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

Abstract

The invention relates to the technical field of gas sensors, in particular to a sensing material based on nanoparticle loading, a preparation method of the sensing material and a gas sensor, and the sensing material comprises a substrate material and transition metal nanoparticles and / or precious metal alloy nanoparticles loaded on the surface of the substrate material; the substrate material comprises one or more of defect oxide, MOF, sulfide, carbide, MXene and phosphide. The semiconductor characteristic of the substrate material is combined with the hydrogen dissociation capability of the transition metal nanoparticles and / or the noble metal alloy nanoparticles, so that the adsorption and dissociation efficiency of hydrogen can be improved; by loading the nanoparticles on the substrate material, the interface hydrogen overflow process is regulated and controlled, the energy barrier of hydrogen overflow is reduced, and the sensitivity and response speed of the hydrogen sensor are further improved. By optimizing the interface structure between the nanoparticles and the substrate material, the process of interface hydrogen overflow is improved, and the hydrogen sensing performance is improved.

Description

Technical Field

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

[0002] At present, many detection technologies have been proposed and applied to the detection of low-concentration hydrogen, such as infrared spectroscopy, chemiluminescence spectroscopy, ultraviolet absorption spectroscopy, and gas chromatography techniques. However, these technologies have disadvantages such as large equipment volume, high cost, cumbersome operation, and the need for professional personnel to operate, and they are still insufficient in terms of portability.

[0003] In the past decade or so, hydrogen sensors based on metal oxide semiconductors have been widely studied and applied due to their high cost-effectiveness, simple manufacturing, easy-to-master detection methods, and compatibility with semiconductor technology. However, metal oxide-based gas sensors usually need to operate at a high temperature of 200-400 °C to obtain good responses, which not only results in high power consumption but also brings potential explosion risks. In addition, problems such as low sensitivity and detection limit, and slow response speed also restrict their practical applications. Moreover, most metal oxide semiconductor hydrogen sensors can only detect the atmosphere based on a single mode, and this single sensing mode and working principle limit their ability to integrate multiple performances, severely restricting the expansion of their application fields.

[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 prior art, the purpose of the present invention is to provide a sensing material based on nanoparticle loading, a preparation method thereof, and a gas sensor, aiming to solve the problems of low sensitivity, slow response speed, and high working temperature of the sensors obtained based on the existing sensing materials.

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

[0007] A sensing material based on nanoparticle loading, comprising a substrate material, and transition metal nanoparticles and / or noble metal alloy nanoparticles loaded on the surface of the substrate material;

[0008] The substrate material includes one or more of defective oxides, MOF, sulfides, carbides, MXene, and phosphides.

[0009] The described nanoparticle-loaded sensing material, wherein the defective oxide includes one or more of defective tungsten oxide, defective tin oxide, defective indium oxide, defective molybdenum oxide, defective niobium oxide, defective zinc oxide, and defective titanium oxide; and / or, the sulfide includes one or more of tungsten sulfide, tin sulfide, indium sulfide, molybdenum sulfide, niobium sulfide, and zinc sulfide; and / or, the phosphide includes one or more of tungsten phosphide, tin phosphide, indium phosphide, nickel phosphide, and cobalt phosphide; and / or, the carbide includes one or more of tungsten carbide and molybdenum carbide.

[0010] The described nanoparticle-loaded sensing material, wherein the transition metal nanoparticles include one or more of Pt nanoparticles, Rh nanoparticles, Pd nanoparticles, Ru nanoparticles, and Ni nanoparticles; and / or, the noble metal alloy nanoparticles include one or more of PtPd alloy nanoparticles, PtAg alloy nanoparticles, PtAu alloy nanoparticles, and PtCu alloy nanoparticles.

[0011] The described nanoparticle-loaded sensing material, wherein the shape of the substrate material includes one or more of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers.

[0012] The described nanoparticle-loaded sensing material, wherein the loading amount of the transition metal nanoparticles and / or the noble metal alloy nanoparticles in the sensing material is 0.5 wt% - 10 wt%.

[0013] A preparation method of a nanoparticle-loaded sensing material, comprising the steps:

[0014] Mix the substrate material with a solvent to obtain a substrate material solution;

[0015] Mix the transition metal nanoparticles and / or the noble metal alloy nanoparticles with the substrate material solution, and perform centrifugation to obtain a composite material;

[0016] Perform calcination on the composite material to obtain a sensing material.

[0017] The preparation method of the nanoparticle-loaded sensing material, wherein the calcination is carried out in a mixed atmosphere of argon and hydrogen; the temperature of the calcination is 100°C - 400°C, and the time of the calcination is 0.5 h - 3 h.

[0018] The preparation method of the nanoparticle-loaded sensing material, wherein the substrate material is tungsten oxide with different oxygen vacancies, and the tungsten oxide with different oxygen vacancies includes one or more of WO 2.72 、WO 2.9 ; The preparation method of the tungsten oxide with different oxygen vacancies includes the steps:

[0019] Mix tungsten hexachloride or tungsten hexacarbonyl with a solvent and conduct a solvothermal reaction to obtain WO 2.72 ;

[0020] Perform a first heat treatment on the WO 2.72 under an air atmosphere to obtain tungsten oxide;

[0021] Perform a second heat treatment on the tungsten oxide under a mixed atmosphere of argon and hydrogen to obtain WO 2.9 .

[0022] A gas sensor includes electrodes and a sensing layer attached to the surface of the electrodes; the sensing layer contains a sensing material based on nanoparticle loading.

[0023] For the gas sensor described above, the thickness of the sensing layer is 0.5 mm - 3 mm.

[0024] Beneficial effects: The present invention provides a sensing material based on nanoparticle loading, its preparation method, and a gas sensor. The sensing material includes a substrate material, and transition metal nanoparticles and / or noble metal alloy nanoparticles loaded on the surface of the substrate material; the substrate material includes one or more of defective oxides, MOF, sulfides, carbides, MXene, and phosphides. The present invention combines the semiconductor characteristics of the substrate material with the hydrogen dissociation ability of nanoparticles (i.e., transition metal nanoparticles and / or noble metal alloy nanoparticles), which helps to improve the adsorption and dissociation efficiency of hydrogen; by loading nanoparticles on the substrate material, the interfacial hydrogen spillover process is regulated, and the energy barrier of hydrogen spillover is reduced, thereby improving the sensitivity and response speed of the hydrogen sensor. Specifically, through the synergistic effect between nanoparticles and the surface of the substrate material, the hydrogen spillover effect is utilized to greatly improve the sensing ability. When used as the sensing layer of the sensor, it can enhance the sensitivity and response speed of the sensor; by optimizing the interfacial structure between nanoparticles and the substrate material, the process of interfacial hydrogen spillover is improved, and the hydrogen sensing performance is enhanced. Description of the Drawings

[0025] Figure 1 is a schematic flow chart of a preparation method of a sensing material based on nanoparticle loading according to the present invention;

[0026] Figure 2 is the TEM images of Pt nanoparticles (a), WO 2.72 -Pt (b) and WO 2.9 -Pt (c) prepared in Example 1;

[0027] Figure 3 is the WO 2.72 -Pt and WO 2.9XRD pattern of -Pt;

[0028] Figure 4 WO obtained in Example 1 2.72 -Pt and WO 2.9 -Pt's sensing response curve graph for H with a concentration of 0.04%-2% at 100°C 2 ;

[0029] Figure 5 WO in Example 1 at 100°C 2.72 -Pt's selectivity test data graph for interfering gases. Detailed implementation mode

[0030] The present invention provides a sensing material based on nanoparticle loading, its preparation method, and a gas sensor. To make the purpose, technical solution, 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 implementation examples described here are only used to explain the present invention and are not used to limit the present invention.

[0031] Those skilled in the art of the present technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used here 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 with an idealized or overly formal meaning unless specifically defined as here.

[0032] Hydrogen (H 2 ) As a green, clean, and efficient energy source, its broad application prospects are full of expectations. Hydrogen not only has the characteristics of high combustion calorific value and pollution-free secondary energy, but also plays an important role in the energy transformation process. However, since hydrogen is extremely prone to explosion when its concentration in the air reaches 4-75%, the safety hazard is serious, which has also become the main obstacle to its wide application. Therefore, developing a hydrogen sensor with high sensitivity and low-temperature operation is crucial for the early leakage detection and concentration monitoring of hydrogen, especially in the hydrogen concentration range as low as the ppm level. However, the sensors prepared from existing sensing materials have low sensitivity and detection limit, and the response speed is also slow.

[0033] Therefore, there is a need to develop a hydrogen sensor with a low working temperature, high sensitivity, and a wide detection range; inspired by the hydrogen spillover phenomenon caused by the metal-support interaction during the thermal hydrogenation process, explore the application of the hydrogen spillover effect in hydrogen sensing.

[0034] Based on this, the present invention provides a sensing material based on nanoparticle loading, including a substrate material, and transition metal nanoparticles and / or noble metal alloy nanoparticles loaded on the surface of the substrate material;

[0035] The substrate material includes one or more of defective oxides, MOF, sulfides, carbides, MXene, and phosphides.

[0036] In this embodiment, by combining the semiconductor characteristics of the substrate material with the hydrogen dissociation ability of the nanoparticles (i.e., transition metal nanoparticles and / or noble metal alloy nanoparticles), it helps to improve the adsorption and dissociation efficiency of hydrogen; by loading the nanoparticles on the substrate material, the interfacial hydrogen spillover process is regulated, and the energy barrier of hydrogen spillover is reduced, thereby improving the sensitivity and response speed of the sensing material. Specifically, through the synergistic effect between the nanoparticles and the surface of the substrate material, the hydrogen spillover effect is utilized to greatly improve the sensing ability. When used as the sensing layer of the sensor, the sensitivity and response speed of the sensor can be enhanced; by optimizing the interfacial structure between the nanoparticles and the substrate material, the process of interfacial hydrogen spillover is improved, and the hydrogen sensing performance is enhanced.

[0037] Specifically, through the synergistic effect of the advantages of the nanoparticles and the substrate material in the present invention, the adsorption and desorption of hydrogen are promoted, and thus the performance of the sensor is improved; this sensing material has significant cost-effectiveness because it can reduce the use of noble metals while still maintaining relatively superior performance. By utilizing the work function difference between the nanoparticles and the substrate material, the energy barrier of interfacial hydrogen spillover is reduced, thereby significantly enhancing the sensitivity and response speed of the sensing material. Moreover, by precisely regulating the electronic structure at the interface between the nanoparticles and the substrate material and optimizing the hydrogen spillover kinetics, when using the sensing material to prepare the sensing layer of the sensor, the energy consumption of the hydrogen sensor can be reduced and the efficiency can be improved.

[0038] It should be noted that the nanoparticles refer to transition metal nanoparticles and / or noble metal alloy nanoparticles.

[0039] In some embodiments, the defective oxides include one or more of defective tungsten oxide, defective tin oxide, defective indium oxide, defective molybdenum oxide, defective niobium oxide, defective zinc oxide, and defective titanium oxide; the defective oxides have different oxygen vacancies, which helps to improve the adsorption and dissociation efficiency of hydrogen; and it can greatly improve the utilization rate of the nanoparticles, while reducing the use of noble metals and lowering the cost.

[0040] In some embodiments, the sulfide includes one or more of tungsten sulfide, tin sulfide, indium sulfide, molybdenum sulfide, niobium sulfide, zinc sulfide; the phosphide includes one or more of tungsten phosphide, tin phosphide, indium phosphide, nickel phosphide, cobalt phosphide; the carbide includes one or more of tungsten carbide, molybdenum carbide. Using sulfide, phosphide, carbide, MOF and MXene as substrate materials can also play a role in improving the adsorption and dissociation efficiency of hydrogen.

[0041] In a preferred embodiment, the defective tungsten oxide includes WO 2.72 , WO 2.9 or one or more of them; the semiconductor properties of tungsten oxide combined with the hydrogen dissociation ability of metal nanoparticles and / or metal alloy nanoparticles contribute to improving the adsorption and dissociation efficiency of hydrogen. By loading metal nanoparticles and / or metal alloy nanoparticles on tungsten oxide supports with different oxygen vacancies, the interfacial hydrogen spillover process is regulated, the energy barrier of hydrogen spillover is reduced, and thus the sensitivity and response speed of the hydrogen sensor are improved.

[0042] In some embodiments, the MOF includes one or more of transition metal MOF, lanthanide metal MOF, main group metal MOF. The MXene includes one or more of Ti-based MXene, V-based MXene, Mo-based MXene.

[0043] In some embodiments, the transition metal nanoparticles include one or more of Pt nanoparticles, Rh nanoparticles, Pd nanoparticles, Ru nanoparticles, Ni nanoparticles; and / or, the noble metal alloy nanoparticles include one or more of PtPd alloy nanoparticles, PtAg alloy nanoparticles, PtAu alloy nanoparticles, PtCu alloy nanoparticles. The above-mentioned transition metal nanoparticles and noble metal alloy nanoparticles all have the ability to dissociate hydrogen. Combining them with the substrate material helps to improve the adsorption and dissociation efficiency of hydrogen; by loading the transition metal nanoparticles and / or noble metal alloy nanoparticles on the surface of the substrate material, the interfacial hydrogen spillover process can be regulated, the energy barrier of hydrogen spillover is reduced, and thus the sensitivity and response speed of the sensing material applied to the hydrogen sensor are improved.

[0044] In some embodiments, the shape of the substrate material includes one or more of one-dimensional nanowires, two-dimensional nanosheets, three-dimensional nanoflowers. The substrate materials with the above shapes have a large specific surface area, which is beneficial to the loading of nanoparticles.

[0045] In some embodiments, the loading amount of the transition metal nanoparticles and / or the noble metal alloy nanoparticles in the sensing material is 0.5 wt% - 10 wt%. By controlling the loading amount of the transition metal nanoparticles or the noble metal alloy nanoparticles, the interaction between the metal and the substrate material is optimized, thereby improving the process of interfacial hydrogen spillover.

[0046] In some embodiments, the particle size of the transition metal nanoparticles is 2 nm - 5 nm; the particle size of the noble metal alloy nanoparticles is 2 nm - 5 nm. By regulating the particle size of the nanoparticles, the interaction between the metal and the substrate material can be optimized, thereby improving the process of interfacial hydrogen spillover.

[0047] In a preferred embodiment, the particle size of the transition metal nanoparticles is about 3 nm; the particle size of the noble metal alloy nanoparticles is about 3 nm.

[0048] In addition, as Figure 1 shown, the present invention also provides a preparation method of a sensing material based on nanoparticle loading, including the steps:

[0049] Step S10: Mix the substrate material with a solvent to obtain a substrate material solution;

[0050] Step S20: Mix the transition metal nanoparticles and / or the noble metal alloy nanoparticles with the substrate material solution, and perform centrifugation to obtain a composite material;

[0051] Step S30: Calcinate the composite material to obtain a sensing material.

[0052] In this embodiment, by loading the transition metal nanoparticles and / or the noble metal alloy nanoparticles on the surface of the substrate material, the adsorption and dissociation efficiency of hydrogen can be improved, and the utilization rate of the nanoparticles can be increased by using the preparation method, while reducing the use of metal and lowering the cost. This preparation method reduces the energy barrier of hydrogen spillover by regulating the hydrogen spillover process between the nanoparticles and the substrate material, and significantly improves the response speed and sensitivity of the hydrogen sensor.

[0053] Specifically, traditional hydrogen sensors mostly rely on the direct reaction of metal nanoparticles. The present invention synergistically uses the metal particles and the surface of the substrate material, and greatly improves the sensing ability by utilizing the hydrogen spillover effect, enhancing the sensitivity and response speed of the sensor. By optimizing the interfacial structure between the metal nanoparticles and the substrate material, and by controlling the size and loading amount of the nanoparticles on the surface of the substrate material, the interaction between the metal and different carriers is optimized, thereby improving the process of interfacial hydrogen spillover and enhancing the hydrogen sensing performance.

[0054] In some embodiments, the calcination treatment is carried out in a mixed atmosphere of argon and hydrogen; the temperature of the calcination treatment is 100°C - 400°C, and the time of the calcination treatment is 0.5 h - 3 h. The calcination treatment can firmly load metal nanoparticles and / or metal alloy nanoparticles on the surface of the substrate material.

[0055] In a preferred embodiment, the calcination treatment is carried out in a mixed atmosphere of 5% argon and hydrogen; the temperature of the calcination treatment is 200°C, and the time of the calcination treatment is 2 h.

[0056] In some embodiments, the substrate material is tungsten oxide with different oxygen vacancies, and the tungsten oxide with different oxygen vacancies includes one or more of WO 2.72 、WO 2.9 ; The preparation method of the tungsten oxide with different oxygen vacancies includes the steps:

[0057] Step S1: Mix tungsten hexachloride or tungsten hexacarbonyl with a solvent, and carry out a solvothermal reaction to obtain WO 2.72 ;

[0058] Step S2: Carry out a first heat treatment on the WO 2.72 in an air atmosphere to obtain tungsten oxide;

[0059] Step S3: Carry out a second heat treatment on the tungsten oxide in a mixed atmosphere of argon and hydrogen to obtain WO 2.9 。

[0060] In some embodiments, the temperature of the solvothermal reaction is 160°C - 200°C, and the time of the solvothermal reaction is 8 h - 24 h; controlling within this range of reaction temperature and reaction time is beneficial to the synthesis of WO 2.72 with oxygen vacancy defects.

[0061] In a preferred embodiment, the temperature of the solvothermal reaction is 180°C, and the time of the solvothermal reaction is 12 h.

[0062] In some embodiments, the temperature of the first heat treatment is 400°C - 500°C, and the time of the first heat treatment is 1 h - 5 h.

[0063] In a preferred embodiment, the temperature of the first heat treatment is 400°C, and the time of the first heat treatment is 3 h.

[0064] In some embodiments, the temperature of the second heat treatment is 500°C - 600°C, and the time of the second heat treatment is 1 h - 5 h.

[0065] In a preferred embodiment, the temperature of the second heat treatment is 550 °C and the time of the second heat treatment is 2 h.

[0066] In some embodiments, the mass ratio of the substrate material to the metal nanoparticles is 0.5 wt% - 10 wt%.

[0067] In some embodiments, the synthesis of the Pt nanoparticles includes the steps of: stirring polyvinylpyrrolidone with a reducing solvent to dissolve it, then adding an aqueous solution of chloroplatinic acid thereto, stirring at room temperature, heating under reflux with stirring at 90 °C - 180 °C, and allowing it to cool naturally to obtain a Pt nanoparticle solution; after drying, Pt nanoparticles are obtained. Among them, the polyvinylpyrrolidone serves as a stabilizer and a surfactant.

[0068] In some embodiments, the reducing solvent includes one or more of isopropanol, methanol, ethanol, and ethylene glycol.

[0069] In addition, the present invention also provides a gas sensor, including an electrode and a sensing layer attached to the surface of the electrode; the sensing layer contains the sensing material based on nanoparticle loading.

[0070] In this embodiment, applying the sensing material to the sensing layer of the gas sensor can improve the adsorption and dissociation efficiency of hydrogen, and further improve the sensitivity and response speed of the hydrogen sensor.

[0071] 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 improve the sensitivity and response speed of the sensor and has a wide detection limit.

[0072] In some embodiments, the electrode is a silver-palladium interdigital electrode, an Au electrode, or a Pt electrode.

[0073] 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.

[0074] Example 1

[0075] This example provides a sensing material based on Pt nanoparticle loading, and the substrate material is a defective oxide, specifically including the following:

[0076] 1. Synthesis of tungsten oxides with different oxygen vacancies WO x (x = 2.9, 2.72)

[0077] Weigh 0.15 g of WCl 6 Put it into a polytetrafluoroethylene inner container, add ethanol to dissolve it completely, 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 the oven to obtain WO 2.72 .

[0078] The obtained WO 2.72 is calcined at 400 °C for 2 h in an air atmosphere to obtain tungsten oxide.

[0079] The obtained tungsten oxide is calcined at 550 °C for 1 h in Ar / H 2 (5% H 2 ) to obtain WO 2.9 .

[0080] 2. Synthesis of Pt nanoparticles

[0081] Weigh 1.7 mg of polyvinylpyrrolidone and place it in a round-bottom flask. Add 45 mL of isopropanol to it, stir to dissolve it, then add 5 mL of 6 mM chloroplatinic acid aqueous solution. After stirring at room temperature for 2 min, heat it under reflux with stirring at 90 °C for 3 h. Wait for it to cool naturally, and the obtained Pt nanoparticle solution is reserved for use.

[0082] 3. Synthesis of Pt-loaded WO 2.72

[0083] Weigh 100 mg of WO 2.72 Add 30 mL of ethanol, ultrasonicate for 5 minutes to disperse it completely, then add 20 mL of the Pt nanoparticle solution prepared in (2) to it. Stir at room temperature for 5 h, centrifuge to collect the product, wash it with acetone and ethanol respectively, and dry it in an oven at 60 °C. The obtained sample is calcined at 200 °C for 2 h in a 5% Ar / H 2 atmosphere to obtain WO 2.72 -Pt, and the Pt loading is about 2.6 wt%.

[0084] 4. Synthesis of Pt-loaded WO 2.9

[0085] Weigh 100 mg of WO 2.9 Add 30 mL of ethanol, ultrasonicate for 5 minutes to disperse it completely, then add 20 mL of the Pt nanoparticle solution prepared in (2) to it. Stir at room temperature for 5 h, centrifuge to collect the product, wash it with acetone and ethanol respectively, and dry it in an oven at 60 °C. The obtained sample is calcined at 200 °C for 2 h in a 5% Ar / H 2 atmosphere to obtain WO 2.9 -Pt, and the Pt loading is about 2.6 wt%.

[0086] ​​The Pt nanoparticles (a), WO 2.72 -Pt (b), and WO 2.9 -Pt (c) prepared in this example were microscopically characterized. The transmission electron microscope (TEM) images are as shown in Figure 2 . It can be observed that the size of the Pt nanoparticles is approximately 3 nm. In WO 2.72 -Pt and WO 2.9 -Pt, Pt is uniformly loaded in the form of nanoparticles on the surface of WO 2.72 nanowires and the surface of WO 2.9 nanowires. The XRD patterns of WO 2.72 -Pt and WO 2.9 -Pt are as shown in Figure 3 . Combining the TEM images and the XRD patterns further verifies that the Pt nanoparticles are loaded in the form of nanoparticles on WO 2.72 nanowires or WO 2.9 nanowires.

[0087] 5. Preparation of Gas Sensor Devices

[0088] 1) The ceramic sheet printed with silver-palladium interdigital electrodes was ultrasonically cleaned in acetone, water, and ethanol for 30 min each in sequence, and then dried in an oven at 60 °C for subsequent testing.

[0089] 2) Samples of WO 2.72 and WO 2.9 were prepared separately: 5 mg of each sample was taken and ultrasonically dispersed in an aqueous solution.

[0090] 3) The uniformly dispersed sample was pipetted and dropped onto the silver-palladium interdigital electrodes, dried, and then tested. The thickness range of the sensing layer is approximately 1.5 mm.

[0091] 6. Gas Sensing Test of the Prepared Gas Sensors

[0092] The gas-sensing test of the samples was carried out using a self-made dynamic gas-sensing system. This instrument consists of the following main components: a gas cylinder for mixing air and test gas, a flow controller for adjusting the gas flow rate, a test chamber for placing the electrode sheets, a source meter for real-time collection of resistance, and a computer for data storage. Before the test, all the electrode sheets to be tested were passed through flowing dry air (21% O 2 + 79% N 2)Until the resistance stabilizes. During the test, the target gas is 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 = Ra / Rg, where Ra is the resistance value exhibited by 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 test 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.

[0093] Figure 4 Shows WO 2.72 -Pt(a) and WO 2.9 -Pt(b) test results of the sensing performance at different hydrogen concentrations. The results show that Pt nanoparticles loaded on WO 2.72 exhibit more excellent gas sensing performance, and under the experimental conditions shown in Figure 5 WO 2.72 -Pt shows good selectivity.

[0094] This example shows that by controlling the size and loading amount of Pt nanoparticles on the material surface, the interaction between the metal and the support is optimized, thus improving the process of interfacial hydrogen spillover. By studying the interaction between Pt and WO x with different oxygen vacancies, it is found that this interaction effectively reduces the energy barrier of interfacial hydrogen spillover and significantly improves the sensitivity and response speed of the hydrogen sensor.

[0095] In summary, a sensing material based on nanoparticle loading, its preparation method, and a gas sensor provided by the present invention. The sensing material includes a substrate material, and metal nanoparticles and / or metal alloy nanoparticles loaded on the surface of the substrate material; the substrate material includes one or more of defective oxides, MOF, sulfides, carbides, MXene, phosphides; the metal nanoparticles are transition metal nanoparticles; the metal alloy nanoparticles are noble metal alloy nanoparticles. The present invention combines the semiconductor characteristics of the substrate material with the hydrogen dissociation ability of the nanoparticles, which helps to improve the adsorption and dissociation efficiency of hydrogen; by loading nanoparticles on the substrate material, the interfacial hydrogen spillover process is regulated, and the energy barrier of hydrogen spillover is reduced, thereby improving the sensitivity and response speed of the hydrogen sensor. Specifically, the present invention uses the synergistic effect between the nanoparticles and the surface of the substrate material, and greatly improves the sensing ability by the hydrogen spillover effect. When used as the sensing layer of the sensor, it can enhance the sensitivity and response speed of the sensor; by optimizing the interfacial structure between the nanoparticles and the substrate material, the process of interfacial hydrogen spillover is improved, and the hydrogen sensing performance is enhanced.

[0096] 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 modifications can be made according to the above description, and all such improvements and modifications shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A sensing material based on nanoparticle loading, characterized in that: It comprises a base material, and transition metal nanoparticles and / or noble metal alloy nanoparticles loaded on the surface of the base material; The substrate material includes one or more of defective oxides, MOFs, sulfides, carbides, MXenes, and phosphides.

2. The nanoparticle-loaded sensing material according to claim 1, characterized in that: The defective oxides include one or more of defective tungsten oxide, defective tin oxide, defective indium oxide, defective molybdenum oxide, defective niobium oxide, defective zinc oxide, and defective titanium oxide; and / or, the sulfides include one or more of tungsten sulfide, tin sulfide, indium sulfide, molybdenum sulfide, niobium sulfide, and zinc sulfide; and / or, the phosphides include one or more of tungsten phosphide, tin phosphide, indium phosphide, nickel phosphide, and cobalt phosphide; and / or, the carbides include one or more of tungsten carbide and molybdenum carbide.

3. The nanoparticle-loaded sensing material according to claim 1, characterized in that: The transition metal nanoparticles include one or more of Pt nanoparticles, Rh nanoparticles, Pd nanoparticles, Ru nanoparticles, and Ni nanoparticles; and / or the noble metal alloy nanoparticles include one or more of PtPd alloy nanoparticles, PtAg alloy nanoparticles, PtAu alloy nanoparticles, and PtCu alloy nanoparticles.

4. The nanoparticle-loaded sensing material according to claim 1, characterized in that: The shape of the base material includes one or more of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers.

5. The nanoparticle-loaded sensing material according to claim 1, characterized in that: The loading amount of the transition metal nanoparticles and / or the noble metal alloy nanoparticles in the sensing material is 0.5 wt % to 10 wt %.

6. A method for preparing a nanoparticle-loaded sensing material according to any one of claims 1 to 5, characterized in that: Includes steps: Mixing the base material with the solvent to obtain a base material solution; Mixing transition metal nanoparticles and / or noble metal alloy nanoparticles with the base material solution, and subjecting the mixture to centrifugal treatment to obtain a composite material; The composite material is calcined to obtain a sensing material.

7. The method for preparing a nanoparticle-loaded sensing material according to claim 6, characterized in that: The calcination treatment is carried out in a mixed atmosphere of argon and hydrogen; the temperature of the calcination treatment is 100° C.-400° C., and the time of the calcination treatment is 0.5 h-3 h.

8. The method for preparing a nanoparticle-loaded sensing material according to claim 6, characterized in that: The substrate material is tungsten oxide with different oxygen vacancies, and the tungsten oxide with different oxygen vacancies includes WO 2.72 , WO 2.9 One or more of; The method for preparing tungsten oxide with different oxygen vacancies comprises the steps of: Mix tungsten hexachloride or tungsten hexacarbonyl with a solvent and undergo a solvent thermal reaction to obtain WO 2.72 ; The WO 2.72 Performing a first heat treatment in an air atmosphere to obtain tungsten oxide; The tungsten oxide is subjected to a second heat treatment in a mixed atmosphere of argon and hydrogen to obtain WO 2.9 .

9. A gas sensor, characterized in that: It comprises an electrode and a sensing layer attached to the surface of the electrode; the sensing layer contains the nanoparticle-loaded sensing material according to any one of claims 1 to 5.

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

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