阅读说明：本技术 一种氧化镍/二氧化钛纳米棒复合结构气体传感器及其制备方法和应用 (Nickel oxide/titanium dioxide nanorod composite structure gas sensor and preparation method and application thereof ) 是由 夏晓红 张欢欢 高云 鲍钰文 凯文·赫姆伍德 于 2020-07-01 设计创作，主要内容包括：本发明涉及气体传感器技术领域,提供了一种氧化镍/二氧化钛纳米棒复合结构气体传感器及其制备方法和应用。本发明提供的气体传感器包括自下而上依次接触的衬底、氧化镍/二氧化钛纳米棒复合结构层和叉指电极。氧化镍/二氧化钛纳米棒复合结构层中氧化镍和二氧化钛复合形成异质结,进而提高传感器的气敏性能,且氧化镍独特的氧化还原特性也能够提高传感器的气敏特性。本发明提供的气体传感器气体浓度探测范围增大、响应恢复时间短、灵敏度和重复性高,对氢气、一氧化碳、氨气等气体均有良好的响应,且在室温下即可实现高灵敏度探测。本发明提供的制备方法步骤简单、成本低、可操作性强、对设备要求低,可用于大量合成。(The invention relates to the technical field of gas sensors, and provides a nickel oxide/titanium dioxide nanorod composite structure gas sensor as well as a preparation method and application thereof. The gas sensor provided by the invention comprises a substrate, a nickel oxide/titanium dioxide nanorod composite structure layer and an interdigital electrode which are sequentially contacted from bottom to top. The nickel oxide and the titanium dioxide in the nickel oxide/titanium dioxide nanorod composite structure layer are compounded to form a heterojunction, so that the gas-sensitive performance of the sensor is improved, and the unique redox characteristic of the nickel oxide can also improve the gas-sensitive characteristic of the sensor. The gas sensor provided by the invention has the advantages of increased detection range of gas concentration, short response recovery time, high sensitivity and repeatability, good response to gases such as hydrogen, carbon monoxide and ammonia, and high-sensitivity detection at room temperature. The preparation method provided by the invention has the advantages of simple steps, low cost, strong operability and low requirement on equipment, and can be used for mass synthesis.)

1. A nickel oxide/titanium dioxide nanorod composite structure gas sensor comprises a substrate, a nickel oxide/titanium dioxide nanorod composite structure layer arranged on the surface of the substrate and an interdigital electrode arranged on the surface of the nickel oxide/titanium dioxide nanorod composite structure layer from bottom to top; the nickel oxide/titanium dioxide nanorod composite structure layer consists of nickel oxide and titanium dioxide nanorods.

2. The gas sensor according to claim 1, wherein the nickel oxide/titanium dioxide nanorod composite structure layer comprises titanium dioxide nanorods and nickel oxide filled between the titanium dioxide nanorods;

or comprises a titanium dioxide nanorod/nickel oxide composite layer and a nickel oxide layer growing on the upper surface of the titanium dioxide nanorod/nickel oxide composite layer; the titanium dioxide nanorod/nickel oxide composite layer comprises titanium dioxide nanorods and nickel oxide filled among the titanium dioxide nanorods;

or comprises a titanium dioxide nano rod layer and a nickel oxide layer grown on the upper surface of the titanium dioxide nano rod layer.

3. The gas sensor according to claim 2, wherein when the nickel oxide/titanium dioxide nanorod composite structure layer comprises titanium dioxide nanorods and nickel oxide filled between the titanium dioxide nanorods, the thickness of the nickel oxide/titanium dioxide nanorod composite structure layer is 1.6-2.0 μm;

when the nickel oxide/titanium dioxide nanorod composite structure layer comprises a titanium dioxide nanorod/nickel oxide composite layer and a nickel oxide layer growing on the upper surface of the titanium dioxide nanorod/nickel oxide composite layer, the thickness of the titanium dioxide nanorod/nickel oxide composite layer is 2.1-2.5 mu m, and the thickness of the nickel oxide layer is 150-200 nm;

when the nickel oxide/titanium dioxide nanorod composite structure layer comprises a titanium dioxide nanorod layer and a nickel oxide layer growing on the upper surface of the titanium dioxide nanorod layer, the thickness of the titanium dioxide nanorod layer is 3.2-3.6 microns, and the thickness of the nickel oxide layer is 250-300 nm.

4. The gas sensor of claim 1, wherein the substrate is an FTO substrate; the interdigital electrode is a platinum interdigital electrode.

5. A method for producing a gas sensor according to any one of claims 1 to 4, comprising the steps of:

(1) preparing a titanium dioxide nanorod film on the surface of the substrate by a hydrothermal method, and then performing first annealing;

(2) growing nickel oxide on the titanium dioxide nanorod film subjected to the first annealing, and then performing second annealing to obtain a nickel oxide/titanium dioxide nanorod composite structure layer;

(3) and preparing an interdigital electrode on the surface of the nickel oxide/titanium dioxide nanorod composite structure to obtain the nickel oxide/titanium dioxide nanorod composite structure gas sensor.

6. The preparation method according to claim 5, wherein the hydrothermal method in the step (1) has a hydrothermal temperature of 120-180 ℃ and a hydrothermal time of 6-16 h; the solvent used in the hydrothermal method is water or a mixed solvent of water and ethanol.

7. The method according to claim 5 or 6, wherein the first annealing is performed at a temperature of 300 to 500 ℃ for 20 to 60min in an atmosphere of air.

8. The preparation method according to claim 5, wherein the method for growing the nickel oxide in the step (2) is a hydrothermal method or a magnetron sputtering method, the hydrothermal temperature of the hydrothermal method is 120-150 ℃, the hydrothermal time is 4-12 h, and the back pressure of the magnetron sputtering is 6 × 10^-4Pa, the radio frequency power for sputtering NiO is 60-100W, and the sputtering time is 15-60 min.

9. The preparation method according to claim 5 or 8, wherein the temperature of the second annealing is 300-500 ℃, the time is 60-120 min, and the annealing atmosphere is air.

10. The use of the nickel oxide/titanium dioxide nanorod composite structure gas sensor as defined in any one of claims 1 to 4 or the nickel oxide/titanium dioxide nanorod composite structure gas sensor prepared by the preparation method as defined in any one of claims 5 to 9 in a gas test.

Technical Field

The invention relates to the technical field of gas sensors, in particular to a nickel oxide/titanium dioxide nanorod composite structure gas sensor and a preparation method and application thereof.

Background

Gas sensing studies are aimed at creating an electronic nose that can detect the presence and concentration levels of various gases in the surrounding air, with sufficient sensitivity, selectivity and repeatability. Several common gases include hydrogen, carbon monoxide, ammonia gas and the like, and the toxic, harmful, flammable and explosive characteristics of the gases bring great potential safety hazards to the application, storage and transportation of the gases, so that obtaining a gas sensor which has high sensitivity, high response and recovery speed, stable performance and low price at room temperature becomes an urgent need in the current industrial field.

TiO₂Is an important wide-band-gap (anatase 3.2eV, rutile 3.0eV) semiconductor functional material. TiO, a common n-type semiconductor oxide material₂The material has the advantages of stable surface performance, no toxicity, easy synthesis, low cost and the like, and becomes one of the most popular materials in the field of gas sensors as a sensitive material. However, most are based on TiO₂The gas sensor still has low sensitivity at room temperature (most TiO)₂The optimal working temperature of the gas sensor is 100-200 ℃), and the response recovery time is long, so that the practical application of the gas sensor is limited to a certain extent.

Disclosure of Invention

In view of the above, the present invention aims to provide a nickel oxide/titanium dioxide nanorod composite structure gas sensor, and a preparation method and an application thereof. The gas sensor provided by the invention has the advantages of high sensitivity at room temperature, short response recovery time and large gas concentration detection range.

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

a nickel oxide/titanium dioxide nanorod composite structure gas sensor comprises a substrate, a nickel oxide/titanium dioxide nanorod composite structure layer arranged on the surface of the substrate and an interdigital electrode arranged on the surface of the nickel oxide/titanium dioxide nanorod composite structure layer from bottom to top; the nickel oxide/titanium dioxide nanorod composite structure layer consists of nickel oxide and titanium dioxide nanorods.

Preferably, the nickel oxide/titanium dioxide nanorod composite structure layer comprises titanium dioxide nanorods and nickel oxide filled between the titanium dioxide nanorods;

or comprises a titanium dioxide nanorod/nickel oxide composite layer and a nickel oxide layer growing on the upper surface of the titanium dioxide nanorod/nickel oxide composite layer; the titanium dioxide nanorod/nickel oxide composite layer comprises titanium dioxide nanorods and nickel oxide filled among the titanium dioxide nanorods;

or comprises a titanium dioxide nano rod layer and a nickel oxide layer grown on the upper surface of the titanium dioxide nano rod layer.

Preferably, when the nickel oxide/titanium dioxide nanorod composite structure layer comprises titanium dioxide nanorods and nickel oxide filled among the titanium dioxide nanorods, the thickness of the nickel oxide/titanium dioxide nanorod composite structure layer is 1.6-2.0 μm;

when the nickel oxide/titanium dioxide nanorod composite structure layer comprises a titanium dioxide nanorod/nickel oxide composite layer and a nickel oxide layer growing on the upper surface of the titanium dioxide nanorod/nickel oxide composite layer, the thickness of the titanium dioxide nanorod/nickel oxide composite layer is 2.1-2.5 mu m, and the thickness of the nickel oxide layer is 150-200 nm;

when the nickel oxide/titanium dioxide nanorod composite structure layer comprises a titanium dioxide nanorod layer and a nickel oxide layer growing on the upper surface of the titanium dioxide nanorod layer, the thickness of the titanium dioxide nanorod layer is 3.2-3.6 microns, and the thickness of the nickel oxide layer is 250-300 nm.

Preferably, the substrate is an FTO substrate; the interdigital electrode is a platinum interdigital electrode.

The invention provides a preparation method of the gas sensor in the scheme, which comprises the following steps:

(1) preparing a titanium dioxide nanorod film on the surface of the substrate by a hydrothermal method, and then performing first annealing;

(2) growing nickel oxide on the titanium dioxide nanorod film subjected to the first annealing, and then performing second annealing to obtain a nickel oxide/titanium dioxide nanorod composite structure layer;

(3) and preparing an interdigital electrode on the surface of the nickel oxide/titanium dioxide nanorod composite structure to obtain the nickel oxide/titanium dioxide nanorod composite structure gas sensor.

Preferably, the hydrothermal temperature of the hydrothermal method in the step (1) is 120-180 ℃, and the hydrothermal time is 6-16 h; the solvent used in the hydrothermal method is water or a mixed solvent of water and ethanol.

Preferably, the first annealing temperature is 300-500 ℃, the time is 20-60 min, and the annealing atmosphere is air.

Preferably, the method for growing the nickel oxide in the step (2) is a hydrothermal method or a magnetron sputtering method, the hydrothermal temperature of the hydrothermal method is 120-150 ℃, the hydrothermal time is 4-12 h, and the back pressure of the magnetron sputtering is 6 × 10^-4Pa, the radio frequency power for sputtering NiO is 60-100W, and the sputtering time is 15-60 min.

Preferably, the temperature of the second annealing is 300-500 ℃, the time is 60-120 min, and the annealing atmosphere is air.

The invention provides an application of the nickel oxide/titanium dioxide nanorod composite structure gas sensor or the nickel oxide/titanium dioxide nanorod composite structure gas sensor prepared by the preparation method in a gas test.

The invention provides a nickel oxide/titanium dioxide nanorod composite structure gas sensor which comprises a substrate, a nickel oxide/titanium dioxide nanorod composite structure layer arranged on the surface of the substrate and an interdigital electrode arranged on the surface of the nickel oxide/titanium dioxide nanorod composite structure layer. The gas sensor provided by the invention comprises a nickel oxide/titanium dioxide nanorod composite structure layer, wherein nickel oxide and titanium dioxide are compounded to form a heterojunction, so that the gas-sensitive performance of the sensor is improved, and the unique redox characteristic of nickel oxide can also improve the gas-sensitive characteristic of the sensor. The gas sensor provided by the invention has the advantages of increased gas concentration detection range, short response recovery time, high sensitivity and repeatability, and can realize high-sensitivity detection at room temperature.

The invention also provides a preparation method of the nickel oxide/titanium dioxide nanorod composite structure gas sensor. The preparation method provided by the invention has the advantages of simple steps, low cost, strong operability, high repeatability and low equipment requirement, and can be used for mass synthesis of finally obtained TiO₂The nano-rod keeps good orientation, NiO is not easy to agglomerate, and the specific surface area of the obtained nickel oxide/titanium dioxide nano-rod composite structure is large.

The invention also provides the application of the nickel oxide/titanium dioxide nanorod composite structure gas sensor in gas detection. The gas sensor provided by the invention has good response to gases such as hydrogen, carbon monoxide, ammonia and the like at room temperature.

Drawings

FIG. 1 shows TiO in comparative example 1₂XRD pattern of nanorods (after annealing);

FIG. 2 shows TiO in comparative example 1₂FESEM picture of the surface of the nanorod film (after annealing);

FIG. 3 shows a graph of a comparative example 1TiO₂The resistance value-time change curve of the nanorod gas sensor responding to hydrogen;

FIG. 4 is an XRD pattern of NiO synthesized in example 1 (after annealing);

FIG. 5 shows NiO/TiO in example 1₂FESEM image of the surface of the nanorod composite structure gas sensor;

FIG. 6 shows NiO/TiO in example 1₂A sectional FESEM image of the nanorod composite structure gas sensor;

FIG. 7 shows NiO/TiO in example 1₂The resistance value-time change curve of the nanorod composite structure gas sensor responding to hydrogen;

FIG. 8 shows NiO/TiO in example 1₂The resistance value-time change curve of the nanorod composite structure gas sensor responding to carbon monoxide;

FIG. 9 shows NiO/TiO in example 1₂The resistance value-time change curve of the nanorod composite structure gas sensor responding to ammonia gas;

FIG. 10 shows NiO/TiO in example 1₂The resistance value-time change curve of the nanorod composite structure gas sensor responding to nitrogen dioxide;

FIG. 11 shows NiO/TiO in example 2₂The resistance value-time change curve of the nanorod composite structure gas sensor responding to hydrogen;

FIG. 12 shows NiO/TiO in example 3₂Resistance value-time change curve of the nanorod composite structure gas sensor in response to hydrogen.

The example results show that when the ethanol dosage in the titanium dioxide nano-rod grown by the hydrothermal method is 0ml, the first annealing temperature is 400 ℃, the time is 20min, the temperature of the nickel oxide grown by the hydrothermal method is 150 ℃, and the time is 8h, the obtained gas sensor has the detectable range of 1ppm to 12000ppm for hydrogen, 1ppm to 8000ppm for carbon monoxide and 1200ppm to 12000ppm for ammonia at room temperature.