Organic phosphoric acid molecule modified tungsten oxide ammonia gas sensor as well as preparation method and application thereof

Abstract

The invention provides an organic phosphoric acid molecule modified tungsten oxide ammonia gas sensor as well as a preparation method and application thereof, and belongs to the field of nanostructure materials and ammonia gas detection. According to the invention, the catalytic decomposition capability of organic phosphoric acid molecules on ammonia gas is utilized, so that the adsorption and catalytic oxidation of ammonia gas molecules on the surface of tungsten trioxide are promoted, and the sensitivity and selectivity of tungsten trioxide on ammonia gas are enhanced; on the other hand, phosphorus-oxygen groups in organic phosphoric acid molecules can be bonded with Lewis reaction active sites (uncoordinated W < 6 + >) on the surface of tungsten trioxide in a covalent form, so that the surface activity of tungsten trioxide is protected, and the service life of the sensor is prolonged. The result of the embodiment shows that the sensitivity of the prepared organic phosphoric acid molecule modified tungsten oxide ammonia gas sensor to ammonia gas is remarkably improved, the organic phosphoric acid molecule modified tungsten oxide ammonia gas sensor has good selectivity to ammonia gas, the performance is not obviously attenuated after 5-month test, and the service life is long.

Description

Technical Field

[0001] The invention relates to the field of nanostructured materials and ammonia detection, and in particular to an organic phosphoric acid molecule modified tungsten oxide ammonia sensor and a preparation method and application thereof. Background Art

[0002] Ammonia is a colorless gas with a pungent odor. It is mainly emitted from agricultural activities, industrial activities, and residential activities. After being inhaled by the human body, it will enter the blood through the alveoli and combine with hemoglobin to destroy the oxygen transport function. Short-term inhalation of ammonia will cause symptoms such as tearing, sore throat, and difficulty breathing. In severe cases, it may cause various respiratory diseases. The maximum allowable concentration of ammonia in indoor air is 0.2mg / m 3 (i.e. 0.2635ppm), while the lowest concentration that the human body can sense is 5.3ppm. Therefore, a highly sensitive ammonia sensor is needed to monitor the ammonia concentration in the air and protect the health of participants.

[0003] Tungsten trioxide is a commonly used gas-sensitive sensing material that is easy to synthesize and has good stability. However, pure tungsten trioxide is not sensitive enough to ammonia and cannot detect low concentrations of ammonia. It responds to a variety of gases and has poor selectivity for ammonia, making it unable to meet the needs of accurately detecting low concentrations of ammonia.

[0004] Therefore, how to improve the sensitivity and selectivity of tungsten trioxide to ammonia and reduce the response of tungsten trioxide to other gases has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The purpose of the present invention is to provide an organophosphate molecule modified tungsten oxide ammonia sensor and a preparation method and application thereof. The organophosphate molecule modified tungsten oxide ammonia sensor prepared by the present invention has significantly increased sensitivity to ammonia and has good selectivity for ammonia. After 5 months of testing, the performance has no obvious attenuation and has a long service life.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing an organophosphate molecule-modified tungsten oxide ammonia sensor, comprising the following steps:

[0008] (1) Mixing organic phosphoric acid, anhydrous ethanol and tungsten trioxide powder to grow organic phosphoric acid molecules to obtain a tungsten trioxide dispersion containing organic phosphoric acid molecules;

[0009] (2) The tungsten trioxide dispersion liquid with grown organic phosphoric acid molecules obtained in step (1) is sequentially coated and dried on the electrode of the sensor to obtain an organic phosphoric acid molecule-modified tungsten oxide ammonia sensor.

[0010] Preferably, the organic phosphoric acid in step (1) includes any one of methyl phosphoric acid, phenyl phosphoric acid and n-dodecyl phosphoric acid.

[0011] Preferably, the organic phosphoric acid in step (1) is methyl phosphoric acid.

[0012] Preferably, the method for preparing tungsten trioxide powder in step (1) comprises the following steps:

[0013] 1) Mix tungsten powder, hydrogen peroxide solution and water to obtain tungstic acid solution;

[0014] 2) The tungstic acid solution, oxalic acid dihydrate, sodium methane sulfonate and sodium hydroxide solution obtained in step 1) are mixed and decomposed to obtain tungsten trioxide powder.

[0015] Preferably, in step 1), the mass ratio of tungsten powder, hydrogen peroxide solution and water is (1-10):(20-40):70.

[0016] Preferably, in the step 2), the mass ratio of tungstic acid solution, oxalic acid dihydrate and sodium methane sulfonate is 10:(0.5-1):(0.5-1).

[0017] Preferably, in step (1), the ratio of the amount of the organic phosphoric acid, the volume of anhydrous ethanol and the mass of the tungsten trioxide powder is (0.1-0.5) mmol:10 mL:(0.05-0.5) g.

[0018] Preferably, in step (1), the temperature for the growth of the organic phosphoric acid molecules is room temperature, and the growth time of the organic phosphoric acid molecules is 18 to 36 hours.

[0019] The present invention provides an organic phosphoric acid molecule-modified tungsten oxide ammonia sensor prepared by the preparation method described in the above technical solution.

[0020] The present invention provides the application of the organophosphate molecule modified tungsten oxide ammonia sensor described in the above technical solution in ammonia detection.

[0021] The present invention provides a method for preparing an organic phosphoric acid molecule modified tungsten oxide ammonia sensor, comprising the following steps: (1) mixing organic phosphoric acid, anhydrous ethanol and tungsten trioxide powder to grow organic phosphoric acid molecules to obtain a tungsten trioxide dispersion liquid with grown organic phosphoric acid molecules; (2) sequentially coating and drying the tungsten trioxide dispersion liquid with grown organic phosphoric acid molecules obtained in step (1) on the electrodes of the sensor to obtain an organic phosphoric acid molecule modified tungsten oxide ammonia sensor. The present invention utilizes the ability of organic phosphoric acid molecules to catalytically decompose ammonia to promote the adsorption and catalytic oxidation of ammonia molecules on the surface of tungsten trioxide, thereby enhancing the sensitivity and selectivity of tungsten trioxide to ammonia; on the other hand, the phosphorus oxygen groups in the organic phosphoric acid molecules can react with the Lewis reaction active sites (uncoordinated W 6+ ) can protect the surface activity of tungsten trioxide through covalent bonding, and increase the service life of the sensor. The results of the embodiment show that the organophosphate molecule modified tungsten oxide ammonia sensor prepared by the present invention has significantly increased sensitivity to ammonia and has good selectivity for ammonia. After 5 months of testing, the performance has not been significantly attenuated and has a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A top view of the structure of the sensor used in the present invention;

[0023] Figure 1 In the figure, 1 is the lead, 2 is the electrode, 3 is the sensitive material, and 4 is the substrate;

[0024] Figure 2 A structural side view of the sensor used in the present invention;

[0025] Figure 2 In the figure, 1 is the lead, 2 is the electrode, 3 is the sensitive material, and 4 is the substrate;

[0026] Figure 3 This is a SEM image of the tungsten trioxide powder prepared in Example 1 of the present invention;

[0027] Figure 4 Gas-sensing performance curves of the tungsten oxide ammonia gas sensors provided in Examples 1 to 3 of the present invention and Comparative Example 1;

[0028] Figure 5 The gas-sensing performance of the organophosphate molecule-modified tungsten oxide ammonia sensor provided in Example 1 of the present invention at 20 ppb to 100 ppm ammonia at 200° C.;

[0029] Figure 6 A comparison chart of the responses of the organophosphate molecule-modified tungsten oxide ammonia sensor provided in Example 1 of the present invention to different gases with a concentration of 100 ppm at 200° C.;

[0030] Figure 7 The response results of the organophosphate molecule-modified tungsten oxide ammonia sensor provided in Example 1 of the present invention to 100 ppm ammonia at 200° C. within 5 months. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing an organophosphate molecule-modified tungsten oxide ammonia sensor, comprising the following steps:

[0032] (1) Mixing organic phosphoric acid, anhydrous ethanol and tungsten trioxide powder to grow organic phosphoric acid molecules to obtain a tungsten trioxide dispersion containing organic phosphoric acid molecules;

[0033] (2) The tungsten trioxide dispersion liquid with grown organic phosphoric acid molecules obtained in step (1) is sequentially coated and dried on the electrode of the sensor to obtain an organic phosphoric acid molecule-modified tungsten oxide ammonia sensor.

[0034] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art.

[0035] The invention mixes organic phosphoric acid, anhydrous ethanol and tungsten trioxide powder, and then grows organic phosphoric acid molecules to obtain a tungsten trioxide dispersion liquid with grown organic phosphoric acid molecules.

[0036] In the present invention, the organic phosphoric acid preferably includes any one of methyl phosphoric acid, phenyl phosphoric acid and n-dodecyl phosphoric acid, and more preferably methyl phosphoric acid. The present invention selects the above organic phosphoric acid to modify tungsten trioxide, thereby improving its sensitivity and selectivity to ammonia and reducing the response of tungsten trioxide to other gases.

[0037] In the present invention, the structure of the tungsten trioxide powder is preferably a nanowire structure. The present invention uses tungsten trioxide with a nanowire structure as a raw material, which has a high specific surface area and can provide more adsorption sites for gas.

[0038] In the present invention, the method for preparing the tungsten trioxide powder preferably comprises the following steps:

[0039] 1) Mix tungsten powder, hydrogen peroxide solution and water to obtain tungstic acid solution;

[0040] 2) The tungstic acid solution, oxalic acid dihydrate, sodium methane sulfonate and sodium hydroxide solution obtained in step 1) are mixed and decomposed to obtain tungsten trioxide powder.

[0041] In the present invention, tungsten powder, hydrogen peroxide solution and water are preferably mixed to obtain a tungstic acid solution.

[0042] The present invention has no particular limitation on the particle size of the tungsten powder, and commercially available tungsten powder well known to those skilled in the art may be used.

[0043] In the present invention, the mass concentration of the hydrogen peroxide solution is preferably 20-30%. As an embodiment of the present invention, the mass concentration of the hydrogen peroxide solution can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%. The present invention can better react with tungsten powder by controlling the mass concentration of the hydrogen peroxide solution.

[0044] In the present invention, the tungsten powder, hydrogen peroxide solution and water are preferably mixed in a manner of first mixing the tungsten powder and hydrogen peroxide solution and then adding water.

[0045] In the present invention, the mass ratio of the tungsten powder, hydrogen peroxide solution and water is preferably (1-10): (20-40): 70, more preferably (2-8): 30: 70, and further preferably (4-6): 30: 70. The present invention can ensure complete reaction and obtain a tungstic acid solution of a desired concentration by controlling the amount of each component.

[0046] After obtaining the tungstic acid solution, the present invention preferably mixes the tungstic acid solution, oxalic acid dihydrate, sodium methane sulfonate and sodium hydroxide solution and then performs a decomposition reaction to obtain tungsten trioxide powder.

[0047] In the present invention, the tungstic acid solution, oxalic acid dihydrate, sodium methane sulfonate and sodium hydroxide solution are preferably mixed by adding oxalic acid dihydrate and sodium methane sulfonate to the tungstic acid solution, and then dropping the sodium hydroxide solution.

[0048] In the present invention, the mass ratio of the tungstic acid solution, oxalic acid dihydrate and sodium methane sulfonate is preferably 10: (0.5-1): (0.5-1), more preferably 10: (0.6-0.9): (0.6-0.9), and further preferably 10: (0.7-0.8): (0.7-0.8). As an embodiment of the present invention, the mass ratio of the tungstic acid solution, oxalic acid dihydrate and sodium methane sulfonate can also be 10: 0.7875: 0.708.

[0049] In the present invention, the mass concentration of the sodium hydroxide solution is preferably 10%. The present invention has no special restrictions on the amount and dripping rate of the sodium hydroxide solution, as long as the pH value of the mixed system meets the requirements.

[0050] In the present invention, the pH value of the system after the tungstic acid solution, oxalic acid dihydrate, sodium methane sulfonate and sodium hydroxide solution are mixed is preferably 1 to 2, more preferably 1.5 to 1.88. The present invention controls the pH value of the system to facilitate the subsequent reaction to obtain the desired tungsten trioxide.

[0051] In the present invention, the temperature of the decomposition reaction is preferably 180-250°C; the time of the decomposition reaction is preferably 18-36h; the decomposition reaction is preferably carried out in a muffle furnace. As an embodiment of the present invention, the temperature of the decomposition reaction can be 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C; the time of the decomposition reaction can be 18h, 21h, 24h, 27h, 30h, 33h or 36h. The present invention can convert tungstic acid into tungsten trioxide powder with a nanowire structure by controlling the parameters of the decomposition reaction.

[0052] After the decomposition reaction is completed, the product of the decomposition reaction is preferably filtered and washed in sequence. The specific operation of the filtering and washing is not particularly limited in the present invention, as long as the solid-liquid separation and the removal of impurities in the tungsten trioxide powder can be achieved. As an embodiment of the present invention, the detergent used in the washing is preferably ultrapure water; the number of washing times can be 4 times, 5 times or 6 times.

[0053] In the present invention, the method of mixing the organic phosphoric acid, anhydrous ethanol and tungsten trioxide powder is preferably to mix the organic phosphoric acid and anhydrous ethanol and then add the tungsten trioxide powder.

[0054] In the present invention, the ratio of the amount of the organic phosphoric acid, the volume of anhydrous ethanol and the mass of tungsten trioxide powder is preferably (0.1-0.5) mmol: 10 mL: (0.05-0.5) g, and more preferably (0.2-0.3) mmol: 10 mL: (0.1-0.15) g. The present invention can control the modification of tungsten trioxide by organic phosphoric acid by controlling the amount of each component, thereby further improving its sensitivity and selectivity to ammonia and reducing the response of tungsten trioxide to other gases.

[0055] In the present invention, the temperature for the growth of the organophosphate molecules is preferably room temperature; the growth time of the organophosphate molecules is preferably 18 to 36 hours. As an embodiment of the present invention, the growth time of the organophosphate molecules can be 18 hours, 21 hours, 24 hours, 27 hours, 30 hours, 33 hours or 36 hours. The present invention can fully modify tungsten trioxide with organophosphate by controlling the parameters of the growth of organophosphate molecules.

[0056] After obtaining the tungsten trioxide dispersion liquid for growing organic phosphoric acid molecules, the present invention sequentially applies and dries the tungsten trioxide dispersion liquid for growing organic phosphoric acid molecules on the electrodes of the sensor to obtain the organic phosphoric acid molecule modified tungsten oxide ammonia sensor.

[0057] In the present invention, the coating amount of the tungsten trioxide dispersion liquid for growing organic phosphoric acid molecules is preferably 50 to 150 μL. As an embodiment of the present invention, the coating amount of the tungsten trioxide dispersion liquid for growing organic phosphoric acid molecules can be 50 μL, 60 μL, 70 μL, 80 μL, 90 μL, 100 μL, 110 μL, 120 μL, 130 μL, 140 μL or 150 μL. The present invention can improve the detection accuracy of the sensor by controlling the coating amount of the tungsten trioxide dispersion liquid for growing organic phosphoric acid molecules.

[0058] In the present invention, the coating method is preferably drip coating. The present invention has no special limitation on the drip coating rate, which can be determined according to the technical common sense of those skilled in the art.

[0059] The present invention has no particular limitation on the drying temperature and time, which can be determined according to the technical common sense of those skilled in the art as long as the anhydrous ethanol can be completely volatilized.

[0060] The present invention utilizes the ability of organic phosphoric acid molecules to catalyze the decomposition of ammonia to promote the adsorption and catalytic oxidation of ammonia molecules on the surface of tungsten trioxide, thereby enhancing the sensitivity and selectivity of tungsten trioxide to ammonia. On the other hand, the phosphorus oxygen groups in the organic phosphoric acid molecules can react with the Lewis reaction active sites (uncoordinated W 6+ ) Protect the surface activity of tungsten trioxide by covalent bonding, increasing the service life of the sensor.

[0061] The present invention also provides an organic phosphoric acid molecule-modified tungsten oxide ammonia sensor prepared by the preparation method described in the above technical solution.

[0062] The present invention also provides the use of the organophosphate molecule modified tungsten oxide ammonia sensor described in the above technical solution in ammonia detection.

[0063] The present invention has no special limitation on the specific operation of the application, which can be determined according to the technical common sense of those skilled in the art.

[0064] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Example 1

[0066] A method for preparing an organophosphate molecule modified tungsten oxide ammonia sensor comprises the following steps:

[0067] (1) Mixing organic phosphoric acid and anhydrous ethanol, then adding tungsten trioxide powder, and then standing at room temperature for 24 hours to grow organic phosphoric acid molecules to obtain a tungsten trioxide dispersion with grown organic phosphoric acid molecules; the organic phosphoric acid is methyl phosphoric acid; the ratio of the amount of the organic phosphoric acid, the volume of anhydrous ethanol and the mass of the tungsten trioxide powder is 0.2mmol:10mL:0.1g;

[0068] (2) applying 100 μL of the tungsten trioxide dispersion liquid with organic phosphoric acid molecules obtained in step (1) to the electrode surface of the sensor, and after drying, obtaining an organic phosphoric acid molecule-modified tungsten oxide ammonia sensor;

[0069] The preparation method of the tungsten trioxide powder comprises the following steps:

[0070] 1) Firstly, tungsten powder and hydrogen peroxide solution are mixed, and then water is added to obtain tungstic acid solution; the mass concentration of the hydrogen peroxide solution is 25%; the mass ratio of the tungsten powder, hydrogen peroxide solution and water is 4:30:70;

[0071] 2) Add oxalic acid dihydrate and sodium methanesulfonate to the tungstic acid solution obtained in step 1), then drop a sodium hydroxide solution with a mass concentration of 10% to make the pH value of the system 1.88, then perform a decomposition reaction in a muffle furnace, and finally filter and wash with ultrapure water for 5 times in sequence to obtain a tungsten trioxide powder with a nanowire structure; the mass ratio of tungstic acid solution, oxalic acid dihydrate and sodium methanesulfonate is 10:0.7875:0.708; the mass concentration of the sodium hydroxide solution is 10%; the temperature of the decomposition reaction is 200°C, and the decomposition reaction time is 24h.

[0072] Example 2

[0073] In the step (1), the organic phosphoric acid is phenyl phosphoric acid, and other conditions are the same as those in Example 1.

[0074] Example 3

[0075] In step (1), the organic phosphoric acid is n-dodecyl phosphoric acid, and other conditions are the same as those in Example 1.

[0076] Comparative Example 1

[0077] A method for preparing a tungsten oxide ammonia sensor comprises the following steps:

[0078] (1) Mix tungsten trioxide powder and anhydrous ethanol to obtain a tungsten trioxide dispersion; the volume ratio of the anhydrous ethanol to the mass ratio of the tungsten trioxide powder is 10 mL: 0.1 g;

[0079] (2) applying 100 μL of the tungsten trioxide dispersion obtained in step (1) to the electrode surface of the sensor, and obtaining a tungsten oxide ammonia sensor after drying;

[0080] The preparation method of the tungsten trioxide powder is the same as that of Example 1.

[0081] Figure 1 This is a top view of the structure of the sensor used in the present invention. Figure 2 This is a structural side view of the sensor used in the present invention. Figure 1 and Figure 2 In the figure, 1 is the lead, 2 is the electrode, 3 is the sensitive material, and 4 is the substrate. Figure 1 and Figure 2 It can be seen that ammonia can be detected by coating tungsten trioxide material modified with organic phosphoric acid molecules on the electrode.

[0082] Figure 3 This is a SEM image of the tungsten trioxide powder prepared in Example 1 of the present invention. Figure 1 It can be seen that the tungsten trioxide powder prepared by the present invention is a nanowire structure, has a high specific surface area, and can provide more adsorption sites for gas.

[0083] Figure 4 The gas-sensing performance curves of the tungsten oxide ammonia sensor provided in Examples 1 to 3 of the present invention and Comparative Example 1 are shown in FIG. Figure 4 It can be seen that when the test temperature is 200°C and the ammonia concentration is 100ppm, the sensitivity of the ammonia sensor modified with tungsten trioxide for growing organic phosphoric acid molecules provided by the present invention is significantly higher than that of tungsten oxide, among which, when the organic phosphoric acid is methyl phosphoric acid, the gas-sensing performance is the best.

[0084] Figure 5 The gas sensing performance of the organophosphate molecule modified tungsten oxide ammonia sensor provided in Example 1 of the present invention at 20 ppb to 100 ppm ammonia at 200°C. Figure 5 It can be seen that although the response time of the organophosphate modified tungsten oxide ammonia sensor will gradually increase with the decrease of ammonia concentration, when the ammonia concentration is ≥20ppb, it still maintains a relatively fast response time, indicating that the organophosphate modified tungsten oxide ammonia sensor provided by the present invention has a high response sensitivity to ammonia.

[0085] Figure 6 This is a comparison chart of the responses of the organophosphate molecule modified tungsten oxide ammonia sensor provided in Example 1 of the present invention to different gases with a concentration of 100 ppm at 200°C. Figure 6It can be seen that the response effect of the organophosphate molecule modified tungsten oxide ammonia sensor provided by the present invention to ammonia is far greater than that of other gases, indicating that the organophosphate molecule modified tungsten oxide ammonia sensor prepared by the present invention has high selectivity for ammonia.

[0086] Figure 7 The response results of the organophosphate molecule modified tungsten oxide ammonia sensor provided in Example 1 of the present invention to 100 ppm ammonia at 200°C within 5 months. Figure 7 It can be seen that the response of the organophosphate molecule modified tungsten oxide ammonia sensor provided by the present invention did not decay within 5 months.

[0087] From the above analysis, it can be seen that the organophosphate molecule modified tungsten oxide ammonia sensor prepared by the present invention has significantly increased sensitivity to ammonia and has good selectivity for ammonia. After 5 months of testing, the performance has not been significantly attenuated and the service life is long.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an organophosphate molecule-modified tungsten oxide ammonia sensor, comprising the following steps: (1) Mixing organic phosphoric acid, anhydrous ethanol and tungsten trioxide powder to grow organic phosphoric acid molecules to obtain a tungsten trioxide dispersion containing organic phosphoric acid molecules; (2) The tungsten trioxide dispersion liquid with grown organic phosphoric acid molecules obtained in step (1) is sequentially coated and dried on the electrode of the sensor to obtain an organic phosphoric acid molecule-modified tungsten oxide ammonia sensor.

2. The preparation method according to claim 1, characterized in that: The organic phosphoric acid in step (1) includes any one of methyl phosphoric acid, phenyl phosphoric acid and n-dodecyl phosphoric acid.

3. The preparation method according to claim 1 or 2, characterized in that: In the step (1), the organic phosphoric acid is methyl phosphoric acid.

4. The preparation method according to claim 1, characterized in that: The method for preparing tungsten trioxide powder in step (1) comprises the following steps: 1) Mix tungsten powder, hydrogen peroxide solution and water to obtain tungstic acid solution; 2) The tungstic acid solution, oxalic acid dihydrate, sodium methane sulfonate and sodium hydroxide solution obtained in step 1) are mixed and decomposed to obtain tungsten trioxide powder.

5. The preparation method according to claim 4, characterized in that: In the step 1), the mass ratio of tungsten powder, hydrogen peroxide solution and water is (1-10):(20-40):

70.

6. The preparation method according to claim 4, characterized in that: In the step 2), the mass ratio of tungstic acid solution, oxalic acid dihydrate and sodium methane sulfonate is 10:(0.5-1):(0.5-1).

7. The preparation method according to claim 1, characterized in that: In the step (1), the ratio of the amount of the organic phosphoric acid, the volume of anhydrous ethanol and the mass of the tungsten trioxide powder is (0.1-0.5) mmol:10 mL:(0.05-0.5) g.

8. The preparation method according to claim 1, characterized in that: The temperature for the growth of the organic phosphoric acid molecules in step (1) is room temperature, and the growth time of the organic phosphoric acid molecules is 18 to 36 hours.

9. An organic phosphoric acid molecule-modified tungsten oxide ammonia sensor prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the organophosphate molecule modified tungsten oxide ammonia sensor according to claim 9 in ammonia detection.

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