Laser-induced graphene / mos2 / a composite material, and preparation method and application thereof

Abstract

The application provides a laser-induced graphene / MoS2 / Au composite material and a preparation method and application thereof, and the preparation method comprises twice laser engraving, so that MoS2 and Au modified laser-induced graphene on a polyimide film is formed, the material preparation method is rapid, economical and efficient, and can realize in-situ modification of Au and MoS2 on a laser-induced graphene sensing area synchronously. The application avoids high-temperature and high-pressure harsh conditions and toxic chemicals involved in a traditional preparation method, and the laser-induced graphene / MoS2 / Au can be used as a gas sensor to efficiently and sensitively detect toxic gases, and has potential application in the fields of environmental monitoring and biomedicine.

Description

Technical Field

[0001] The present invention belongs to the technical field of toxic gas detection, and specifically relates to a laser-induced graphene / MoS2 / Au composite material and a preparation method and application thereof. Background Art

[0002] NO2 is a reddish-brown, acidic gas with a pungent odor. It can cause secondary atmospheric pollution, reduce atmospheric visibility, acidify surface water, and even cause acid rain, among other environmental issues. NO2 also poses a serious threat to human health. Short-term exposure to high-concentration NO2 vapor can cause acute poisoning, while long-term exposure to low-concentration NO2 can cause chronic poisoning, leading to conditions such as dullness, insomnia, polyneuritis, and atherosclerosis. Given these challenges, real-time and accurate NO2 detection is crucial for both environmental protection and medicine, placing higher demands on related NO2 detection technologies.

[0003] Existing NO₂ detection methods primarily include laser spectroscopy, infrared spectroscopy, Raman spectroscopy, ion mobility spectrometry, mass spectrometry, surface acoustic wave sensors, chromatography, and semiconductor gas sensors. Metal oxide semiconductor (MOS) gas sensors have been widely studied due to their simple structure, low cost, long life, and high sensitivity. However, they also have numerous drawbacks, including the need for high-temperature operation, high power consumption, and complex fabrication methods.

[0004] Graphene's inherently large surface area, along with surface defects and dangling bonds, provides numerous adsorption sites for target gas molecules, reducing the activation energy required for adsorption, thereby improving sensitivity and effectively lowering detection temperature. However, the sensitivity of single-graphene-based gas sensors still lags behind practical applications, with long response / recovery times. Composites with other materials or functional modifications can further enhance gas sensing performance. MoS2 has attracted considerable attention due to its abundant active sites, selective adsorption of NO2, and inherent semiconductor properties. Composites of MoS2 with graphene to form pn heterojunctions can increase the carrier density of the composite near room temperature, optimizing gas sensing response. Furthermore, noble metals can act as electron traps to suppress electron-hole recombination, further increasing carrier concentration and thus optimizing gas sensor sensitivity. However, current methods for preparing graphene are often complex and environmentally and economically expensive. Further modification requires additional experimental steps, and ultimately, the material must be attached to interdigitated electrodes and installed with a heater to reach operating temperature. Therefore, there is an urgent need to develop an efficient, economical and environmentally friendly preparation method for graphene-based composites and apply them to gas sensing. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] The present invention proposes a laser-induced graphene / MoS2 / Au composite material and its preparation method and application to solve the technical problem of efficient and accurate detection of toxic gases.

[0007] (2) Technical solution

[0008] In order to solve the above technical problems, the present invention proposes a method for preparing a laser-induced graphene / MoS2 / Au composite material, which comprises the following steps:

[0009] S1. Fix the carbon precursor material on a glass plate, then wash and dry at room temperature;

[0010] S2. Draw a sensor pattern using drawing software, import the pattern into the laser, and form a laser-induced graphene region on the carbon precursor material by laser etching. Rinse with ultrapure water and dry at room temperature.

[0011] S3. MoS2 source precursor solution and Au source precursor solution are added dropwise to the laser-induced graphene area, and after drying, laser secondary etching is performed to allow the precursor solution to decompose and react to generate MoS2 and Au and deposit on the surface of the laser-induced graphene area. Finally, ultrapure water and anhydrous ethanol are used to clean and dry at room temperature to obtain a laser-induced graphene / MoS2 / Au composite material.

[0012] Furthermore, in step S1, the carbon precursor material is a polyimide film.

[0013] Furthermore, in step S2, the drawing software is CorelDRAW.

[0014] Furthermore, in step S2, the shape of the etched area is dumbbell-shaped, and the area of ​​the etched area is not greater than 5mm 2 .

[0015] Furthermore, in step S2, the laser is a CO2 laser, the etching adopts a grating mode, the etching power is 3.6 to 4.5 W, and the scanning speed is 120 to 180 mm / s.

[0016] Furthermore, in step S3, the solute of the Au source precursor solution is one of HAuCl4, HAuCl4·3H2O, and HAuCl4·4H2O, the solvent is ultrapure water, and the solution concentration is 0.05-0.5 mol L -1 .

[0017] Furthermore, in step S3, the solute of the MoS2 precursor solution is a soluble molybdenum salt and a sulfur-containing compound, and the solvent is ultrapure water; the soluble molybdenum salt is (NH4)6Mo7O 24 .4H2O、(NH4)6Mo7O 24, one of Na2MoO4, Li2MoO4, and the sulfur-containing compound is CH4N2S or sulfur powder.

[0018] Furthermore, in step S3, the etching power of the laser secondary etching is 1.0 to 2.4 W, and the scanning speed is 25 to 70 mm / s.

[0019] In addition, the present invention also proposes a laser-induced graphene / MoS2 / Au composite material, which is prepared by the above method.

[0020] In addition, the present invention also proposes an application of a laser-induced graphene / MoS2 / Au composite material, and the above-mentioned laser-induced graphene / MoS2 / Au composite material is prepared into a gas sensor for the detection of chemical toxic gases.

[0021] (3) Beneficial effects

[0022] This invention proposes a laser-induced graphene / MoS2 / Au composite material, its preparation method, and its application. The preparation method involves two laser engraving steps, forming MoS2- and Au-modified laser-induced graphene on a polyimide film. This material preparation method is rapid, economical, and efficient, enabling simultaneous in-situ modification of Au and MoS2 within the laser-induced graphene sensing region. This invention avoids the harsh conditions of high temperature, high pressure, and toxic chemicals associated with traditional preparation methods. Laser-induced graphene / MoS2 / Au can be used as a gas sensor for efficient and sensitive detection of toxic gases, with potential applications in environmental monitoring and biomedicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the preparation of laser-induced graphene / MoS2 / Au (LIG / MoS2 / Au) gas sensor;

[0024] Figure 2 is the XRD pattern of LIG / MoS2 / Au;

[0025] Figure 3a and 3b SEM images of LIG and LIG / MoS2 / Au, respectively, with a scale of 500 nm;

[0026] Figure 4a AFM images of LIG / MoS2 / Au, with scales of 400 nm, Figure 4b is the corresponding cross-sectional profile curve;

[0027] Figure 5a and 5b TEM and HRTEM images of LIG / MoS2 / Au, with scale bars of 50 nm and 5 nm, respectively;

[0028] Figure 6a is the XPS spectrum of LIG / MoS2 / Au, Figure 6b is the C1s spectrum, Figure 6c is the Mo 3d spectrum, Figure 6d is the S2p spectrum, Figure 6e is the Au4f spectrum;

[0029] Figure 7 The response curves of LIG / MoS2 / Au, LIG / MoS2, LIG / Au, and LIG gas sensors to 1 ppm NO2 at 90°C are shown. The response value is defined as ΔR / R0 (ΔR=R a -R NO2 , R NO2 is the resistance of the sensor in NO2, R a is the resistance of the sensor in air);

[0030] Figure 8 The response curves of LIG / MoS2 / Au to 1ppmNO2 prepared at different secondary powers, the test temperature is 90℃;

[0031] Figure 9 This is a statistical graph of the response values ​​of LIG / MoS2 / Au prepared with different concentrations of HAuCl4 as the Au source to 1ppmNO2. The test temperature is 90℃. DETAILED DESCRIPTION

[0032] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0033] This embodiment provides a method for preparing a laser-induced graphene / MoS2 / Au composite material, which specifically includes the following steps:

[0034] S1. Place a 170 μm thick polyimide (PI) film tape (area: 1.5 × 1.5 cm 2 ) pasted on a glass plate, then repeatedly washed with anhydrous ethanol and dried at room temperature;

[0035] S2. Draw a dumbbell-shaped pattern using CorelDRAW drawing software and import the pattern file into a commercial CO2 laser (wavelength 10.6 μm). In air, the CO2 laser uses a grating pattern to perform a first etching of the PI film tape from step S1, forming a laser-induced graphene (LIG) region. The etched region consists of two rectangles and a single line, and the single line area is 0.24 × 8 mm. 2 , as the sensing area, the rectangular area at both ends is 1.5×2mm 2, used to connect with copper foil, such as Figure 1 As shown; the laser parameters used are: scanning speed of 130 mm / s, etching power of 3.7 W, and pixel density of 1000 PPI;

[0036] S3. Add 0.35mmol (NH4)6Mo7O 24 ·4H2O and 15mmol CH4N2S were dissolved in 5mL ultrapure water to prepare a MoS2 precursor solution; 0.197g HAuCl4·3H2O was dissolved in 5mL ultrapure water to prepare a 0.1mol L -1 Au source precursor solution; add 0.004 mL of MoS2 precursor solution to the dumbbell-shaped line area of ​​laser-induced graphene, add 0.004 mL of Au source precursor solution after natural drying, and then place it in a constant temperature forced air drying oven at 60 ° C for 10 minutes to obtain a precursor;

[0037] The S4.CO2 laser was used in grating mode to perform a second laser etching on the dumbbell-shaped line area of ​​the laser-induced graphene precursor. The laser parameters used were: scanning speed 65 mm / s, scanning power 1.2 W, pixel density 1000 PPI; after laser heating, (NH4)6Mo7O 24 .4H2O and CH4N2S react to form MoS2, and HAuCl4 decomposes to form Au and simultaneously adheres to the LIG line area; the dumbbell-shaped area is cleaned and dried with ultrapure water and ethanol to obtain a LIG / MoS2 / Au composite material.

[0038] A gas sensor is made based on the LIG / MoS2 / Au composite material. Conductive silver paste is coated on the square contact pads on both sides of the dumbbell-shaped LIG / MoS2 / Au to form two contact points. Two copper foils are used as wires and connected to the two contact points to form a gas sensor.

[0039] XRD characterization of LIG / MoS2 / Au was performed. Figure 2 This is the XRD pattern of LIG / MoS2 / Au. The characteristic peaks of graphene, Au and MoS2 appear simultaneously in the spectrum, confirming the successful preparation of LIG / MoS2 / Au.

[0040] SEM, AFM, and TEM characterization of LIG / MoS2 / Au: Figure 3a and 3b These are the SEM images of LIG and LIG / MoS2 / Au, respectively. LIG exhibits a three-dimensional honeycomb structure composed of stacked sheets. After Au and MoS2 are loaded, the LIG sheet becomes thicker. Figure 4a and 4bThe AFM images of LIG / MoS2 / Au and the corresponding cross-sectional profile curves respectively indicate that the thickness of the LIG / MoS2 / Au sheet is about 35 nm. Figure 5a As shown in the TEM image of LIG / MoS2 / Au, MoS2 and Au are dispersed on the LIG surface in the form of flake structures and nanoparticles, respectively. The HRTEM image of LIG / MoS2 / Au ( Figure 5b ) corresponds to the (111) plane of Au, the (002) plane of MoS2 and the (110) plane of LIG, respectively.

[0041] XPS characterization of LIG / MoS2 / Au: Mo, S, Au and C signals appear in the total XPS spectrum of LIG / MoS2 / Au ( Figure 6a ); Figure 6b The C1s spectrum of LIG / MoS2 / Au in the medium is fitted into five characteristic peaks corresponding to sp 2 Hybridized carbon (284.4eV), sp 3 Hybrid carbon (285.2V), CS (286.4eV), C=O (288.6eV) and satellite peaks (291.7eV). The peak at 284.4eV and the satellite peak at 291.7eV are the signature peaks of graphene structure (Adv. Mater., 2018, 30, 170731). The formation of CS bond indicates that there is a strong interaction between MoS2 and C (Adv. Energy Mater., 2019, 9, 1802553); Figure 6c This is the high-resolution XPS spectrum of Mo3d. The two characteristic peaks at binding energies of 232.1eV and 229.0eV correspond to Mo 3d 3 / 2 and Mo 3d 5 / 2 The two peaks at binding energies of 233.7eV and 235.5eV are related to the unsaturated sulfur ligand (MoS4 2- ) and slightly oxidized surface (MoO3) (Adv.EnergyMater., 2019, 9, 1802553), the small peak at 226.2eV corresponds to S2s in MoS2; Figure 6d This is the high-resolution XPS spectrum of S2p. The two characteristic peaks at the binding energies of 161.5 eV and 162.7 eV correspond to S2p, respectively. 3 / 2 and S2p 1 / 2 , corresponding to the basal plane S of MoS2 2- The peak at 164.4 eV corresponds to the bridging disulfide S2 on the edge of MoS2 2-ligands, which indicates that there are sulfur defects in LIG / MoS2 / Au; Au4f high-resolution XPS spectrum of LIG / MoS2 / Au ( Figure 6e ) show two characteristic peaks at binding energies of 84.4 eV and 88.1 eV, corresponding to Au4f 7 / 2 and Au4f 5 / 2 .

[0042] The gas-sensing performance of the LIG / MoS2 / Au composite was characterized by connecting the two ends of the prepared sensor to the positive and negative electrodes of a source meter (Keithley 2400), respectively. The voltage was set based on the temperature of the LIG sensing area measured by a thermal imaging camera (FLIR ONE PRO). The fabricated sensor was first fixed in an air chamber, and after its resistance stabilized in air, 1 ppm NO2 gas was introduced into the chamber. After the resistance of the sensor stabilized again, air was introduced into the test chamber to desorb NO2 from the LIG / MoS2 / Au surface. The response value was calculated based on the change in the LIG / MoS2 / Au resistance before and after the introduction of NO2.

[0043] The response curves of LIG, LIG / Au, LIG / MoS2 and LIG / MoS2 / Au to 1ppmNO2 at 90℃ are shown in Figure 2. Figure 7 As shown, all curves have negative responses, indicating that all sensors exhibit p-type semiconductor characteristics. Compared with pure LIG, the response value of LIG / MoS2 / Au increases significantly; Figure 8 The response curves of LIG / MoS2 / Au obtained under different secondary laser powers. As the laser power increases, the response value of the LIG / MoS2 / Au sensor to 1ppm NO2 first increases and then decreases. The response value is the largest when the laser power is 4% P0 (P0: total laser power); Figure 9 The response curve of the sensor to 1ppm NO2 obtained by adding different concentrations of HAuCl4 was observed. It was found that the response value of the sensor first increased and then decreased with the increase of HAuCl4 concentration. When the concentration of HAuCl4 was 0.1M, the response value was the largest.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a laser-induced graphene / MoS2 / Au composite material, characterized in that: The preparation method comprises the following steps: S1. Fix the carbon precursor material on a glass plate, then wash and dry at room temperature; S2. Draw a sensor pattern using drawing software, import the pattern into the laser, and form a laser-induced graphene region on the carbon precursor material by laser etching. Rinse with ultrapure water and dry at room temperature. S3. MoS2 source precursor solution and Au source precursor solution are added dropwise to the laser-induced graphene area, and after drying, laser secondary etching is performed to allow the precursor solution to decompose and react to generate MoS2 and Au and deposit on the surface of the laser-induced graphene area. Finally, ultrapure water and anhydrous ethanol are used to clean and dry at room temperature to obtain a laser-induced graphene / MoS2 / Au composite material.

2. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S1 , the carbon precursor material is a polyimide film.

3. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S2, the drawing software is CorelDRAW.

4. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S2, the shape of the etched area is dumbbell-shaped and the area of ​​the etched area is no more than 5mm 2 .

5. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S2, the laser is a CO2 laser, the etching adopts a raster mode, the etching power is 3.6 to 4.5 W, and the scanning speed is 120 to 180 mm / s.

6. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S3, the solute of the Au source precursor solution is one of HAuCl4, HAuCl4·3H2O, and HAuCl4·4H2O, the solvent is ultrapure water, and the solution concentration is 0.05-0.5 mol / L -1 .

7. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S3, the solute of the MoS2 precursor solution is a soluble molybdenum salt and a sulfur-containing compound, and the solvent is ultrapure water; the soluble molybdenum salt is (NH4)6Mo7O 24 .4H2O、(NH4)6Mo7O 24 , one of Na2MoO4, Li2MoO4, and the sulfur-containing compound is CH4N2S or sulfur powder.

8. The method for preparing the laser-induced graphene / MoS2 / Au composite material according to claim 1, wherein: In step S3 , the etching power of the laser secondary etching is 1.0 to 2.4 W, and the scanning speed is 25 to 70 mm / s.

9. A laser-induced graphene / MoS2 / Au composite material, characterized in that: The laser-induced graphene / MoS2 / Au composite material is prepared by the method according to any one of claims 1 to 8.

10. An application of a laser-induced graphene / MoS2 / Au composite material, characterized in that: The laser-induced graphene / MoS2 / Au composite material described in claim 9 is prepared into a gas sensor for detecting chemical toxic gases.

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