Preparation method and application of Co3O4 / In2O3 heterostructure

Abstract

The invention discloses a preparation method and application of a Co3O4 / In2O3 heterostructure, and the preparation method at least comprises the following steps: grinding and mixing Co3O4 and In2O3 powder, and calcining to obtain the Co3O4 / In2O3 heterostructure. The preparation method comprises the following steps: firstly, physically mixing Co3O4 and In2O3 by adopting a mechanical grinding method, further calcining the mixed Co3O4 / In2O3 at a high temperature, and enabling Co3O4 and In2O3 to interact under the induction of heat to form a heterostructure. The Co3O4 / In2O3 heterostructure based hydrogen sensor is prepared by taking the Co3O4 / In2O3 heterostructure as a gas sensing film. In hydrogen sensing detection, the response value of the Co3O4 / In2O3 heterostructure-based hydrogen sensor to 10 ppm hydrogen at 200 DEG C can reach 100, and the defect of poor hydrogen sensing performance is overcome.

Description

Technical Field

[0001] This application relates to a method for preparing a Co3O4 / In2O3 heterostructure and its application, belonging to the field of gas sensor technology. Background Technology

[0002] The world is currently facing a severe energy shortage. Hydrogen (H2), due to its high conversion efficiency, abundant reserves, and lack of harmful byproducts, is considered the most attractive next-generation renewable energy source and is already widely used in various sectors including energy, industry, and power. However, potential safety issues exist in the storage and use of hydrogen, making hydrogen detection and monitoring a crucial aspect of hydrogen energy development. With the growing demand for a sustainable hydrogen economy, the demand for hydrogen gas sensors is expected to continue to grow. However, hydrogen sensors using a single semiconductor metal oxide sensing film have limitations such as low response, low selectivity, high detection limits, and high operating temperatures. Improving the performance of hydrogen gas sensors remains a key challenge.

[0003] The fabrication of semiconductor metal-oxide heterostructures is an effective strategy for improving the performance of gas sensors. Typically, two materials are closely packed and interact at an interface to form a heterostructure. Developing simple and low-cost semiconductor metal-oxide heterostructures for enhancing gas sensing performance remains a significant challenge. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a Co3O4 / In2O3 heterostructure, its preparation, and its application. The Co3O4 / In2O3 heterostructure-based hydrogen sensor provided by this invention exhibits excellent performance for hydrogen, including high response value, good selectivity, cycle stability, and low detection limit, overcoming the shortcomings of poor performance in hydrogen sensors.

[0005] According to one aspect of this application, a method for preparing a Co3O4 / In2O3 heterostructure is provided, comprising at least the following steps:

[0006] Co3O4 and In2O3 powders were ground and mixed, then calcined to obtain a Co3O4 / In2O3 heterostructure.

[0007] Optionally, the mass ratio of Co3O4 to In2O3 is (0.1-30):100.

[0008] Optionally, the calcination conditions are as follows:

[0009] The calcination is carried out in an atmosphere of air, nitrogen, or argon.

[0010] The calcination temperature is 200–800℃;

[0011] The calcination time is 0.5 to 12 hours.

[0012] Optionally, the Co3O4 / In2O3 heterostructure includes p-type semiconductor Co3O4 and n-type semiconductor In2O3.

[0013] Optionally, the Co3O4 / In2O3 heterostructure has an octahedral block morphology;

[0014] The particle size of the Co3O4 / In2O3 heterostructure is 30–300 nm.

[0015] According to another aspect of this application, an application of a Co3O4 / In2O3 heterostructure in hydrogen sensing is provided. A Co3O4 / In2O3 heterostructure-based hydrogen sensor is coated on a substrate, and the temperature is controlled to obtain a Co3O4 / In2O3 heterostructure-based hydrogen sensor.

[0016] Optionally, the substrate is selected from at least one of ceramic tubes, interdigitated electrodes, and planar electrodes.

[0017] Optionally, the temperature is 50–3500°C.

[0018] Optionally, the hydrogen detection limit of the sensor is 50 ppb.

[0019] The beneficial effects that this application can produce include:

[0020] 1) The preparation process of the Co3O4 / In2O3 heterostructure provided in this application is simple, easy to operate, and low in cost.

[0021] 2) The preparation method provided in this application successfully generates a Co3O4 / In2O3 heterostructure under thermal induction, which promotes rapid electron transport.

[0022] 3) This application successfully prepared a Co3O4 / In2O3 heterostructure-based hydrogen sensor using the prepared Co3O4 / In2O3 heterostructure sensing material. It has a high response value to hydrogen and also exhibits excellent selectivity, linear response, cycle stability and low actual detection limit. It overcomes the shortcomings of poor performance of hydrogen sensors and is conducive to the vigorous development of the hydrogen energy industry. Attached Figure Description

[0023] Figure 1 Scanning electron microscope images of commercial Co3O4, physically mixed Co3O4 / In2O3 powder, Co3O4 / In2O3 heterostructure, and high-resolution transmission electron microscope images of Co3O4 / In2O3 heterostructure.

[0024] Figure 2A comparison of the response values ​​of hydrogen sensors made from commercially available Co3O4, commercially available In2O3, Co3O4 / In2O3 mixed powder, and Co3O4 / In2O3 heterostructure as sensing materials to 10 ppm hydrogen at different operating temperatures.

[0025] Figure 3 This is a gas selectivity test diagram of the Co3O4 / In2O3 heterostructure-based hydrogen sensor of this application;

[0026] Figure 4 This is a linear fitting curve of the response value of the Co3O4 / In2O3 heterostructure-based hydrogen sensor of this application to different concentrations of hydrogen;

[0027] Figure 5 The graph shows the cyclic response performance of the Co3O4 / In2O3 heterostructure-based hydrogen sensor of this application.

[0028] Figure 6 The graph shows the response performance of the Co3O4 / In2O3 heterostructure-based hydrogen sensor of this application to hydrogen concentrations as low as 50 ppb.

[0029] Figure 7 Test images of the hydrogen sensors prepared for comparative examples 1 and 2. Detailed Implementation

[0030] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0031] Unless otherwise specified, the raw materials and reagents used in the embodiments of this application were all purchased commercially.

[0032] The analysis method in the embodiments of this application is as follows:

[0033] Using scanning electron microscopy (Zeiss Supra 55) and transmission electron microscopy (JEOL)

[0034] The material morphology was analyzed using JEM 2100F.

[0035] The properties of the material were analyzed using a digital multimeter (VICTOR, 86E).

[0036] According to one embodiment of this application, the provided Co3O4 / In2O3 heterostructure-based hydrogen sensor uses a Co3O4 / In2O3 heterostructure as the sensing material.

[0037] The preparation method of the Co3O4 / In2O3 heterostructure includes the following steps:

[0038] (1) Take Co3O4 and In2O3 powders, grind and mix them, and the mass ratio of Co3O4 to In2O3 is (0.1~30):100;

[0039] (2) The mixed Co3O4 / In2O3 powder is placed in a tube furnace and calcined at 200-800℃; after cooling, the product is collected, namely the Co3O4 / In2O3 heterostructure.

[0040] The Co3O4 / In2O3 heterostructure-based hydrogen sensor provided by this invention is prepared by uniformly drop-coating a Co3O4 / In2O3 heterostructure-based hydrogen sensor onto a ceramic tube substrate. The ceramic tube contains electrodes, and a heating wire passes through the center of the ceramic tube to control the operating temperature.

[0041] This invention provides an application of the above-mentioned Co3O4 / In2O3 heterostructure in hydrogen sensing.

[0042] The present invention provides a sensor for hydrogen detection, comprising the above-described Co3O4 / In2O3 heterostructure.

[0043] Example 1

[0044] The preparation of the Co3O4 / In2O3 heterostructure includes the following steps:

[0045] 2.5 mg of Co3O4 and 100 mg of In2O3 powder were ground and mixed to make the mass ratio of Co3O4 to In2O3 2.5:100; the mixed Co3O4 / In2O3 powder was placed in a tube furnace and calcined at 600°C for 4 hours in air atmosphere; after cooling, the product was collected to obtain the Co3O4 / In2O3 heterostructure. Figure 1 (a), (b), and (c) are scanning electron microscope (SEM) images of Co3O4, Co3O4 / In2O3 powder, and Co3O4 / In2O3 heterostructure, respectively. It can be seen that the morphologies of Co3O4 and In2O3 are nanoparticles and bulk, respectively. The mixed Co3O4 / In2O3 powder was calcined to obtain the Co3O4 / In2O3 heterostructure. The morphology and structure of Co3O4 / In2O3 did not change during the calcination process. Figure 1 (d) is a high-resolution transmission electron microscope image of the Co3O4 / In2O3 heterostructure, which shows that the Co3O4 nanoparticles and In2O3 are closely attached to each other to form a heterostructure.

[0046] Comparative Example 1

[0047] Take 100mg of Co3O4 powder and grind it. Place the ground powder into a tube furnace and calcine it at 600℃ for 4 hours in an air atmosphere. After cooling, collect the product to obtain the Co3O4 product.

[0048] Comparative Example 2

[0049] Take 100mg of In2O3 powder and grind it. Place the ground powder into a tube furnace and calcine it at 600℃ for 4 hours in air atmosphere. After cooling, collect the product to obtain the In2O3 product.

[0050] Test Example 1

[0051] Construction of a hydrogen sensor:

[0052] A hydrogen sensor based on commercially available Co3O4, commercially available In2O3, Co3O4 / In2O3 mixed powder, and Co3O4 / In2O3 heterostructure was fabricated by uniformly drop-coating the commercially available Co3O4, commercially available In2O3, Co3O4 / In2O3 mixed powder, and Co3O4 / In2O3 heterostructure as the sensing membrane. The ceramic tube contains electrodes, and a heating wire passes through the center of the ceramic tube.

[0053] The Co3O4 and In2O3 products obtained in Comparative Examples 1 and 2 were uniformly coated onto a ceramic tube substrate. Electrodes were mounted on the ceramic tube, and a heating wire passed through the center of the ceramic tube, thus fabricating a hydrogen sensor with a sensing membrane composed of the Co3O4 and In2O3 products. Specific test results are shown in [link to test results]. Figure 7 .

[0054] Performance testing of hydrogen sensor:

[0055] A digital multimeter is used to continuously record the change in the resistance value of the sensor in air and the gas atmosphere to be measured, which is used as the sensor signal. The response value of the sensor is defined as: S = Ra / Rg, where Ra and Rg are the resistance values ​​of the sensor in air and the gas atmosphere to be measured, respectively.

[0056] The response values ​​of the Co3O4-based, In2O3-based, Co3O4 / In2O3 mixed-base, and Co3O4 / In2O3 heterostructure-based hydrogen sensors to 10 ppm hydrogen at different operating temperatures are as follows: Figure 2As shown, the Co3O4-based, In2O3-based, and Co3O4 / In2O3 hybrid hydrogen sensors all exhibit very low responses to hydrogen, especially the Co3O4-based hydrogen sensor, whose response value to 10 ppm hydrogen is less than 2 at any operating temperature. In contrast, the Co3O4 / In2O3 heterostructure-based hydrogen sensor exhibits the highest response value of 102.5 at an operating temperature of 200℃, significantly higher than the response values ​​of the Co3O4-based, In2O3-based, and Co3O4 / In2O3 hybrid hydrogen sensors. Therefore, 200℃ is the optimal operating temperature for the Co3O4 / In2O3 heterostructure-based hydrogen sensor, and all other performance tests were conducted at this operating temperature.

[0057] The response values ​​of the Co3O4 / In2O3 heterostructure-based hydrogen sensor to hydrogen and other interfering gases at an operating temperature of 200℃ are shown in the bar chart below. Figure 3 As shown, the response values ​​of the Co3O4 / In2O3 heterostructure-based hydrogen sensor to 10 ppm hydrogen, 5000 ppm carbon dioxide, 10 ppm methane, 10 ppm sulfur dioxide, and 10 ppm carbon monoxide are 102.5, 2.4, 5.2, 3.1, and 1.7, respectively. It exhibits a high response value to hydrogen, while the response value to interfering gases is very low, indicating that the Co3O4 / In2O3 heterostructure-based hydrogen sensor has good hydrogen selectivity.

[0058] The Co3O4 / In2O3 heterostructure-based hydrogen sensor, operating at 200℃, exhibits linear fitting curves for response values ​​to different hydrogen concentrations (0.5-14 ppm) as shown below. Figure 4 As shown. The linear fitting equation is S = 11.715C + 0.8418, and the correlation coefficient squared (R²) is... 2 The value is 0.9967, where S and C represent the hydrogen response value and hydrogen concentration, respectively. This indicates that the Co3O4 / In2O3 heterostructure-based hydrogen sensor has a good linear response to hydrogen, which is convenient for practical hydrogen detection.

[0059] The cycling performance of the Co3O4 / In2O3 heterostructure-based hydrogen sensor at 200℃ is as follows: Figure 5 As shown, in 7 cycles, the response value of the Co3O4 / In2O3 heterostructure-based hydrogen sensor to 10ppm hydrogen remained stable at around 100, indicating that the Co3O4 / In2O3 heterostructure-based hydrogen sensor has good cyclic stability.

[0060] The Co3O4 / In2O3 heterostructure-based hydrogen sensor responds to 50 ppb of hydrogen at 200°C as follows: Figure 6As shown, even with hydrogen concentrations as low as 50 ppb, the Co3O4 / In2O3 heterostructure-based hydrogen sensor can still detect it stably, with a response value of around 2.6, indicating that the Co3O4 / In2O3 heterostructure-based hydrogen sensor has a low practical detection limit.

[0061] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a Co3O4 / In2O3 heterostructure, characterized in that, At least the following steps are included: Co3O4 and In2O3 powders were ground and mixed, then calcined to obtain a Co3O4 / In2O3 heterostructure.

2. The preparation method according to claim 1, characterized in that, The mass ratio of Co3O4 to In2O3 is (0.1-30):

100.

3. The preparation method according to claim 1, characterized in that, The calcination conditions are as follows: The calcination is carried out in an atmosphere of air, nitrogen, or argon. The calcination temperature is 200–800℃; The calcination time is 0.5 to 12 hours.

4. The preparation method according to claim 1, characterized in that, The Co3O4 / In2O3 heterostructure includes p-type semiconductor Co3O4 and n-type semiconductor In2O3.

5. The preparation method according to claim 1, characterized in that, The Co3O4 / In2O3 heterostructure exhibits an octahedral blocky morphology. The particle size of the Co3O4 / In2O3 heterostructure is 30–300 nm.

6. An application of a Co3O4 / In2O3 heterostructure in hydrogen sensing, characterized in that, A Co3O4 / In2O3 heterostructure-based hydrogen sensor was coated onto a substrate, and the temperature was controlled to obtain a Co3O4 / In2O3 heterostructure-based hydrogen sensor. The Co3O4 / In2O3 heterostructure is prepared by any one of the preparation methods in claims 1 to 5.

7. The application according to claim 6, characterized in that, The substrate is selected from at least one of ceramic tubes, interdigitated electrodes, and planar electrodes.

8. The application according to claim 6, characterized in that, The temperature ranges from 50 to 3500℃.

9. The application according to claim 6, characterized in that, The sensor has a hydrogen detection limit of 50 ppb.

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