Preparation method and application of Co3O4 material with porous nanosheet structure
By preparing porous nanosheet Co3O4 materials, the problems of high operating temperature and high energy consumption of Co3O4 materials were solved, realizing a low-temperature, high-sensitivity triethylamine gas sensor suitable for industrial production.
Patent Information
- Application Number
- CN202510968029.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-14
- Publication Date
- 2025-10-28
AI Technical Summary
Existing Co3O4 materials, as triethylamine gas sensing materials, have high operating temperatures and high energy consumption, which limits their practical applications.
A method for preparing porous nanosheet-structured Co3O4 material was adopted, which involves dissolving cobalt acetate tetrahydrate, adding ammonia to generate a precipitate, drying, and sintering at a specific temperature to form a Co3O4 material with a porous nanosheet structure.
A triethylamine gas sensor was developed with high sensitivity detection at 120℃~140℃, a response sensitivity of over 42, a minimum detection limit of 100ppb, and a good linear relationship between sensitivity and gas concentration, making it suitable for large-scale industrial production.
Smart Images
Figure CN120841578A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing Co3O4 material and its application. Background Technology
[0002] Triethylamine (TEA), as an important industrial raw material, is commonly used in the preparation of catalysts, surfactants, preservatives, polymerization inhibitors, organic solvents, and high-energy fuels. However, triethylamine is also a highly toxic, irritating, and corrosive gas. Prolonged exposure to certain concentrations of triethylamine gas, even at low concentrations, can cause pulmonary edema, visual impairment, respiratory headaches, and nervous system disorders; higher concentrations can lead to permanent damage to bodily functions or even death. Furthermore, triethylamine is highly volatile and flammable. When exposed to open flames or high temperatures, it forms a flammable gas mixture, posing a potential explosion hazard. Therefore, developing triethylamine gas sensing materials that are low-cost, low-energy, and highly selective is of significant practical value. Traditional metal oxide semiconductor materials (such as In₂O₃, Co₃O₄, NiO, SnO₂, and MoO₃) have been widely applied in the field of triethylamine gas sensors. Among them, Co3O4 has become one of the most promising triethylamine gas-sensitive materials due to its unique physicochemical properties, but its high operating temperature (180℃) and large energy consumption bring inconvenience to practical applications. Summary of the Invention
[0003] This invention aims to address the problems of high operating temperature and high energy consumption of existing Co3O4 as a triethylamine gas-sensitive material, and further provides a method for preparing Co3O4 material with a porous nanosheet structure and its application.
[0004] A method for preparing a Co3O4 material with a porous nanosheet structure, comprising the following steps:
[0005] 1. Add cobalt acetate tetrahydrate to distilled water and stir to dissolve, obtaining a red transparent cobalt acetate solution;
[0006] 2. Adding ammonia to a red, transparent cobalt acetate solution yields a light blue solution;
[0007] 3. Heat the light blue solution in a water bath until a red precipitate is formed, then filter, wash and dry to obtain the precursor;
[0008] IV. The precursor is heated to 300℃~800℃ at a heating rate of 5℃ / min~10℃ / min, and sintered at 300℃~800℃ for 2h~4h to obtain a Co3O4 material with a porous nanosheet structure.
[0009] An application of a Co3O4 material with a porous nanosheet structure, used to prepare a triethylamine gas sensor.
[0010] The beneficial effects of this invention are:
[0011] (1) The preparation method of the present invention is simple, low cost, mild conditions, and easy to be industrialized and mass-produced.
[0012] (2) The porous nanosheet Co3O4 material prepared by this invention has a stable structure, uniform morphology, and smooth surface. It also has excellent triethylamine gas sensitivity. At an operating temperature of 120℃~140℃, the triethylamine gas sensor has a response sensitivity of over 42 to 100ppm triethylamine gas and a detection limit of less than 100ppb, which is superior to most triethylamine gas sensors in the same series. Furthermore, the sensitivity shows a good linear relationship with the triethylamine gas concentration, which has great application value. Attached Figure Description
[0013] Figure 1 This is an electronic photograph of the Al2O3 ceramic tube described in Example 1;
[0014] Figure 2 This is a scanning electron microscope image of the precursor prepared in step three of Example 1;
[0015] Figure 3 Scanning electron microscope images of the porous nanosheet Co3O4 materials prepared in step four of Examples 1 to 6: (a) Example 1, (b) Example 2, (c) Example 3, (d) Example 4, (e) Example 5, (f) Example 6;
[0016] Figure 4 The XRD pattern of the precursor prepared in step three of Example 1;
[0017] Figure 5 The XRD patterns of the porous nanosheet-structured Co3O4 materials prepared in step four of Examples 1 to 6 are shown.
[0018] Figure 6 The BET and BJH spectra of the porous nanosheet Co3O4 materials prepared in step four of Examples 1 to 6 are shown in (a) Example 1, (b) Example 2, (c) Example 3, (d) Example 4, (e) Example 5, and (f) Example 6.
[0019] Figure 7 The response sensitivity curves of the triethylamine gas sensors in Examples 1 to 6 to 50 ppm triethylamine gas at different operating temperatures are shown.
[0020] Figure 8Example 4 shows the response recovery curve of the triethylamine gas sensor to 0.1ppm~2ppm triethylamine gas at an operating temperature of 133°C;
[0021] Figure 9 Example 4 shows the response recovery curve of the triethylamine gas sensor to 2ppm~100ppm triethylamine gas at an operating temperature of 133°C;
[0022] Figure 10 Example 4 shows the relationship curves of the triethylamine gas sensor for 0.1ppm~2ppm triethylamine gas at an operating temperature of 133°C;
[0023] Figure 11 Example 4: The relationship curve of triethylamine gas sensor for 2ppm~100ppm triethylamine gas at an operating temperature of 133°C;
[0024] Figure 12 The bar chart shows the response sensitivity of the triethylamine gas sensor in Example 4 to 11 different gases, each with a concentration of 50 ppm, at an operating temperature of 133°C. Detailed Implementation
[0025] Specific Implementation Method 1: This implementation method describes a method for preparing a Co3O4 material with a porous nanosheet structure. The remaining steps are as follows:
[0026] 1. Add cobalt acetate tetrahydrate to distilled water and stir to dissolve, obtaining a red transparent cobalt acetate solution;
[0027] 2. Adding ammonia to a red, transparent cobalt acetate solution yields a light blue solution;
[0028] 3. Heat the light blue solution in a water bath until a red precipitate is formed, then filter, wash and dry to obtain the precursor;
[0029] IV. The precursor is heated to 300℃~800℃ at a heating rate of 5℃ / min~10℃ / min, and sintered at 300℃~800℃ for 2h~4h to obtain a Co3O4 material with a porous nanosheet structure.
[0030] The beneficial effects of this embodiment are:
[0031] (1) The preparation method of this embodiment is simple, low cost, mild conditions, and easy to industrialize and mass-produce.
[0032] (2) The porous nanosheet Co3O4 material prepared in this embodiment has a stable structure, uniform morphology, and smooth surface. It also has excellent triethylamine gas sensitivity. At an operating temperature of 120℃~140℃, the triethylamine gas sensor has a response sensitivity of over 42 to 100ppm triethylamine gas and a detection limit of less than 100ppb, which is superior to most triethylamine gas sensors in the same series. Furthermore, the sensitivity shows a good linear relationship with the triethylamine gas concentration, which has great application value.
[0033] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass ratio of cobalt acetate tetrahydrate to distilled water in step one is 1g:(78~82)mL. Everything else is the same as in Specific Implementation Method One.
[0034] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the mass percentage of ammonia water mentioned in step two is 24%~26%. Everything else is the same as in Specific Implementation Method One or Two.
[0035] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the mass ratio of cobalt acetate tetrahydrate mentioned in step one to the volume ratio of ammonia water mentioned in step two is 1g:(4~10)mL. Everything else is the same as in Specific Implementation Method Three.
[0036] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the water bath heating in step three is specifically carried out at a temperature of 40℃ to 60℃ for 20 to 50 minutes. Everything else is the same as in Specific Implementation Methods One to Four.
[0037] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the washing and drying in step three involves washing multiple times with deionized water and ethanol, followed by drying at a temperature of 60℃~80℃ for 18h~34h. Everything else is the same as in Specific Implementation Methods One to Five.
[0038] Specific Implementation Method Seven: This implementation method describes the application of a Co3O4 material with a porous nanosheet structure, which is used to prepare a triethylamine gas sensor.
[0039] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the triethylamine gas sensor is specifically prepared according to the following steps:
[0040] A porous nanosheet-structured Co3O4 material was ground and terpineol was added to obtain a slurry. This slurry was coated onto an Al2O3 ceramic tube with a thickness of 0.5 mm to 2 mm, then dried. This coating and drying process was repeated 3 to 5 times. Finally, the tube was sintered at 100℃ to 300℃ for 2 to 4 hours to obtain a gas-sensitive element. A Ni-Cr alloy resistance wire was passed through the ceramic tube of the gas-sensitive element and then assembled and welded to a six-pin element base. After aging, a triethylamine gas sensor was obtained. Other procedures are the same as in Specific Embodiment Seven.
[0041] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Seven or Eight in that: the mass ratio of the porous nanosheet structured Co3O4 material to terpineol is 1:(0.8~1.2); the drying is specifically carried out at a temperature of 60℃~80℃; and the aging is specifically carried out at a temperature of 80℃~130℃ for 18h~24h. Everything else is the same as in Specific Implementation Method Seven or Eight.
[0042] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Seven to Nine in that, at an operating temperature of 120℃~140℃, the triethylamine gas sensor exhibits a response sensitivity of 42 or higher to 100ppm triethylamine gas, and a minimum detection limit of 100ppb or lower. All other aspects are the same as in Specific Implementation Methods Seven to Nine.
[0043] The beneficial effects of the present invention are verified using the following embodiments:
[0044] Example 1:
[0045] A method for preparing a Co3O4 material with a porous nanosheet structure, comprising the following steps:
[0046] 1. Add cobalt acetate tetrahydrate to distilled water and stir at 800 rpm for 0.5 h to dissolve it, resulting in a red transparent cobalt acetate solution.
[0047] The mass ratio of cobalt acetate tetrahydrate to distilled water is 1 g: 80 mL;
[0048] 2. Adding ammonia to a red, transparent cobalt acetate solution yields a light blue solution;
[0049] The mass percentage of the ammonia solution is 25%; the mass ratio of cobalt acetate tetrahydrate in step one to the volume ratio of the ammonia solution in step two is 1g:5.4mL;
[0050] 3. Under the condition of 60℃, the light blue solution was heated in a water bath for 30 minutes to generate a red precipitate, which was then filtered, washed and dried to obtain the precursor.
[0051] IV. The precursor was heated to 300℃ at a heating rate of 5℃ / min, and sintered at 300℃ for 2 hours to obtain a Co3O4 material with a porous nanosheet structure.
[0052] The washing and drying process described in step three involves washing twice with deionized water and ethanol respectively, and then drying at 60°C for 24 hours.
[0053] In step two of this embodiment, after adding ammonia, a precipitate first appears in the solution and then disappears, and the solution color changes from red to light blue; during the water bath heating process in step three, blue flocculent matter first appears, then gradually turns white, and finally the flocculent matter turns into red precipitate.
[0054] The above-prepared Co3O4 material with a porous nanosheet structure is used to prepare a triethylamine gas sensor.
[0055] The triethylamine gas sensor is specifically prepared according to the following steps:
[0056] Co3O4 material with a porous nanosheet structure was ground and terpineol was added to obtain a slurry. The slurry was coated onto an Al2O3 ceramic tube with a coating thickness of 1 mm, and then dried at 60°C. The coating and drying were repeated 3 times. Finally, the tube was sintered at 200°C for 2 hours to obtain a gas-sensitive element. A Ni-Cr alloy resistance wire was passed through the ceramic tube of the gas-sensitive element and then assembled and welded to a six-pin element base. Finally, the tube was aged at 100°C for 24 hours to obtain a triethylamine gas sensor.
[0057] The mass ratio of the porous nanosheet-structured Co3O4 material to terpineol is 1:0.8.
[0058] The Al2O3 ceramic tube is 4 mm long, with an inner diameter of 0.8 mm and an outer diameter of 1.2 mm. It has two parallel gold electrodes (1 mm apart) plated on it. The hollow section can accommodate heating resistance wires. Each gold electrode is welded with two platinum wires for connection to a gas-sensitive testing system. Figure 1 As shown, Figure 1 This is an electronic photograph of the Al2O3 ceramic tube described in Example 1.
[0059] Example 2: This example differs from Example 1 in that, in step four, the precursor is heated to 400°C at a heating rate of 5°C / min, and then sintered at 400°C for 2 hours. Everything else is the same as in Example 1.
[0060] Example 3: This example differs from Example 1 in that in step four, the precursor is heated to 500°C at a heating rate of 5°C / min, and then sintered at 500°C for 2 hours. Everything else is the same as in Example 1.
[0061] Example 4: This example differs from Example 1 in that, in step four, the precursor is heated to 600°C at a heating rate of 5°C / min, and then sintered at 600°C for 2 hours. Everything else is the same as in Example 1.
[0062] Example 5: This example differs from Example 1 in that, in step four, the precursor is heated to 700°C at a heating rate of 5°C / min, and then sintered at 700°C for 2 hours. Everything else is the same as in Example 1.
[0063] Example 6: This example differs from Example 1 in that, in step four, the precursor is heated to 800°C at a heating rate of 5°C / min, and then sintered at 800°C for 2 hours. Everything else is the same as in Example 1.
[0064] Figure 2 The image shows a scanning electron microscope (SEM) image of the precursor prepared in step three of Example 1. As can be seen from the image, the Co(OH)2 precursor exists in the form of irregular nanosheets, which are intertwined and overlapped.
[0065] Figure 3 The images show scanning electron microscope (SEM) images of the porous nanosheet Co3O4 materials prepared in step four of Examples 1 to 6: (a) Example 1, (b) Example 2, (c) Example 3, (d) Example 4, (e) Example 5, and (f) Example 6. As can be seen from the images, after the Co(OH)2 precursor is sintered at 500°C, the nanosheets begin to show a porous structure, forming porous nanosheets. After sintering at 600°C, the pore structure becomes larger. At 700°C, adjacent particles melt and bond together at high temperature, the pore structure becomes smaller, and the nanosheets collapse.
[0066] Figure 4 The XRD pattern of the precursor prepared in step three of Example 1 is shown in the figure. As can be seen from the figure, the X-ray diffraction peak positions of the precursor powder are completely consistent with the Co(OH)2 JCPDS card (No. 30-0443), indicating that the phase of the precursor is Co(OH)2.
[0067] Figure 5The XRD patterns of the porous nanosheet Co3O4 material prepared in step four of Examples 1 to 6 are shown in the figure. As can be seen from the figure, the X-ray diffraction peak positions of the sample powder are completely consistent with the Co3O4 JCPDS card (No. 42-1467), indicating that the sample dehydrates from Co(OH)2 and transforms into the Co3O4 phase after sintering at 300℃~800℃. Moreover, the intensity of the diffraction peaks of the sample increases with the increase of sintering temperature, indicating that the degree of crystallization increases.
[0068] Figure 6 The BET and BJH spectra of the porous nanosheet-structured Co3O4 materials prepared in step four of Examples 1 to 6 are shown in the figures: (a) Example 1, (b) Example 2, (c) Example 3, (d) Example 4, (e) Example 5, and (f) Example 6. As can be seen from the figures, after sintering at 300℃~800℃, the specific surface area of the sample powders is 28.2 m². 2 / g, 14.7m 2 / g, 5.3m 2 / g, 4.7m 2 / g, 3.2m 2 / g and 1.4m 2 / g, it can be seen that as the sintering temperature increases, the specific surface area of the sample gradually decreases; while the pore size shows a gradual increasing trend in the calcination range of 300℃~600℃, concentrated at 7nm, 10nm, 13nm and 19nm respectively, and after exceeding 700℃, the nanosheets collapse, and the pore size of the sample drops sharply to about 2nm, which is consistent with the SEM test results.
[0069] Gas Sensing Performance Testing: The gas sensing performance of the triethylamine gas sensors prepared using porous nanosheet Co3O4 material in Examples 1 to 6 was tested using the static gas mixing method. First, a 10 L test chamber was evacuated using a vacuum pump, then a certain volume of triethylamine solution was injected, and finally, the pressure relief valve was opened to balance the pressure inside and outside the test chamber. The operating temperature of the gas sensing element was controlled by adjusting the voltage of the heating resistance wire. The response-recovery characteristics of the gas sensing element were characterized by the change in resistance of the sensor in fresh air and in the target gas atmosphere. The gas response sensitivity (S) was defined as: S = R g / R a , where R a R represents the resistance value of the gas-sensitive element in fresh air. g This indicates the resistance value of the gas-sensitive element in the test gas.
[0070] Figure 7The figures show the response sensitivity curves of triethylamine gas sensors in Examples 1 to 6 to 50 ppm triethylamine gas at different operating temperatures. As can be seen from the figures, the porous Co3O4 nanosheet gas sensor sintered at 600℃ exhibits the highest response sensitivity at an operating temperature of 133℃, where its response sensitivity to 50 ppm triethylamine can reach 23.59.
[0071] Figure 8 Example 4 shows the response recovery curve of the triethylamine gas sensor to 0.1ppm~2ppm triethylamine gas at an operating temperature of 133°C; Figure 9 Example 4 shows the response recovery curves of the triethylamine gas sensor at an operating temperature of 133°C for triethylamine gas ranging from 2 ppm to 100 ppm. As can be seen from the figure, the porous Co3O4 nanosheet gas-sensitive element sintered at 600°C exhibits significant resistance changes in response to triethylamine gas within a concentration range of 0.1 ppm to 100 ppm at an operating temperature of 133°C. The sensitivity to 100 ppm triethylamine gas is as high as 42.84, and the minimum detection limit is as low as 100 ppb. Furthermore, it can completely recover to its initial resistance value during the recovery process, demonstrating excellent triethylamine gas sensitivity performance.
[0072] Figure 10 Example 4 shows the relationship curves of the triethylamine gas sensor for 0.1ppm~2ppm triethylamine gas at an operating temperature of 133°C; Figure 11 Example 4 shows the relationship curves of the triethylamine gas sensor at an operating temperature of 133°C for triethylamine gas concentrations ranging from 2 ppm to 100 ppm. As can be seen from the graph, at 133°C, the response sensitivity exhibits a good linear relationship with the triethylamine gas concentration in the ranges of 0.1 ppm to 2 ppm and 2 ppm to 100 ppm, respectively, with a fitting coefficient R0. 2 The values are 0.996 (0.1ppm~2ppm) and 0.998 (2ppm~100ppm), respectively. This characteristic lays a good foundation for the gas-sensitive material to monitor triethylamine gas in the environment in real time.
[0073] Figure 12 Example 4 shows the response sensitivity of the triethylamine gas sensor to 11 different gases, all at a concentration of 50 ppm, at an operating temperature of 133°C. The graph shows that the porous Co3O4 nanosheet gas sensor obtained after sintering at 600°C achieves a sensitivity of 23.59 for 50 ppm triethylamine at an operating temperature of 133°C, while the response sensitivities to ethanol, benzene, formaldehyde, xylene, aniline, trimethylamine, triethanolamine, ammonia, and acetone, all at the same concentration of 50 ppm, are all less than 2, demonstrating excellent selectivity for triethylamine gas.
Claims
1. A method for preparing a Co3O4 material with a porous nanosheet structure, characterized in that... It is done in the following steps:
1. Add cobalt acetate tetrahydrate to distilled water and stir to dissolve, obtaining a red transparent cobalt acetate solution; 2. Adding ammonia to a red, transparent cobalt acetate solution yields a light blue solution; 3. Heat the light blue solution in a water bath until a red precipitate is formed, then filter, wash and dry to obtain the precursor; IV. The precursor is heated to 300℃~800℃ at a heating rate of 5℃ / min~10℃ / min, and sintered at 300℃~800℃ for 2h~4h to obtain a Co3O4 material with a porous nanosheet structure.
2. The method for preparing a Co3O4 material with a porous nanosheet structure according to claim 1, characterized in that... The mass ratio of cobalt acetate tetrahydrate to distilled water in step one is 1 g: (78~82) mL.
3. The method for preparing a Co3O4 material with a porous nanosheet structure according to claim 1, characterized in that... The mass percentage of ammonia water mentioned in step two is 24% to 26%.
4. The method for preparing a Co3O4 material with a porous nanosheet structure according to claim 1, characterized in that... The mass ratio of cobalt acetate tetrahydrate mentioned in step one to the volume ratio of ammonia water mentioned in step two is 1g:(4~10)mL.
5. The method for preparing a Co3O4 material with a porous nanosheet structure according to claim 1, characterized in that... In step three, the water bath heating is specifically carried out at a temperature of 40℃~60℃ for 20min~50min.
6. The method for preparing a Co3O4 material with a porous nanosheet structure according to claim 1, characterized in that... The washing and drying process described in step three involves washing the product multiple times with deionized water and ethanol, and then drying it at a temperature of 60℃~80℃ for 18h~34h.
7. The application of a Co3O4 material with a porous nanosheet structure prepared according to claim 1, characterized in that... It is used to prepare triethylamine gas sensors.
8. The application of a Co3O4 material with a porous nanosheet structure according to claim 7, characterized in that... The triethylamine gas sensor is specifically prepared according to the following steps: Co3O4 material with a porous nanosheet structure was ground and terpineol was added to obtain a slurry. The slurry was coated onto an Al2O3 ceramic tube with a coating thickness of 0.5 mm to 2 mm, and then dried. The coating and drying were repeated 3 to 5 times. Finally, the tube was sintered at a temperature of 100℃ to 300℃ for 2 to 4 hours to obtain a gas-sensitive element. A Ni-Cr alloy resistance wire was passed through the ceramic tube of the gas-sensitive element and then assembled and welded to a six-pin element base. Finally, the tube was aged to obtain a triethylamine gas sensor.
9. The application of a Co3O4 material with a porous nanosheet structure according to claim 8, characterized in that... The mass ratio of the porous nanosheet structure Co3O4 material to terpineol is 1:(0.8~1.2); the drying is specifically carried out at a temperature of 60℃~80℃; the aging is specifically carried out at a temperature of 80℃~130℃ for 18h~24h.
10. The application of a Co3O4 material with a porous nanosheet structure according to claim 7, characterized in that... At an operating temperature of 120℃~140℃, the triethylamine gas sensor has a response sensitivity of 42 or higher to 100ppm triethylamine gas and a minimum detection limit of 100ppb or lower.