Plasma modified MoS2 / rGO / PVP humidity-sensitive sensing material, preparation method thereof and humidity sensor prepared from plasma modified MoS2 / rGO / PVP humidity-sensitive sensing material

Abstract

The invention provides a plasma modified MoS2 / rGO / PVP humidity-sensitive sensing material, a preparation method and a humidity sensor prepared from the plasma modified MoS2 / rGO / PVP humidity-sensitive sensing material, and belongs to the technical field of humidity sensors. The lower limit of detection of the plasma modified MoS2 / rGO / PVP humidity-sensitive sensing material prepared by introducing polyvinylpyrrolidone on the basis of the MoS2 / rGO material and then performing plasma modification is greatly reduced from 197 ppm of the base material MoS2 / rGO to 129 ppm, which is further reduced by 13.4% compared with the optimal value 149 ppm of the plasma modified MoS2 / rGO material. The response / recovery time is 23s / 62s, and compared with 38s / 101s of a base material MoS2 / rGO and 33s / 80s of a plasma modified MoS2 / rGO material, the response rate is increased by 39.5% and 30.3%.

Description

Technical Field

[0001] The present invention relates to the technical field of humidity sensors, and in particular to a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material, a preparation method, and a humidity sensor prepared therefrom. Background Art

[0002] Gases such as sulfur hexafluoride (SF6), air, and sulfur dioxide are widely used in high-voltage electrical equipment, and their insulation properties directly impact the safe operation of the equipment. However, moisture in the insulating medium can significantly degrade the gas's stability, triggering partial discharge, corroding insulation materials, and even causing equipment failure. For example, excessive moisture in SF6 gas can cause it to decompose and produce toxic compounds, seriously threatening equipment reliability and personnel safety. Therefore, accurately monitoring trace moisture in gas, particularly within 1000 ppm, is a critical issue that needs to be addressed in the power industry.

[0003] Currently, mainstream trace moisture detection technologies, such as electrolysis, dew point, and spectroscopy, are all offline methods that require periodic gas sampling and analysis. These methods are unable to reflect dynamic changes in humidity within the equipment in real time. They are significantly affected by ambient temperature and cannot guarantee accuracy under extreme climate conditions. Furthermore, offline testing cycles are long (e.g., weekly or monthly), making it difficult to capture sudden humidity fluctuations, potentially leading to equipment hazards going undetected. Existing sensors made of traditional humidity-sensitive materials, such as ceramics and polymer films, are low-cost but have a limited detection range, sensing only gases with a moisture content above 1000 ppm. This cannot meet the trace moisture monitoring needs of power equipment.

[0004] Therefore, there is an urgent need for a moisture-sensitive sensing material with a lower detection limit. Summary of the Invention

[0005] In order to solve the above-mentioned defects and deficiencies in the prior art, the present application aims to provide a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material, a preparation method and a humidity sensor prepared therefrom.

[0006] One of the purposes of the present invention is to provide a method for preparing a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material, which is characterized by comprising the following steps: The MoS2 / rGO humidity-sensitive material and PVP were dispersed in deionized water and mixed evenly to obtain the MoS2 / rGO / PVP humidity-sensitive material; The MoS2 / rGO / PVP humidity sensitive material is plasma modified to obtain a plasma modified MoS2 / rGO / PVP humidity sensitive sensing material.

[0007] Preferably, the molecular weight of PVP is 40,000.

[0008] Preferably, the mass ratio of MoS2 / rGO humidity-sensitive material to PVP is 1~2:1.

[0009] Preferably, the mass ratio of MoS2 / rGO humidity-sensitive material to PVP is 2:1.

[0010] Preferably, the MoS2 / rGO / PVP humidity sensitive material is plasma modified to obtain a plasma modified MoS2 / rGO / PVP humidity sensitive sensing material comprising: The MoS2 / rGO / PVP humidity-sensitive material is placed in the discharge area of ​​a plasma generator; The discharge was conducted under the conditions of 7000V voltage, 15000Hz frequency and 15000ns pulse width, and plasma was formed by a mixture of argon, ethanol and oxygen; The plasma is used to bombard the surface of the MoS2 / rGO / PVP humidity-sensitive material to obtain a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material.

[0011] Preferably, the time for bombarding the surface of the MoS2 / rGO / PVP humidity-sensitive material is 15 to 60 seconds.

[0012] Preferably, the time for bombarding the surface of the MoS2 / rGO / PVP humidity-sensitive material is 45 s.

[0013] Preferably, the volume ratio of argon, ethanol and oxygen is 50:15:2.

[0014] The second object of the present invention is to provide a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material prepared by the preparation method as described above.

[0015] A third object of the present invention is to provide an application of the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material as described above in a humidity sensor.

[0016] A fourth object of the present invention is to provide a humidity sensor prepared by the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material as described above.

[0017] Preferably, the preparation method of the humidity sensor includes: Fix the interdigital electrodes in the grooves of the glass sheet, fix the side of the glass sheet away from the grooves to the PCB, and solder thick wires to the two pins of the interdigital electrodes; The plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material was prepared into a suspension; The suspension is drop-coated on the interdigital electrodes and dried, and the drop-coating and drying process is repeated at least three times to obtain a humidity sensor.

[0018] Beneficial effects of the present invention: The present invention introduces polyvinyl pyrrolidone on the basis of MoS2 / rGO material, and utilizes its unique molecular structure to inhibit the agglomeration of nanosheets, thereby achieving highly dispersed and uniform film formation, while enhancing the bonding strength between the humidity-sensitive material and the electrode. Then, through plasma modification, directional etching of pores and regulation of surface functional groups, the composite material is etched to form a three-dimensional porous network structure, the surface hydrophilic groups are distributed in a gradient, the Mo-O ratio is further reduced, water molecule penetration and electron migration are accelerated, and the humidity-sensitive sensing performance is further improved.

[0019] The detection limit of the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material in the present invention is greatly reduced, from 197 ppm of the basic material MoS2 / rGO to 129 ppm, which is another 13.4% lower than the optimal value of 149 ppm of the plasma-modified MoS2 / rGO material.

[0020] The response / recovery time of the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material in the present invention is 23s / 62s, which is 39.5% and 30.3% higher than that of the basic material MoS2 / rGO (38s / 101s) and the plasma-modified MoS2 / rGO material (33s / 80s). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention, in which: Figure 1 SEM test results of MoS2 / rGO; Figure 2 SEM test results of MoS2 / rGO / PVP; Figure 3 SEM test results of plasma-modified MoS2 / rGO / PVP; Figure 4 The lower detection limit of plasma-modified MoS2 / rGO / PVP humidity sensor; Figure 5 To test the humidity-resistance response characteristics of plasma-modified MoS2 / rGO / PVP humidity-sensitive materials; Figure 6 Response / recovery time test of plasma-modified MoS2 / rGO / PVP humidity-sensitive materials; Figure 7 Response / recovery time test of MoS2 / rGO humidity sensitive material; Figure 8 Response / recovery time test of plasma-modified MoS2 / rGO humidity-sensitive material. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below with reference to the accompanying drawings and examples. The specific embodiments described herein are intended only to explain the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings. The embodiments and features in the embodiments of the present application may be combined with each other unless there is a conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the examples.

[0023] According to a first aspect of the present invention, a method for preparing a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material is provided, characterized in that it comprises the following steps: First, the MoS2 / rGO humidity-sensitive material and PVP were dispersed in deionized water and mixed evenly to obtain the MoS2 / rGO / PVP humidity-sensitive material; The MoS2 / rGO / PVP humidity-sensitive material is then plasma-modified to obtain a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material.

[0024] In the present invention, polyvinyl pyrrolidone (PVP) is a water-soluble polymer prepared by free radical polymerization of N-vinyl pyrrolidone monomer, referred to as PVP, with a molecular formula of (C6H9NO) n Its chemical structure, shown in Formula 1, consists of a highly polar lactam structure and a nonpolar methylene group within its molecular chain and ring. The pyrrolidone ring imparts excellent coordination and hydrogen bonding capabilities, while the polyethylene backbone adapts to diverse interfacial environments. PVP exhibits thermal stability, strong adsorption, and excellent film-forming and adhesive properties.

[0025]

[0026] Formula 1 In the present invention, Figure 1 、 Figure 2 and Figure 3As shown, the MoS2 / rGO surface exhibits a dense cluster structure. Compared to the pure MoS2 / rGO system, the addition of PVP to the MoS2 / rGO / PVP material significantly improves the dispersibility of the MoS2 / rGO. Furthermore, the polymer colloid fills the pores, resulting in a non-porous overall morphology. Regarding the surface microstructure, the unique structure of the PVP molecular chain (hydrophobic carbon chains and hydrophilic pyrrolidone rings) inhibits MoS2 / rGO aggregation through steric hindrance, resulting in a uniform dispersion of the nanosheets and exposure of more active edge sites. PVP acts as a binder to strengthen the contact between the material and the interdigitated electrodes, reducing interfacial resistance fluctuations. The uniformly dispersed nanosheets increase the electron conduction pathway, improving signal transmission efficiency at low humidity. The stable electrode-material interface reduces background current noise, making weak humidity signals easier to detect. After plasma modification, the surface morphology of the plasma-modified MoS2 / rGO / PVP material undergoes significant changes. A three-dimensional porous network gradually emerges within the material, with the edges of the nanosheets clearly visible and evenly distributed pores forming between them. This phenomenon is attributed to the action of high-energy plasma particles: on the one hand, the plasma bombardment selectively etches the PVP on the surface, gradually dissociating its dense coating to expose the active surface of MoS2 / rGO; on the other hand, it forms a stable porous framework by cross-linking with the sulfur vacancies and oxygen-containing functional groups of MoS2 / rGO.

[0027] This etching-cross-linking mechanism not only retains the enhancing effect of PVP on the dispersion and interfacial bonding of the material, but also promotes the formation of a three-dimensional network of the material by forming pores and functional groups, establishes adsorption-diffusion channels, and significantly improves the adsorption capacity of the material.

[0028] The formation of a three-dimensional porous network increases the material's specific surface area, providing more sites for water molecule adsorption and enhancing the signal response strength per unit humidity change. The open pore structure shortens the diffusion path for water molecules, accelerating the adsorption process, allowing even low humidity changes to trigger significant signal changes. Plasma modification results in a uniform pore distribution and tighter interlayer bonding.

[0029] Furthermore, compared to the plasma-modified MoS2 / rGO (PVP-free) system, the composite material (MoS2 / rGO / PVP) exhibits a more uniform pore distribution and higher interlayer bonding strength, as the plasma treatment partially eliminates the surface PVP coating. The addition of PVP effectively improves the material's dispersibility and bonding capacity. However, simply adding PVP tightly encapsulates the MoS2 / rGO, reducing porosity. Plasma modification effectively optimizes the pore structure of the MoS2 / rGO / PVP composite. Its open, porous nature facilitates the rapid transfer of water molecules during adsorption and desorption. The combination of PVP addition and plasma modification further enhances the sensor's overall performance.

[0030] Uniform pores prevent water molecules from being retained or unevenly diffused in local areas, reducing background noise and improving signal stability under low humidity conditions. The high-strength interlayer structure inhibits structural collapse of the material during humidity cycles, maintaining long-term detection reliability.

[0031] The plasma's energetic particles crosslink with sulfur vacancies and oxygen-containing functional groups (such as hydroxyl and carboxyl groups) in MoS2 / rGO, forming polar adsorption sites. The three-dimensional network and polar functional groups together create a rapid adsorption-diffusion pathway. The polar functional groups enhance the specific adsorption of water molecules through hydrogen bonding, allowing them to capture water even at low humidity levels. The interconnected pore network allows water molecules to quickly penetrate the material, amplifying the adsorption signal and lowering the detection threshold.

[0032] In a preferred embodiment of the present invention, the molecular weight of PVP is 40,000.

[0033] In the present invention, the molecular weight of PVP is 40,000, which has both steric hindrance effect and solution processability in the composite material, and is the key to balancing dispersibility and process feasibility.

[0034] PVP with a molecular weight of 40,000 has a moderate chain length. Its hydrophobic carbon chains can entangle and wrap around the MoS2 / rGO nanosheets, creating sufficient steric hindrance to effectively inhibit the nanosheets' π-π stacking and aggregation. If the molecular weight is lower than 40,000, the molecular chains are too short, resulting in insufficient steric hindrance and limited improvement in dispersibility. If the molecular weight is higher than 40,000, the molecular chains are too long and easily entangled, causing a sudden increase in solution viscosity and, in turn, promoting bridging and aggregation of the nanosheets. At a molecular weight of 40,000, PVP forms a stable colloid in the solvent, allowing for uniform adsorption on the nanosheet surface, preventing aggregation caused by localized high concentrations.

[0035] PVP with a molecular weight of 40,000 has a moderate chain length, forming a coating of moderate thickness on the MoS2 / rGO surface. This allows for selective etching by high-energy plasma particles without overly thick layers, which can lead to incomplete etching or uneven pore formation. If the molecular weight is lower than 40,000, the coating is too thin, exposing the nanosheets after etching and losing the PVP's ability to maintain dispersion. If the molecular weight is higher than 40,000, the coating is too thick, requiring longer plasma etching times or higher energies, potentially destroying the layered structure of MoS2 / rGO. The cross-linked products (such as pyrrolidone ring fragments) left after etching by PVP with a molecular weight of 40,000 can form a stable framework with the functional groups of MoS2 / rGO, preventing pore collapse.

[0036] As a binder, PVP, with a molecular weight of 40,000, has a molecular chain length that allows for moderate crosslinking between the interdigitated electrodes and MoS2 / rGO. If the molecular chain is too short, there are insufficient bonding sites, resulting in weak interfacial bonding and easy detachment. If the molecular chain is too long, PVP forms an insulating layer on the electrode surface, increasing electron transport resistance and reducing sensor conductivity. The balance between bonding strength and conductivity at a molecular weight of 40,000 ensures signal stability during humidity cycling.

[0037] Aqueous solutions of PVP with a molecular weight of 40,000 have a moderate viscosity (approximately 50-100 cP at 25°C), avoiding excessive viscosity caused by high K values ​​or film cracking caused by low K values. In common solvents (such as water and ethanol), PVP with a molecular weight of 40,000 exhibits good solubility and can mix uniformly with MoS2 / rGO to form a stable dispersion, avoiding aggregation or phase separation caused by poor solubility.

[0038] Finally, the 40,000 molecular weight PVP molecule has a moderate ratio of hydrophobic carbon chains to hydrophilic pyrrolidone rings. During plasma etching, the hydrophobic segments are preferentially bombarded and dissociated, while the hydrophilic pyrrolidone rings readily cross-link with the oxygen-containing functional groups of MoS2 / rGO, forming a dynamic equilibrium of "etching-crosslinking" and ultimately optimizing the pore structure. Combined with the plasma modification parameters (7000V voltage, 15,000Hz frequency, etc.), the 40,000 molecular weight PVP exhibits a moderate etching rate (approximately 0.1-0.5nm / s) at this energy. This, combined with a modification time of 15-60s, allows for precise control of the amount of coating removed and avoids over-etching.

[0039] In a preferred embodiment of the present invention, the mass ratio of MoS2 / rGO humidity-sensitive material to PVP is 1-2:1.

[0040] In the present invention, the molecular chains of PVP (hydrophobic carbon chains and hydrophilic pyrrolidone rings) can wrap around the MoS2 / rGO nanosheets through steric hindrance, reducing π-π stacking and agglomeration caused by van der Waals forces. When the mass ratio is between 1 and 2:1, the amount of PVP is sufficient to cover the MoS2 / rGO surface without forming an excessive, dense coating. If the mass ratio of the MoS2 / rGO humidity-sensitive material to PVP is less than 1:1, the dispersion is insufficient, and the MoS2 / rGO tends to agglomerate into large clusters, resulting in insufficient exposure of active sites. If the mass ratio of the MoS2 / rGO humidity-sensitive material to PVP is greater than 2:1, the PVP overwraps the nanosheets, even forming a continuous polymer film, which hinders the subsequent plasma modification and pore etching.

[0041] As a binder, the polar groups of PVP's pyrrolidone rings can form hydrogen bonds or covalent interactions with the sulfur vacancies in MoS2 and the oxygen-containing functional groups in rGO, enhancing the adhesion of the material to the interdigitated electrodes. A 1-2:1 ratio ensures a stable PVP bond at the material-electrode interface while preventing the increase in interfacial resistance caused by excessive PVP.

[0042] When PVP is added alone, excess polymer fills the interlayer pores of MoS2 / rGO, reducing the number of channels for water molecule adsorption. At a mass ratio of 1 to 2:1, PVP only partially fills the pores, preserving the interlamellar spaces between the MoS2 / rGO sheets and allowing space for subsequent plasma modification and etching to form a three-dimensional porous structure. Plasma treatment selectively etches surface PVP. If the initial PVP dosage is excessive, a large amount of polymer may remain after etching, resulting in uneven pore distribution. If the dosage is too low, the material tends to reagglomerate after etching, reducing pore stability. Within this ratio range, PVP's "etching-crosslinking" mechanism is more readily implemented. The high-energy particles in the plasma can both dissociate part of the PVP coating, exposing the active surface of MoS2 / rGO, and maintain the stability of the pore framework by cross-linking with residual PVP groups. A mass ratio exceeding 1 to 2:1 can result in over-etching or insufficient cross-linking, affecting pore uniformity and connectivity.

[0043] A mass ratio of 1 to 2:1 ensures that the modified material possesses both sufficient MoS2 / rGO active sites (such as sulfur vacancies and oxygen-containing groups) for water adsorption and a uniform porous network (formed by PVP etching and MoS2 / rGO sheet stacking) that promotes rapid water diffusion. Excessive PVP coverage of the material surface with polymer reduces adsorption sites; too little leads to material aggregation, narrowing diffusion channels and reducing sensor response. At this ratio, the dispersing effect of PVP and the pore optimization achieved through plasma modification synergistically enhance the material's responsiveness to low-humidity environments. PVP dosages outside this range may result in insufficient water adsorption due to aggregation or pore clogging, preventing the sensor from responding to low-concentration conditions.

[0044] From a process perspective, a mass ratio of 1 to 2:1 facilitates uniform mixing and has strong operability. If the ratio is too high or too low, it may lead to abnormal slurry viscosity (too much PVP will make it viscous, and too little will make it easy to precipitate), affecting the uniformity of film formation.

[0045] In a preferred embodiment of the present invention, the MoS2 / rGO / PVP humidity sensitive material is plasma modified to obtain a plasma-modified MoS2 / rGO / PVP humidity sensitive sensing material comprising: The MoS2 / rGO / PVP humidity-sensitive material is placed in the discharge area of ​​a plasma generator; The discharge was conducted under the conditions of 7000V voltage, 15000Hz frequency and 15000ns pulse width, and plasma was formed by a mixture of argon, ethanol and oxygen; The plasma is used to bombard the surface of the MoS2 / rGO / PVP humidity-sensitive material to obtain a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material.

[0046] In a preferred embodiment of the present invention, the time for bombarding the surface of the MoS2 / rGO / PVP humidity-sensitive material is 15 to 60 seconds.

[0047] In a preferred embodiment of the present invention, the time for bombarding the surface of the MoS2 / rGO / PVP humidity-sensitive material is 45 s.

[0048] When bombarding the MoS2 / rGO / PVP humidity-sensitive material surface for 15 seconds, the plasma's high-energy particles (argon ions, oxygen free radicals, etc.) only etched the shallow PVP coating on the material's surface, partially exposing the edges of the MoS2 / rGO sheets. However, a large amount of PVP remained inside, and the pore network had not yet fully formed. Although micropores began to appear in the material at this point, the channel connectivity was insufficient, hindering the diffusion of water molecules.

[0049] When bombarding the MoS2 / rGO / PVP humidity-sensitive material surface for 60 seconds, prolonged bombardment can lead to excessive etching of the PVP, even destroying the covalent bonds of the MoS2 / rGO sheets (such as breaking the S-Mo bond). This causes fragmentation and peeling of the nanosheet edges, and irregular pores due to skeleton collapse. Furthermore, excessive oxygen free radicals can introduce excessive oxygen-containing functional groups (such as carboxyl groups), increasing the material's resistance and decreasing the humidity-sensitive response.

[0050] When the bombardment time of the MoS2 / rGO / PVP humidity-sensitive material surface is 45s, the etching depth is moderate: it can completely dissociate the dense coating layer of PVP on the surface, and maintain the stable support of the pores between the sheets through the cross-linking effect between plasma and the residual groups of PVP (such as the reaction between the pyrrolidone ring and the hydroxyl group of rGO).

[0051] In a preferred embodiment of the present invention, the volume ratio of argon, ethanol and oxygen is 50:15:2.

[0052] According to a second aspect of the present invention, a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material prepared by the preparation method described above is provided.

[0053] According to a third aspect of the present invention, there is provided an application of the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material as described above in a humidity sensor.

[0054] According to a fourth aspect of the present invention, a humidity sensor prepared from the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material as described above is provided.

[0055] In a preferred embodiment of the present invention, a method for preparing a humidity sensor includes: Fix the interdigital electrodes in the grooves of the glass sheet, fix the side of the glass sheet away from the grooves to the PCB, and solder thick wires to the two pins of the interdigital electrodes; The plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material was prepared into a suspension; The suspension is drop-coated on the interdigital electrodes and dried, and the drop-coating and drying process is repeated at least three times to obtain a humidity sensor.

[0056] In the present invention, the preparation method of the humidity sensor specifically includes: selecting the metal material of the sensor as Ti / Pt, the finger spacing as 20 The interdigitated electrodes are made of quartz glass. The interdigitated electrodes are fixed in grooves on a custom glass sheet, the back of which is fixed to a PCB. Thick wires are soldered to the two pins of the interdigitated electrodes. Then, a suspension of the plasma-modified MoS2 / rGO / PVP humidity-sensitive material is prepared in deionized water at a concentration of 10 g / L. The prepared solution is ultrasonically oscillated to evenly disperse the humidity-sensitive material throughout the solution. Finally, a 3 μL droplet of the suspension is applied directly above the interdigitated electrodes using a micropipette and dried in a 60°C drying oven. A uniform thin film of the humidity-sensitive material forms on the electrode surface. This process is repeated three times to complete the sensor fabrication.

[0057] Example The preparation method of plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material comprises the following steps: First, the MoS2 / rGO humidity-sensitive material and PVP were dispersed in deionized water and mixed evenly to prepare the MoS2 / rGO / PVP humidity-sensitive material with a mass ratio of MoS2 / rGO to PVP of 1:1 and the MoS2 / rGO / PVP humidity-sensitive material with a mass ratio of MoS2 / rGO to PVP of 2:1, respectively. Then, the MoS2 / rGO / PVP humidity-sensitive material with a mass ratio of MoS2 / rGO to PVP of 1:1 and the MoS2 / rGO / PVP humidity-sensitive material with a mass ratio of MoS2 / rGO to PVP of 2:1 were placed in the discharge area of ​​the plasma generator respectively; The discharge was conducted under the conditions of 7000V voltage, 15000Hz frequency and 15000ns pulse width, and plasma was formed by a mixture of argon, ethanol and oxygen; The plasma was used to bombard the surface of the MoS2 / rGO / PVP humidity-sensitive material to prepare plasma-modified MoS2 / rGO / PVP (1:1) humidity-sensitive sensing materials with bombardment times of 0s, 15s, 30s, 45s and 60s, and plasma-modified MoS2 / rGO / PVP (2:1) humidity-sensitive sensing materials with bombardment times of 0s, 15s, 30s, 45s and 60s, respectively.

[0058] Performance testing: 1. Test the detection limit of humidity sensors for the above materials The humidity sensor was prepared by the above humidity sensitive material and the detection limit of the humidity sensor of the above material was tested. The test results are as follows Figure 4 As shown, the detection limit of humidity sensors prepared with two mass ratios (the mass ratio of MoS2 / rGO humidity sensitive material to PVP is 1:1 and 2:1) of MoS2 / rGO humidity sensitive material and PVP under different plasma modification times.

[0059] The detection limits for the unmodified MoS2 / rGO / PVP (1:1) were 171 ppm, and for the MoS2 / rGO / PVP (2:1) mixture, they were 161 ppm. This indicates that the detection limits for both materials are high in their initial state, and the detection limit for the 1:1 MoS2 / rGO to PVP ratio is slightly higher than that for the 2:1 ratio, indicating that the 1:1 material is relatively insensitive to humidity.

[0060] When the modification time was 15 seconds, the detection limit of MoS2 / rGO / PVP (1:1) dropped to 164 ppm, and that of MoS2 / rGO / PVP (2:1) dropped to 154 ppm. The decrease in the detection limit for both materials indicates that plasma modification has begun to have a positive impact on the material properties, making the sensor more sensitive to humidity. However, the decrease is relatively small, indicating that the 15-second modification time is insufficient.

[0061] When the modification time was 30 seconds, the detection limits for MoS2 / rGO / PVP (1:1) were 167 ppm, and for MoS2 / rGO / PVP (2:1) was 143 ppm. The detection limit for the 1:1 material increased slightly, likely due to the fact that the modification had some impact on the material structure, but not yet reached its optimal state. The detection limit for the 2:1 material decreased further, indicating that the 30-second modification significantly improved the humidity-sensing properties of the 2:1 material.

[0062] When the modification time was 45 seconds, the detection limits of MoS2 / rGO / PVP (1:1) dropped to 158 ppm, and those of MoS2 / rGO / PVP (2:1) dropped to 129 ppm. Both significantly reduced detection limits, with the 2:1 material reaching its lowest value, indicating that a 45-second modification time significantly improved the humidity-sensitivity of both materials, with the 2:1 material showing the best effect, achieving a good balance between material structure and performance.

[0063] When the modification time was 60 seconds, the detection limits for MoS2 / rGO / PVP (1:1) were 143 ppm, and for MoS2 / rGO / PVP (2:1) was 147 ppm. The detection limit for the 1:1 material continued to decrease, but it actually increased for the 2:1 material. This suggests that the 60-second modification time was too long, potentially destroying the structure of the 2:1 material and reducing its humidity-sensing properties. However, there is still room for improvement for the 1:1 material.

[0064] Therefore, the plasma modification time significantly affects the detection limit of the humidity sensor of the MoS2 / rGO / PVP humidity-sensitive sensing material. A suitable modification time (e.g., 45 seconds) can effectively reduce the detection limit and improve humidity-sensitive performance. MoS2 / rGO / PVP materials with different mass ratios respond differently to the modification time. The material with a 2:1 MoS2 / rGO:PVP mass ratio exhibits optimal humidity-sensitive performance at 45 seconds, while the 1:1 material shows a continued improvement at 60 seconds. However, further research is needed to avoid the negative effects of excessive modification times.

[0065] 2. Humidity-resistance response characteristics test of plasma-modified MoS2 / rGO / PVP humidity-sensitive material The resistance of the MoS2 / rGO / PVP humidity-sensitive material (MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material) with a mass ratio of MoS2 / rGO to PVP of 2:1 and plasma modification for 45s was tested under different relative humidity (%RH) environments. The test results are as follows: Figure 5 As shown, the broken line represents the resistance change of the MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material. The relative humidity changes from 8%RH to 34%RH, 56%RH, 75%RH, and 95%RH at different time points. There is a period of time in the 8%RH environment before each humidity change.

[0066] As the relative humidity increases from 8% RH to other humidity levels (such as 34% RH, 56% RH, 75% RH, and 95% RH), the material's resistance increases rapidly. This demonstrates that the MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material is sensitive to humidity changes. Increasing humidity increases the material's resistance, consistent with the principle that humidity sensors detect humidity through resistance changes. The magnitude of the resistance change increases with increasing relative humidity. There is a modest increase in resistance from 8% RH to 34% RH, with a greater increase at 56% RH, further increases at 75% RH, and a peak resistance at 95% RH. This indicates that the material is more sensitive to high humidity and can more clearly distinguish between different humidity levels.

[0067] After each humidity increase, when the ambient humidity returned to 8% RH, the resistance dropped rapidly and essentially returned to its initial resistance value at 8% RH. This indicates that the material can quickly return to its initial state when the humidity decreases, has good recovery properties, and can operate stably in cycles of varying humidity environments.

[0068] The figure shows that the MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material has good response and recovery capabilities to different humidity levels, can accurately reflect humidity changes through resistance changes, and has good application potential in the field of humidity detection.

[0069] 3. Test response / recovery time The response / recovery time of MoS2 / rGO / PVP (2:1, 45s) humidity sensitive material, the response / recovery time of MoS2 / rGO humidity sensitive material and the response / recovery time of plasma modified MoS2 / rGO humidity sensitive material were tested respectively. The test results are as follows Figure 6 、 Figure 7 and Figure 8 shown.

[0070] As can be seen from the figure, the humidity levels of the response / recovery time test of MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material are 8%RH and 56%RH, and the response / recovery time of MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material is 23s / 62s. Compared with 38s / 101s of MoS2 / rGO humidity-sensitive material and 33s / 80s of plasma-modified MoS2 / rGO humidity-sensitive material, the response rate is increased by 39.5% and 30.3%.

[0071] Therefore, the MoS2 / rGO / PVP (2:1, 45s) humidity-sensitive material exhibits significant advantages in humidity sensing performance. Its significantly improved response rate means it can more quickly sense changes in ambient humidity. This is particularly true in applications where timely humidity response is crucial, such as real-time weather monitoring and precise humidity control in industrial production environments. This provides timely feedback on humidity information, facilitating more precise decision-making and regulation.

[0072] In terms of recovery time, the recovery time of 62s is significantly shorter than that of the other two materials. This shows that the material can recover to its initial stable state faster after humidity changes, ensuring the stability and reliability of the sensor in different humidity cycle tests, effectively reducing measurement errors, and improving the ability to maintain accuracy during long-term use.

[0073] This performance advantage stems from the synergistic effect of PVP and plasma modification. The introduction of PVP improves the dispersibility of MoS2 / rGO and optimizes the material's microstructure, making it easier for water molecules to adsorb and desorb. Plasma modification further constructs a three-dimensional porous network, promoting the diffusion and transport of water molecules. The combination of these two effectively reduces the transport resistance of water molecules in the material, significantly shortening the response / recovery time. This provides a new and effective approach for the preparation of high-performance humidity sensors and is expected to promote their widespread application and upgrading in more fields.

Claims

1. A method for preparing a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material, characterized in that: The following steps are involved: The MoS2 / rGO humidity-sensitive material and PVP were dispersed in deionized water and mixed evenly to obtain the MoS2 / rGO / PVP humidity-sensitive material; The MoS2 / rGO / PVP humidity sensitive material is plasma modified to obtain a plasma modified MoS2 / rGO / PVP humidity sensitive sensing material.

2. The preparation method according to claim 1, wherein The molecular weight of the PVP is 40,000.

3. The preparation method according to claim 2, wherein The mass ratio of the MoS2 / rGO humidity-sensitive material to PVP is 1-2:

1.

4. The preparation method according to claim 1, wherein The plasma-modified MoS2 / rGO / PVP humidity-sensitive material to obtain the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material comprises: The MoS2 / rGO / PVP humidity-sensitive material is placed in the discharge area of ​​a plasma generator; The discharge was conducted under the conditions of 7000V voltage, 15000Hz frequency and 15000ns pulse width, and plasma was formed by a mixture of argon, ethanol and oxygen; The plasma is used to bombard the surface of the MoS2 / rGO / PVP humidity-sensitive material to obtain a plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material.

5. The preparation method according to claim 4, wherein The time for bombarding the surface of the MoS2 / rGO / PVP humidity-sensitive material is 15 to 60 seconds.

6. The preparation method according to claim 5, wherein The bombardment time of the MoS2 / rGO / PVP humidity-sensitive material surface is 45s.

7. A plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material according to claim 7 in a humidity sensor.

9. A humidity sensor, characterized in that: The sensor is prepared from the plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material described in claim 7.

10. The humidity sensor according to claim 9, wherein The preparation method of the humidity sensor includes: Fix the interdigital electrodes in the grooves of the glass sheet, fix the side of the glass sheet away from the grooves to the PCB, and solder thick wires to the two pins of the interdigital electrodes; The plasma-modified MoS2 / rGO / PVP humidity-sensitive sensing material was prepared into a suspension; The suspension is drop-coated on the interdigital electrodes and dried, and the drop-coating and drying process is repeated at least three times to obtain a humidity sensor.

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