Method for constructing and detecting noble metal-sensitized volatile aroma substance sensor

Abstract

The invention relates to the technical field of tea aroma detection, in particular to a noble metal-sensitized volatile aroma substance sensor construction and detection method, which comprises the following steps: dissolving zinc acetate dihydrate, urea and trisodium citrate dihydrate in deionized water to obtain a mixed precursor solution; controlling the hydrothermal reaction of the precursor solution; after naturally cooling to room temperature, washing, centrifuging, drying and calcining to obtain a zinc oxide material; the preparation method comprises the following steps: impregnating a zinc oxide material with deionized water, adding an ammonium carbonate solution while stirring, stirring, and then adding a noble metal solution to obtain a noble metal modified zinc oxide mixed solution; centrifuging, drying and calcining to obtain a powder zinc oxide loaded noble metal material; dissolving the zinc oxide loaded noble metal material in ethanol, performing ultrasonic treatment to form turbid liquid, and further dispensing the turbid liquid to the surface of a planar electrode to construct a semiconductor sensor for detecting tea aroma; the sensor prepared by the method has excellent sensing characteristics of high sensitivity, high stability and the like on tea aroma.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tea aroma detection, and particularly relates to a noble metal sensitized volatile aroma substance sensor construction and detection method. BACKGROUND

[0002] During the growth of tea trees, the infestation of pests and diseases is a problem that cannot be ignored. In order to detect and deal with these threats in a timely manner, scientists have explored methods for detecting volatile organic compounds produced by tea trees. For example, leaf alcohol, geraniol, n-octanol, or linalool as specific volatile organic compounds will significantly increase when tea trees are infested by pests and diseases. By detecting the concentration of leaf alcohol, geraniol, n-octanol, or linalool in the air with professional instruments, we can indirectly infer whether the tea trees have been infested by pests and diseases. This method is not only fast and effective, but also highly sensitive and accurate. By regularly monitoring the volatile organic compounds produced by tea trees, tea farmers can detect the early signs of pests and diseases and take appropriate control measures to ensure the healthy growth of tea trees and the quality and safety of tea. Therefore, using specific tea aroma to detect whether tea trees are infested by pests and diseases has become an indispensable part of tea production. In recent years, volatile organic compounds have become an effective means of detecting and diagnosing tea pests and diseases.

[0003] Metal oxide semiconductor gas sensors are one of the most common types of semiconductor gas sensors. Zinc oxide, as a semiconductor material, has a wide range of applications in the field of gas sensors. Its excellent electrical properties, chemical stability, and high sensitivity to volatile organic compounds make it an ideal gas sensitive material. The chemical properties and physical structure of the zinc oxide surface enable it to effectively interact with specific types of organic molecules. In particular, zinc oxide sensors perform well in detecting aliphatic and aromatic compounds. When zinc oxide is loaded with noble metals such as gold, silver, platinum, and palladium, the performance of zinc oxide-based gas sensors can be significantly improved through enhanced catalytic activity, reduced operating temperature, improved selectivity, and accelerated response recovery time. This makes zinc oxide noble metal modification widely applicable in various fields. However, there are few reports on the use of related materials for tea pest and disease detection. Therefore, we constructed four types of zinc oxide gas sensitive materials modified with noble metals to rapidly detect leaf alcohol, geraniol, n-octanol, and linalool in tea aroma. The properties and performance of the sensors were improved, effectively enabling the evaluation of tea quality and the monitoring of tea tree pest and disease conditions. SUMMARY

[0004] The application aims to provide a noble metal sensitized volatile aroma substance sensor construction and detection method.

[0005] The application can be achieved by the following technical solutions. A noble metal sensitized volatile aroma substance sensor construction method, comprising the following steps: Step A: zinc acetate dihydrate, urea and trisodium citrate dihydrate are dissolved in deionized water to obtain a mixed precursor solution; the precursor solution is hydrothermally reacted for 6 h; Step B: after natural cooling to room temperature, the suspension obtained by reaction is washed, centrifuged and dried to obtain a zinc hydroxide carbonate precursor; the zinc hydroxide carbonate precursor is calcined at 350 DEG C in an air atmosphere for 2 h to obtain a zinc oxide material; Step C: the zinc oxide material is immersed in deionized water, under stirring, ammonia carbonate solution is added and stirred, then noble metal solution is added to obtain a noble metal modified zinc oxide mixed solution; the supernatant is poured out by using a centrifuge, and the precipitate is dried; Step D: the dried sample is calcined at 500 DEG C in a mixed atmosphere of hydrogen and argon for 1 h to obtain a powder of zinc oxide loaded with noble metal material; Step E: the zinc oxide loaded with noble metal material is dissolved in ethanol, forms a suspension after ultrasonic treatment, and is further drop-coated on the surface of a planar electrode to construct a semiconductor sensor for detecting tea aroma.

[0006] As a further scheme of the application, in step A, the mass ratio of zinc acetate dihydrate, urea and trisodium citrate dihydrate is 0.443:0.2:0.059.

[0007] As a further scheme of the application, in step B, the centrifugal washing is performed 3 times, the centrifugal speed is 6000-9000 rpm, and the centrifugal time is 5-8 min.

[0008] As a further scheme of the application, in step B, the drying temperature is 60-80 DEG C, and the drying time is 6-24 h.

[0009] As a further scheme of the application, in step B, the heating rate during the calcination process is 10 DEG C·min -1 .

[0010] As a further scheme of the application, the noble metal solution includes palladium chloride aqueous solution, silver chloride aqueous solution, chloroauric acid aqueous solution and potassium chloroplatinite solution.

[0011] As a further scheme of the present application: the concentration of the aqueous solution of palladium chloride, the aqueous solution of silver chloride, the aqueous solution of chloroauric acid, and the potassium chloroplatinite solution is respectively 10 mg·mL -1 , 10 mg·mL -1 , 2 mg·mL -1 , 2 mg·mL -1 .

[0012] As a further scheme of the present application: in step D, the heating rate during calcination is 10℃·min -1 .

[0013] As a further scheme of the present application: the zinc oxide supported noble metal gas sensitive material includes zinc oxide supported palladium, zinc oxide supported silver, zinc oxide supported gold, and zinc oxide supported platinum, and the morphology of the zinc oxide supported noble metal material is in the form of a granular sheet with a particle size of 50 nm.

[0014] A volatile aroma substance sensor detection method of noble metal sensitization, the zinc oxide supported noble metal gas sensitive material prepared by the above method is dispersed in anhydrous ethanol, then is dropped and coated on the surface of a plane electrode by using a liquid transfer gun, is naturally dried, is built into a gas sensor, and is further used for gas sensitive testing of tea aroma such as leaf alcohol, geraniol, n-octanol, and linalool.

[0015] The present application has the following beneficial effects: In the present application, the preparation method of the entire zinc oxide supported noble metal (palladium, silver, gold, and platinum) gas sensitive material is simple and easy to operate, and the sensor based on the obtained zinc oxide noble metal modified gas sensitive material exhibits better high sensitivity and high stability and other sensing properties than the sensor based on pure zinc oxide gas sensitive material in four kinds of tea aroma (leaf alcohol, geraniol, n-octanol, and linalool). In the process of using the zinc oxide noble metal modified gas sensitive material for constructing a tea aroma sensor, the prepared zinc oxide noble metal modified gas sensitive material is subjected to a sensor sensitive film process to construct a tea aroma sensor, so that the zinc oxide supported palladium, the zinc oxide supported silver, the zinc oxide supported gold, and the zinc oxide supported platinum can realize rapid sensing response to leaf alcohol, geraniol, n-octanol, and linalool, respectively, and exhibit excellent gas sensitive properties in the gas sensitive research of volatile substances such as leaf alcohol, geraniol, n-octanol, and linalool in tea aroma. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to make the technical solutions in the embodiments of the present application clearer, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without any creative work based on the embodiments in the present application should belong to the protection scope of the present application.

[0017] Figure 1 is the SEM picture of the zinc oxide supported palladium (a), zinc oxide supported silver (b), zinc oxide supported gold (c), and zinc oxide supported platinum (d) material samples prepared in the present application; Figure 2 is the XRD picture of the zinc oxide supported noble metal (palladium, silver, gold, and platinum) gas sensitive material provided in the present application; Figure 3 is the sensitivity-time / sec curve of the gas sensitive performance test of the zinc oxide supported palladium material in the present application on leaf alcohol at a working temperature of 175℃; Figure 4 is the sensitivity-time / sec curve of the gas sensitive performance test of the zinc oxide supported silver material in the present application on geraniol at a working temperature of 175℃; Figure 5 is the sensitivity-time / sec curve of the gas sensitive performance test of the zinc oxide supported gold material in the present application on n-octanol at a working temperature of 225℃; Figure 6 is the sensitivity-time / sec curve of the gas sensitive performance test of the zinc oxide supported platinum material in the present application on linalool at a working temperature of 275℃. DETAILED DESCRIPTION

[0018] In order to make those skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work should belong to the protection scope of the present application.

[0019] Embodiment 1 The embodiments of the present application provide a construction method of a volatile aroma substance sensor with noble metal sensitization, which comprises the following steps: Step A: 0.443 g of zinc acetate dihydrate, 0.2 g of urea, and 0.059 g of trisodium citrate dihydrate are weighed and dissolved in 35 mL of deionized water. The above mixed solution is continuously magnetically stirred for 30 minutes to obtain a mixed precursor solution. The precursor solution is transferred to a 50 mL polytetrafluoroethylene liner, the liner is sealed and placed in a reaction kettle, and the reaction kettle is placed in an oven at 130℃ for hydrothermal reaction for 6 h. Step B: After natural cooling to room temperature, the inner liner was taken out, the first suspension solution in the inner liner was transferred to a centrifuge tube, the turbid white precipitate in the inner liner was washed by centrifugation using deionized water, and the collected white precipitate was dried; the obtained zinc hydroxide carbonate (ZHC) precursor was obtained. The zinc hydroxide carbonate (ZHC) precursor was calcined at 350℃ under air atmosphere for 2 h, and the obtained white powder was the zinc oxide material; wherein, the turbid white precipitate in the inner liner was washed by centrifugation for 3 times, the centrifugal speed was 6000 rpm, and the centrifugal time was 5 min.

[0020] The temperature for drying the precipitate was 60℃, and the drying time was 6 h, so as to remove the water in the precipitate.

[0021] The heating rate of the zinc hydroxide carbonate (ZHC) precursor in the calcination process was 10℃·min -1 .

[0022] Step C: 0.1 g of the zinc oxide material was immersed in 5 ml of deionized water, 2.5 mL of 1M ammonium carbonate solution was slowly added under magnetic stirring to obtain a second suspension solution; 1 mL of palladium chloride aqueous solution was added to the second suspension solution under magnetic stirring to obtain a noble metal modified zinc oxide mixed solution; the supernatant was poured out by using a centrifuge, and the collected precipitate was dried; wherein, the concentration of the palladium chloride aqueous solution was 10mg·mL -1 .

[0023] Step D: The obtained dried sample was calcined at 500℃ under a mixed gas atmosphere of hydrogen and argon for 1 h, and the obtained powder was zinc oxide loaded with palladium, zinc oxide loaded with silver, zinc oxide loaded with gold and zinc oxide loaded with platinum material, respectively; wherein, the heating rate of the dried sample in the calcination process was 10℃·min -1 .

[0024] Step E: 20 mg of the zinc oxide loaded palladium metal gas sensitive material was dissolved in 25 μL of ethanol to form a suspension solution after ultrasonic treatment, and was further drop-coated on the surface of a planar electrode to construct four kinds of semiconductor sensors that can be used for detecting tea aroma.

[0025] Example 2 The application embodiment provides a noble metal sensitized volatile aroma substance sensor construction method, which comprises the following steps: Step A: 0.443 g of zinc acetate dihydrate, 0.2 g of urea and 0.059 g of trisodium citrate dihydrate were weighed and dissolved in 35 mL of deionized water, and the mixed precursor solution was continuously stirred magnetically for 30 min to obtain a mixed precursor solution; the precursor solution was transferred to a 50 mL polytetrafluoroethylene liner, the liner was sealed in a reaction kettle, and the reaction kettle was placed in an oven at 130°C for hydrothermal reaction for 6 h; Step B: After natural cooling to room temperature, the liner was taken out, the first suspension in the liner was transferred to a centrifuge tube, the turbid white precipitate in the liner was washed and centrifuged with deionized water, and the collected white precipitate was dried; the obtained zinc hydroxide carbonate (ZHC) precursor was calcined at 350°C in an air atmosphere for 2 h, and the obtained white powder was a zinc oxide material; The turbid white precipitate in the liner was centrifuged and washed 3 times at a centrifugal speed of 7000 rpm for 6 min.

[0026] The temperature for drying the precipitate was 70°C, and the drying time was 15 h to remove the water in the precipitate.

[0027] The heating rate of the zinc hydroxide carbonate (ZHC) precursor during calcination was 10°C·min -1 .

[0028] Step C: 0.1 g of the zinc oxide material was immersed in 5 mL of deionized water, 2.5 mL of 1M ammonium carbonate solution was slowly added under magnetic stirring to obtain a second suspension; 2 mL of silver chloride aqueous solution was added to the second suspension under magnetic stirring to obtain a noble metal modified zinc oxide mixed solution; the supernatant was centrifuged and the collected precipitate was dried; The concentration of the silver chloride aqueous solution was 10 mg·mL -1 .

[0029] Step D: The obtained dried sample was calcined at 500°C in a mixed atmosphere of hydrogen and argon for 1 h, and the obtained powder was a zinc oxide loaded palladium, zinc oxide loaded silver, zinc oxide loaded gold and zinc oxide loaded platinum material; The heating rate of the dried sample during calcination was 10°C·min -1 .

[0030] Step E: 20 mg of the zinc oxide loaded silver metal gas sensitive material was dissolved in 25 μL of ethanol to form a suspension after ultrasonic treatment, and was further drop-coated on the surface of a planar electrode to construct four kinds of semiconductor sensors that can be used for detecting tea aroma.

[0031] Example 3 The embodiment of the present application provides a kind of noble metal sensitized volatile aroma substance sensor construction method, comprising the following steps: Step A: 0.443g of zinc acetate dihydrate, 0.2g of urea and 0.059g of trisodium citrate dihydrate are weighed, dissolved in 35 mL of deionized water, and the above mixed solution is continuously magnetically stirred for 30 minutes to obtain a mixed precursor solution; the precursor solution is transferred to a 50 mL polytetrafluoroethylene liner, the liner is sealed in a reaction kettle, and the reaction kettle is placed in an oven at 130 DEG C for hydrothermal reaction for 6 hours; Step B: after natural cooling to room temperature, the liner is taken out, the first suspension in the liner is transferred to a centrifuge tube, the turbid white precipitate in the liner is washed and centrifuged with deionized water, and the collected white precipitate is dried; the obtained zinc hydroxide carbonate (ZHC) precursor is calcined at 350 DEG C in air atmosphere for 2 hours, and the obtained white powder is zinc oxide material; Among them, the turbid white precipitate in the liner is centrifuged and washed 3 times, the centrifugal speed is 8000 rpm, and the centrifugal time is 7 min.

[0032] The temperature for drying the precipitate is 60-80 DEG C, and the drying time is 6-24 hours to remove the moisture in the precipitate.

[0033] The heating rate of the zinc hydroxide carbonate (ZHC) precursor during calcination is 10 DEG C·min -1 .

[0034] Step C: 0.1 g of zinc oxide material is immersed in 5 ml of deionized water, 2.5 mL of 1M ammonium carbonate solution is slowly added under magnetic stirring to obtain a second suspension; 2 mL of chloroauric acid aqueous solution, potassium chloroplatinate solution is added to the second suspension under magnetic stirring to obtain a noble metal modified zinc oxide mixed solution; the supernatant is centrifuged and poured out, and the collected precipitate is dried; Among them, the concentration of chloroauric acid aqueous solution is 2mg·mL -1 .

[0035] Step D: the obtained dried sample is calcined at 500 DEG C in a mixed gas atmosphere of hydrogen and argon for 1 hour, and the obtained powder is zinc oxide loaded palladium, zinc oxide loaded silver, zinc oxide loaded gold and zinc oxide loaded platinum material; Among them, the heating rate of the dried sample during calcination is 10 DEG C·min -1 .

[0036] Step E: 20 mg of gold metal gas sensitive material supported on zinc oxide was dissolved in 25 μL of ethanol to form a suspension, which was further drop-coated on the surface of the planar electrode to construct four semiconductor sensors for detecting the aroma of tea.

[0037] Example 4 The embodiment of the present application provides a noble metal sensitized volatile aroma sensor construction method, comprising the following steps: Step A: 0.443 g of zinc acetate dihydrate, 0.2 g of urea and 0.059 g of trisodium citrate dihydrate were weighed and dissolved in 35 mL of deionized water, and the mixed precursor solution was continuously magnetically stirred for 30 minutes to obtain a mixed precursor solution; the precursor solution was transferred to a 50 mL polytetrafluoroethylene liner, the liner was sealed and placed in a reaction kettle, and the reaction kettle was placed in an oven at 130°C for hydrothermal reaction for 6 h; Step B: After natural cooling to room temperature, the liner was taken out, and the first suspension in the liner was transferred to a centrifuge tube, the turbid white precipitate in the liner was washed and centrifuged with deionized water, and the collected white precipitate was dried; the obtained zinc hydroxide carbonate (ZHC) precursor was calcined at 350°C in air atmosphere for 2 h, and the obtained white powder was zinc oxide material; Among them, the turbid white precipitate in the liner was washed and centrifuged 3 times, the centrifugal speed was 9000 rpm, and the centrifugal time was 8 min.

[0038] The temperature for drying the precipitate was 80°C, and the drying time was 24 h, so as to remove the water in the precipitate.

[0039] The heating rate of the zinc hydroxide carbonate (ZHC) precursor during the calcination process was 10°C·min -1 .

[0040] Step C: 0.1 g of zinc oxide material was immersed in 5 ml of deionized water, 2.5 mL of 1M ammonium carbonate solution was slowly added under magnetic stirring to obtain a second suspension; 3 mL of potassium chloroplatinite solution was added to the second suspension under magnetic stirring to obtain four kinds of noble metal modified zinc oxide mixed solutions; the supernatant was centrifuged and the collected four kinds of precipitates were dried; Among them, the concentration of gold potassium chloroplatinite solution was 2 mg·mL -1 .

[0041] Step D: The obtained dried sample was calcined at 500°C in a mixed atmosphere of hydrogen and argon for 1 h, and the obtained powder was zinc oxide supported palladium, zinc oxide supported silver, zinc oxide supported gold and zinc oxide supported platinum material, respectively; The temperature rising rate of the dry sample in the calcination process is 10℃·min -1 .

[0042] Step E: 20 mg of zinc oxide loaded platinum metal gas sensitive material was dissolved in 25 μL of ethanol, and after ultrasonic treatment, a suspension was formed, which was further drop-coated on the surface of the planar electrode to construct four semiconductor sensors for detecting tea aroma.

[0043] Example 5 The application provides a noble metal sensitized volatile aroma sensor detection method, which comprises the following steps: The zinc oxide noble metal modified gas sensitive material is prepared by the method described in the above examples, and the gas sensitive material is zinc oxide loaded noble metal (palladium, silver, gold, platinum). The morphology of the zinc oxide gas sensitive material is granular flake, and the particle size is about 50 nm. The zinc oxide noble metal modified gas sensitive material is used for rapid detection of four kinds of tea aroma substances, and the specific steps are as follows: The zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive material is dispersed in anhydrous ethanol, drop-coated on the surface of the planar electrode by using a pipette, and naturally dried to further construct a gas sensor for performance testing of four kinds of tea aroma. In the production process of the zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive material used in the tea aroma sensor, the zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive material prepared in the above examples is subjected to a sensor sensitive film process to construct a tea aroma sensor, which realizes rapid sensing response to linalool, geraniol, n-octanol and linalool in tea aroma. In the gas sensitive research of volatile substances linalool, geraniol, n-octanol and linalool in tea aroma, excellent gas sensitive characteristics can be quickly exhibited.

[0044] In the process of morphology observation and performance detection of the zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive material prepared in the above examples, the following results can be obtained: (1) As shown in Figure 1 , the SEM images of the materials prepared in examples 1-4, from Figure 1 (a), it can be seen that the zinc oxide loaded palladium gas sensitive material is in the form of elliptical particles, the surface is covered with small protruding structures, the morphology is relatively dense and the edge is clear, showing certain crystallinity. Figure 1 In (b), the zinc oxide loaded silver gas sensitive material presents a typical flower-like aggregate structure, which is formed by mutual entanglement and stacking of nanosheet layers, and has a high specific surface area. Figure 1(c) The surface morphology of the zinc oxide loaded with gold gas sensitive material is uniformly distributed in a granular structure, the whole presents a dense porous cluster shape, the surface is composed of a large number of micron-sized spherical particles tightly packed, the structure is compact and has good uniformity; and Figure 1 (d) The zinc oxide loaded with platinum has a folded sheet structure in a local area on the basis of a similar granular surface. In summary, the zinc oxide loaded with noble metals corresponding to the four sensors shows differences in macroscopic morphology and microstructure, which may be affected by different noble metal loading. Different noble metals (palladium, silver, gold, platinum) loading can not only change the surface morphology of the zinc oxide gas sensitive material, but also optimize its gas sensing performance by adjusting the electronic structure of the material. Further affect its response characteristics and stability in gas sensing applications.

[0045] (2) As shown in Figure 2 The X-ray diffraction (XRD) pattern of the zinc oxide loaded with noble metals (such as palladium, silver, gold, platinum) sample can be observed, and the diffraction peaks at 2θ angles of 31.8, 34.5, 36.3, 56.7 and 63.1 appear obviously, which correspond to the (100), (002), (101), (110) and (103) crystal planes of hexagonal zinc oxide. It is worth noting that in the zinc oxide loaded with silver sample, the diffraction peaks at 2θ angles of 38.1 and 44.3 appear obviously, which correspond to the (111) and (200) crystal planes of face-centered cubic silver. This indicates that the sample not only contains hexagonal zinc oxide, but also contains a high content of silver, and the existence of silver and its high content is clearly shown in the XRD pattern. And the sharp peak shape indicates that the product has complete crystallization; The above-mentioned gas sensitive application of the zinc oxide nanomaterial of the application, the zinc oxide loaded with noble metals (palladium, silver, gold, platinum) gas sensitive material is dispersed in a small amount of ethanol, then is dropped and coated on the surface of a plane electrode by a pipette gun, is naturally dried, is further constructed into a gas sensor, is aged on an aging table for one day, and then is subjected to gas sensitive detection; the four zinc oxide loaded with noble metals (palladium, silver, gold, platinum) sensors are respectively subjected to gas sensitive test on linalool, geraniol, n-octanol and linalool at respective optimal working temperatures; (3) As shown in Figures 3-6As shown in the figure, the dynamic response curve of the sensor prepared based on the zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive material to different concentrations (1 to 10 ppm) of leaf alcohol, geraniol, n-octanol and linalool at the optimum working temperature under the humidity of 70%. It can be seen from the figure that the response value of the sensor based on the zinc oxide loaded palladium gas sensitive material is 122 under the concentration of 10 ppm of leaf alcohol, the response value of the sensor based on the zinc oxide loaded silver gas sensitive material is 456 under the concentration of 10 ppm of geraniol, the response value of the zinc oxide loaded gold gas sensitive material is 172 under the concentration of 10 ppm of n-octanol, and the response value of the sensor based on the zinc oxide loaded platinum gas sensitive material is 80 under the concentration of 10 ppm of linalool. In addition, the sensitivity of the zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive sensor increases with the increase of the corresponding gas concentration, indicating that the four prepared sensors have good reversibility. As can be seen from the above, the zinc oxide loaded noble metal (palladium, silver, gold, platinum) gas sensitive material has excellent gas sensitive performance at the optimum working temperature.

[0046] The above describes one embodiment of the present application in detail, but the content described is only the preferred embodiment of the present application and cannot be considered as limiting the implementation scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the patent coverage scope of the present application.

Claims

1. A method for constructing a precious metal-sensitized volatile aroma substance sensor, characterized in that, Includes the following steps: Step A: Dissolve zinc acetate dihydrate, urea, and trisodium citrate dihydrate in deionized water to obtain a mixed precursor solution; control the hydrothermal reaction of the precursor solution for 6 h; Step B: After naturally cooling to room temperature, wash, centrifuge, and dry the suspension obtained from the reaction. A zinc hydroxide precursor was obtained; the zinc hydroxide precursor was calcined in air at 350°C for 2 h to obtain zinc oxide material. Step C: Impregnate the zinc oxide material with deionized water, add ammonium carbonate solution while stirring, then add noble metal solution to obtain a mixed solution of zinc oxide modified with noble metal. Centrifuge the sample, pour out the supernatant, and dry the precipitate. Step D: The dried sample was calcined at 500°C for 1 h in a mixed atmosphere of hydrogen and argon to obtain powdered zinc oxide loaded with noble metal materials. Step E: Dissolve zinc oxide-loaded noble metal material in ethanol, sonicate to form a suspension, and then drop it onto the surface of a planar electrode to construct a semiconductor sensor for detecting tea aroma.

2. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, In step A, the mass ratio of zinc acetate dihydrate, urea, and trisodium citrate dihydrate is 0.443:0.2:0.

059.

3. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, In step B, the centrifuge is washed 3 times, with a centrifugation speed of 6000-9000 rpm and a centrifugation time of 5-8 min.

4. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, In step B, the drying temperature is 60-80 ℃ and the drying time is 6-24 h.

5. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, In step B, the heating rate during calcination is 10 °C·min. -1 .

6. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, Noble metal solutions include aqueous solutions of palladium chloride, silver chloride, chloroauric acid, and potassium chloroplatinate.

7. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, The concentrations of palladium chloride aqueous solution, silver chloride aqueous solution, chloroauric acid aqueous solution, and potassium chloroplatinate solution were 10 mg·mL. -1 10 mg·mL -1 2 mg·mL -1 2 mg·mL -1 .

8. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, In step D, the heating rate during calcination is 10 °C·min. -1 .

9. The method for constructing a precious metal-sensitized volatile aroma substance sensor according to claim 1, characterized in that, Zinc oxide-loaded precious metal gas-sensitive materials include zinc oxide-loaded palladium, zinc oxide-loaded silver, zinc oxide-loaded gold, and zinc oxide-loaded platinum. The morphology of zinc oxide-loaded precious metal materials is granular and flake-like, with a particle size of 50 nm.

10. A method for detecting volatile aroma substances using a precious metal-sensitized sensor, characterized in that, The zinc oxide-loaded noble metal gas-sensitive material prepared by the method according to any one of claims 1-9 is dispersed in anhydrous ethanol, then drop-coated onto the surface of a planar electrode by a pipette, naturally dried, and then assembled into a gas sensor, which is further used for gas-sensitive testing of tea aromas of geraniol, n-octanol, and linalool.

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