Ferric vanadate gas sensor and preparation method thereof
By modulating the nanostructure of iron vanadate using a solvothermal method, a gas sensor with high specific surface area and active sites was prepared, solving the problems of high energy consumption and insufficient material selectivity in traditional gas sensors, and achieving gas detection effects with high sensitivity and fast response at low temperature.
Patent Information
- Application Number
- CN202511214424.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2025-10-31
AI Technical Summary
Existing gas sensors consume a lot of energy when operating at high temperatures, have insufficient material selectivity and stability, and high cost and difficulty in uniformity control due to the doping of precious metals, making it difficult to meet the application requirements of fast response and high precision.
A solvothermal method was used to combine polyvinylpyrrolidone, hexadecyltrimethylammonium bromide and hydrazine hydrate to regulate the nanostructure of iron vanadate and prepare an iron vanadate gas sensor. By combining vanadium source, iron source, template agent and reducing agent, a nanomaterial with high specific surface area and active sites was formed. The crystallinity was enhanced by heat treatment and coordination agent.
It achieves high-sensitivity gas detection at low temperatures, fast response and recovery time, good selectivity and stability, low sensor cost and simple equipment, and is suitable for complex gas environments.
Smart Images
Figure CN120870259A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor technology, specifically relating to an iron vanadate gas sensor and its preparation method. Background Technology
[0002] Reducing gases play an important role in industrial production and daily life, but they also pose potential risks and require high caution during use. For example, hydrogen has an extremely wide explosive limit range (4%-75% by volume concentration). Even a low-concentration leak, when mixed with air, can trigger a violent explosion with only a tiny ignition energy, posing a significant safety hazard in chemical storage and transportation, fuel cells, and other fields. Similarly, ethylene has wide applications as a plant growth regulator and industrial raw material, but long-term exposure can cause neurological disorders, and short-term exposure to high concentrations can lead to acute dizziness and respiratory depression. Furthermore, its strong reducing properties may induce a chain reaction of oxidation accidents. The hazards of CO are particularly insidious; its binding capacity to hemoglobin is 240 times that of oxygen, and exposure to a concentration of only 0.08% for 2 hours can be fatal. More importantly, long-term exposure to low concentrations can cause hypoxic damage to the myocardium, leading to irreversible cardiovascular disease.
[0003] Current gas monitoring technologies mainly revolve around two major systems: electrochemistry and optics. Electrochemical sensors generate current signals by detecting the redox reactions of gas molecules on the electrode surface, featuring rapid response but being susceptible to environmental temperature and humidity. Optical sensors utilize the characteristic spectral absorption properties of gas molecules, offering high selectivity but suffering from limitations such as complex equipment and high maintenance costs.
[0004] Metal-oxide-semiconductor (MOS) sensors dominate the market due to their simple fabrication and low cost. Their working principle is based on the resistance response caused by changes in the oxygen adsorption state on the surface of a gas-sensitive material. However, traditional tin oxide-based materials require operation at high temperatures of 280-350°C, which not only consumes a large amount of energy but also accelerates material aging. Furthermore, the selectivity and stability of MOS materials remain insufficient in complex gas environments, especially in applications requiring rapid response and high precision, such as battery thermal runaway monitoring, where the performance of existing materials struggles to meet practical needs.
[0005] Recent research has focused on developing novel composite oxides and nanostructure modulation techniques, aiming to overcome the performance bottleneck between operating temperature and sensitivity. Developing novel gas-sensitive materials with low operating temperatures, high sensitivity, and low cost has become an important research direction in the field of gas sensors. However, the synthesis methods for developing novel composite oxides or using nanostructure modulation are usually complex. Among these methods, metal doping significantly increases manufacturing costs due to the use of 1-3 wt% of precious metals, and controlling doping uniformity is difficult. These problems severely limit the application potential of gas sensors. Summary of the Invention
[0006] In view of this, the purpose of the present invention is to provide a ferric vanadate gas sensor and its preparation method to solve the above problems.
[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a ferric vanadate gas sensor, wherein the raw materials of the gas sensor are composed of a vanadium source, an iron source, a template agent, a reducing agent, and an auxiliary agent; the vanadium source is ammonium metavanadate or vanadium pentoxide, the iron source is ferric nitrate nonahydrate or ferrous sulfate, the template agent is polyvinylpyrrolidone or hexadecyltrimethylammonium bromide, the reducing agent is hydrazine hydrate, and the auxiliary agent is disodium ethylenediaminetetraacetate.
[0008] Furthermore, the vanadium source is ammonium metavanadate, the iron source is ferric nitrate nonahydrate, and the template agent is hexadecyltrimethylammonium bromide.
[0009] Furthermore, the mass ratio of the vanadium source to the iron source is 1:1; the mass ratio of the template agent, reducing agent, and auxiliary agent is 1:1:1.
[0010] Furthermore, it also includes a method for preparing an iron vanadate gas sensor, wherein the preparation steps are as follows: S1. Dissolve the vanadium source and iron source in deionized water, add the additives and stir until uniform; S2. Then add the template agent and reducing agent and continue stirring until homogeneous to obtain a mixed solution; S3. Place the mixed solution in a reaction vessel and hydrothermally heat it at 180°C for 3-12 hours; S4. After the reaction is complete, the product is naturally cooled to room temperature, washed with washing solution, and dried to obtain iron vanadate nanomaterials. S5. The dried iron vanadate nanomaterials are transferred to a muffle furnace to improve crystallinity, and then iron vanadate powder is obtained. S6. Take iron vanadate powder into a mortar, then add deionized water, and grind it in the mortar for 15-20 minutes until an oily and uniform slurry is formed. Then, apply it to the sensor surface with the gold interdigitated flat electrode, and then transfer the sensor to the aging stage for aging treatment to obtain the iron vanadate gas sensor.
[0011] Furthermore, in step S4, the washing solution is composed of deionized water and ethanol in a mass ratio of 1:1.
[0012] Furthermore, in step S5, after being transferred to a muffle furnace, the temperature is increased to 500°C at a rate of 5°C per minute and calcined for 2 hours.
[0013] Furthermore, in step S6, the aging process involves aging at 60°C for 48 hours.
[0014] The beneficial effects of this invention are as follows: 1. In this invention, the precise control of the nanostructure of iron vanadate is achieved by combining polyvinylpyrrolidone, hexadecyltrimethylammonium bromide and hydrazine hydrate via a solvothermal method. The prepared iron vanadate nanomaterials have high specific surface area and excellent crystallinity.
[0015] 2. The iron vanadate of the present invention has a unique crystal structure and abundant oxygen vacancies, which can adsorb gas molecules. Preparing it into a nanostructure can increase the specific surface area and the number of active sites, thereby improving the gas adsorption efficiency.
[0016] 3. In this invention, polyvinylpyrrolidone or hexadecyltrimethylammonium bromide is used as a template agent, and hydrazine hydrate is used as a reducing agent to regulate the nanostructure of iron vanadate and increase the specific surface area and the number of active sites; EDTA is used as a ligand to enhance the crystallinity and stability of the material.
[0017] 4. The gas sensor prepared by the present invention, when the target gas is adsorbed on the surface of iron vanadate, the gas molecules react chemically with oxygen vacancies or active sites, resulting in a change in the conductivity or resistance of the material. By detecting this change in electrical properties, high-sensitivity detection of the gas can be achieved.
[0018] 5. Due to the high specific surface area and active sites of the nanostructure, the gas sensor prepared by this invention has high sensitivity to low concentration gases; the sensor has a fast response and recovery time when detecting gases; by regulating oxygen vacancies and surface active sites, the sensor has good selectivity for specific gases; after heat treatment and with the assistance of a ligand, the material has good crystallinity and stability and can work in a wide temperature range.
[0019] 6. The gas sensor of the present invention is simple to prepare, low in cost and does not require complex equipment. It has a wide operating temperature range and good stability. Its gas response at low concentrations is close to 20%.
[0020] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description
[0021] To make the purpose, technical solution, and beneficial effects of the invention clearer, the following figures are provided for illustration: Figure 1 This is a morphology image of the iron vanadate powder of Example 1 of the present invention under an electron scanning microscope; Figure 2This is a comparison diagram of the X-ray diffraction pattern of the iron vanadate powder sample of Example 1 of the present invention and the FeVO4 standard card; Figure 3 The graph shows the working temperature test of the iron vanadate powder of Example 1 of the present invention under the condition of ethylene concentration of 100 ppm. Figure 4 This is a diagram illustrating the selectivity of ferric vanadate powder to different gases at 160°C and 100ppm in Example 1 of the present invention. Figure 5 This is a diagram illustrating the response of the iron vanadate powder of Example 1 of the present invention to 5ppm-1000ppm ethylene at 160°C. Detailed Implementation
[0022] like Figure 1-5 As shown, the present invention provides a method for preparing an iron vanadate gas sensor.
[0023] Example 1 S1. Dissolve 2 mmol ammonium metavanadate and 2 mmol ferric nitrate nonahydrate in 20 ml deionized water, add 0.5 g disodium ethylenediaminetetraacetate and stir well; S2. Then add 0.5g of cetyltrimethylammonium bromide and 0.5g of hydrazine hydrate and continue stirring until homogeneous to obtain a mixed solution; S3. Place the mixed solution in a reaction vessel and hydrothermally heat it at 180°C for 3 hours; S4. After the reaction is complete, the product is naturally cooled to room temperature, washed with deionized water and ethanol, and dried to obtain iron vanadate nanomaterials. S5. The dried iron vanadate nanomaterials are transferred to a muffle furnace and heated to 500°C at a rate of 5°C per minute and then calcined for 2 hours to improve crystallinity, thus obtaining iron vanadate powder. S6. Take iron vanadate powder into a mortar, then add 2-3 drops of deionized water, and grind it in the mortar for 15-20 minutes until an oily and uniform slurry is formed. Then, apply it to the surface of the sensor with the gold interdigitated flat electrode, and then transfer the sensor to the aging stage and age it at 60 ℃ for 48 hours to obtain the iron vanadate gas sensor.
[0024] Example 2 The difference between Example 2 and Example 1 is that in step S3, hydrothermal treatment is performed at 180°C for 6 hours, while the rest is the same as in Example 1.
[0025] Example 3 The difference between Example 3 and Example 1 is that in step S3, hydrothermal treatment is performed at 180°C for 12 hours, while the rest is the same as in Example 1.
[0026] Sensor testing: Using artificial air (21% O2, 79% N2) as the background gas, different types of target gases were selected for testing.
[0027] The sensor's response is defined as: Where R a R is the resistance value of the sensor in the background gas. g The resistance value of the sensor in a target gas at a specific concentration. The gas sensor prepared by the technology of this invention has excellent sensitivity to reducing gases. In an environment of 160°C and 100ppm, the responses to H2, CO, and C2H4 are 30%, 24%, and 42.5%, respectively. At the same time, compared with carbon dioxide and methane, the gas sensor of this invention has better selectivity.
[0028] like Figure 1 As shown, the gas sensor of Example 1 is made of a material that is needle-shaped with particles attached to its surface. The needle-shaped particles have a diameter of approximately 100 nm and a length between 1 and 10 μm, while the particle diameter is between 0 and 100 nm. The gas sensor forms a three-dimensional porous network, which significantly increases the specific surface area of the material, exposes more edge active sites, and provides a large number of adsorption and reaction sites for gas molecules. Furthermore, the synergistic effect of the one-dimensional pine needle-shaped structure and the surface particles can accelerate electron transport and reduce interfacial resistance, thereby improving the response sensitivity to low-concentration gases.
[0029] Figure 2 The X-ray diffraction pattern and FeVO4 standard card of the iron vanadate powder sample in Example 1 are shown. according to Figure 2 The results showed that the diffraction peaks of Example 1 corresponded to the diffraction peak positions of the iron vanadate standard card, confirming the crystal structure of the material in Example 1.
[0030] Figure 3 The optimal operating temperature of the iron vanadate powder sample in Example 1 was tested under the condition of ethylene concentration of 100 ppm. As shown in the figure, the iron vanadate powder in Example 1 has a relatively stable response in the temperature range of 120-160℃, and its operating temperature is significantly lower.
[0031] Figure 4 The figure shows the selectivity of the ferric vanadate powder of Example 1 to different gases at 160℃ and 100ppm. As can be seen from the figure, the selectivity of the ferric vanadate powder of Example 1 to strong reducing gases such as C2H4, H2, and CO is significantly higher than that to CO2 and CH4. The responses to H2, CO, and C2H4 at 100ppm are 30%, 24%, and 42.5%, respectively, with the response to ethylene being 10 times higher than that to CH4.
[0032] Figure 5 The figure shows the response of the iron vanadate powder of Example 1 to ethylene at 160°C in the range of 5 ppm to 1000 ppm. As can be seen from the figure, the iron vanadate powder of Example 1 can achieve a response of 19.1% to 5 ppm C2H4, and the response gradually increases with the increase of gas concentration.
[0033] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.
Claims
1. A ferric vanadate gas sensor, characterized in that: The gas sensor is composed of a vanadium source, an iron source, a template agent, a reducing agent, and an auxiliary agent. The vanadium source is ammonium metavanadate or vanadium pentoxide, the iron source is ferric nitrate nonahydrate or ferrous sulfate, the template agent is polyvinylpyrrolidone or hexadecyltrimethylammonium bromide, the reducing agent is hydrazine hydrate, and the auxiliary agent is disodium ethylenediaminetetraacetate.
2. The iron vanadate gas sensor according to claim 1, characterized in that: The vanadium source is ammonium metavanadate, the iron source is ferric nitrate nonahydrate, and the template agent is hexadecyltrimethylammonium bromide.
3. The iron vanadate gas sensor according to claim 1, characterized in that: The mass ratio of the vanadium source to the iron source is 1:1; the mass ratio of the template agent, reducing agent, and auxiliary agent is 1:1:
1.
4. A ferric vanadate gas sensor according to any one of claims 1-3, further comprising a method for preparing the ferric vanadate gas sensor, characterized in that: The preparation steps are as follows: S1. Dissolve the vanadium source and iron source in deionized water, add the additives and stir until uniform; S2. Then add the template agent and reducing agent and continue stirring until homogeneous to obtain a mixed solution; S3. Place the mixed solution in a reaction vessel and hydrothermally heat it at 180°C for 3-12 hours; S4. After the reaction is complete, the product is naturally cooled to room temperature, washed with washing solution, and dried to obtain iron vanadate nanomaterials. S5. The dried ferric vanadate nanomaterials are transferred to a muffle furnace to improve crystallinity, and then ferric vanadate powder is obtained. S6. Take iron vanadate powder into a mortar, then add deionized water, and grind it in the mortar for 15-20 minutes until an oily and uniform slurry is formed. Then, apply it to the sensor surface with the gold interdigitated flat electrode, and then transfer the sensor to the aging stage for aging treatment to obtain the iron vanadate gas sensor.
5. The method for preparing an iron vanadate gas sensor according to claim 4, characterized in that: In step S4, the washing solution is composed of deionized water and ethanol in a mass ratio of 1:
1.
6. The method for preparing an iron vanadate gas sensor according to claim 4, characterized in that: In step S5, after being transferred to a muffle furnace, the temperature is increased to 500°C at a rate of 5°C per minute and calcined for 2 hours.
7. The method for preparing an iron vanadate gas sensor according to claim 4, characterized in that: In step S6, the aging process involves aging at 60°C for 48 hours with electricity.