Sensing material based on metal nanoparticle loading, preparation method thereof and NO2 gas sensor

Abstract

The invention relates to the technical field of gas sensing, in particular to a sensing material based on metal nanoparticle loading, a preparation method of the sensing material and an NO2 gas sensor, the sensing material comprises a defective oxide matrix and metal nanoparticles loaded on the surface of the defective oxide matrix; wherein both the defect oxide and the metal nanoparticles have a local surface plasma resonance effect. The metal nanoparticles with the local surface plasma resonance effect are combined with the defect oxide matrix, and the sensing performance of the sensing material on NO2 gas is improved by utilizing the double plasma resonance effect excited by light. Moreover, by doping the metal nanoparticles on the surface of the defective oxide matrix, the energy band structure of the material can be regulated and controlled, the formation of superoxide free radicals on the surface of the material is promoted, the sensing sensitivity to NO2 in a photo-assisted greenhouse is improved, and quick response and recovery can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensing, and particularly to a sensing material based on metal nanoparticle loading, a preparation method thereof, and a NO2 gas sensor. Background Art

[0002] Traditional metal oxide gas sensors usually need to work at high temperatures of 200°C - 600°C to activate the reaction between the gas and the sensing material, which not only results in high energy consumption but also limits their development in portable and integrated applications. Therefore, the research and development of low-power, highly sensitive, and integrated room-temperature gas sensors have become a research hotspot.

[0003] The photo-assisted strategy is an effective method to reduce the sensing temperature of oxide semiconductors and increase the sensitivity. Its mechanism is mainly to increase the electron concentration, accelerate the electron transport efficiency, increase the desorption path, and photodecomposition. Defective tungsten oxide has good absorption in the visible and near-infrared light bands due to the presence of oxygen vacancies, and thus has attracted much attention in room-temperature sensor applications. However, defective tungsten oxide has many defects, such as poor stability, low mobility, long response and recovery times, low sensitivity, and difficulty in recovery, which limit its application in room-temperature gas sensors. In addition, due to poor ability to adsorb activated molecules and the accumulation of surface reaction substances, there are still limitations.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above deficiencies of the existing technology, the object of the present invention is to provide a sensing material based on metal nanoparticle loading, a preparation method thereof, and a NO2 gas sensor, aiming to solve the problems of low sensitivity, long response and recovery times, and high working temperature of the existing sensing materials.

[0006] The technical solution of the present invention is as follows:

[0007] A sensing material based on metal nanoparticle loading, comprising a defective oxide matrix and metal nanoparticles loaded on the surface of the defective oxide matrix;

[0008] Wherein, both the defective oxide matrix and the metal nanoparticles have a local surface plasmon resonance effect.

[0009] The sensing material based on metal nanoparticle loading, wherein the defective oxide matrix includes one of a defective tungsten oxide matrix, a defective titanium oxide matrix, a defective cerium oxide matrix, a defective molybdenum oxide matrix, a defective cobalt oxide matrix, a defective copper oxide matrix, a defective indium oxide matrix, a defective niobium oxide matrix, and a defective zinc oxide matrix.

[0010] The described sensing material based on metal nanoparticle loading, wherein the metal nanoparticles include one or more of Au nanoparticles, Ag nanoparticles, Cu nanoparticles, Pt nanoparticles, Pd nanoparticles, and Bi nanoparticles.

[0011] The described sensing material based on metal nanoparticle loading, wherein the loading mass percentage of the metal nanoparticles in the sensing material is 0.3 wt% - 10 wt%.

[0012] The described sensing material based on metal nanoparticle loading, wherein the defective oxide has a nanowire structure with a diameter of 10 nm - 80 nm; the particle size of the metal nanoparticles is 3 nm - 30 nm.

[0013] A preparation method of a sensing material based on metal nanoparticle loading, comprising the steps:

[0014] Mix the metal compound corresponding to the defective oxide with an organic solvent, and then obtain the defective oxide through a solvothermal reaction.

[0015] Mix the defective oxide with a metal salt and a solvent to obtain a mixed solution.

[0016] Perform light stirring treatment on the mixed solution to obtain a sensing material based on metal nanoparticle loading.

[0017] The described preparation method of a sensing material based on metal nanoparticle loading, wherein the temperature of the solvothermal reaction is 160°C - 200°C, and the time of the solvothermal reaction is 10 h - 16 h.

[0018] The described preparation method of a sensing material based on metal nanoparticle loading, wherein the step of light stirring treatment includes: introducing an inert gas into the mixed solution to remove the dissolved oxygen in the mixed solution, and then performing light stirring for 0.5 h - 2 h.

[0019] A NO2 gas sensor, comprising electrodes and a sensing layer disposed on the surface of the electrodes; the sensing layer contains a sensing material based on metal nanoparticle loading.

[0020] The described NO2 gas sensor, wherein the thickness of the sensing layer is 0.5 mm - 3 mm.

[0021] Beneficial effects: The present invention provides a sensing material based on metal nanoparticle loading, a preparation method thereof, and a NO2 gas sensor. The sensing material includes a defective oxide matrix and metal nanoparticles loaded on the surface of the defective oxide matrix; wherein, both the defective oxide matrix and the metal nanoparticles have a local surface plasmon resonance effect. By combining metal nanoparticles with a local surface plasmon resonance (LSPR) effect with a defective oxide matrix, the present invention utilizes the double plasmon resonance effect excited by light to improve the sensing performance of the sensing material for NO2 gas. Specifically, the combination of metal nanoparticles and the defective oxide matrix can promote the generation of more high-energy hot electrons and holes and delay the decay of hot electrons, thereby improving the reaction performance and NO2 sensing performance. Moreover, by doping metal nanoparticles on the surface of the defective oxide matrix, the energy band structure of the material can be regulated, promoting the formation of superoxide radicals on the surface of the material, enhancing the sensing sensitivity to NO2 at room temperature under light assistance, enabling rapid response and recovery, and realizing visible light-assisted NO2 sensing at room temperature. Description of the Drawings

[0022] Figure 1 It is a process flow chart of a preparation method of a sensing material based on metal nanoparticle loading according to the present invention;

[0023] Figure 2 It is an XRD spectrum of pure defective tungsten oxide and defective tungsten oxide loaded with Au nanoparticles prepared in Example 1;

[0024] Figure 3 It is W prepared in Example 1 18 O 49 -Au-2's TEM spectrum;

[0025] Figure 4 It is a graph of the room temperature sensing performance data of defective tungsten oxide and defective tungsten oxide loaded with Au nanoparticles prepared in Example 1 for 10 ppm NO under light assistance;

[0026] Figure 5 It is a graph of the room temperature sensing performance data of W 18 O 49 -Au-2 for 2 - 10 ppm NO;

[0027] Figure 6 It is the EPR spectrum of superoxide radicals of W 18 O 49 and W 18 O 49 -Au-2 in the presence of DMPO under illumination;

[0028] Figure 7 It is W 18 O49 - Room temperature sensing performance graph of the long-term stability of Au-2 towards 10 ppm NO2. Detailed implementation manners

[0029] The present invention provides a sensing material based on metal nanoparticles loading, a preparation method thereof, and a NO2 gas sensor. To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the field to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0031] With the rapid development of the Internet of Things, sensors and their related technologies have been widely applied. In the industrial production process, various sensors are used to monitor and control the status of equipment in real time to ensure the stability and safety of production. Sensor technology has deeply penetrated into multiple fields, including industrial production, environmental monitoring, medical diagnosis, resource exploration, and bioengineering. With the continuous progress of technology and the improvement of the automation level, the performance requirements for sensors in various industries are also increasing day by day. In recent years, the demand for gas sensors has increased significantly in aspects such as air pollution monitoring, industrial safety detection, military protection, space exploration, and human health monitoring. With the acceleration of the industrialization and urbanization processes, the air pollution problem has become increasingly severe. Among them, nitrogen dioxide (NO2), as a typical air pollutant, has caused serious harm to the environment and human health. NO2 mainly comes from the combustion of fossil fuels and is one of the main pollutants in the formation of photochemical smog and acid rain. Long-term exposure to a high-concentration NO2 environment can cause chronic respiratory diseases such as pulmonary edema and bronchitis, and may even lead to serious health hazards. In addition, NO2 can also be used as a biomarker. By analyzing its concentration in exhaled breath, it can be used for the early detection and diagnosis of intestinal and lung-related diseases. Therefore, achieving highly sensitive NO2 detection is of great significance in environmental protection, health monitoring, and safety warning. To adapt to the development of the times, gas sensors need to meet requirements such as low cost, low power consumption, and easy operation in order to be integrated into portable and intelligent devices. However, traditional metal oxides have slow carrier mobility and low surface activity at room temperature, resulting in an increase in the working temperature, a decrease in selectivity, slow response and recovery kinetics, and incomplete recovery in the application of gas sensors. Utilizing the local surface plasmon resonance (LSPR) effect, plasmonic materials can generate high-energy "hot electrons" and "hot holes", which helps to reduce the reaction barrier and achieve reactions kinetically. However, existing plasmonic materials face problems such as a limited light absorption range, low hot carrier conversion efficiency, and a fast self-thermalization rate, which severely limits their applications.

[0032] Based on this, the present invention provides a sensing material based on metal nanoparticle loading, including a defective oxide matrix and metal nanoparticles loaded on the surface of the defective oxide matrix;

[0033] Among them, both the defective oxide matrix and the metal nanoparticles have a local surface plasmon resonance effect.

[0034] In this embodiment, by combining metal nanoparticles with local surface plasmon resonance (LSPR) effects with a defective oxide matrix, the dual plasmon resonance effect excited by light is utilized to improve the sensing performance of the sensing material for NO2 gas. Specifically, the combination of metal nanoparticles and the defective oxide matrix can promote the generation of more high-energy hot electrons and holes, and delay the decay of hot electrons, thereby improving the reaction performance and NO2 sensing performance. Moreover, by doping metal nanoparticles on the surface of the defective oxide matrix, the energy band structure of the material can be regulated, the formation of superoxide radicals on the material surface can be promoted, the sensing sensitivity to NO2 at room temperature under light assistance can be improved, and rapid response and recovery can be achieved. Meanwhile, visible light-assisted NO2 sensing at room temperature is realized.

[0035] Specifically, through the defective oxide matrix loaded with metal nanoparticles, the plasmonic metal nanoparticles are combined with the defective oxide semiconductor with local surface plasmon resonance effects, promoting the generation of more high-energy hot electrons and holes on the material surface, delaying the decay of hot electrons, improving the reaction performance, and thus enhancing the sensing performance of the light-assisted material for NO2 gas; the plasmonic metal nanoparticles with local surface plasmon resonance (LSPR) effects are used to broaden the light response range of the sensing material and increase the local electric field strength, thereby enhancing the sensing performance of the light-assisted material (i.e., the defective oxide) for NO2 gas. Under the local surface double plasmon resonance coupling effect caused by light excitation, the local electromagnetic field of the defective oxide loaded with metal nanoparticles is greatly enhanced, accelerating the formation of high-energy hot electrons and hot holes. In addition, the internal electric field caused by the difference in surface work function promotes the spatial separation and transfer of photoexcited electrons and holes, thus prolonging the lifetime of hot carriers. Moreover, a large number of high-energy hot electrons and photoexcited electrons promote the generation of reactive oxygen species on the material surface, promoting the improvement of NO2 gas sensing performance, and the material exhibits good stability. The sensing material demonstrates the feasibility of constructing a non-precious metal double plasmon structure to achieve the directional and full utilization of photoexcited electrons and holes, opening up a new way to improve the NO2 gas sensing performance under light assistance.

[0036] In some embodiments, the defective oxide matrix includes but is not limited to one of a defective tungsten oxide matrix, a defective titanium oxide matrix, a defective cerium oxide matrix, a defective molybdenum oxide matrix, a defective cobalt oxide matrix, a defective copper oxide matrix, a defective indium oxide matrix, a defective niobium oxide matrix, and a defective zinc oxide matrix. The above-mentioned defective oxides have local surface plasmon resonance effects. Loading metal nanoparticles on their surfaces can promote the generation of more high-energy hot electrons and holes on the material surface, delay the decay of hot electrons, improve the reaction performance, and thus enhance the sensing performance of the light-assisted material for NO2 gas.

[0037] In some embodiments, the metal nanoparticles include, but are not limited to, one or more of Au nanoparticles, Ag nanoparticles, Cu nanoparticles, Pt nanoparticles, Pd nanoparticles, and Bi nanoparticles. The above metal nanoparticles can regulate the energy band structure of the defective oxide, promote the formation of superoxide radicals on the surface of the defective oxide, improve the sensing sensitivity to NO2 gas at room temperature under light assistance, and can respond and recover quickly, showing broad application prospects in the detection of NO2 gas.

[0038] In a preferred embodiment, the defective oxide is tungsten oxide with defects, and the metal nanoparticles are Au nanoparticles. By combining the plasmonic metal nanoparticles Au with the defective tungsten oxide semiconductor with local surface plasmon resonance effect, a sensing material with high sensitivity and selectivity for room temperature detection under visible light is synthesized.

[0039] In some embodiments, the mass percentage of the metal nanoparticles loaded in the sensing material is 0.3 wt% - 10 wt%. Controlling the loading amount of the metal nanoparticles within the above range can improve the response speed of the sensing material and enhance the sensing sensitivity to NO2 at room temperature under light assistance.

[0040] In a preferred embodiment, the mass percentage of the metal nanoparticles loaded in the sensing material is 0.62 wt%.

[0041] In some embodiments, the defective oxide has a nanowire structure with a diameter of about 10 nm - 80 nm; the particle size of the metal nanoparticles is about 3 nm - 30 nm.

[0042] In addition, as Figure 1 shown, the present invention also provides a preparation method of a sensing material based on metal nanoparticle loading, including the steps:

[0043] Step S10: Mix the metal compound corresponding to the defective oxide with an organic solvent, and then perform a solvothermal reaction to obtain the defective oxide;

[0044] Step S20: Mix the defective oxide with a metal salt and a solvent to obtain a mixed solution;

[0045] Step S30: Perform light stirring treatment on the mixed solution to obtain a sensing material based on metal nanoparticle loading.

[0046] In this embodiment, during the synthesis of defective oxides by the solvothermal method, the weak reducibility of the organic solvent can induce the formation of oxygen defects in the lattice of the oxide during the reaction; then, through light irradiation and stirring treatment, photo-generated electrons are generated by photo-exciting the semiconductor defective oxide, and these electrons are used to reduce metal salts to metal nanoparticles, which are deposited on the surface of the defective oxide to achieve the preparation of the sensing material. This preparation method combines metal nanoparticles with a local surface plasmon resonance (LSPR) effect with a defective oxide matrix, and uses the double plasmon resonance effect excited by light to improve the sensing performance of the sensing material for NO2 gas. And this preparation method has a simple process and is easy to realize large-scale production.

[0047] In some embodiments, the organic solvent is one or more of, but not limited to, ethanol, n-propanol, and isopropanol. It has weak reducibility and can induce the formation of oxygen defects in the lattice of the oxide during the solvothermal reaction, thereby obtaining defective oxides.

[0048] In some embodiments, the temperature of the solvothermal reaction is 160°C - 200°C, and the time of the solvothermal reaction is 10 h - 16 h. Using the above conditions of the solvothermal reaction can enable the formation of oxygen defects in the oxide to obtain defective oxides.

[0049] In a preferred embodiment, the temperature of the solvothermal reaction is 180°C, and the time of the solvothermal reaction is 12 h.

[0050] Specifically, on the surface of the defective oxide, oxygen vacancies and lattice defects can provide more active sites, enhance the local accumulation and transfer efficiency of photo-generated electrons, thereby increasing the adsorption and reduction reaction rates of metal salts; in addition, the defective surface helps to inhibit the formation of metal oxides, promotes the stability and uniformity of metal deposition, and thus makes the subsequent photo-deposition effect better.

[0051] In some embodiments, in step S10, after the solvothermal reaction, it further includes centrifugal washing treatment, specifically including: obtaining a mixed solution after the solvothermal reaction. After the mixed solution is naturally cooled, the product is centrifugally collected, and the collected product is washed with water and ethanol respectively, and then dried at 60°C - 80°C to obtain defective oxides.

[0052] In some embodiments, the metal compound includes, but is not limited to, one of WCl6, tungsten hexacarbonyl, titanium tetrachloride, cerium nitrate, molybdenum chloride, cobalt nitrate, copper nitrate, niobium chloride, indium chloride, and zinc nitrate. The above metal compounds are used to provide metal atoms in the defective oxide.

[0053] In some embodiments, the metal salt includes, but is not limited to, one or more of chloroauric acid, AuCl3, AgCl, chloroplatinic acid, palladium chloride, and bismuth nitrate. Using the metal ions in the above metal salts as the source of metal nanoparticles, the reduction of metal ions can be achieved by light irradiation and deposited on the surface of defective oxides.

[0054] In some embodiments, the mass ratio of the defective oxide to the metal salt is 0.3 wt% - 10 wt%.

[0055] In some embodiments, the steps of the light irradiation and stirring treatment include: after introducing an inert gas into the mixed solution to remove the dissolved oxygen in the mixed solution, performing light irradiation and stirring for 0.5 h - 2 h. The purpose of using the inert gas to remove the dissolved oxygen in the mixed solution is to prevent O2 from competitively consuming photo-generated electrons, avoid the oxidation of metal ions in the metal salt, and reduce the formation of by-products, thereby improving the deposition efficiency and the uniformity of metal particles.

[0056] In some embodiments, the inert gas includes one of nitrogen, helium, and argon.

[0057] In some embodiments, in step S20, the solvent is a mixed solution of water and ethanol or a mixed solution of water and methanol.

[0058] In a preferred embodiment, the solvent is obtained by mixing water and ethanol in a volume ratio of 4:1.

[0059] In some embodiments, in step S30, after the light irradiation and stirring treatment of the mixed solution, a centrifugal washing treatment is further included, specifically including: obtaining a mixed liquid after the light irradiation and stirring treatment, waiting for the mixed liquid to cool naturally, then centrifuging to collect the product, washing the collected product with water and ethanol respectively, and drying at 60 °C - 80 °C to obtain the sensing material.

[0060] In addition, the present invention also provides a NO2 gas sensor, including an electrode and a sensing layer disposed on the surface of the electrode; the sensing layer contains the sensing material based on metal nanoparticle loading.

[0061] In this embodiment, using the sensing material to prepare the sensing layer of the NO2 gas sensor, the doping of metal nanoparticles on the surface of the defective oxide matrix can be utilized to realize the regulation of the energy band structure of the material, promote the formation of superoxide radicals on the material surface, improve the sensing sensitivity to NO2 under light-assisted conditions, and enable rapid response and recovery. At the same time, the device preparation process is simple, the volume is small, the material is easy to form a film, and it is easy to realize commercial application.

[0062] In some embodiments, the thickness of the sensing layer is 0.5 mm - 3 mm. Controlling the thickness of the sensing layer within this range can save the preparation cost while ensuring the sensitivity and fast response recovery of the sensor.

[0063] In some embodiments, the electrode includes but is not limited to a silver palladium interdigital electrode, an Au interdigital electrode, or a Pt interdigital electrode.

[0064] In some embodiments, the method for preparing the NO2 gas sensor includes the steps of: ultrasonically cleaning the ceramic sheet printed with the electrode in acetone, water, and ethanol for 30 minutes each in sequence, and then drying it in an oven at 60°C; taking a certain amount of the sensing material and adding it to a mixed solution of ethanol and ethylene glycol, and ultrasonically dispersing it to obtain a sensing solution; coating the sensing solution on the electrode, and after drying, obtaining the gas sensor.

[0065] In some embodiments, the concentration of the sensing solution is 20 mg / mL - 100 mg / mL.

[0066] The following further gives examples to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention.

[0067] Example 1

[0068] In this example, the defective oxide is tungsten defective oxide, and the metal nanoparticles are Au nanoparticles. The specific steps for preparing the sensing material are as follows:

[0069] (1) Synthesis of tungsten defective oxide (W 18 O 49 )

[0070] Weigh 0.15 g of WCl6 and put it into the polytetrafluoroethylene inner liner, add ethanol to dissolve it fully, and then transfer the reaction kettle to an oven for solvothermal reaction at 180°C for 12 h. Wait for it to cool naturally, centrifuge to collect the product, wash it with water and ethanol respectively, and dry it in an oven at 60°C to obtain tungsten defective oxide.

[0071] (2) Synthesis of tungsten defective oxide supported with Au nanoparticles (W 18 O 49 -Au)

[0072] Weigh 100 mg of the synthesized defective tungsten oxide in (1) and add it to a mixed solution of water and ethanol. Stir to disperse it thoroughly. Subsequently, add chloroauric acid solutions in different proportions. After purging with N2 for 20 min, carry out light stirring for 1 h. Centrifuge to collect the product, wash it with water and ethanol respectively, and dry it in an oven at 60 °C to obtain the sensing material W 18 O 49 -Au-1, W 18 O 49 -Au-2 and W 18 O 49 -Au-3, where the Au loadings in W 18 O 49 -Au-1, W 18 O 49 -Au-2 and W 18 O 49 -Au-3 are 0.31 wt%, 0.62 wt% and 1.24 wt% respectively.

[0073] The XRD patterns of the pure defective tungsten oxide prepared in step (1) and the defective tungsten oxide loaded with Au nanoparticles prepared in step (2) are as Figure 2 shown. Among them, the new diffraction peak appearing at 2θ ≈ 38.18° corresponds to the characteristic peak of Au, proving that the photo-deposition successfully realizes the loading of Au nanoparticles.

[0074] The transmission electron microscope (TEM) image of the sensing material W 18 O 49 -Au-2 is as Figure 3 shown. It can be observed that the size of the Au nanoparticles is about 24 nm, and the Au in W 18 O 49 -Au-2 is uniformly loaded on the surface of the nanowires in the form of nanoparticles.

[0075] (3) Preparation of NO2 gas sensor

[0076] The ceramic sheet printed with silver-palladium interdigital electrodes is ultrasonically cleaned in acetone, water and ethanol for 30 min each in turn, and then dried in an oven at 60 °C for subsequent use.

[0077] Take 5 mg of the sensing material prepared in (2) and place it in a mixed solution of ethanol and ethylene glycol. Ultrasonically disperse it evenly, and then coat it on the silver-palladium interdigital electrodes. After drying, a NO2 gas sensor is obtained.

[0078] The fabricated sensors were tested. The gas-sensing test of the NO2 gas sensor was carried out using a self-made dynamic gas-sensing system, which consists of the following main components: a gas tank for mixing air and test gas, a flow controller for adjusting the gas flow rate, a test chamber for placing the electrode sheet, a source meter for collecting the resistance in real time, and a computer for data storage.

[0079] Before the test, all the electrode sheets to be measured were dried in dry air by flowing dry air (21% O2 + 79% N2) until the resistance became stable. During the experiment, the target gas was mixed with dry air by adjusting the flow rate of the flowmeter to configure the gas concentration required for the test. The sensitivity of the gas sensor is defined as S = Rg / Ra, where Ra is the resistance value of the gas sensor in air, and Rg is the stable resistance value measured by the gas sensor in the test chamber of the target gas. In addition, the response and recovery times of the gas sensor are defined as follows: under the experimental conditions, the time required for the gas sensor to contact the measured gas until it reaches 90% of the stable indication value, and the time required for its resistance to recover to 90% of the resistance value in normal air starting from when it is separated from the detection gas.

[0080] Figure 4 The room-temperature gas-sensing performance of defective tungsten oxide and defective tungsten oxide loaded with Au nanoparticles under photo-assisted conditions for 10 ppm NO was demonstrated. The results show that the gas-sensing performance is significantly improved after loading Au. Figure 5 The room-temperature gas-sensing performance of W 18 O 49 -Au-2 for 2 - 10 ppm NO under photo-assisted conditions was further characterized, indicating that the detection of NO2 at the ppm level concentration can be achieved.

[0081] Under illumination and in the presence of DMPO, the EPR spectra of superoxide radicals of W 18 O 49 and W 18 O 49 -Au-2 are as shown in Figure 6 It can be seen that Au loading under illumination can promote the generation of superoxide radicals on the material surface, thereby enhancing the NO2 gas-sensing performance. During the gas-sensing process, the reactive oxygen species on the material surface play a key role in improving the gas-sensing performance.

[0082] In addition, the room-temperature gas-sensing performance diagram of the long-term stability of W 18 O 49 -Au-2 for 10 ppm NO2 under photo-assisted conditions is as shown in Figure 7 It can be seen that W O-Au-2 shows excellent stability under the experimental conditions.

[0083] In summary, a sensing material based on metal nanoparticle loading, its preparation method, and a NO2 gas sensor provided by the present invention. The sensing material includes a defective oxide matrix and metal nanoparticles loaded on the surface of the defective oxide matrix. Among them, both the defective oxide matrix and the metal nanoparticles have a local surface plasmon resonance effect. The present invention combines metal nanoparticles with a local surface plasmon resonance (LSPR) effect with a defective oxide matrix, and utilizes the double plasmon resonance effect excited by light to improve the sensing performance of the sensing material for NO2 gas. Specifically, the combination of metal nanoparticles and the defective oxide matrix can promote the generation of more high-energy hot electrons and holes, and delay the decay of hot electrons, thereby improving the reaction performance and NO2 sensing performance. Moreover, by doping metal nanoparticles on the surface of the defective oxide matrix, the energy band structure of the material can be regulated, promoting the formation of superoxide radicals on the material surface, enhancing the sensing sensitivity to NO2 at room temperature under visible light assistance, enabling rapid response and recovery, and simultaneously realizing visible light-assisted NO2 sensing at room temperature.

[0084] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A sensing material based on metal nanoparticle loading, characterized in that, It includes a defective oxide matrix and metal nanoparticles supported on the surface of the defective oxide matrix; Among them, both the defective oxide matrix and the metal nanoparticles have a local surface plasmon resonance effect.

2. The sensing material based on metal nanoparticle loading according to claim 1, wherein The defective oxide matrix includes one of a defective tungsten oxide matrix, a defective titanium oxide matrix, a defective cerium oxide matrix, a defective molybdenum oxide matrix, a defective cobalt oxide matrix, a defective copper oxide matrix, a defective indium oxide matrix, a defective niobium oxide matrix, and a defective zinc oxide matrix.

3. The sensing material based on metal nanoparticle loading according to claim 1, characterized in that, The metal nanoparticles include one or more of Au nanoparticles, Ag nanoparticles, Cu nanoparticles, Pt nanoparticles, Pd nanoparticles, and Bi nanoparticles.

4. The sensing material based on metal nanoparticle loading according to claim 1, wherein The loading mass percentage of the metal nanoparticles in the sensing material is 0.3wt% - 10wt%.

5. The sensing material based on metal nanoparticle loading according to claim 1, characterized in that The defective oxide is in a nanowire structure with a diameter of 10nm - 80nm; the particle size of the metal nanoparticles is 3nm - 30nm.

6. A preparation method of a sensing material based on metal nanoparticle loading as described in any one of claims 1-5, characterized in that, It includes the steps: Mix the metal compound corresponding to the defective oxide with an organic solvent, and then obtain the defective oxide through a solvothermal reaction; Mix the defective oxide with a metal salt and a solvent to obtain a mixed solution; Perform light stirring treatment on the mixed solution to obtain a sensing material based on the loading of metal nanoparticles.

7. The preparation method of the sensing material based on metal nanoparticle loading according to claim 6, characterized in that, The temperature of the solvothermal reaction is 160°C - 200°C, and the time of the solvothermal reaction is 10h - 16h.

8. The preparation method of the sensing material based on metal nanoparticle loading according to claim 6, characterized in that, The step of the light stirring treatment includes: introducing an inert gas into the mixed solution to remove the dissolved oxygen in the mixed solution, and then performing light stirring for 0.5h - 2h.

9. A NO2 gas sensor, comprising an electrode and a sensing layer disposed on the surface of the electrode, characterized in that, The sensing layer contains the sensing material based on the loading of metal nanoparticles as described in any one of claims 1 - 5.

10. The NO2 gas sensor according to claim 9, wherein, The thickness of the sensing layer is 0.5mm - 3mm.

Images