阅读说明：本技术 一种基于Pd-Ag合金纳米晶的氢气传感器及其制备方法 (Hydrogen sensor based on Pd-Ag alloy nanocrystalline and preparation method thereof ) 是由 许鹏程 徐东升 李昕欣 王雪晴 于海涛 陈滢 于 2019-04-28 设计创作，主要内容包括：本发明提供一种基于Pd-Ag合金纳米晶氢气传感器,包括有金属氧化物敏感材料,所述金属氧化物敏感材料的表面负载有Pd-Ag合金纳米晶颗粒。本发明进一步提供一种基于Pd-Ag合金纳米晶的氢气传感器的制备方法及其应用。本发明提供的一种基于Pd-Ag合金纳米晶的氢气传感器及其制备方法,能够增强氢气传感器检测氢气的灵敏度,实现协同催化作用,其制备方法简单成熟、易于操作、价格低廉,用途先进、具有现实的应用意义,对易燃易爆气体的检测等有着积极的意义。(The invention provides a Pd-Ag alloy nanocrystalline-based hydrogen sensor which comprises a metal oxide sensitive material, wherein Pd-Ag alloy nanocrystalline particles are loaded on the surface of the metal oxide sensitive material. The invention further provides a preparation method and application of the hydrogen sensor based on the Pd-Ag alloy nanocrystalline. The hydrogen sensor based on the Pd-Ag alloy nanocrystalline and the preparation method thereof can enhance the sensitivity of the hydrogen sensor for detecting hydrogen and realize the synergetic catalysis effect, and the preparation method is simple and mature, easy to operate, low in price, advanced in use, practical in application significance and positive in detection of inflammable and explosive gases and the like.)

1. A hydrogen sensor is characterized by comprising a metal oxide sensitive material, wherein Pd-Ag alloy nanocrystalline particles are loaded on the surface of the metal oxide sensitive material.

2. A hydrogen sensor according to claim 1, characterized in that the metal oxide sensitive material is selected from ZnO, SnO₂、In₂O₃Or WO₃Any one of them.

3. The hydrogen sensor according to claim 1, wherein the atomic ratio of the Pd element to the Ag element in the Pd-Ag alloy nanocrystal is 1:4 to 5: 1.

4. The hydrogen sensor according to claim 1, wherein the Pd-Ag alloy nanocrystals account for 0.1-1% by mass of the metal oxide-sensitive material in the hydrogen sensor.

5. The production method of a hydrogen sensor according to any one of claims 1 to 4, comprising the steps of:

1) dispersing the Pd-Ag alloy nanocrystalline into a solvent to obtain a Pd-Ag alloy nanocrystalline dispersion solution;

2) mixing the Pd-Ag alloy nanocrystalline dispersion solution obtained in the step 1) with a metal oxide sensitive material and then carrying out ultrasonic treatment to obtain a Pd-Ag alloy nanocrystalline modified hydrogen sensitive material;

3) and (3) coating the hydrogen sensitive material obtained in the step (2) on comb electrodes of a sensor chip to obtain the hydrogen sensor modified by the needed Pd-Ag alloy nanocrystals.

6. The method for preparing a hydrogen sensor according to claim 5, wherein in the step 1), the ratio of the mass g of the Pd-Ag alloy nanocrystals added to the volume mL of the solvent added is 0.012-0.030: 5 to 60.

7. The method for preparing a hydrogen sensor according to claim 5, wherein in step 1), the solvent is selected from one of n-hexane, ethanol or toluene.

8. The method for preparing a hydrogen sensor according to claim 5, wherein the ratio of the volume mL of the Pd-Ag alloy nanocrystal dispersion solution to the mass g of the metal oxide sensitive material is 1-2: 0.02 to 0.15.

9. The method for preparing a hydrogen sensor according to claim 5, wherein the step 2) further comprises any one or more of the following conditions:

A) the mixing is stirring mixing, and the mixing time is 0.5-1.5 min;

B) the ultrasonic time is 50-70 s;

C) the power of the ultrasonic wave is 50-200W.

10. Use of a hydrogen sensor according to any one of claims 1 to 4 in hydrogen detection.

Technical Field

The invention belongs to the technical field of gas sensors, relates to a novel hydrogen sensor and a preparation method thereof, and particularly relates to a Pd-Ag alloy nanocrystalline-based hydrogen sensor and a preparation method thereof.

Background

High-sensitivity detection of hydrogen is of great significance in the widely applied fields of fuel cells, semiconductor industry, power plants and the like. Since hydrogen has high flammability and explosiveness, development of a high-performance hydrogen sensor is required. Although the traditional metal oxide sensitive material (such as zinc oxide) has certain sensitivity to hydrogen, the sensitivity and selectivity of the traditional metal oxide sensitive material still cannot meet the requirement of hydrogen detection in an actual detection environment.

Palladium catalysts are often used to improve the hydrogen sensitivity of the sensing material. But palladium metal alone is susceptible to poisoning and loss of activity. The Pd-M alloy catalyst with synergistic enhancement effect is formed by alloying with other noble metals, and is a way to overcome the defects that single palladium metal is easy to be poisoned and the like. In addition, since palladium is one of the rarest noble metals in the world, the amount of palladium can be reduced by doping a metal such as silver to prepare an alloy catalyst. From the perspective of application prospect, the development of the Pd-M-based alloy catalyst not only has theoretical research significance, but also has long-term consideration in the aspect of application.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a hydrogen sensor based on Pd-Ag alloy nanocrystals and a method for preparing the same, which can improve the efficiency and sensitivity of hydrogen detection.

In order to achieve the above and other related objects, a first aspect of the present invention provides a Pd-Ag alloy nanocrystal-based hydrogen sensor, including a metal oxide sensitive material, the surface of which is loaded with Pd-Ag alloy nanocrystal particles.

Preferably, the metal oxide sensitive material is selected from ZnO and SnO ₂、In₂O₃Or WO₃Any one of them. More preferably, the metal oxide sensitive material is selected from ZnO, SnO₂Or In₂O₃Any one of them. Most preferably, the metal oxide sensitive material is ZnO.

Preferably, the atomic ratio of the Pd element to the Ag element (Pd/Ag) in the Pd-Ag alloy nanocrystalline is 1: 4-5: 1.

More preferably, the atomic ratio of the Pd element to the Ag element (Pd/Ag) in the Pd-Ag alloy nanocrystalline is 1: 1-5: 1.

Most preferably, the atomic ratio of the Pd element to the Ag element (Pd/Ag) in the Pd-Ag alloy nanocrystalline is 3.9-4.1: 1.

Preferably, in the hydrogen sensor, the mass percentage of the Pd-Ag alloy nanocrystals in the metal oxide sensitive material is 0.1-1%.

Preferably, the hydrogen sensor is a semiconductor type sensor that is conventionally used. Specifically, the semiconductor type sensor is a resistance type semiconductor sensor, also called a metal oxide semiconductor hydrogen sensor. The working principle is as follows: after hydrogen is adsorbed, the hydrogen is taken as a donor to release electrons to be combined with oxygen ions in the chemical adsorption layer, so that the carrier concentration is changed, and the change value has a certain functional relation with the volume fraction of the hydrogen.

Preferably, in the hydrogen sensor, the metal oxide sensitive material is used as an electrode of the hydrogen sensor. Particularly, the metal oxide sensitive material is used as a comb electrode of a hydrogen sensor chip.

Preferably, the Pd-Ag alloy nanocrystalline particles are loaded on the surface of the metal oxide sensitive material, namely the Pd-Ag alloy nanocrystalline particles are coated on the surface of the metal oxide sensitive material.

The invention provides a preparation method of a hydrogen sensor based on Pd-Ag alloy nanocrystals, which comprises the following steps:

1) dispersing the Pd-Ag alloy nanocrystalline into a solvent to obtain a Pd-Ag alloy nanocrystalline dispersion solution;

2) mixing the Pd-Ag alloy nanocrystalline dispersion solution obtained in the step 1) with a metal oxide sensitive material and then carrying out ultrasonic treatment to obtain a Pd-Ag alloy nanocrystalline modified hydrogen sensitive material;

3) and (3) coating the hydrogen sensitive material obtained in the step (2) on comb electrodes of a sensor chip to obtain the required hydrogen sensor based on the Pd-Ag alloy nanocrystalline.

Preferably, in the step 1), the ratio of the mass (g) of the added Pd-Ag alloy nanocrystals to the volume (mL) of the added solvent is 0.012-0.030: 5 to 60.

More preferably, the ratio of the mass (g) of the Pd-Ag alloy nanocrystals added to the volume (mL) of the solvent added is 0.012 to 0.030: 10 to 50.

Preferably, in step 1), the solvent is selected from one of n-hexane, ethanol or toluene. More preferably, the solvent is n-hexane.

Preferably, in the step 2), the ratio of the volume (mL) of the Pd-Ag alloy nanocrystal dispersion solution to the mass (g) of the metal oxide sensitive material is 1-2: 0.02 to 0.15.

More preferably, the ratio of the volume (mL) of the added Pd-Ag alloy nanocrystalline dispersion solution to the mass (g) of the added metal oxide sensitive material is 1-2: 0.05 to 0.10.

Preferably, in the step 2), the mixing is stirring and mixing, and the mixing time is 0.5-1.5 min. More preferably, the mixing time is 1 min.

Preferably, in the step 2), the time of the ultrasonic treatment is 50-70 s. More preferably, the time of the ultrasound is 60 s.

Preferably, in the step 2), the power of the ultrasound is 50-200W. More preferably, the power of the ultrasound is 100W.

Preferably, in step 3), the sensor is a hydrogen sensor. More preferably, the hydrogen sensor is a resistive hydrogen sensor.

Preferably, in step 3), the sensor chip is a silicon chip of a conventionally used hydrogen sensor. The comb-teeth electrode of the sensor chip is a comb-teeth electrode of a silicon chip of a conventionally used hydrogen sensor.

The third aspect of the invention provides application of a hydrogen sensor based on Pd-Ag alloy nanocrystals in hydrogen detection.

As mentioned above, the hydrogen sensor based on Pd-Ag alloy nanocrystalline and the preparation method thereof provided by the invention improve the existing hydrogen sensor, load Pd-Ag alloy nanocrystalline particles on the surface of semiconductor metal oxide by adopting an ultrasonic method to obtain a Pd-Ag alloy nanocrystalline modified hydrogen sensitive material, and further coat the sensitive material on comb teeth electrodes of a microsensor chip to obtain the required resistance-type hydrogen sensor. As shown in figure 1, oxygen ions on the surface of the Pd-Ag alloy nanocrystalline can react with hydrogen molecules to generate water molecules and release electrons, and the process causes the resistance of the sensing material to be reduced, so that the detection of the hydrogen is realized. The addition of Ag can change the adsorption state of hydrogen molecules on the surface of the sensing material and adjust the activation energy required by the catalytic reaction. When Pd and Ag in the Pd-Ag alloy nanocrystalline modified on the hydrogen sensor are kept in a certain proportion, the semiconductor metal oxide hydrogen sensor has the largest response, and the synergistic effect of the Pd-Ag alloy is the most obvious. The hydrogen sensor can detect the hydrogen with the lowest sensitivity reaching 1ppm, thereby enhancing the sensitivity of the hydrogen sensor for detecting the hydrogen.

The hydrogen sensor based on the Pd-Ag alloy nanocrystalline provided by the invention applies the hydrogen sensor modified by the Pd-Ag alloy nanocrystalline to the detection of hydrogen, wherein the Pd-Ag alloy nanocrystalline material plays a role of a catalyst in the reaction of the semiconductor metal oxide nanowire and the hydrogen. The composite structure nano material generates a new higher-level complex structure system by different functionalized nano elements through a certain assembly arrangement mode, and shows flexible and changeable synergetic catalysis in heterogeneous catalysis.

The hydrogen sensor based on the Pd-Ag alloy nanocrystalline is simple and mature in preparation, easy to operate, low in price, advanced in application, practical in application significance and positive in detection of toxic gases and combustible gases and the like.

Drawings

Fig. 1 shows scanning electron micrographs of hydrogen sensors prepared by Pd-Ag alloy nanocrystal/zinc oxide recombination in examples 1 and 2.

Fig. 2 is a transmission electron microscope photograph showing the Pd — Ag alloy nanocrystals prepared in example 1.

Fig. 3 is a transmission electron microscope photograph showing the Pd-Ag alloy nanocrystal/zinc oxide composite prepared in example 1.

Fig. 4 is a graph showing a comparison of the responses of the hydrogen sensor # 1 and the zinc oxide hydrogen sensor in example 1 to detect hydrogen.

Detailed Description

The present invention is further illustrated below with reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention.

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be understood that the processing equipment or devices not specifically mentioned in the following examples are conventional in the art; all pressure values and ranges refer to relative pressures.

Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.