阅读说明：本技术 一种基于三氧化钼纳米片的硫化氢气体传感器制备方法 (Preparation method of hydrogen sulfide gas sensor based on molybdenum trioxide nanosheets ) 是由 郑雁公 鲍军强 潘均柏 张晓伟 董梦云 于 2020-12-24 设计创作，主要内容包括：本发明涉及到硫化氢气体传感器领域,特别涉及到一种基于三氧化钼纳米片的硫化氢气体传感器制备方法。技术方案：在传感器中先将三氧化钼纳米片粉末分散在去离子水或者乙醇中形成悬浮液,然后均匀涂覆在金叉指电极上并在不超过150℃的温度下下加热以形成薄膜；传感器的工作温度在200-350℃范围内；传感器的实时监测信号是在1V的直流电压下,传感器的电阻值的变化。本发明的效果和益处是：相对于报道的硫化氢气体传感器,利用三氧化钼纳米片材料的气体传感器具有更好的选择性,且灵敏度高,制备简单。(The invention relates to the field of hydrogen sulfide gas sensors, in particular to a preparation method of a hydrogen sulfide gas sensor based on molybdenum trioxide nanosheets. The technical scheme is as follows: in the sensor, molybdenum trioxide nanosheet powder is dispersed in deionized water or ethanol to form a suspension, and then the suspension is uniformly coated on a gold interdigital electrode and heated at the temperature of not more than 150 ℃ to form a thin film; the working temperature of the sensor is within the range of 200-350 ℃; the real-time monitoring signal of the sensor is the change of the resistance value of the sensor under the direct-current voltage of 1V. The invention has the advantages that: compared with the reported hydrogen sulfide gas sensor, the gas sensor using the molybdenum trioxide nanosheet material has better selectivity, high sensitivity and simple preparation.)

1. A preparation method of a hydrogen sulfide gas sensor based on molybdenum trioxide nanosheets is characterized by comprising the following steps:

s1, dispersing molybdenum trioxide nanosheet powder in deionized water or ethanol to form a suspension;

s2, uniformly coating the suspension on a gold interdigital electrode and heating at a temperature not higher than 150 ℃ to form a film; the working temperature of the sensor is within the range of 200-350 ℃, and the real-time monitoring signal of the sensor is under the direct-current voltage of 1V.

2. The method of manufacturing a molybdenum trioxide nanosheet based hydrogen sulfide gas sensor as recited in claim 1 in which the bulk molybdenum trioxide is exfoliated into nanosheets using a liquid phase exfoliation method, then collected by centrifugation and lyophilized.

3. The method for preparing a hydrogen sulfide gas sensor based on molybdenum trioxide nanosheets of claim 1, wherein the method for preparing the molybdenum trioxide nanosheets comprises the following steps:

d1, mixing and grinding molybdenum trioxide and acetonitrile in a molar ratio of less than or equal to 3: 20;

d2, putting the fully ground powder into ethanol/water or isopropanol/water solution with volume fraction, and carrying out ultrasonic treatment for 1-4 hours by using an ultrasonic processor;

d3, centrifuging at low speed at room temperature to separate large-particle molybdenum trioxide;

d4, collecting a yellowish blue supernatant containing the high-concentration molybdenum trioxide nanosheets, and centrifuging at a high speed for a sufficient time to separate the molybdenum trioxide nanosheets;

and D5, collecting the blue precipitate, and performing freeze-drying by using a freeze dryer to obtain molybdenum trioxide nanosheet powder.

Technical Field

The invention belongs to the field of hydrogen sulfide gas sensors, and particularly relates to a preparation method of a molybdenum trioxide nanosheet sensitive material and a preparation method of a sensor.

Background

It is well known that a certain amount of H2S can be a serious hazard to the human body and even a life-threatening hazard. The maximum permissible concentration of H2S is 10mg/m3 (about 7.2ppm) within a working day according to the national occupational health standards of the people's republic of china (GBZ 2.1.1-2007) workplace hazard occupational exposure limit chemical hazard. When the concentration of H2S is higher than 250ppm, death may result. Therefore, it is of great significance to develop a reliable and efficient H2S gas sensor. Molybdenum trioxide is an important n-type semiconductor, has an energy band gap of about 2.39-2.9eV, and has unique gas-sensitive characteristics. Nanostructured molybdenum trioxide is widely recognized as a viable gas sensor, such as nanorods, nanobelts, nanomembranes, hollow spheres, and the like. However, the development of high performance gas sensors based on nano molybdenum trioxide remains a challenge. There are currently two common strategies to improve the performance of gas sensors: a method for improving the performance of a gas sensor is to load noble metals such as silver, platinum, gold and the like on the surface of a sensitive material; another approach is to control the growth of nanomaterials by specially designed sizes, shapes and morphologies, since the properties of gas sensors are highly dependent on their specific surface area. Among various complicated nanostructures, two-dimensional nanostructures such as nanosheets can be effective as a building block for constructing a crystal-oriented nanodevice due to their anisotropic structure.

Disclosure of Invention

The invention aims to provide a preparation method of a hydrogen sulfide gas sensor based on a molybdenum trioxide nanosheet material, which aims to solve the technical problem that a liquid phase stripping method is utilized to strip bulk molybdenum trioxide into nanosheets, and the characteristics of large specific surface area and many surface active sites are utilized, so that better gas-sensitive response of the hydrogen sulfide gas is obtained.

The technical scheme is as follows:

a preparation method of a hydrogen sulfide gas sensor based on molybdenum trioxide nanosheets is characterized by comprising the following steps:

s1, dispersing molybdenum trioxide nanosheet powder in deionized water or ethanol to form a suspension;

s2, uniformly coating the suspension on a gold interdigital electrode and heating at a temperature not higher than 150 ℃ to form a film; the working temperature of the sensor is within the range of 200-350 ℃, and the real-time monitoring signal of the sensor is under the direct-current voltage of 1V.

Further, the bulk molybdenum trioxide is stripped into nanosheets by a liquid phase stripping method, and then collected by centrifugal separation and lyophilized.

Further, the preparation method of the nano-scale trioxide comprises the following steps:

d1, mixing and grinding molybdenum trioxide and acetonitrile in a molar ratio of less than or equal to 3: 20;

d2, putting the fully ground powder into ethanol/water or isopropanol/water solution with volume fraction, and carrying out ultrasonic treatment for 1-4 hours by using an ultrasonic processor;

d3, centrifuging at low speed at room temperature to separate large-particle molybdenum trioxide;

d4, collecting a yellowish blue supernatant containing the high-concentration molybdenum trioxide nanosheets, and centrifuging at a high speed for a sufficient time to separate the molybdenum trioxide nanosheets;

and D5, collecting the blue precipitate, and performing freeze-drying by using a freeze dryer to obtain molybdenum trioxide nanosheet powder.

The invention has the beneficial effects that:

the sensor prepared by the preparation method of the hydrogen sulfide gas sensor based on the molybdenum trioxide nanosheets has the characteristics of large surface area and many surface active sites, so that better gas-sensitive response of the hydrogen sulfide gas is obtained; compared with the existing molybdenum trioxide hydrogen sulfide gas sensor, the gas sensor using the molybdenum trioxide nanosheet material has better selectivity, good repeatability and simple preparation.

Drawings

FIG. 1 is an X-ray diffraction pattern of a prepared molybdenum trioxide nanosheet;

FIG. 2 is a transmission electron micrograph of the prepared molybdenum trioxide nanosheets;

FIG. 3 is a real diagram of a gold interdigital electrode;

FIG. 4 is a graph of the change in resistance of the sensor to hydrogen sulfide gas at 300 deg.C;

FIG. 5 is a graph of the change in resistance of the sensor at 300 deg.C for various concentrations of hydrogen sulfide gas;

figure 6 is a graph comparing the response of the sensor to common VOC gases at 300 c.

Detailed Description

The preparation method of the hydrogen sulfide gas sensor based on the molybdenum trioxide nanosheets is further described with reference to the accompanying drawings 1-6.

Example 1

A preparation method of a hydrogen sulfide gas sensor based on molybdenum trioxide nanosheets is characterized by comprising the following steps:

s1, dispersing molybdenum trioxide nanosheet powder in deionized water or ethanol to form a suspension;

s2, uniformly coating the suspension on a gold interdigital electrode and heating at a temperature not higher than 150 ℃ to form a film; the working temperature of the sensor is within the range of 200-350 ℃, and the real-time monitoring signal of the sensor is under the direct-current voltage of 1V.

Further, the bulk molybdenum trioxide is stripped into nanosheets by a liquid phase stripping method, and then collected by centrifugal separation and lyophilized.

Further, the preparation method of the nano-scale trioxide comprises the following steps:

d1, mixing and grinding molybdenum trioxide and acetonitrile in a molar ratio of 3: 20;

d2, putting the fully ground powder into ethanol/water or isopropanol/water solution with volume fraction, and carrying out ultrasonic treatment for 1-4 hours by using an ultrasonic processor;

d3, centrifuging at low speed at room temperature to separate large-particle molybdenum trioxide;

d4, collecting a yellowish blue supernatant containing high-concentration molybdenum trioxide nano-sheets, wherein the concentration is more than 1 mg/ml; centrifuging at high speed for a sufficient time to separate molybdenum trioxide nanosheets, wherein the rotating speed is more than 8000 rpm;

and D5, collecting the blue precipitate, and performing freeze-drying by using a freeze dryer to obtain molybdenum trioxide nanosheet powder.

The technical scheme of the invention is that firstly, a liquid phase stripping method is utilized to strip the bulk molybdenum trioxide material into nanosheets. Typical XRD and surface micro-morphology characteristics of the prepared nano-sheet are respectively shown in attached figures 1 and 2. And finally, coating the nanosheet material on a gold interdigital electrode to obtain the final molybdenum trioxide nanosheet sensor shown in the attached figure 3.

Example 2

Preparing a nano sheet material: molybdenum trioxide and acetonitrile were mixed and milled in a molar ratio of 3: 20. The fully ground powder is put into ethanol/water or isopropanol/water solution with volume fraction, and is treated by ultrasonic for 1-4 hours by an ultrasonic processor, and then is centrifuged at low speed at room temperature to separate out large-particle molybdenum trioxide. And collecting the yellowish blue supernatant containing the high-concentration molybdenum trioxide nanosheets, and centrifuging at a high speed for a sufficient time to separate the molybdenum trioxide nanosheets. Collecting blue precipitate, and freeze-drying by using a freeze dryer to obtain molybdenum trioxide nanosheet powder.

Preparing a sensor: molybdenum trioxide nanosheet powder is dispersed in deionized water, ethanol or isopropanol to form a suspension, and the suspension is uniformly coated on a gold interdigital electrode of an alumina ceramic substrate shown in figure 3. The electrode is then heated at a temperature not exceeding 150 c for a period of time to evaporate the water and form a film.

And (3) testing of the sensor: the prepared sensor is placed in a flowing air atmosphere, the sensor is heated to the working temperature range of 200-350 ℃, and then target gas is introduced. The 1V DC voltage is provided by a digital source meter and the resistance change is measured. FIG. 4 shows the resistance change (i.e., the sensing signal) of a typical fabricated sensor under an atmosphere of about 10ppm hydrogen sulfide. After 20 minutes from the sensor, the sensor resistance changed by about 75%. Fig. 5 shows the resistance change (i.e., sensing signal) of a typical prepared sensor under hydrogen sulfide atmosphere with different concentrations. The sensor still responds significantly to a concentration of 0.5ppm hydrogen sulfide gas. Figure 6 shows the response of a typical prepared sensor to 10ppm of different gases. Compared with the reported hydrogen sulfide sensor, the gas sensitive selectivity is better.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.