Optical excitation low-consumption gas sensor based on bismuth telluride material and preparation method of optical excitation low-consumption gas sensor

Abstract

The invention discloses an optical excitation low-consumption gas sensor based on a bismuth telluride material and a preparation method of the optical excitation low-consumption gas sensor, and relates to the technical field of environmental monitoring. The invention discloses a preparation method of an optical excitation low-consumption gas sensor based on a bismuth telluride material, which comprises the following steps: coating a gas sensitive material layer on the surface of a sensing substrate to obtain a gas sensitive detection element; a visible light source is arranged above the gas-sensitive detection element, so that the light-excited low-consumption gas-sensitive sensor is obtained; the gas-sensitive material layer is obtained by coating the surface of the sensing substrate with a bismuth telluride mixed solution; the bismuth telluride mixed solution is obtained by mixing bismuth telluride powder and poly (3, 4-ethylenedioxythiophene): polystyrene sulfonate dispersoid. The light-excited low-consumption gas sensor prepared by the invention shows strong response sensitivity and restorability to hydrogen (1%) under the excitation of visible light.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring, and in particular to a light-excited low-consumption gas-sensitive sensor based on bismuth telluride material and a preparation method thereof. Background Art

[0002] With the development of science and technology, facing the tense situation of resource shortage, hydrogen, solar energy and nuclear energy are called the three major new energy sources. Among them, hydrogen is widely used in fuel cell vehicles, military and other fields. At the same time, hydrogen, as a reducing gas and carrier gas, has extremely important application value in electronics, medical chemicals, metal smelting and other fields. However, the molecular weight of hydrogen is very small, colorless and odorless. In the process of daily production and use, it is very easy to leak and difficult to be discovered. When hydrogen is mixed with air, it is flammable in the concentration range of 4-75vt%. Traditional hydrogen concentration detection equipment mainly includes: gas chromatograph, mass spectrometer and other analytical instruments. These traditional equipment are relatively large in size, expensive, high in maintenance cost, and slow in sampling and response time. In addition to traditional hydrogen detection equipment, hydrogen sensors have been developing rapidly in recent years. Hydrogen sensors are a kind of conversion device. When a certain volume fraction of hydrogen molecules is detected, an electrical signal is output. This electrical signal is proportional to the detected hydrogen concentration.

[0003] The development of resistive chemical gas sensors has gone through about 30 years and has achieved great success, but there are still several problems that need to be better studied and solved; among them, the difficulties mainly exist in: (1) Sensors based on oxidizing materials generally require heating elements and need to work at a specific temperature; (2) Sensors based on heterogeneous materials have improved the above problems, but they are difficult to synthesize and are still a challenge for mass production; (3) At present, most gas sensors perform adsorption detection on hydrogen gas, and desorption after detection and preparation for the next detection are key issues that need to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a light-excited low-consumption gas sensor based on bismuth telluride material and a preparation method thereof, to solve the following technical problems:

[0005] Existing resistive gas sensors have the problems of low response sensitivity and long recovery time after detection.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a light-excited low-consumption gas-sensitive sensor based on bismuth telluride material comprises the following steps:

[0008] S1: coating a gas-sensitive material layer on the surface of a sensing substrate to obtain a gas-sensitive detection element;

[0009] S2: a visible light source is arranged above the gas-sensitive detection element to obtain a light-excited low-consumption gas-sensitive sensor;

[0010] The gas-sensitive material layer is obtained by coating a bismuth telluride mixed solution on the surface of the sensing substrate;

[0011] The bismuth telluride mixed solution is obtained by mixing bismuth telluride powder with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion.

[0012] As a further embodiment of the present invention, the addition ratio of bismuth telluride powder, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion in the bismuth telluride mixed solution is 4.5-5.5 mg:10 mL.

[0013] As a further embodiment of the present invention, the solid content of the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion is 1.2-1.4 wt %.

[0014] As a further solution of the present invention: the visible light source is blue light with a wavelength of 450nm.

[0015] As a further embodiment of the present invention: a method for preparing bismuth telluride powder comprises the following steps: mixing bismuth telluride with ethanol, and ultrasonically crushing to obtain a mixed solution; and centrifugally separating and purifying the mixed solution to obtain bismuth telluride powder.

[0016] As a further embodiment of the present invention: the solid-liquid ratio of bismuth telluride to ethanol is 5 mg:23-26 mL.

[0017] As a further embodiment of the present invention: the particle size of the bismuth telluride powder is 1-2 μm.

[0018] As a further solution of the present invention: the sensing substrate is an interdigital electrode.

[0019] A light-excited low-consumption gas sensor based on bismuth telluride material, made by any of the above-mentioned preparation methods.

[0020] Beneficial effects of the present invention:

[0021] The present invention uses bismuth telluride as a sensing material, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is a medium as a neutral carrier material. The obtained bismuth telluride mixed solution can maintain excellent long-term uniformity and good physical adsorption properties of gas molecules at room temperature. The drop coating method is applied to high-density fork electrode sensors, and under visible light excitation, it shows strong response sensitivity and recovery to hydrogen (1%). BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings.

[0023] Figure 1 This is a scanning electron microscope (SEM) characterization image of the bismuth telluride material prepared in Example 1 of the present application;

[0024] Figure 2 The energy dispersive X-ray elemental spatial distribution analysis diagram (EDS mapping) of the bismuth telluride material prepared in Example 1 of the present application;

[0025] Figure 3 A statistical graph showing the results of a gas-sensing test of a high-density fork-electrode substrate prepared in Example 1 of the present application in a 1% (10000 ppm) hydrogen environment;

[0026] Figure 4 This is a response speed analysis diagram of the high-density fork-type electrode substrate prepared in Example 1 of the present application in a 1% (10000 ppm) hydrogen environment;

[0027] Figure 5 This is a recovery rate analysis diagram of the high-density fork-type electrode substrate prepared in Example 1 of the present application in a 1% (10000 ppm) hydrogen environment; DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1 A method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material comprises the following steps:

[0030] S1: 5 mg of bismuth telluride was mixed with 25 mL of ethanol and ultrasonically crushed for 15 min to obtain a mixed solution; the mixed solution was centrifuged and purified to obtain bismuth telluride powder with a particle size of 1-2 μm;

[0031] S2: 5 mg of bismuth telluride powder was mixed with 10 mL of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion (solid content 1.3 wt%) to obtain a bismuth telluride mixed solution;

[0032] S3: After coating the surface of the interdigital electrode with a gas-sensitive material layer and drying at room temperature, the surface of the interdigital electrode contains 20 mg of bismuth telluride material per square millimeter, thereby obtaining a gas-sensitive detection element;

[0033] S4: a blue light with a wavelength of 450 nm is arranged above the gas-sensitive detection element as a visible light source to obtain a light-excited low-consumption gas-sensitive sensor;

[0034] Performance Testing

[0035] (1) Observation by scanning electron microscope

[0036] from Figure 1 It can be seen that the bismuth telluride material prepared in Example 1 of the present application is in powder form, and the size is 1-2 μm.

[0037] (2) Spatial distribution analysis of elements by energy dispersive X-ray analysis

[0038] from Figure 2 It can be seen that it can be proved that the detection material presents tellurium and bismuth element signals.

[0039] (3) Gas sensing performance

[0040] The WS-30A gas-sensitive test system was used for testing. The test environment was as follows: 1% (10000ppm) hydrogen was injected into the test chamber at room temperature and one atmosphere, during which the sensor resistance value decreased. During the recovery phase, the hydrogen injection was stopped and pure air was injected, and the sensor resistance recovered. The response factor α was calculated according to the following formula:

[0041] α=(R H2 -R Air ) / R Air ×100%

[0042] Where, α-response factor, %; R H2 -Saturation resistance value when the sensor is exposed to hydrogen, Ω; R Air -Saturation resistance value in pure air, Ω.

[0043] from Figure 3 It can be seen that the Y-axis in the figure uses the response factor to express the responsiveness of the sensor;

[0044] from Figure 4 It can be seen that the response speed after injecting 1% (10000ppm) hydrogen under the high-density fork electrode substrate prepared by the bismuth telluride material prepared in this application is 13 seconds under the T90 (time to reach 90% of the saturation value) standard.

[0045] from Figure 5 It can be seen that the recovery speed after injecting 1% (10000 ppm) hydrogen under the high-density fork electrode substrate prepared by the bismuth telluride material prepared in this application is 13 seconds under the T90 (time to reach 90% of the saturation value) standard.

[0046] As can be seen from the figure, the light-excited low-consumption gas-sensitive sensor based on bismuth telluride material prepared in the present application shows strong response sensitivity and recovery to low concentration 1% hydrogen.

[0047] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material, characterized in that: The steps include: S1: coating a gas-sensitive material layer on the surface of a sensing substrate to obtain a gas-sensitive detection element; S2: a visible light source is arranged above the gas-sensitive detection element to obtain a light-excited low-consumption gas-sensitive sensor; The gas-sensitive material layer is obtained by coating a bismuth telluride mixed solution on the surface of the sensing substrate; The bismuth telluride mixed solution is obtained by mixing bismuth telluride powder with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion.

2. The method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to claim 1, characterized in that: The addition ratio of bismuth telluride powder and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion in the bismuth telluride mixed solution is 4.5-5.5 mg:10 mL.

3. A method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to any one of claims 1 or 2, characterized in that: The solid content of the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate dispersion is 1.2-1.4 wt%.

4. The method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to claim 1, characterized in that: The visible light source is blue light with a wavelength of 450nm.

5. The method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to claim 1, characterized in that: The preparation method of the bismuth telluride powder comprises the following steps: mixing bismuth telluride with ethanol and subjecting the mixture to ultrasonic crushing to obtain a mixed solution; and centrifugally separating and purifying the mixed solution to obtain bismuth telluride powder.

6. The method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to claim 5, characterized in that: The solid-liquid ratio of bismuth telluride to ethanol is 5 mg:23-26 mL.

7. The method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to claim 1, characterized in that: The particle size of the bismuth telluride powder is 1-2 μm.

8. The method for preparing a light-excited low-consumption gas sensor based on bismuth telluride material according to claim 1, characterized in that: The sensing substrate is an interdigitated electrode.

9. A light-excited low-consumption gas sensor based on bismuth telluride material, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

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