Three-dimensional resistance type gas sensor, preparation method and application thereof

Abstract

The present application relates to the technical field of gas sensing, and discloses a three-dimensional resistance type gas sensitive sensor and a preparation method and application thereof. The two-dimensional transition metal sulfide is filled into a wood cellulose support micro-nano scale channel to form a gas sensitive sensing part, which can not only effectively utilize the anisotropic mechanical compression resistance of the wood cellulose support, but also is beneficial to providing a full range and rapid transmission channel for carriers. In order to further optimize the electron output and input and reduce the noise of the electric signal, end electrodes are made on the upper and lower end faces of the gas sensitive sensing part, so that low resistance ohmic contact is formed between the end electrodes. The new three-dimensional resistance type gas sensitive sensor has the characteristics of low cost, low energy consumption, no pollution, sustainability and practicality in addition to excellent gas sensitive sensing performance, and meets the development needs of semiconductor type gas sensitive sensors.

Description

Technical Field

[0001] This invention relates to the field of gas sensing technology, specifically to a three-dimensional resistive gas sensor, its fabrication method, and its application. Background Technology

[0002] Gas sensing, as an important branch of sensor technology, has been widely used to detect various toxic, harmful, explosive, and volatile gases, playing a crucial role in human production and daily life. Based on their detection principles, gas sensors are mainly classified into electrochemical, optical, semiconductor, and gas chromatographic types. At a certain operating temperature, the redox reaction between the detected gas and the surface of the gas-sensitive material causes a change in the carrier concentration (i.e., a change in resistance) within the sensor. Semiconductor gas sensors utilize this change to determine the concentration and type of the detected gas. Compared to other types of gas sensors, semiconductor gas sensors are widely researched and applied due to their advantages such as high sensitivity, simple structure, small size, and low power consumption.

[0003] With the widespread use of semiconductor gas sensors, higher demands are being placed on their sensing performance. To improve the performance of resistive gas sensors, current focus is mainly on structure, materials, and fabrication processes. Research and development of novel gas-sensitive materials or modification of existing materials aim to increase the specific surface area and provide more active sites for the analyte, thereby improving sensitivity and response. However, the overly complex fabrication and modification processes for gas-sensitive materials also hinder success rates and production costs. Furthermore, most semiconductor gas sensors are based on a planar structure with forked electrodes, primarily fabricated on silicon substrates using MEMS technology. This complex fabrication process and high production costs are also significant challenges. Therefore, developing portable, low-cost, simple-structure, and high-performance semiconductor gas sensors is of great importance. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a three-dimensional resistive gas sensor and its preparation method, which has higher responsivity and better repeatability and selectivity when detecting nitrogen dioxide, especially when detecting low concentrations of nitrogen dioxide.

[0005] Another object of the present invention is to provide the application of the above-mentioned three-dimensional resistive gas sensor in the detection of nitrogen dioxide or in the preparation of nitrogen dioxide detection products.

[0006] To solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, the present invention provides a method for solving the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems. As a first aspect of the present invention, a three-dimensional resistive gas sensor is provided, including an upper electrode, a wood cellulose support, and a lower electrode; the upper electrode and the lower electrode are respectively disposed on the upper end surface and the lower end surface of the wood cellulose support, and two-dimensional transition metal sulfides are loaded on the micro-nano-scale channel walls of the wood fiber support.

[0007] Optionally, the loading rate of the two-dimensional transition metal sulfide on the micro / nanoscale channel walls of the wood cellulose scaffold is 2.5%-3.75%. Further optionally, the two-dimensional transition metal sulfide comprises tungsten disulfide.

[0008] Optionally, the wood cellulose scaffold is a wood scaffold with micro- and nano-scale channels, obtained by chemically removing lignin from the logs and dehydrating them. Further optionally, the logs include any one of balsa wood, linden wood, beech wood, willow wood, arborvitae, camphor wood, oak wood, pine wood, cedar wood, birch wood, cypress wood, juniper wood, and poplar wood.

[0009] Optionally, the upper electrode and the lower electrode comprise elemental metals.

[0010] As a second aspect of the present invention, a method for preparing the gas sensor is also provided, comprising:

[0011] Chemical reagents were used to remove lignin and moisture from logs to obtain wood cellulose scaffolds with micro- and nano-scale channels.

[0012] A dispersion solution containing two-dimensional transition metal sulfides was prepared, and after multiple rounds of titration and drying, the dispersion solution was loaded onto the micro-nano scale channel wall of a wood cellulose scaffold.

[0013] The two surfaces perpendicular to the micro-nano-scale channel are the upper and lower surfaces of the wood cellulose scaffold. After loading the wood cellulose scaffold with a two-dimensional transition metal sulfide, electrodes are set on the two end surfaces by sputtering to obtain the gas sensor.

[0014] Optionally, the dispersion solution containing the two-dimensional transition metal sulfide is prepared using a lithium-ion intercalation method.

[0015] Optionally, the titration and drying procedure includes:

[0016] The wood cellulose scaffold is heated to 40-50℃, and a two-dimensional transition metal sulfide dispersion is titrated onto the end face of the wood cellulose scaffold to allow the dispersion to enter the micro-nano scale channels. After drying, the process is repeated multiple times until the two-dimensional transition metal sulfide is evenly distributed in the micro-nano scale channels of the wood cellulose scaffold.

[0017] As a third aspect of the invention, the application of the gas sensor in detecting nitrogen dioxide or in preparing products for detecting nitrogen dioxide is provided.

[0018] This invention fills two-dimensional transition metal sulfides into micro- and nano-scale channels within a wood cellulose scaffold to form a gas-sensitive region. This not only effectively utilizes the anisotropic mechanical compressive strength of the wood cellulose scaffold but also facilitates the provision of omnidirectional and rapid transport channels for charge carriers. To further optimize electron output and input and reduce electrical signal noise, end electrodes are fabricated on the upper and lower end faces of the gas-sensitive region, forming low-resistance ohmic contacts between them. This novel three-dimensional resistive gas sensor not only possesses excellent gas-sensing performance but also features low cost, low energy consumption, no pollution, sustainability, and practicality, meeting the needs of the development of semiconductor-based gas sensors. Attached image description:

[0019] Figure 1 The diagram shows the structure of the gas sensor of the present invention; upper electrode 11, wood cellulose support 12 and lower electrode 13;

[0020] Figure 2 The diagram shows the internal structure of the micro-nanoscale channel of the wood cellulose scaffold in the gas sensor of the present invention; two-dimensional transition metal sulfide 51, micro-nanoscale channel wall 52;

[0021] Figure 3 The diagram shown is a schematic of the wood cellulose support structure of the present invention; 12 represents the entire wood cellulose support, and 31 and 32 represent the upper and lower end faces of the support, respectively;

[0022] Figure 4 The diagram shown illustrates the working principle of the gas sensor of this invention.

[0023] Figure 5 The diagram shown is a process flow chart of the gas sensor of the present invention.

[0024] Figure 6 and Figure 7 The image shown is an SEM image of a wood cellulose scaffold; the arrows indicate that after lignin removal, many small pores will appear in the wood microstructure, increasing the porosity of the wood.

[0025] Figure 8 The image shows SEM and EDS images of wood cellulose scaffolds.

[0026] Figure 9 The results show the selective test results of the three-dimensional resistive gas sensor of the present invention for hydrogen sulfide, nitrogen dioxide, ammonia, formaldehyde, sulfur dioxide, acetone and methane at 30°C.

[0027] Figure 10 The figure shows the dynamic response curve of the three-dimensional resistive gas sensor of the present invention to nitrogen dioxide at a concentration of 5 ppm at 30°C.

[0028] Figure 11 The figure shows the dynamic response test of the three-dimensional resistive gas sensor of the present invention to nitrogen dioxide gas of different concentrations (300ppb, 600ppb, 900ppb, 1.2ppm, 1.5ppm, 5ppm, 10ppm, 15ppm, 20ppm) at 30℃.

[0029] Figure 12 The figure shows the response fitting curves of the three-dimensional resistive gas sensor of the present invention to nitrogen dioxide gas of different concentrations (300ppb, 600ppb, 900ppb, 1.2ppm, 1.5ppm, 5ppm, 10ppm, 15ppm, 20ppm) at 30℃.

[0030] Figure 13 The figure shows the repeatability test results of the three-dimensional resistive gas sensor of the present invention at 30°C for 5 ppm nitrogen dioxide gas. Detailed implementation method:

[0031] This invention discloses a three-dimensional resistive gas sensor, its fabrication method, and its applications. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the same result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The products, applications, and fabrication methods of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the products, applications, and fabrication methods described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0032] Wood is a natural composite material with a honeycomb-like porous structure, mainly composed of cellulose, hemicellulose, and lignin. The cell walls of wood exhibit a multi-layered structure (composed of primary walls, secondary walls, and an intermediate layer), with the highly lignified intermediate layer playing a role in adhering to and filling adjacent cell walls. The distinctly layered porous structure of wood contains numerous micro / nanopores and well-arranged channels, interconnected in three-dimensional space. As a three-dimensional porous material, wood can retain naturally arranged nanocellulose by removing lignin and hemicellulose using a top-down strategy. The resulting wood cellulose scaffold after lignin removal has even more micro / nano-scale channels, further improving porosity, specific surface area, and pore size distribution. Uniformly distributing gas-sensitive materials within porous materials, leveraging their high specific surface area, high porosity, and regularly ordered channels, provides more active sites for gas detection, representing a new approach to improving the performance of gas sensors.

[0033] In a first aspect of the invention, a three-dimensional resistive gas sensor is provided, comprising an upper electrode 11, a wood cellulose scaffold 12, and a lower electrode 13. The upper electrode 11 and the lower electrode 13 are respectively disposed on the upper and lower surfaces of the wood cellulose scaffold. A two-dimensional transition metal sulfide 51 is loaded on the micro-nanoscale channel wall 52 of the wood cellulose scaffold, and the two are bonded by hydrogen bonds or van der Waals forces, so that the two-dimensional transition metal sulfide 51 is firmly distributed in the micro-nanoscale channel wall 52 of the wood cellulose scaffold. (See schematic diagram below.) Figure 1 and Figure 2 .

[0034] In some embodiments of the present invention, the loading rate of the two-dimensional transition metal sulfide on the micro / nanoscale channel wall of the wood cellulose scaffold is 2.5%-3.75%, or it achieves a loading effect that allows a resistance signal to be detected at any position on the micro / nanoscale channel wall of the wood fiber scaffold. The loading rate of the two-dimensional transition metal sulfide in the gas sensor can be calculated using the formula: (sensor mass after loading - sensor mass before loading) / sensor mass before loading.

[0035] In some other embodiments of the present invention, the two-dimensional transition metal sulfide includes tungsten disulfide.

[0036] In some embodiments of the present invention, the wood cellulose scaffold is a wood scaffold with micro- and nano-scale channels, obtained by chemically removing lignin from logs and dehydrating them; in other embodiments of the present invention, the chemical reagents include acids, oxidants, buffer solutions, and organic solvents; in still other embodiments of the present invention, the chemical reagents include glacial acetic acid, sodium chlorite, acetate buffer, ethanol, and acetone; wherein, delignification occurs through the free radical action of ClO2, and under the action of glacial acetic acid, sodium chlorite, and acetate buffer, the aromatic ring is oxidized, undergoing a ring-opening reaction, effectively decomposing lignin; while ethanol and acetone are used for dehydration through extraction with different concentration gradients.

[0037] In some embodiments of the present invention, the logs include any one of balsa wood, linden wood, beech wood, willow wood, arborvitae, camphor wood, oak wood, pine wood, fir wood, birch wood, cypress wood, juniper wood, and poplar wood.

[0038] In some embodiments of the present invention, the wood cellulose scaffold has a side length of 2mm-20mm and a thickness of 800μm-4mm. The side length is perpendicular to the wood growth direction, and the thickness is along the wood growth direction.

[0039] In some embodiments of the present invention, the upper and lower electrodes comprise elemental metals; in other embodiments of the present invention, the elemental metals comprise any one of aluminum, copper, gold, platinum, silver, tungsten, molybdenum, titanium, nickel, and indium; in other embodiments of the present invention, the elemental metals are deposited on the two end faces of the wood cellulose scaffold by a sputtering process, such as ion sputtering or magnetron sputtering, with a deposition thickness of 100-300 nanometers.

[0040] In a second aspect of the invention, a method for preparing the gas sensor is provided, comprising:

[0041] Chemical reagents were used to remove lignin and moisture from logs to obtain wood cellulose scaffolds with micro- and nano-scale channels.

[0042] A dispersion solution containing two-dimensional transition metal sulfides was prepared, and after multiple rounds of titration and drying, the dispersion solution was loaded onto the micro-nano scale channel wall of a wood cellulose scaffold.

[0043] The two surfaces perpendicular to the micro-nano-scale channel are the upper and lower surfaces of the wood cellulose scaffold. After loading the wood cellulose scaffold with a two-dimensional transition metal sulfide, electrodes are set on the two end surfaces by sputtering to obtain the gas sensor.

[0044] In some embodiments of the present invention, the process of obtaining a wood cellulose scaffold with micro- and nano-scale channels includes:

[0045] The logs are cut into thin wood slices along channels perpendicular to their micro- and nano-scale dimensions, dried, and a lignin-removing solution is prepared using sodium acetate buffer, sodium chlorite, and glacial acetic acid. The dried wood slices are then immersed in the lignin-removing solution to react until the lignin is completely removed, and then washed.

[0046] The cleaned wood veneers were placed in an organic solvent for gradient dehydration to obtain a wood cellulose scaffold. (See schematic diagram below.) Figure 3 12 represents the entire wood cellulose support, and 31 and 32 represent the upper and lower end faces of the support, respectively;

[0047] If not in use at the moment, the wood cellulose scaffold can be sealed in anhydrous ethanol solution.

[0048] In some other embodiments of the present invention, the lignin removal reaction conditions are a reaction temperature of 70-90°C and a reaction time of 4-6 hours; the lignin removal solution is prepared by mixing 1-2 wt% sodium chlorite with sodium acetate buffer, and then adding glacial acetic acid to adjust the pH of the solution to 4.5 to 5; the organic solvent gradient dehydration is performed by sequentially using different concentration gradients, such as 30%, 50%, 70%, 90%, and 100% ethanol, as well as a 1:1 volume ratio mixture of ethanol and acetone and pure acetone, for ultrasonic extraction and dehydration, each time for 3-5 minutes.

[0049] In some embodiments of the present invention, the dispersion solution containing the two-dimensional transition metal sulfide is prepared by lithium-ion intercalation; in other embodiments of the present invention, tungsten disulfide is used as the two-dimensional transition metal sulfide for preparation. Tungsten disulfide and an organic solvent containing n-butyllithium are thoroughly stirred. After adding water, hydrogen gas generated by the vigorous reaction between lithium ions and water in the interlayer of tungsten disulfide is used to open the interlayer. The upper layer solution is collected by centrifugation, and the thinned tungsten disulfide is collected by filter membrane. Then, it is dispersed in water to prepare a tungsten disulfide dispersion of the target concentration.

[0050] More specifically:

[0051] 0.8 g of tungsten disulfide powder was weighed and poured into an Erlenmeyer flask, followed by 15 ml of a hexane solution containing n-butyllithium (concentration 0.12 mol / ml). The mixture was magnetically stirred for 48 hours. After the reaction was complete, the product was repeatedly washed with hexane solution to remove residual lithium ions from the surface. Then, 100 ml of deionized water was added, and the mixture was sonicated for 1 hour. The hydrogen gas generated by the vigorous reaction between lithium ions and water in the tungsten disulfide interlayer was used to open the interlayer. The reactants were centrifuged at 1200 rpm / min, and the supernatant was collected. The thinned tungsten disulfide was collected using a filter membrane and then dispersed in deionized water to prepare a tungsten disulfide dispersion with a concentration of 0.5 mg / ml.

[0052] In some embodiments of the present invention, the titration and drying procedure includes:

[0053] The wood cellulose scaffold is heated to 40-50℃, and a two-dimensional transition metal sulfide dispersion is titrated onto the end face of the wood cellulose scaffold to allow the dispersion to enter the micro-nano scale channels. After drying, the process is repeated multiple times until the two-dimensional transition metal sulfide is evenly distributed in the micro-nano scale channels of the wood cellulose scaffold.

[0054] In a third aspect of the invention, the three-dimensional resistive gas sensor described herein was used to selectively detect various gases at a concentration of 5 ppm (hydrogen sulfide, nitrogen dioxide, ammonia, formaldehyde, sulfur dioxide, acetone, and methane). The results showed that the three-dimensional resistive gas sensor of the present invention exhibited significantly higher selectivity for nitrogen dioxide than for the other gases. Furthermore, at room temperature (30°C), the three-dimensional resistive gas sensor of the present invention showed a dynamic response time of 211 s, a recovery time of 343 s, and a response value of 1.2 for nitrogen dioxide at a concentration of 5 ppm. In addition, the response value of the three-dimensional resistive gas sensor was fitted, and the results showed that the sensor could successfully detect nitrogen dioxide at a minimum concentration of 300 ppb. The response value increased with increasing gas concentration, and the three-dimensional resistive gas sensor also exhibited good repeatability.

[0055] Based on the above-mentioned superior technical effects, the present invention provides the application of the gas sensor in detecting nitrogen dioxide or preparing products for detecting nitrogen dioxide.

[0056] The principle of nitrogen dioxide detection by the gas sensor of this invention is explained using p-type tungsten disulfide material as an example. In the air environment, oxygen molecules are adsorbed on the surface of tungsten disulfide (…). Figure 4 a) Oxygen molecules steal some electrons from the valence band of tungsten disulfide to become negative oxygen ions, resulting in an increase in the concentration of p-type tungsten disulfide holes and a decrease in electrical resistance. Figure 4 b) When oxidizing gas NO2 is introduced, electrons are taken from the valence band of tungsten disulfide to form NO2. - ion( Figure 4 c); As the hole concentration of p-type tungsten disulfide continues to increase, the electrical resistance decreases. Figure 4 d).

[0057] In specific embodiments of the present invention, unless otherwise specified, the experimental environment and parameter conditions of each group in the test are kept consistent, except for the differences that are explicitly pointed out.

[0058] The following is a further description of a three-dimensional resistive gas sensor, its preparation method, and its application provided by the present invention.

[0059] Example 1: Preparation of the gas sensor of the present invention

[0060] 1. Preparation of wood cellulose scaffolds

[0061] Balsa wood was selected as the log and cut into thin wood slices along both the growth direction and perpendicular to it. The dimensions of the wood slices were 2mm-20mm in length perpendicular to the wood growth direction and 800μm-4mm in thickness along the wood growth direction. The upper and lower surfaces of the wood slices (i.e., the upper and lower surfaces of the wood cellulose scaffold obtained later) were perpendicular to the wood growth direction. During cutting, the flatness of the upper and lower surfaces of the wood slices was ensured.

[0062] Place the wood veneer in an environment of 100℃-120℃ to remove moisture from the wood veneer;

[0063] A lignin removal solution is prepared by mixing 1 wt% to 2 wt% sodium chlorite with sodium acetate buffer, and then adding glacial acetic acid to adjust the pH of the solution to 4.5 to 5. The prepared lignin removal solution is poured into a beaker, and the dried wood shavings are immersed in the lignin removal solution. The mouth of the beaker is sealed with aluminum foil or plastic wrap until the lignin in the wood shavings is completely removed.

[0064] After removing the wood shavings from the lignin-removing solution, boil / rinse them repeatedly in deionized / distilled water until all residual chemicals are removed.

[0065] After removing residual chemicals, the wood shavings are placed in an organic solvent for gradient dehydration to obtain a wood cellulose scaffold. The organic solvent gradient dehydration involves sequentially using different concentration gradients (30%, 50%, 70%, 90%, 100%) of ethanol, a 1:1 volume ratio mixture of ethanol and acetone, and pure acetone for ultrasonic extraction and dehydration, each time for 3 to 5 minutes.

[0066] The flatness of the upper and lower surfaces of the wood cellulose scaffold is prevented from being damaged during lignin removal, washing, and dehydration.

[0067] The wood cellulose scaffold was sealed in anhydrous ethanol solution for later use;

[0068] 2. Fabrication of Gas Sensors

[0069] 0.8 g of tungsten disulfide powder was weighed and poured into an Erlenmeyer flask, followed by 15 ml of a hexane solution containing n-butyllithium (concentration 0.12 mol / ml). The mixture was magnetically stirred for 48 hours. After the reaction was complete, the product was repeatedly washed with hexane solution to remove residual lithium ions from the surface. Then, 100 ml of deionized water was added, and the mixture was sonicated for 1 hour. The hydrogen gas generated by the vigorous reaction between lithium ions and water in the tungsten disulfide interlayer was used to open the interlayer. The reactants were centrifuged at 1200 rpm / min, and the supernatant was collected. The thinned tungsten disulfide was collected using a filter membrane and then dispersed in deionized water to prepare a tungsten disulfide dispersion with a concentration of 0.5 mg / ml.

[0070] Remove the wood cellulose scaffold from the anhydrous ethanol solution and dry it in an environment of 90℃-100℃ to remove all the anhydrous ethanol from the wood cellulose scaffold.

[0071] Place the dried wood cellulose scaffold with its lower end facing down. Use a pipette / dropper to draw a small amount of tungsten disulfide dispersion and drop it vertically onto the upper end of the wood cellulose scaffold. Since the wood cellulose scaffold contains a large number of hydroxyl groups, the tungsten disulfide dispersion will diffuse inside the wood cellulose scaffold. Place it in an environment of 40℃-50℃ to dry. Repeat this step several times until the tungsten disulfide is evenly distributed in the pores of the wood cellulose scaffold, with a loading rate of 2.5%-3.75%.

[0072] The upper and lower electrodes are deposited on the upper and lower surfaces of the wood cellulose scaffold using ion sputtering / magnetron sputtering. Specifically, the deposition thickness of the electrode material is 100 nm to 300 nm. Specifically, both the upper and lower electrodes are conductive at any point. See the process flow diagram. Figure 5

[0073] The wood cellulose scaffolds prepared above were analyzed by SEM and EDS, and the results are shown in the figure. Figure 6-8 ;from Figure 6 and Figure 7 It can be seen that after the wood veneers were deligninized to become cellulose scaffolds, they retained their original structure, and the sidewalls of the micro-nano channels had many more small pores. From Figure 8 As can be seen, when tungsten disulfide dispersion is dripped into a wood cellulose scaffold, after a titration and drying process, tungsten disulfide is uniformly distributed in the micro-nano channels of the cellulose scaffold.

[0074] Example 2: Performance Testing of Gas Sensor

[0075] 1. Selective detection

[0076] The three-dimensional resistive gas sensor prepared in Example 1 was installed in the CGS-MT optoelectronic integrated test platform. Selective testing was performed on hydrogen sulfide, nitrogen dioxide, ammonia, formaldehyde, sulfur dioxide, acetone, and methane at a concentration of 5 ppm at room temperature (30°C). The results are as follows: Figure 9 As shown, the three-dimensional resistive gas sensor of the present invention exhibits a significantly higher response to nitrogen dioxide than other gases, indicating that it has excellent selectivity for nitrogen dioxide.

[0077] 2. Dynamic response detection of nitrogen dioxide

[0078] The dynamic response of a three-dimensional resistive gas sensor to nitrogen dioxide at a concentration of 5 ppm was tested at room temperature (30℃). The results are as follows: Figure 10 As shown, the response time is 211s, the recovery time is 343s, and the response value is 1.2.

[0079] like Figure 11 and Figure 12As shown, dynamic response tests were conducted on nitrogen dioxide at different concentrations (300ppb, 600ppb, 900ppb, 1.2ppm, 1.5ppm, 5ppm, 10ppm, 15ppm, and 20ppm) at room temperature (30℃), and the response values ​​were fitted. The results show that the gas sensor can successfully detect nitrogen dioxide at a minimum concentration of 300ppb, and the response value increases with increasing gas concentration.

[0080] 3. Repeatability test of nitrogen dioxide

[0081] like Figure 13 As shown, the three-dimensional resistive gas sensor exhibits good repeatability when subjected to repeated dynamic response tests on nitrogen dioxide at a concentration of 5 ppm at room temperature (30℃).

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A three-dimensional resistive gas sensor, characterized in that, It includes an upper electrode, a wood cellulose scaffold, and a lower electrode; the upper electrode and the lower electrode are respectively disposed on the upper end face and the lower end face of the wood cellulose scaffold; the micro-nano scale channel walls of the wood fiber scaffold are loaded with two-dimensional transition metal tungsten disulfide, which is prepared by lithium ion intercalation; the wood cellulose scaffold is a wood scaffold with micro-nano scale channels, which is obtained by chemically removing lignin and dehydrating logs.

2. The gas sensor according to claim 1, characterized in that, The loading rate of the two-dimensional transition metal sulfide on the micro-nano scale channel walls of the wood cellulose scaffold is 2.5%-3.75%.

3. The gas sensor according to claim 1, characterized in that, The logs include any one of the following: balsa wood, linden wood, beech wood, willow wood, arborvitae, camphor wood, oak wood, pine wood, fir wood, birch wood, cypress wood, juniper wood, and poplar wood.

4. The gas sensor according to claim 1, characterized in that, The upper and lower electrodes are composed of elemental metals.

5. The method for preparing the gas sensor according to claim 1, characterized in that, include: Chemical reagents were used to remove lignin and moisture from logs to obtain wood cellulose scaffolds with micro- and nano-scale channels. A dispersion solution containing two-dimensional transition metal sulfides was prepared by lithium-ion intercalation. After multiple rounds of titration and drying, the dispersion solution was loaded onto the micro-nano scale channel wall of a wood cellulose scaffold. The two surfaces perpendicular to the micro-nano-scale channel are the upper and lower surfaces of the wood cellulose scaffold. After loading the wood cellulose scaffold with a two-dimensional transition metal sulfide, electrodes are set on the two end surfaces by sputtering to obtain the gas sensor.

6. The preparation method according to claim 5, characterized in that, The titration and drying procedures include: The wood cellulose scaffold is heated to 40-50℃, and a two-dimensional transition metal sulfide dispersion is titrated onto the end face of the wood cellulose scaffold to allow the dispersion to enter the micro-nano scale channels. After drying, the process is repeated multiple times until the two-dimensional transition metal sulfide is evenly distributed in the micro-nano scale channels of the wood cellulose scaffold.

7. The application of the gas sensor according to any one of claims 1-4 in the detection of nitrogen dioxide or in the preparation of products for detecting nitrogen dioxide.

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