A zinc ferrite nanosheet carbon monoxide sensor material, a preparation method and application thereof
By preparing zinc ferrite nanosheet carbon monoxide sensor material, the high cost and high temperature problems of ZnO-based sensors were solved, achieving high sensitivity and low cost gas detection, and improving the selectivity and response speed of the sensor.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHONGQING INNOVATION CENTER OF BEIJING INSTITUTE OF TECHNOLOGY
- Filing Date
- 2023-05-29
- Publication Date
- 2026-06-26
Smart Images
Figure CN116858894B_ABST
Abstract
Description
1.1.1 Technical Field
[0002] This invention relates to the field of gas sensor technology, and in particular to a zinc ferrite nanosheet carbon monoxide sensor material, its preparation method, and its application. 1.1.2 Background Technology
[0004] Carbon monoxide is one of the most dangerous toxic gases in human life. When the concentration of carbon monoxide reaches 667 ppm, it can convert about half of the hemoglobin in a human body into carboxyhemoglobin. At a concentration as high as 800 ppm, a healthy adult will experience dizziness, nausea, and convulsions within 45 minutes, and death within 2-3 hours. Moreover, incomplete combustion of carbon-containing substances in our surroundings, such as industrial coal and oil combustion, transportation, and household activities, constantly increases carbon monoxide emissions. Therefore, detecting carbon monoxide in daily life is extremely important.
[0005] Currently, the most commonly used carbon monoxide sensors include electrochemical, thermally conductive, and semiconductor types. Thermally conductive sensors suffer from low sensitivity and poor selectivity. Electrochemical carbon monoxide sensors are the most widely used, offering high sensitivity and fast response, but electrolyte leakage during use can affect their lifespan, and they are relatively expensive. Semiconductor sensors are gaining increasing attention due to their good stability, simple structure, and low cost. ZnO, as a typical n-type semiconductor, is an ideal material for manufacturing gas sensors, with a bandgap energy reaching 3.37 eV and excellent electron mobility. However, pure ZnO gas sensors typically operate at 300–500℃ and suffer from poor selectivity and long response / recovery times.
[0006] To further improve the sensing performance of ZnO gas sensors and reduce their operating temperature, methods such as surface modification, doping, and composite with semiconductors and conductive polymers are generally employed. For example, Chinese invention patent application CN115748247A discloses a method for preparing Pd cluster-modified ZnO nanomaterials, along with its products and applications. This method prepares Zn nanofibers via electrospinning, followed by a hydrothermal reaction in a methanol solution of 2-methylimidazole, forming numerous nanoscale pores on the surface to filter hydrogen. Pd modification within the pores enhances the material's catalytic reaction with hydrogen. The combined effect of these two factors enables highly sensitive detection of hydrogen. While this method improves detection sensitivity, its drawback is also significant: the high cost associated with noble metal doping. Meanwhile, Guo Weiwei et al. prepared a ZnO-based gas sensor (Guo,Weiwei. Design of Gas Sensor Based on Fe-Doped ZnO Nanosheet-Spheres for Low Concentration of Formaldehyde Detection[J]. Journal of the Electrochemical Society, 2016, 163(9):B517-B525.), which can be used to detect formaldehyde, but its drawbacks are that the operating temperature is high and the sensitivity is poor.
[0007] In conclusion, the current ZnO-based gas sensors still require significant improvement. 1.1.3 Summary of the Invention
[0009] To address the aforementioned technical problems, the present invention aims to provide a zinc ferrite nanosheet carbon monoxide sensor material, its preparation method, and its application. This zinc ferrite nanosheet carbon monoxide sensor material avoids the high cost problem caused by precious metal doping, while reducing the sensor's operating temperature. Furthermore, it has low preparation cost, is easy to operate, and is suitable for industrial applications.
[0010] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:
[0011] First, the present invention provides a zinc ferrite nanosheet carbon monoxide sensor material, which is composed of zinc ferrite nanosheets. The surface of the zinc ferrite nanosheets has rough, loose and porous surface characteristics. The zinc ferrite nanosheets are uniformly stacked together, and the diameter of the zinc ferrite nanosheets is 30 to 100 nm. Preferably, the diameter of the zinc ferrite nanosheets is 40 to 60 nm.
[0012] Secondly, the present invention also provides a method for preparing the above-mentioned zinc ferrite nanosheet carbon monoxide sensor material, comprising the following steps:
[0013] S1: Dissolve zinc salt and iron salt in an alcohol solution at a certain molar ratio, and mix them evenly by ultrasonic or mechanical stirring.
[0014] S2: Add NaOH aqueous solution dropwise according to the amount of zinc salt and iron salt added, stir the reaction for 20 to 70 minutes to form a hydrothermal reaction system;
[0015] S3: After the reaction is complete, the above hydrothermal reaction system is transferred to an autoclave for hydrothermal reaction at a temperature of 130-160°C for 1-20 hours. After the reaction, the system is cooled to room temperature, filtered to obtain precipitate, and the precipitate is washed and dried.
[0016] S4: The dried precipitate is activated at 300-500°C for 2-6 hours and then cooled to room temperature to obtain the sensor material. Preferably, the activation temperature is 450°C.
[0017] Preferably, the zinc salt is any one or more of zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate.
[0018] Preferably, the iron salt is any one or more of ferric sulfate, ferric chloride, and ferric nitrate.
[0019] Preferably, the molar ratio of the iron salt to the zinc salt is 4 to 6%.
[0020] Preferably, the molar amount of NaOH is the sum of twice the molar amount of zinc salt and three times the molar amount of iron salt.
[0021] Thirdly, the present invention also provides an application of the above-mentioned zinc ferrite nanosheet carbon monoxide sensor material in the preparation of gas sensors.
[0022] Preferably, the gas sensor is prepared according to the following method:
[0023] A substrate material is provided, the sensor material is mixed with a solvent and ground into a liquid slurry, the liquid slurry is coated on at least one side of the substrate material, and then the solvent is evaporated to prepare the gas sensor.
[0024] Furthermore, the substrate material is any one of silicon substrate material, organic polymer substrate material, metal substrate material or graphite substrate material, and preferably a metal substrate material.
[0025] Furthermore, the solvent is either deionized water or an alcohol solution, preferably deionized water.
[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0027] This invention provides a zinc ferrite nanosheet carbon monoxide sensor material that avoids the high cost associated with precious metal doping while simultaneously reducing the sensor's operating temperature. By doping this sensor material with Fe ions, the gas-sensing performance and anti-interference capabilities of the sensor are effectively improved, while the operating temperature is significantly reduced. Furthermore, its preparation method is simple, involving only a one-step hydrothermal synthesis of zinc ferrite nanomaterials. The raw materials are readily available, inexpensive, and easy to operate. 1.1.4 Description of the attached figures
[0029] Figure 1 SEM images of test samples I-III and control sample II provided for the test examples of this invention;
[0030] Figure 2 This is the CO2 resistance response diagram of test sample II provided in the test examples of this invention;
[0031] Figure 3 This is the C2H4 resistance response diagram of test sample II provided in the test examples of this invention;
[0032] Figure 4 This is the CH4 resistance response diagram of test sample II provided in the test examples of this invention;
[0033] Figure 5 This is the H2 resistance response diagram of test sample II provided in the test examples of this invention;
[0034] Figure 6 This is the CO resistance response diagram of test sample II provided in the test examples of this invention;
[0035] Figure 7 This is a comparison chart of the anti-interference of five gases in test sample III provided in the test examples of this invention;
[0036] Figure 8 This is a comparison chart of the responses of gas sensors to CO under different doping levels and preparation conditions. 1.1.5 Detailed Implementation
[0038] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.
[0039] The specific embodiments listed in this invention are merely examples, and the invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of this invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of this invention should be covered within its scope.
[0040] Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments without a specified manufacturer are commercially available, conventional products. Numerous specific details are provided in the following detailed embodiments to better illustrate the invention. Those skilled in the art should understand that the invention can be practiced even without certain specific details. In other embodiments, methods, means, equipment, and steps well-known to those skilled in the art are not described in detail in order to highlight the spirit of the invention.
[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Unless otherwise specified, all units used in this specification are International Standard Units (SI), and all numerical values and ranges appearing in this invention should be understood to include systematic errors unavoidable in industrial production.
[0042] Example 1
[0043] This embodiment provides a zinc ferrite nanosheet carbon monoxide sensor material and its preparation method. Specifically, the zinc ferrite nanosheet carbon monoxide sensor material uses iron instead of noble metals as dopant in a ZnO sensor to achieve high-sensitivity detection of carbon monoxide. The preparation method of the zinc ferrite nanosheet carbon monoxide sensor material is as follows:
[0044] Using (CH3COO)2Zn and FeCl3·6H2O as raw materials, 1.8348 g of (CH3COO)2Zn and 0.13515 g of Fe (molar doping of 5%) were weighed and dissolved in a mixed solution of 10 ml deionized water and 10 ml anhydrous ethanol, and sonicated for 50 min. 1.4 g of NaOH was weighed and dissolved in 10 ml deionized water. The mixed solution was transferred to a magnetic stirrer, and NaOH solution was added dropwise at a uniform rate of 1 drop / s. After stirring for 30 min until the precipitation reaction was complete, the precipitate solution was transferred to a 50 ml autoclave for hydrothermal treatment at 150℃ for 10 h. After naturally cooling to room temperature, the solution was washed 3–5 times alternately by centrifugation with anhydrous ethanol and deionized water until neutral. It was then dried in a forced-air drying oven at 60℃ and ground into powder.
[0045] The composite material was ground with deionized water for about 15 minutes, then coated onto the hexagonal plate electrode of the gold electrode, and aged at 54 mA for 35 h to prepare a gas sensor, thus obtaining test sample I.
[0046] Example 2
[0047] This embodiment provides a zinc ferrite nanosheet carbon monoxide sensor material and its preparation method. Specifically, the zinc ferrite nanosheet carbon monoxide sensor material uses iron instead of noble metals as dopant in a ZnO sensor to achieve high-sensitivity detection of carbon monoxide. The preparation method of the zinc ferrite nanosheet carbon monoxide sensor material is as follows:
[0048] Using (CH3COO)2Zn and FeCl3·6H2O as raw materials, 1.8348 g of (CH3COO)2Zn and 0.13515 g of Fe (molar doping of 5%) were weighed and dissolved in a mixed solution of 10 ml deionized water and 10 ml anhydrous ethanol, respectively, and sonicated for 50 min. 1.4 g of NaOH was weighed and dissolved in 10 ml deionized water. The mixed solution was transferred to a magnetic stirrer, and NaOH solution was added dropwise at a uniform rate of 1 drop / s. After stirring for 30 min until the precipitation reaction was complete, the precipitate solution was transferred to a 50 ml autoclave for hydrothermal treatment at 150℃ for 10 h. After naturally cooling to room temperature, the solution was washed 3–5 times alternately by centrifugation with anhydrous ethanol and deionized water until neutral, dried in a forced-air drying oven at 60℃, and ground into powder. The composite powder was placed in a crucible and heated to 450°C at a rate of about 3°C / min for 3 hours to activate it. After natural cooling to room temperature, the zinc ferrite nano carbon monoxide sensor material was finally obtained.
[0049] The composite material was ground with deionized water for about 15 minutes, then coated onto the hexagonal plate electrode of the gold electrode, and aged at 30mA for 35 h to prepare a gas sensor, thus obtaining test sample II.
[0050] Example 3
[0051] This embodiment provides a zinc ferrite nanosheet carbon monoxide sensor material and its preparation method. Specifically, the zinc ferrite nanosheet carbon monoxide sensor material uses iron instead of noble metals as dopant in a ZnO sensor to achieve high-sensitivity detection of carbon monoxide. The preparation method of the zinc ferrite nanosheet carbon monoxide sensor material is as follows:
[0052] Using (CH3COO)2Zn and FeCl3·6H2O as raw materials, 1.8348 g of (CH3COO)2Zn and 0.13515 g of Fe (molar doping of 5%) were weighed and dissolved in a mixed solution of 10 ml deionized water and 10 ml anhydrous ethanol, respectively, and sonicated for 50 min. 1.4 g of NaOH was weighed and dissolved in 10 ml deionized water. The mixed solution was transferred to a magnetic stirrer, and NaOH solution was added dropwise at a uniform rate of 1 drop / s. After stirring for 30 min until the precipitation reaction was complete, the precipitate solution was transferred to a 50 ml autoclave for hydrothermal treatment at 150℃ for 10 h. After naturally cooling to room temperature, the solution was washed 3–5 times alternately by centrifugation with anhydrous ethanol and deionized water until neutral, dried in a forced-air drying oven at 60℃, and ground into powder. The composite powder was placed in a crucible and heated to 450°C at a rate of about 3°C / min for 3 hours to activate it. After natural cooling to room temperature, the zinc ferrite nano carbon monoxide sensor material was finally obtained.
[0053] The composite material was ground with deionized water for about 15 minutes, then coated onto the hexagonal plate electrode of the gold electrode, and aged at 54mA for 35 h to prepare a gas sensor, thus obtaining test sample III.
[0054] Comparative Example 1
[0055] This embodiment provides a ZnO-based gas sensor material, which is prepared according to the following method:
[0056] Weigh 1.8348 g of (CH3COO)2Zn (0% Fe molar content) and dissolve it in a mixed solution of 10 ml deionized water and 10 ml anhydrous ethanol, and sonicate for 50 min. Weigh 0.8 g of NaOH and dissolve it in 10 ml deionized water. Transfer the mixed solution to a magnetic stirrer and add NaOH solution dropwise at a uniform rate of 1 drop / s. After stirring for 30 min until the precipitation reaction is complete, transfer the precipitate solution to a 50 ml autoclave for hydrothermal treatment at 150℃ for 10 h. After naturally cooling to room temperature, wash the solution 3-5 times with alternating centrifugation using anhydrous ethanol and deionized water until neutral. Dry the solution in a forced-air drying oven at 60℃ and grind it into powder.
[0057] Zinc oxide nanomaterials were ground with deionized water for about 15 minutes, then coated onto a hexagonal plate electrode of gold electrode, and aged at 54mA for 35 h to prepare a gas sensor, thus obtaining control sample I.
[0058] Comparative Example 2
[0059] This embodiment provides a ZnO-based gas sensor material, which is prepared according to the following method:
[0060] 1.8348 g of (CH3COO)2Zn (0% Fe molar content) was weighed and dissolved in a mixture of 10 ml deionized water and 10 ml anhydrous ethanol, and sonicated for 50 min. 0.8 g of NaOH was weighed and dissolved in 10 ml deionized water. The mixture was transferred to a magnetic stirrer, and NaOH solution was added dropwise at a rate of 1 drop / s. After stirring for 30 min until the precipitation reaction was complete, the precipitate was transferred to a 50 ml autoclave for hydrothermal treatment at 150 °C for 10 h. After naturally cooling to room temperature, the mixture was washed 3–5 times alternately by centrifugation with anhydrous ethanol and deionized water until neutral. It was then dried in a forced-air drying oven at 60 °C and ground into powder. The composite powder was placed in a crucible and activated at 450 °C for 3 h at a rate of approximately 3 °C / min. After naturally cooling to room temperature, the zinc oxide nano-carbon monoxide sensor material was finally obtained.
[0061] Zinc oxide nanomaterials were ground with deionized water for about 15 minutes, then coated onto a hexagonal plate electrode of a gold electrode, and aged at 54 mA for 30 h to prepare a gas sensor, thus obtaining control sample II.
[0062] Test case
[0063] In this embodiment, the performance of test samples I-III and control samples I-II prepared in the above embodiments and comparative examples were tested. The test contents included:
[0064] (1) SEM test
[0065] Experimental results are as follows Figure 1 As shown, in Figure 1 middle, Figure 1 (a) is a SEM image of test sample I magnified 3000 times; Figure 1 (b) is a SEM image of test sample II magnified 3000 times; Figure 1 (d) is a SEM image of test sample III magnified 50,000 times; Figure 1 (c) is a SEM image of Comparative Example 2 magnified 50,000 times;
[0066] The results above show that: Figure 1 (d) The sample surface is covered by numerous micro- and nanoparticles. The zinc ferrite nanosheets are uniformly stacked together, with an average particle size of approximately 50 nm and a relatively uniform particle size distribution. (Comparison) Figure 1 (a) Figure 1 (b) It can be seen that after the heat treatment process, the porosity of the zinc ferrite surface increases. Therefore, the formed zinc ferrite nano-surface has rough, loose and porous surface characteristics, which can generate more gas diffusion channels, which is conducive to the adsorption and desorption of target gas, thereby improving the gas-sensitive performance of the material.
[0067] (2) Gas response test
[0068] The test sample II prepared in Example 2 was used for sensitivity testing in a dynamic gas mixing system. Before introducing the target gas, background gas was introduced into the calibration chamber for 30 minutes. After the chamber atmosphere stabilized, five gases—CO, H2, C2H4, CO2, and CH4—were introduced at concentrations of 50 ppm, 100 ppm, 200 ppm, 300 ppm, and 400 ppm respectively for testing. Figures 2-6 The test sample II exhibited different changes in sensor resistance for different gas environments. Figure 6 In the test, when the CO gas concentration was 400 ppm, the initial resistance of the sensor decreased from 6573 KΩ to 614 KΩ, and the ΔR value was the largest, indicating that the test sample II exhibited excellent gas-sensing performance for CO gas.
[0069] (3) Gas anti-interference test
[0070] The test sample III prepared in Example 3 was used for sensitivity testing in a dynamic gas mixing system. Before introducing the target gas, background gas was introduced into the calibration chamber for 30 minutes. After the chamber atmosphere stabilized, five gases (CO, H2, C2H4, CO2, and CH4) at concentrations of 50 ppm, 100 ppm, 200 ppm, 300 ppm, and 400 ppm were introduced for testing. The selectivity of test sample III for different concentrations of different gases was compared as follows: Figure 7 As shown, when the gas concentration is 50 ppm, the sensor's sensitivity to C2H4 gas is 0.8%, while its sensitivity to CO reaches 67.9%. When the gas concentration is 400 ppm, the sensor's sensitivity to C2H4 gas is 7.8%, and its sensitivity to CO is 91%. These experimental results indicate that the selectivity of the zinc ferrite sensor material for the above five gases is in the order: CO > H2 > CH4 > CO2 > C2H4. The test sample III provided in Example III of this invention exhibits excellent selectivity for CO.
[0071] (4) Gas response test
[0072] Sensitivity tests were conducted on a dynamic gas mixing system using test sample I, test sample II, and control sample I. The specific method was as follows:
[0073] Test sample I, test sample II, and control sample I were placed in a sealed chamber. Before introducing the target gas, background gas was introduced into the calibration chamber for 30 minutes. After the chamber atmosphere stabilized, CO gas at concentrations of 50 ppm, 100 ppm, 200 ppm, 300 ppm, and 400 ppm was introduced, respectively. The selective response sensitivity to different concentrations of CO gas was measured as follows: Figure 8 As shown, in this Figure 8 In the table, Zn represents the test result for control sample I, Zn-Fe (5%) without heating represents the test result for test sample I, and Zn-Fe (5%) 450℃ heat treatment represents the test result for test sample II.
[0074] from Figure 8 As can be seen, when the CO gas concentration is 400 ppm, the response of pure ZnO in control sample I is approximately 57%, while the response of test sample I after Fe ion doping is approximately 82%, indicating that doping improves the CO sensitivity of the material by 25%. Test sample II, after undergoing a 450℃ heat treatment process, increased the porosity and specific surface area of the material, providing channels for gas adsorption and desorption; at a gas concentration of 400 ppm, the sensitivity was 91%. In the preferred embodiment of this invention, test sample II shows a 34% improvement in CO gas sensing performance compared to control sample I.
[0075] The above experimental results show that the performance of test sample I provided by the present invention is significantly improved compared with the control sample. At the same time, the performance of test sample II after being treated at 450℃ is further improved on the basis of test sample I. Test sample II shows excellent selectivity for CO.
[0076] The above 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 with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.
Claims
1. A method for preparing a zinc ferrite nanosheet carbon monoxide sensor material, characterized in that, Including the following steps: S1: Dissolve zinc salt and iron salt in anhydrous ethanol solution at a certain molar ratio, and mix them evenly by ultrasonic or mechanical stirring. S2: Add NaOH aqueous solution dropwise according to the amount of zinc salt and iron salt added, stir the reaction for 20 to 70 minutes to form a hydrothermal reaction system; S3: After the reaction is complete, the above hydrothermal reaction system is transferred to an autoclave for hydrothermal reaction at a temperature of 130-160°C for 1-20 hours. After the reaction, the system is cooled to room temperature, filtered to obtain precipitate, and the precipitate is washed and dried. S4: The dried precipitate is activated at 300-500℃ for 2-6 h, and then cooled to room temperature to obtain the sensor material; The zinc ferrite nanosheet carbon monoxide sensor material is composed of zinc ferrite nanosheets with a diameter of 30-100 nm; the zinc salt is any one or more of zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate; the iron salt is any one or more of ferric sulfate, ferric chloride, and ferric nitrate; and the molar ratio of the iron salt to the zinc salt is 4-6%.
2. The method for preparing the zinc ferrite nanosheet carbon monoxide sensor material as described in claim 1, characterized in that: The molar amount of NaOH is the sum of twice the molar amount of the zinc salt and three times the molar amount of the iron salt.
3. An application of a carbon monoxide ferric acid nanosheet sensor material in the fabrication of gas sensors, characterized in that, The gas sensor is prepared as follows: A substrate material is provided, and the material obtained by the preparation method of zinc ferrite nanosheet carbon monoxide sensor material as described in any one of claims 1-2 is mixed with a solvent and ground into a liquid slurry. The liquid slurry is coated on at least one side of the substrate material, and then the solvent is evaporated to prepare the gas sensor.
4. The application of the ferric acid nanosheet carbon monoxide sensor material as described in claim 3 in the preparation of gas sensors, characterized in that: The substrate material is any one of silicon substrate material, organic polymer substrate material, metal substrate material or graphite substrate material.
5. The application of the ferric acid nanosheet carbon monoxide sensor material as described in claim 3 in the preparation of gas sensors, characterized in that: The solvent is either deionized water or an alcohol solution.