and finally obtain the ZIF-8 / PANI gas sensor.

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