Ga-doped Co3O4 nanoflower, preparation method and application of Ga-doped Co3O4 nanoflower as gas sensitive material

Abstract

The invention belongs to the field of nano materials, and particularly relates to a Ga-doped Co3O4 nano flower, a preparation method and application of the Ga-doped Co3O4 nano flower as a gas sensitive material. The Ga-doped Co3O4 nanoflower is in a flower-ball shape, and the diameter of the Ga-doped Co3O4 nanoflower is 10 microns; the doping amount of the metal Ga is 1%-5% of the substance amount of the metal Co; the preparation method of the Ga-doped Co3O4 nanoflower comprises the following steps: synthesizing a multi-metal Co (OH) 2 nanoflower by a wet impregnation and freeze drying method, taking the multi-metal Co (OH) 2 nanoflower as a template, and roasting in an air atmosphere to prepare a Ga-Co3O4 gas sensitive material with a nanoflower morphology; the Ga-Co3O4 nanoflower gas sensitive material prepared by the preparation method disclosed by the invention has a good sensitive characteristic on CO; according to the invention, the heterogeneous element is used for replacing and preparing the bimetallic MOS to improve the gas-sensitive performance of the metal oxide, and the cost is low; the method is low in raw material cost, wide in source, simple in step, environmentally friendly, free of pollution, free of impurity ion introduction, capable of achieving mass production and convenient to achieve large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials, and in particular relates to a Ga-doped Co3O4 nanoflower, a preparation method and an application thereof as a gas-sensitive material. Background Art

[0002] Coal mine accidents, especially coal mine fires and explosions, are the main factors restricting coal mine safety production. CO is a flammable and explosive gas in coal mines. It is produced by the spontaneous combustion of coal at low temperatures. CO is usually used as an indicator gas to monitor coal spontaneous combustion, and CO gas is highly toxic to the human body. Therefore, real-time monitoring of CO concentration can effectively prevent coal mine fires and ensure coal mine safety production and the safety of workers' lives and property.

[0003] In terms of CO detection, sensors based on metal oxide semiconductors (MOS) are widely used for CO detection due to their low price, high response and good selectivity. In particular, Co3O4 sensing materials as p-type MOS have been widely studied in CO detection due to their changeable chemical valence state and excellent redox properties. In addition, Co3O4 materials exhibit excellent low-temperature catalytic activity for CO oxidation, which is mainly due to the high activity of Co 3+ As active sites. However, the CO detection capability of a single metal oxide is limited by its high operating temperature, usually above 250°C. The usual strategy to solve this problem is to load precious metals to increase the response value and reduce the operating temperature of the sensor. However, the disadvantage of this solution is that precious metals are relatively scarce and expensive.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a Ga-doped Co3O4 nanoflower, a preparation method and its application as a gas-sensitive material.

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

[0007] A Ga-doped Co3O4 nanoflower, wherein the Ga-doped Co3O4 nanoflower is in a flower ball shape and has a diameter of 10 μm; the doping amount of the metal Ga is 1% to 5% of the amount of the metal Co substance

[0008] Furthermore, the Ga-doped Co3O4 nanoflower is composed of a plurality of nanosheets with a thickness of 100 to 200 nm, and the diameter of each nanoflower is 4 to 10 μm.

[0009] The present invention also proposes a method for preparing the aforementioned Ga-doped Co3O4 nanoflowers, comprising the following steps:

[0010] (1) C4H6CoO4·4H2O and deionized water are uniformly stirred and ultrasonically mixed to obtain solution A; solution A is heated at 60-100°C for a period of time to obtain solution B; ammonia solution is added dropwise to solution B so that the pH is maintained at 9-11 to obtain solution C; solution C is transferred to room temperature, and then naturally cooled while stirring, solution C is washed with anhydrous ethanol and deionized water for multiple times and centrifuged to obtain a precipitate, and the precipitate is vacuum dried to obtain a Co(OH)2 nanoflower precursor;

[0011] (2) uniformly dispersing the Co(OH)2 precursor obtained in step (1) in deionized water and subjecting it to ultrasonic and stirring treatment to obtain a mixed solution D; adding Ga(NO3)3·xH2O to the mixed solution D and continuing the ultrasonic stirring treatment, and then freeze-drying the mixed solution to obtain a Ga-Co(OH)2 precipitate;

[0012] (3) The Ga-Co(OH)2 precipitate obtained in step (2) is calcined at 200-350°C in an air atmosphere to obtain a Ga-Co3O4 nanoflower gas-sensitive material.

[0013] Furthermore, in solution A, the amount ratio of the amount of metal salt, the volume of deionized water, and the amount of ammonia water is (0.008-0.012 mol):(35-45 mL):(8-12 mL).

[0014] Furthermore, in solution A, the molar ratio of the amount of the metal salt C4H6CoO4·4H2O, the volume of deionized water, and the amount of ammonia water is 0.01 mol:40 mL:10 mL.

[0015] Furthermore, in step (1), solution A is heated in an oil bath for 25 to 35 minutes.

[0016] Furthermore, in step (2), the ratio of the total amount of the metal salts Ga(NO3)3·xH2O and Co(OH)2 to the volume of deionized water is (0.3-2.216 mol):(5-30 mL).

[0017] Furthermore, the ultrasonic treatment time is 6 to 12 hours, the temperature is 40 to 60°C, and the power is 360W; the freeze-drying time is 12 to 24 hours, and the temperature is -30°C.

[0018] Furthermore, during the calcination treatment of Ga-Co(OH)2 precipitation, the temperature is gradually increased to 280-320°C at a heating rate of 0.5-2°C / min and maintained for 2-4h.

[0019] The present invention also proposes an application of the aforementioned Ga-doped Co3O4 nanoflower as a gas-sensitive material, which is used as a gas-sensitive material in carbon monoxide detection for detecting 1 to 900 ppm CO at a temperature of 170 to 270°C.

[0020] The beneficial effects of the present invention are:

[0021] The present invention synthesizes multi-metal Co(OH)2 nanoflowers by wet impregnation and freeze drying, and uses the multi-metal Co(OH)2 nanoflowers as templates to prepare Ga-Co3O4 gas-sensitive materials with nanoflower morphology by calcining in an air atmosphere; the material can provide more surface active sites for the gas to be tested due to its unique flower-like structure, and Ga replaces part of Co 2+ A large number of oxygen vacancies were generated, allowing the target gas CO to participate more fully in the redox reaction. The results showed that Ga-Co3O4 has abundant oxygen vacancies and also has high surface oxidation activity, and its response value is greatly improved.

[0022] Compared with using precious metals to improve the response value, the present invention uses heterogeneous elements to replace and prepare bimetallic MOS to improve the gas-sensitive performance of metal oxides, which is low in cost. The method synthesizes the nanoflower precursor by a simple oil bath, introduces the heterogeneous elements by wet impregnation, and finally further anneals to obtain the bimetallic MOS nanoflower. The raw material cost of the present invention is low, the source is wide, the steps are simple, the environment is friendly and pollution-free, no impurity ions are introduced, and it can be mass-produced, which is convenient for large-scale industrial production.

[0023] The Ga-Co3O4 nanoflower gas-sensitive material prepared by the present invention has good sensitivity to CO, with a detection limit of 1 ppm and a corresponding response value of 1.32. The material has good sensing performance for CO above 1 ppm concentration, and the optimum working temperature is 210°C, which is at least 40°C lower than the conventional working dimension of CO detection sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0025] Figure 1 XRD spectra of 1Ga-Co3O4, 3Ga-Co3O4, 5Ga-Co3O4 and Co3O4 nanoflower gas-sensitive materials in Examples 1-3 of the present invention and the comparative example.

[0026] Figure 2 is the XPS spectrum of 3Ga-Co3O4 in Example 2 of the present invention; wherein,

[0027] (a) XPS spectrum of Co 2p of 3Ga-Co3O4;

[0028] (b) is the XPS spectrum of Ga 2p of 3Ga-Co3O4;

[0029] Figure 3 The SEM images of 1Ga-Co3O4, 3Ga-Co3O4, 5Ga-Co3O4 and Co3O4 nanoflower gas-sensitive materials in Examples 1-3 of the present invention and the comparative example are shown in FIG.

[0030] (a) and (b) are SEM images of Co3O4 nanoflower gas-sensitive materials in the comparative example;

[0031] (c) and (d) are SEM images of the 1Ga-Co3O4 nanoflower gas-sensitive material in Example 1, respectively;

[0032] (e) and (f) are SEM images of the 3Ga-Co3O4 nanoflower gas-sensitive material in Example 2, respectively;

[0033] (g) and (h) are SEM images of the 5Ga-Co3O4 nanoflower gas-sensitive material in Example 3;

[0034] Figure 4 The sensitivity curves of 1Ga-Co3O4, 3Ga-Co3O4, 5Ga-Co3O4 and Co3O4 nanoflower gas-sensitive materials to 100ppm CO gas at different temperatures in Examples 1-3 of the present invention and the comparative example;

[0035] Figure 5 The sensitivity curves of the 3Ga-Co3O4 nanoflower gas-sensitive material in Example 2 of the present invention and the Co3O4 nanoflower gas-sensitive material in the comparative example to CO gas of different concentrations at 210°C;

[0036] Figure 6 This is the real-time response recovery curve of the 3Ga-Co3O4 nanoflower gas-sensitive material in Example 2 of the present invention to different concentrations of CO.

[0037] Figure 7 This is the response recovery time curve of the 3Ga-Co3O4 nanoflower gas-sensitive material in Example 2 of the present invention to different concentrations of CO gas. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0039] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0040] A Ga-doped Co3O4 nanoflower, wherein the Ga-doped Co3O4 nanoflower is in a flower ball shape and has a diameter of 10 μm; the doping amount of the metal Ga is 1% to 5% of the amount of the metal Co substance

[0041] Furthermore, the Ga-doped Co3O4 nanoflower is composed of a plurality of nanosheets with a thickness of 100 to 200 nm, and the diameter of each nanoflower is 4 to 10 μm.

[0042] The present invention also proposes a method for preparing the aforementioned Ga-doped Co3O4 nanoflowers, comprising the following steps:

[0043] (1) C4H6CoO4·4H2O and deionized water are uniformly stirred and ultrasonically mixed to obtain solution A, wherein the amount of metal salt, the volume of deionized water, and the amount of ammonia water in solution A are in the ratio of (0.008-0.012 mol):(35-45 mL):(8-12 mL); solution A is heated in an oil bath at 60-100° C. for a period of time to obtain solution B; ammonia solution is added dropwise to solution B so that the pH is maintained at 9-11 to obtain solution C; solution C is transferred to room temperature, and then cooled naturally while stirring, solution C is washed with anhydrous ethanol and deionized water for multiple times and centrifuged to obtain a precipitate, and the precipitate is vacuum dried to obtain a Co(OH)2 nanoflower precursor;

[0044] (2) The Co(OH)2 precursor obtained in step (1) is uniformly dispersed in deionized water and subjected to ultrasonic and stirring treatment to obtain a mixed solution D; the ultrasonic treatment time is 6 to 12 h, the temperature is 40 to 60° C., and the power is 360 W;

[0045] Add Ga(NO3)3·xH2O to the mixed solution D and continue to carry out ultrasonic stirring treatment. The total amount of the metal salt Ga(NO3)3·xH2O and Co(OH)2 and the volume of deionized water are in the ratio of (0.3-2.216 mol):(5-30 mL). Then, the mixed solution is freeze-dried to obtain Ga-Co(OH)2 precipitate; the freeze-drying time is 12-24 h and the temperature is -30°C;

[0046] (3) The Ga-Co(OH)2 precipitate obtained in step (2) is gradually heated to 280-320°C at a heating rate of 0.5-2°C / min in an air atmosphere and maintained for 2-4 hours to obtain a Ga-Co3O4 nanoflower gas-sensitive material.

[0047] The present invention also proposes an application of the aforementioned Ga-doped Co3O4 nanoflower as a gas-sensitive material, which is used as a gas-sensitive material in carbon monoxide detection for detecting 1 to 900 ppm CO at a temperature of 170 to 270°C.

[0048] In the following embodiments, the response value of the gas sensor is expressed as S = R g / R a , where R a is the resistance of the device in air, R g is the resistance of the device in CO gas.

[0049] Example 1

[0050] In this embodiment, the doping amount of the metal Ga is 1% of the amount of the metal Co substance.

[0051] A method for preparing Ga-doped Co3O4 nanoflowers comprises the following steps:

[0052] (1) Dissolve 2.4908 g of C4H6CoO4·4H2O in 40 mL of deionized water under stirring to obtain solution A; place the mixed solution A in an oil bath and heat for 30 min to obtain solution B; add 10 mL of ammonia solution dropwise to the obtained solution B to obtain solution C; transfer the mixed solution C to room temperature, and then cool it naturally for 2 h while stirring, wash it three times with deionized water, then wash it twice with anhydrous ethanol and centrifuge it to obtain a precipitate, and vacuum dry the precipitate to obtain a Co(OH)2 nanoflower precursor;

[0053] (2) 200 mg of the Co(OH)2 precursor obtained in step (1) was taken out and uniformly dispersed in 30 mL of deionized water, and then ultrasonicated for 1 h and stirred for 30 min to obtain a mixed solution D. 0.00548 g of Ga(NO3)3·xH2O was added to the mixed solution D, and then ultrasonicated for 3 h at 50°C, stirred for 6 h, and then the mixed solution was freeze-dried to obtain a 1Ga-Co(OH)2 precipitate;

[0054] (3) The 1Ga-Co(OH)2 obtained in step (2) was heated in an air atmosphere at 1°C min -1 The heating rate was gradually increased to 300°C and maintained for 3 h to obtain 1Ga-Co3O4 nanoflower gas-sensitive material.

[0055] like Figure 1As shown, from the XRD spectrum of the 1Ga-Co3O4 nanoflower gas-sensitive material prepared in this embodiment, it can be seen that the diffraction peaks of the obtained 1Ga-Co3O4 coincide with those of Co3O4, without any impurity peaks, and without any phase separation, which proves that Co3O4 has been successfully doped with heterogeneous element Ga. Figure 3 (c) and (d) are SEM images of the obtained 1Ga-Co3O4 nanoflowers. It can be seen from the images that the 1Ga-Co3O4 nanoflowers are in the shape of flower balls. Figure 4 As shown, the response value of the 1Ga-Co3O4 nanoflower gas-sensitive material prepared in this embodiment to 100 ppm CO gas at 210°C is 2.4.

[0056] Example 2

[0057] In this embodiment, the doping amount of the metal Ga is 3% of the amount of the metal Co substance.

[0058] A method for preparing Ga-doped Co3O4 nanoflowers comprises the following steps:

[0059] (1) Dissolve 2.4908 g of C4H6CoO4·4H2O in 40 mL of deionized water under stirring to obtain solution A; place the mixed solution A in an oil bath and heat for 30 min to obtain solution B; add 10 mL of ammonia solution dropwise to the obtained solution B to obtain solution C; transfer the mixed solution C to room temperature, and then cool it naturally for 2 h while stirring, wash it three times with deionized water, then wash it twice with anhydrous ethanol and centrifuge it to obtain a precipitate, and vacuum dry the precipitate to obtain a Co(OH)2 nanoflower precursor;

[0060] (2) 200 mg of the Co(OH)2 precursor obtained in step (1) was taken out and uniformly dispersed in 30 mL of deionized water, and then ultrasonicated for 1 h and stirred for 30 min to obtain a mixed solution D. 0.01646 g of Ga(NO3)3·xH2O was added to the mixed solution D, and then ultrasonicated for 3 h at 50°C, stirred for 6 h, and then the mixed solution was freeze-dried to obtain a 3Ga-Co(OH)2 precipitate;

[0061] (3) The 3Ga-Co(OH)2 obtained in step (2) was heated in an air atmosphere at 1°C min -1 The temperature was gradually increased to 300°C at a heating rate and maintained for 3 h to obtain 3Ga-Co3O4 nanoflower gas-sensitive material.

[0062] like Figure 1As shown, from the XRD spectrum of the 3Ga-Co3O4 nanoflower gas-sensitive material prepared in this embodiment, it can be seen that the diffraction of the obtained 3Ga-Co3O4 is consistent with that of Co3O4, there is no impurity peak, and no phase separation occurs, which proves that Co3O4 has been successfully doped with the heterogeneous element Ga. Figure 3 (e) and (f) are 3Ga-Co3O4 nanoflowers obtained in this example. Figure 4 , Figure 5 , Figure 6 As shown in the figure, the sensitivity curve of the 3Ga-Co3O4 nanoflower gas-sensitive material prepared in this embodiment to different concentrations of CO gas at 210°C. The test results show that as the concentration of the detected CO gas increases, the influence value of the 3Ga-Co3O4 nanoflower gas-sensitive material on CO also gradually increases. Figure 4 , Figure 5 It can be seen that the response value of the 3Ga-Co3O4 nanoflower gas-sensitive material to 100ppm of CO gas at an operating temperature of 210°C is 6.8. This embodiment also has a response value of 1.32 for the lowest detection value of 1ppm.

[0063] This embodiment is the best embodiment of the present invention. Figure 7 As shown, under the conditions of a temperature of 210 degrees Celsius and a gas concentration of 1 to 900 ppm, the gas sensor in this embodiment has a response time of 2 to 30 seconds and a recovery time of 25 to 35 seconds to CO gas. Note that the performance standard of the sensor is affected by many factors, including moisture resistance, stability, and selectivity, and is not determined solely by the response value.

[0064] Example 3

[0065] In this embodiment, the doping amount of the metal Ga is 5% of the amount of the metal Co substance.

[0066] A method for preparing Ga-doped Co3O4 nanoflowers comprises the following steps:

[0067] (1) Dissolve 2.4908 g of C4H6CoO4·4H2O in 40 mL of deionized water under stirring to obtain solution A; place the mixed solution A in an oil bath and heat for 30 min to obtain solution B; add 10 mL of ammonia solution dropwise to the obtained solution B to obtain solution C; transfer the mixed solution C to room temperature, and then cool it naturally for 2 h while stirring, wash it three times with deionized water, then wash it twice with anhydrous ethanol and centrifuge it to obtain a precipitate, and vacuum dry the precipitate to obtain a Co(OH)2 nanoflower precursor;

[0068] (2) 200 mg of the Co(OH)2 precursor obtained in step (1) was taken out and uniformly dispersed in 30 mL of deionized water, and then ultrasonicated for 1 h and stirred for 30 min to obtain a mixed solution D. 0.02743 g of Ga(NO3)3·xH2O was added to the mixed solution D, and then ultrasonicated for 3 h at 50°C, stirred for 6 h, and then the mixed solution was freeze-dried to obtain a 5Ga-Co(OH)2 precipitate;

[0069] (3) The 5Ga-Co(OH)2 obtained in step (2) was heated in an air atmosphere at 1°C min -1 The heating rate was gradually increased to 300°C and maintained for 3 h to obtain 5Ga-Co3O4 nanoflower gas-sensitive material.

[0070] like Figure 1 As shown, from the XRD spectrum of the 5Ga-Co3O4 nanoflower gas-sensitive material prepared in this embodiment, it can be seen that the diffraction peaks of the obtained 5Ga-Co3O4 correspond to those of Co3O4, without any impurity peaks and without any phase separation, which proves that Co3O4 has been successfully doped with the heterogeneous element Ga. Figure 2 XPS spectrum analysis shows that the heterogeneous element Ga mainly exists in the +3 valence, which has a stronger oxidizing property than Ga with a valence of +1. Figure 3 (g) and (h) are the morphologies of 5Ga-Co3O4 nanoflowers obtained in this example. Figure 4 As shown, the response value of the 5Ga-Co3O4 nanoflower gas-sensitive material prepared in this embodiment to 100 ppm CO gas at 210°C is 1.3.

[0071] Comparative Example

[0072] (1) Dissolve 2.4908 g of C4H6CoO4·4H2O in 40 mL of deionized water under stirring to obtain solution A; place the mixed solution A in an oil bath and heat for 30 min to obtain solution B; add 10 mL of ammonia solution dropwise to the obtained solution B to obtain solution C; transfer the mixed solution C to room temperature, and then cool it naturally for 2 h while stirring, wash it three times with deionized water, then wash it twice with anhydrous ethanol and centrifuge it to obtain a precipitate, and vacuum dry the precipitate to obtain a Co(OH)2 nanoflower precursor;

[0073] (2) The Co(OH)2 obtained in step (1) was heated in an air atmosphere at 1°C min -1 The temperature was gradually increased to 300°C at a heating rate and maintained for 3 h to obtain Co3O4 nanoflower gas-sensitive material.

[0074] The characterization results of the Co3O4 nanoflower gas-sensitive material obtained in this example are as follows:

[0075] like Figure 1 As shown, from the XRD spectrum of the Co3O4 nanoflower gas-sensitive material prepared in this embodiment, it can be seen that there are no impurity peaks and no phase separation occurs, which proves that Co3O4 is successfully prepared. Figure 3 (a) and (b) are the SEM images of the final Co3O4 nanoflowers. Figure 4 , Figure 5 As shown, the comparative material Co3O4 exhibits a lower response to CO. The test results show that as the concentration of the detected CO gas increases, the influence value of the Co3O4 nanoflower gas-sensitive material on CO gradually increases. At an operating temperature of 210°C, the response value of the Co3O4 nanoflower gas-sensitive material to 100ppm of CO gas is 2.08. It is speculated that this is because 3Ga / Co3O4 has a higher oxygen vacancy content than the other three materials. High oxygen vacancies can provide more unpaired electrons for the gas sensing material, further allowing the surface to adsorb more oxygen ions, resulting in an enhanced response. In addition, an appropriate proportion of Ga 3+ Co 3+ The content of Co 3+ The oxidizing property is better than Co 2+ Strong, CO molecules preferentially bind to Co3+ and 3+ Nearby oxygen species combine to form CO2, while Co 3+ is reduced to Co 2+ Therefore, 3Ga / Co3O4 exhibits better sensing performance compared with the other three materials. 3+ When the content is too high, it may lead to the formation of Ga oxide complex phase, resulting in a decrease in sensing performance.

[0076] By comparing Examples 1-3 of the present invention with the comparative example, it can be seen that Example 1, Example 2 and the comparative example can obtain response values ​​of more than 2 to 100ppm of CO gas, and the 5Ga-Co3O4 in Example 3 shows a lower response, which indicates that with the increase of Ga content in Ga-doped Co3O4 nanoflowers, its response value to CO gas at each concentration increases first and then decreases, and it is inferred that a response value of more than 3.0 can be obtained at a doping amount of 2%-4%, which has the best performance.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A Ga-doped Co3O4 nanoflower, characterized in that: The Ga-doped Co3O4 nanoflower is in a flower ball shape with a diameter of 10 μm; the doping amount of the metal Ga is 1% to 5% of the amount of the metal Co substance.

2. The Ga-doped Co3O4 nanoflower according to claim 1, characterized in that: The Ga-doped Co3O4 nanoflower is composed of a plurality of nanosheets with a thickness of 100-200 nm, and the diameter of each nanoflower is 4-10 μm.

3. A method for preparing Ga-doped Co3O4 nanoflowers as claimed in claim 1 or 2, characterized in that: The following steps are involved: (1) C4H6CoO4·4H2O and deionized water are uniformly stirred and ultrasonically mixed to obtain solution A; solution A is heated at 60-100°C for a period of time to obtain solution B; ammonia solution is added dropwise to solution B so that the pH is maintained at 9-11 to obtain solution C; solution C is transferred to room temperature, and then naturally cooled while stirring, solution C is washed with anhydrous ethanol and deionized water for multiple times and centrifuged to obtain a precipitate, and the precipitate is vacuum dried to obtain a Co(OH)2 nanoflower precursor; (2) uniformly dispersing the Co(OH)2 precursor obtained in step (1) in deionized water and subjecting it to ultrasonic and stirring treatment to obtain a mixed solution D; adding Ga(NO3)3·xH2O to the mixed solution D and continuing the ultrasonic stirring treatment, and then freeze-drying the mixed solution to obtain a Ga-Co(OH)2 precipitate; (3) The Ga-Co(OH)2 precipitate obtained in step (2) is calcined at 200-350°C in an air atmosphere to obtain a Ga-Co3O4 nanoflower gas-sensitive material.

4. The method for preparing Ga-doped Co3O4 nanoflowers according to claim 3, characterized in that: In solution A, the amount ratio of the amount of metal salt, the volume of deionized water, and the amount of ammonia water is (0.008-0.012 mol):(35-45 mL):(8-12 mL).

5. The method for preparing Ga-doped Co3O4 nanoflowers according to claim 3, characterized in that: In solution A, the molar ratio of the amount of metal salt C4H6CoO4·4H2O, the volume of deionized water, and the amount of ammonia water is 0.01 mol:40 mL:10 mL.

6. The method for preparing Ga-doped Co3O4 nanoflowers according to claim 3, characterized in that: In step (1), solution A is heated in an oil bath for 25 to 35 minutes.

7. The method for preparing Ga-doped Co3O4 nanoflowers according to claim 3, characterized in that: In step (2), the total amount of the metal salts Ga(NO3)3·xH2O and Co(OH)2 and the volume of deionized water is in the ratio of (0.3-2.216 mol):(5-30 mL).

8. The method for preparing Ga-doped Co3O4 nanoflowers according to claim 3, characterized in that: In step (2), the ultrasonic treatment time is 6 to 12 hours, the temperature is 40 to 60° C., and the power is 360 W; the freeze-drying time is 12 to 24 hours, and the temperature is -30° C.

9. The method for preparing Ga-doped Co3O4 nanoflowers according to claim 3, characterized in that: During the calcination treatment of Ga-Co(OH)2 precipitation, the temperature is gradually increased to 280-320°C at a heating rate of 0.5-2°C / min and maintained for 2-4h.

10. A use of the Ga-doped Co3O4 nanoflower as claimed in any one of claims 1 to 2 as a gas-sensitive material, characterized in that: It is used as a gas-sensitive material in carbon monoxide detection, and is used to detect 1 to 900 ppm CO at a temperature of 170 to 270°C.

Images