Room-temperature DMMP sensor based on platinum diselenide van der Waals heterojunction
By loading low-dimensional nanomaterials onto a platinum diselenide substrate to form a heterojunction, the problems of sensitivity and selectivity contradiction, high operating temperature and poor stability of existing DMMP sensors are solved, and high sensitivity and high selectivity of DMMP detection at room temperature are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NAT UNIV OF DEFENSE TECH
- Filing Date
- 2026-01-30
- Publication Date
- 2026-04-21
AI Technical Summary
Existing DMMP sensors suffer from problems such as a contradiction between sensitivity and selectivity, high operating temperature, slow response recovery speed, poor stability, and insufficient detection limit, mainly due to the limitations of sensitive material design and unclear interface interaction mechanisms.
A platinum diselenide van der Waals heterojunction structure is adopted, in which low-dimensional nanomaterials such as carbon nanotubes, graphene or metal disulfides are loaded on the platinum diselenide matrix to form a heterojunction, thereby achieving high sensitivity and selectivity for DMMP detection.
It achieves high-sensitivity detection of DMMP at room temperature, reduces the operating temperature, improves response recovery speed and stability, and expands the detection limit.
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Figure CN121899207A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas sensing technology, and in particular to a room temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction. Background Technology
[0002] Dimethyl methylphosphonate (DMMP), as a typical simulant of organophosphorus nerve agents (such as sarin), has important detection needs in fields such as environmental monitoring and public safety. Currently, research on gas sensors targeting DMMP has made some progress, covering various sensing mechanisms and material systems, but many technical bottlenecks still need to be overcome.
[0003] DMMP is a polar molecule containing a phosphorus-oxygen double bond (P=O). Its detection mainly relies on the specific interaction between the sensor material and the DMMP molecule, such as hydrogen bonding, coordination bonding or physical adsorption.
[0004] Common types of DMMP sensors include: (1) Quartz crystal microbalance (QCM) sensor: Based on the principle of mass change, the frequency changes after DMMP adsorption are caused by coating the surface of the quartz crystal with a sensitive material (such as functionalized mesoporous material); (2) Organic field-effect transistor (OFET) sensor: Utilizes the change in conductivity of organic semiconductor layer (such as poly(3-hexylthiophene)) to respond to the gas; (3) Resistive metal oxide sensor: Utilizes the change in conductivity caused by the charge transfer between gas molecules and metal oxide semiconductor for measurement; (4) Surface acoustic wave (SAW) sensor: Response to DMMP adsorption by acoustic wave frequency shift.
[0005] Despite the advantages of each of the above sensors, the following common and individual problems still exist: (1) The contradiction between sensitivity and selectivity: Most sensors have poor selectivity for DMMP in complex atmospheres (such as high humidity or the presence of volatile organic compounds). This is mainly because the interaction mechanism between the sensitive material and DMMP is simple (such as relying solely on hydrogen bonds), and is easily interfered with by other polar molecules (such as water and alcohols). (2) High operating temperature requirements: Since high temperature is a necessary condition for activating oxygen vacancies on the material surface and promoting gas adsorption-desorption, common metal oxide sensors (such as MoO3 and SnO2) need to operate at 200–400°C, resulting in high power consumption and difficulty in portability. (3) Slow response recovery speed: There is a strong adsorption effect between DMMP molecules and the sensitive material, and the desorption energy barrier is high, resulting in slow recovery. For example, polymer-based and some QCM sensors have long response times and incomplete recovery, making it difficult to achieve continuous monitoring. (4) Poor stability and repeatability: The material is easily affected by the environment (such as oxidation and moisture adsorption), and the interface stability between the sensitive layer and the substrate is insufficient, especially for room temperature sensors (such as PPy-rGO), which show significant performance degradation during long-term use. (5) Insufficient detection limit: Existing sensors have limited detection capabilities for ultra-low concentrations of DMMP at the ppb level. This is mainly due to the limited specific surface area of the sensitive material, insufficient active sites, and low signal-to-noise ratio of the signal conversion mechanism (such as resistance and frequency).
[0006] In summary, while current research on DMMP sensors covers multiple technical approaches, it still generally faces challenges in selectivity, operating temperature, response speed, and stability. These problems stem from limitations in the design of sensitive materials, unclear interfacial mechanisms, and insufficient optimization of device structures.
[0007] In view of this, the present invention is proposed. Summary of the Invention
[0008] The purpose of this invention is to provide a room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction, addressing the problems existing in the prior art. This invention's platinum diselenide van der Waals heterojunction sensor primarily relies on the high-sensitivity signal conversion of the platinum diselenide substrate and the specific recognition of the loading layer to achieve trace detection of DMMP. The platinum diselenide substrate possesses advantages such as high carrier mobility and strong environmental stability, ensuring that minute charge disturbances are rapidly transmitted and converted into significant current or resistance changes. However, due to the limited responsiveness and selectivity of pure platinum diselenide to DMMP, it is usually necessary to modify or integrate a layer of a sensitive material with a strong affinity for DMMP (such as oxides containing specific metals, disulfides, or nanomaterials). These sensitive materials can form hydrogen bonds or Lewis acid-base interactions with the P=O groups in DMMP molecules, thereby achieving selective capture of trace molecules.
[0009] To achieve the above objectives, the present invention provides the following solution: This invention provides a room temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction, comprising: an electrode, a platinum diselenide layer loaded on the surface of the electrode, and nanomaterials loaded on the surface of the platinum diselenide layer. The platinum diselenide layer forms a van der Waals heterojunction with the nanomaterial.
[0010] As a further preferred embodiment of the present invention, the nanomaterial is a low-dimensional nanomaterial, specifically selected from at least one of carbon nanotubes, graphene, zinc oxide, and metal disulfides.
[0011] As a further preferred embodiment of the present invention, the metal disulfide includes molybdenum disulfide (MoS2) or tungsten disulfide (WS2).
[0012] As a further preferred embodiment of the present invention, the electrode is an interdigital electrode.
[0013] This invention also provides a method for fabricating the above-mentioned room-temperature DMMP sensor based on platinum diselenide van der Waals heterojunction, comprising the following steps: Platinum diselenide grown on the substrate is transferred to the electrode surface to obtain a platinum diselenide layer loaded on the electrode surface; The dispersion of the nanomaterial is added to the surface of the platinum diselenide layer for wetting, and then the solvent is removed. The platinum diselenide layer and the nanomaterial form a van der Waals heterojunction, thus obtaining the room temperature DMMP sensor based on the platinum diselenide van der Waals heterojunction.
[0014] As a further preferred embodiment of the present invention, the concentration of the dispersion of the nanomaterial is 0.1-10 mg / mL.
[0015] As a further preferred embodiment of the present invention, the preparation method includes the following steps: (1) Wet transfer: Platinum diselenide (PtSe2) grown on silicon oxide or aluminum oxide substrate is transferred to the surface of interdigitated electrode to obtain a platinum diselenide (PtSe2) film loaded on interdigitated electrode; (2) Wetting load: The prepared nanomaterial dispersion is dropped onto the surface of the platinum diselenide (PtSe2) film obtained in step (1) for wetting, and then heated to evaporate the solvent. The platinum diselenide (PtSe2) film and the nanomaterial form a van der Waals heterojunction, thus obtaining the DMMP sensor based on the platinum diselenide van der Waals heterojunction.
[0016] This invention further provides the application of the above-mentioned room-temperature DMMP sensor based on platinum diselenide van der Waals heterojunction in the detection of dimethyl methylphosphonate. It is particularly suitable for trace detection of DMMP at room temperature.
[0017] The present invention discloses the following technical effects: This invention addresses the common problems of high operating temperature and slow response speed in current DMMP sensors by proposing a novel sensing material based on platinum diselenide van der Waals heterojunction for the detection of trace DMMP at room temperature.
[0018] Platinum diselenide (PtSe2), as a two-dimensional transition metal sulfide, has advantages such as large specific surface area, excellent electrical properties, strong chemical activity and high environmental stability. This invention constructs van der Waals heterojunctions by loading low-dimensional nanomaterials such as carbon nanotubes, graphene, zinc oxide and metal disulfides on the surface of platinum diselenide, thereby realizing trace detection of DMMP gas at room temperature. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the gas sensing structure based on platinum diselenide van der Waals heterojunction of the present invention; wherein, 1-interdigitated electrode, 2-PtSe2 thin film, 3-nanomaterial. Detailed Implementation
[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0026] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0027] A first aspect of the present invention provides a room temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction, comprising: an electrode, a platinum diselenide layer loaded on the surface of the electrode, and nanomaterials loaded on the surface of the platinum diselenide layer. The platinum diselenide layer forms a van der Waals heterojunction with the nanomaterial.
[0028] Furthermore, the nanomaterial is a low-dimensional nanomaterial, specifically selected from at least one of carbon nanotubes, graphene, zinc oxide, and metal disulfides.
[0029] Furthermore, the metal disulfide includes molybdenum disulfide (MoS2) or tungsten disulfide (WS2).
[0030] As a further preferred embodiment of the present invention, the electrode is an interdigital electrode.
[0031] A second aspect of the present invention provides a method for fabricating the above-mentioned room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction, comprising the following steps: Platinum diselenide grown on the substrate is transferred to the electrode surface to obtain a platinum diselenide layer loaded on the electrode surface; The dispersion of the nanomaterial is added to the surface of the platinum diselenide layer for wetting, and then the solvent is removed. The platinum diselenide layer and the nanomaterial form a van der Waals heterojunction, thus obtaining the room temperature DMMP sensor based on the platinum diselenide van der Waals heterojunction.
[0032] Furthermore, the concentration of the dispersion of the nanomaterial is 0.1-10 mg / mL.
[0033] Furthermore, the preparation method includes the following steps: (1) Wet transfer: Platinum diselenide (PtSe2) grown on silicon oxide or aluminum oxide substrate is transferred to the surface of interdigitated electrode to obtain a platinum diselenide (PtSe2) film loaded on interdigitated electrode; (2) Wetting load: The prepared nanomaterial dispersion is dropped onto the surface of the platinum diselenide (PtSe2) film obtained in step (1) for wetting, and then heated to evaporate the solvent. The platinum diselenide (PtSe2) film and the nanomaterial form a van der Waals heterojunction, thus obtaining the room temperature DMMP sensor based on the platinum diselenide van der Waals heterojunction.
[0034] More specifically, the preparation method mainly includes two parts: transferring PtSe2 grown on a silicon oxide or aluminum oxide substrate to an interdigitated electrode via wet transfer, and loading nanomaterials onto the PtSe2 surface using an impregnation method. The specific process is as follows: (1) Add 1-10 drops of polymethyl methacrylate (PMMA) to the surface of PtSe2 grown on the substrate, and then place the material on a spin coater and spin coat it at a speed of 500-4000 r / min for 10-30 s to make PMMA uniformly cover the PtSe2 film.
[0035] (2) Place the material obtained in step (1) on a heating table and heat it at 40-80°C to cure PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (2) is placed in a 0.5-5 mol / L KOH solution for 1-7 days for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigitated electrode obtained in step (3) in any glass container, add acetone solution to the container, soak for 30 min-2 h, and PMMA can be removed to obtain PtSe2 film loaded on interdigitated electrode. (5) Disperse appropriate amounts of carbon nanotubes, graphene, zinc oxide or metal disulfide and other nanomaterials in single or mixed solvents such as water and ethanol to prepare a dispersion of loaded material with a concentration of 0.1-10 mg / mL, and sonicate for 0.5-5 h. (6) Take 5-50 μL of the dispersion droplet and immerse it on the PtSe2 film obtained in step (4). Then place it on the heating stage and heat it to 60-80℃. After the solvent evaporates, you can obtain a variety of van der Waals heterojunction sensors based on platinum diselenide.
[0036] A third aspect of the present invention is to provide the application of the above-mentioned room temperature DMMP sensor based on platinum diselenide van der Waals heterojunction in the detection of dimethyl methylphosphonate.
[0037] The fabrication of the room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction according to the present invention will be described in detail below with reference to specific embodiments: Example 1 (1) Add 1 drop of PMMA to the PtSe2 surface with a substrate, and then place the material on a spin coater and spin coat at a speed of 500 r / min for 10 s to make PMMA uniformly cover the PtSe2 film.
[0038] (2) Place the material obtained in step (1) on a heating table and heat it at 40°C to solidify PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (2) is placed in a 0.5 mol / L KOH solution for 1 day for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigitated electrode obtained in step (3) in a glass container, add acetone solution to the container, soak for 30 min, and PMMA can be removed to obtain PtSe2 film loaded on interdigitated electrode. (5) Disperse an appropriate amount of carbon nanotubes (CNTs) in water to prepare a dispersion of the loaded material with a concentration of 0.1 mg / mL, and sonicate for 0.5 h; (6) Take 5 μL of the dispersion droplet obtained in step (5) and wet it on the PtSe2 film obtained in step (4). Then place it on the heating stage and heat it to 60°C. After the solvent evaporates, the CNT / PtSe2 van der Waals heterojunction sensor can be obtained.
[0039] Referring to GB / T 15653-1995 "Test Methods for Metal Oxide Semiconductor Gas Sensing Elements", the sensing performance of the CNT / PtSe2 van der Waals heterojunction sensor prepared in Example 1 of this invention was tested at room temperature for DMMP. (1) Detection limit test. Under room temperature conditions of 25℃, let the steady-state resistance of the sample in clean air be R0, and the steady-state resistance in the detection gas of a specified concentration be R. aThen test response value S for: Test the response values of samples with DMMP gas concentrations ranging from 1 ppb to 100 ppb. S The signal-to-noise ratio (SNR) was used, and then the detection limit (gas concentration at SNR=3) was calculated using the step concentration method. The experimental data are shown in the table below: Table 1 Based on the above data, the theoretical limit of detection (LOD) for DMMP of this sample can be calculated to be 24.6 ppb.
[0040] (2) Cyclic performance test. At room temperature of 25°C, 50 ppb of DMMP was introduced into the test environment. After the resistance value of the sample tended to stabilize, its resistance R was recorded. a Then, remove the sample from the detection gas and place it in clean air. Once the sample returns to R0, one test cycle is complete. Repeat the above steps for 100 cycles, measuring the response value in each cycle. S i Calculate the decay rate α after 100 cycles: The test results are shown below: Table 2 Based on the above data, the attenuation rate of this sample after 100 DMMP detection training cycles can be calculated to be 15.6%.
[0041] Example 2 (1) Add 10 drops of PMMA to the PtSe2 surface with a substrate, and then place the material on a spin coater and spin coat at a speed of 4000 r / min for 30 s to make PMMA uniformly cover the PtSe2 film.
[0042] (2) Place the material obtained in step (1) on a heating table and heat it at 80°C to solidify PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (1) is placed in a 5 mol / L KOH solution for 7 days for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigitated electrode obtained in step (3) in a glass container, add acetone solution to the container, soak for 2 hours to remove PMMA and obtain PtSe2 film loaded on interdigitated electrode. (5) Disperse an appropriate amount of graphene in ethanol to prepare a dispersion of the loaded material with a concentration of 10 mg / mL, and sonicate for 5 h. (6) Take 50 μL of the dispersed droplets obtained in step (5) and wet them onto the PtSe2 film obtained in step (4). Then place it on a heating stage and heat it to 80°C. After the solvent evaporates, the Graphene / PtSe2 van der Waals heterojunction sensor can be obtained.
[0043] Referring to GB / T 15653-1995 "Test Methods for Metal Oxide Semiconductor Gas Sensing Elements", the sensing performance of the Graphene / PtSe2 van der Waals heterojunction sensor prepared in Example 2 of this invention was tested at room temperature for DMMP. (1) Detection limit test. Under room temperature conditions of 25℃, let the steady-state resistance of the sample in clean air be R0, and the steady-state resistance in the detection gas of a specified concentration be R. a Then test response value S for: Test the response values of samples with DMMP gas concentrations ranging from 1 ppb to 100 ppb. S The signal-to-noise ratio (SNR) was used, and then the detection limit (gas concentration at SNR=3) was calculated using the step concentration method. The experimental data are shown in the table below: Table 3 Based on the above data, the theoretical limit of detection (LOD) for DMMP of this sample can be calculated to be 15.05 ppb.
[0044] (2) Cyclic performance test. At room temperature of 25°C, 50 ppb of DMMP was introduced into the test environment. After the resistance value of the sample tended to stabilize, its resistance R was recorded. a Then, remove the sample from the detection gas and place it in clean air. Once the sample returns to R0, one test cycle is complete. Repeat the above steps for 100 cycles, measuring the response value in each cycle. S i Calculate the decay rate α after 100 cycles: The test results are shown below: Table 4 Based on the above data, the attenuation rate of this sample after 100 DMMP detection training cycles can be calculated to be 36.5%.
[0045] Example 3 (1) Add 3 drops of PMMA to the PtSe2 surface with a substrate, and then place the material on a spin coater and spin coat at a speed of 2000 r / min for 20 s to make PMMA uniformly cover the PtSe2 film.
[0046] (2) Place the material obtained in step (1) on a heating table and heat it at 60°C to cure PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (2) is placed in a 3 mol / L KOH solution for 5 days for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigitated electrode obtained in step (3) in a glass container, add acetone solution to the container, soak for 1 hour to remove PMMA and obtain PtSe2 film loaded on interdigitated electrode. (5) Disperse an appropriate amount of zinc oxide (ZnO) in an ethanol / water mixed solvent to prepare a dispersion of the loaded material with a concentration of 1 mg / mL, and sonicate for 1 h; (6) Take 25 μL of the dispersed droplet obtained in step (5) and wet it on the PtSe2 film obtained in step (4). Then place it on the heating stage and heat it to 70°C. After the solvent evaporates, the ZnO / PtSe2 van der Waals heterojunction sensor can be obtained.
[0047] Referring to GB / T 15653-1995 "Test Methods for Metal Oxide Semiconductor Gas Sensing Elements", the sensing performance of the ZnO / PtSe2 van der Waals heterojunction sensor prepared in Example 3 of this invention was tested at room temperature for DMMP. (1) Detection limit test. Under room temperature conditions of 25℃, let the steady-state resistance of the sample in clean air be R0, and the steady-state resistance in the detection gas of a specified concentration be R. a Then test response value S for: Test the response values of samples with DMMP gas concentrations ranging from 1 ppb to 100 ppb. S The signal-to-noise ratio (SNR) was used, and then the detection limit (gas concentration at SNR=3) was calculated using the step concentration method. The experimental data are shown in the table below: Table 5 Based on the above data, the theoretical limit of detection (LOD) for DMMP of this sample can be calculated to be 2.6 ppb.
[0048] (2) Cyclic performance test. At room temperature of 25°C, 50 ppb of DMMP was introduced into the test environment. After the resistance value of the sample tended to stabilize, its resistance R was recorded. a Then, remove the sample from the detection gas and place it in clean air. Once the sample returns to R0, one test cycle is complete. Repeat the above steps for 100 cycles, measuring the response value in each cycle. S i Calculate the decay rate α after 100 cycles: The test results are shown below: Table 6 Based on the above data, the attenuation rate of this sample after 100 DMMP detection training cycles can be calculated to be 8.3%.
[0049] Example 4 (1) Add 7 drops of PMMA to the surface of PtSe2, and then place the material on a spin coater and spin coat at a speed of 3000 r / min for 30s to make PMMA evenly cover the PtSe2 film.
[0050] (2) Place the material obtained in step (1) on a heating table and heat it at 80°C to solidify PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (2) is placed in a 3 mol / L KOH solution for 7 days for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigitated electrode obtained in step (3) in a glass container, add acetone solution to the container, soak for 2 hours to remove PMMA and obtain PtSe2 film loaded on interdigitated electrode. (5) Disperse an appropriate amount of molybdenum disulfide (MoS2) in ethanol solvent to prepare a dispersion of the loaded material with a concentration of 2 mg / mL, and sonicate for 2 h; (6) Take 15 μL of the dispersed droplet obtained in step (5) and wet it on the PtSe2 film obtained in step (4). Then place it on the heating stage and heat it to 70°C. After the solvent evaporates, the MoS2 / PtSe2 van der Waals heterojunction sensor can be obtained.
[0051] Referring to GB / T 15653-1995 "Test Methods for Metal Oxide Semiconductor Gas Sensing Elements", the sensing performance of the MoS2 / PtSe2 van der Waals heterojunction sensor prepared in Example 4 of this invention was tested at room temperature for DMMP. (1) Detection limit test. Under room temperature conditions of 25℃, let the steady-state resistance of the sample in clean air be R0, and the steady-state resistance in the detection gas of a specified concentration be R. a Then test response value S for: Test the response values of samples with DMMP gas concentrations ranging from 1 ppb to 100 ppb. S The signal-to-noise ratio (SNR) was used, and then the detection limit (gas concentration at SNR=3) was calculated using the step concentration method. The experimental data are shown in the table below: Table 7 Based on the above data, the theoretical limit of detection (LOD) for DMMP of this sample can be calculated to be 7.05 ppb.
[0052] (2) Cyclic performance test. At room temperature of 25°C, 50 ppb of DMMP was introduced into the test environment. After the resistance value of the sample tended to stabilize, its resistance R was recorded. a Then, remove the sample from the detection gas and place it in clean air. Once the sample returns to R0, one test cycle is complete. Repeat the above steps for 100 cycles, measuring the response value in each cycle. S i Calculate the decay rate α after 100 cycles: The test results are shown below: Table 8 Based on the above data, the attenuation rate of this sample after 100 DMMP detection training cycles can be calculated to be 11.7%.
[0053] Example 5 (1) Add 7 drops of PMMA to the surface of PtSe2, and then place the material on a spin coater and spin coat at a speed of 3000 r / min for 60s to make PMMA evenly cover the PtSe2 film.
[0054] (2) Place the material obtained in step (1) on a heating table and heat it at 80°C to solidify PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (2) is placed in a 3 mol / L KOH solution for 7 days for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigitated electrode obtained in step (3) in a glass container, add acetone solution to the container, soak for 2 hours to remove PMMA and obtain PtSe2 film loaded on interdigitated electrode; (5) Disperse an appropriate amount of tungsten disulfide (WS2) in ethanol solvent to prepare a dispersion of the loaded material with a concentration of 2 mg / mL, and sonicate for 2 h; (6) Take 15 μL of the dispersion droplet and immerse it on the PtSe2 film obtained in step (4), then place it on the heating stage and heat it to 70°C. After the solvent evaporates, the WS2 / PtSe2 van der Waals heterojunction sensor can be obtained.
[0055] Referring to GB / T 15653-1995 "Test Methods for Metal Oxide Semiconductor Gas Sensing Elements", the sensing performance of the WS2 / PtSe2 van der Waals heterojunction sensor prepared in Example 5 of this invention was tested at room temperature for DMMP. (1) Detection limit test. Under room temperature conditions of 25℃, let the steady-state resistance of the sample in clean air be R0, and the steady-state resistance in the detection gas of a specified concentration be R. a Then test response value S for: Test the response values of samples with DMMP gas concentrations ranging from 1 ppb to 100 ppb. S The signal-to-noise ratio (SNR) was used, and then the detection limit (gas concentration at SNR=3) was calculated using the step concentration method. The experimental data are shown in the table below: Table 9 Based on the above data, the theoretical limit of detection (LOD) for DMMP of this sample can be calculated to be 6.86 ppb.
[0056] (2) Cyclic performance test. At room temperature of 25°C, 50 ppb of DMMP was introduced into the test environment. After the resistance value of the sample tended to stabilize, its resistance R was recorded. aThen, remove the sample from the detection gas and place it in clean air. Once the sample returns to R0, one test cycle is complete. Repeat the above steps for 100 cycles, measuring the response value in each cycle. S i Calculate the decay rate α after 100 cycles: The test results are shown below: Table 10 Based on the above data, the attenuation rate of this sample after 100 DMMP detection training cycles can be calculated to be 7.91%.
[0057] Comparative Example 1 (1) Add 3 drops of PMMA to the PtSe2 surface with a substrate, and then place the material on a spin coater and spin coat at a speed of 2000 r / min for 20 s to make PMMA uniformly cover the PtSe2 film.
[0058] (2) Place the material obtained in step (1) on a heating table and heat it at 60°C to cure PMMA and form a composite structure of PMMA / PtSe2 / substrate; (3) The PMMA / PtSe2 / substrate composite structure obtained in step (2) is placed in a 3 mol / L KOH solution for 5 days for etching. Then the PMMA / PtSe2 film is separated from the substrate and transferred to the interdigitated electrode to form a PMMA / PtSe2 / interdigitated electrode composite structure. (4) Place the composite structure of PMMA / PtSe2 / interdigital electrode obtained in step (3) in a glass container, add acetone solution to the container, soak for 1 hour to remove PMMA and obtain PtSe2 film loaded on interdigital electrode.
[0059] Referring to GB / T 15653-1995 "Test Methods for Metal Oxide Semiconductor Gas Sensing Elements", the sensing performance of the PtSe2 thin film prepared in the comparative example of this invention for DMMP at room temperature was tested: (1) Detection limit test. Under room temperature conditions of 25℃, let the steady-state resistance of the sample in clean air be R0, and the steady-state resistance in the detection gas of a specified concentration be R. a Then test response value S for: Test the response values of samples with DMMP gas concentrations ranging from 1 ppb to 100 ppb. SThe signal-to-noise ratio (SNR) was used, and then the detection limit (gas concentration at SNR=3) was calculated using the step concentration method. The experimental data are shown in the table below: Table 11 Based on the above data, the theoretical limit of detection (LOD) for DMMP of this sample can be calculated to be 700 ppb.
[0060] (2) Cyclic performance test. At room temperature of 25°C, 1 ppm of DMMP was introduced into the test environment. After the resistance value of the sample tended to stabilize, its resistance R was recorded. a Then, remove the sample from the detection gas and place it in clean air. Once the sample returns to R0, one test cycle is complete. Repeat the above steps for 100 cycles, measuring the response value in each cycle. S i Calculate the decay rate α after 100 cycles: The test results are shown below: Table 12 Based on the above data, the attenuation rate of this sample after 100 DMMP detection cycles can be calculated to be 20.0%.
[0061] The comparative experimental data show that when the thin film does not form a heterojunction with the aforementioned nanomaterials, its response to DMMP is not significant, and the cycle decay rate is relatively high. This is because pure PtSe2 has limited responsiveness and selectivity to DMMP, and it is necessary to load a layer of a sensitive material with a strong affinity for DMMP to achieve selective capture of trace DMMP molecules.
[0062] The room temperature DMMP sensor based on platinum diselenide van der Waals heterojunction has the advantages of low operating temperature, high sensitivity, and good stability.
[0063] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction, characterized in that, include: Electrode, platinum diselenide layer supported on the surface of the electrode, and nanomaterials supported on the surface of the platinum diselenide layer; The platinum diselenide layer forms a van der Waals heterojunction with the nanomaterial.
2. The room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction according to claim 1, characterized in that, The nanomaterial is selected from at least one of carbon nanotubes, graphene, zinc oxide, and metal disulfides.
3. A room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction according to claim 2, characterized in that, The metal disulfide includes molybdenum disulfide or tungsten disulfide.
4. The room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction according to claim 1, characterized in that, The electrode is an interdigitated electrode.
5. The method for fabricating a room-temperature DMMP sensor based on a platinum diselenide van der Waals heterojunction as described in any one of claims 1-4, characterized in that, Includes the following steps: Platinum diselenide grown on the substrate is transferred to the electrode surface to obtain a platinum diselenide layer loaded on the electrode surface; The dispersion of the nanomaterial is added to the surface of the platinum diselenide layer for wetting, and then the solvent is removed. The platinum diselenide layer and the nanomaterial form a van der Waals heterojunction, thus obtaining the room temperature DMMP sensor based on the platinum diselenide van der Waals heterojunction.
6. The preparation method according to claim 5, characterized in that, The concentration of the dispersion of the nanomaterial is 0.1-10 mg / mL.
7. The application of the room temperature DMMP sensor based on platinum diselenide van der Waals heterojunction as described in any one of claims 1-4 in the detection of dimethyl methylphosphonate.