A titanium dioxide nanostructure-enhanced ethanol gas sensor
By introducing titanium dioxide nanostructures into the gas-sensitive material layer and using ultraviolet light to form a strong ultraviolet light field, the problem of insufficient sensitivity of the iron molybdate ethanol gas sensor at room temperature was solved, and higher ethanol gas detection sensitivity was achieved.
Patent Information
- Application Number
- CN202310139255.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-20
- Publication Date
- 2025-09-09
- Estimated Expiration
- 2043-02-20
AI Technical Summary
The existing iron molybdate ethanol gas sensor has low sensitivity at room temperature, mainly due to the insufficient number of surface oxygen negative ions, resulting in insufficient sensitivity.
Titanium dioxide nanostructures are introduced into the gas-sensitive material layer, and a strong ultraviolet light field is formed through ultraviolet light irradiation, which promotes the separation of electrons and holes, increases the adsorption of oxygen molecules on the surface of iron molybdate, forms more oxygen negative ions, and releases more free electrons under the action of ethanol gas molecules, thereby achieving a greater resistance change.
The sensitivity of the ethanol gas sensor is improved by enhancing the separation of electrons and holes in the gas-sensitive material layer under the ultraviolet light field, increasing the generation of oxygen negative ions and the release of electrons, and achieving higher sensitivity ethanol gas detection.
Smart Images
Figure CN115980144B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of ethanol sensing, and in particular to an ethanol gas sensor enhanced by a titanium dioxide nanostructure. Background Art
[0002] Molybdates are important functional materials with promising applications in catalysis and gas sensing. Experiments have shown that iron molybdate can be used for ethanol gas sensing. In an air environment, oxygen molecules in the air bind to oxygen vacancies on the sensor surface, capturing free electrons in the iron molybdate's conduction band. These oxygen molecules ionize to form oxygen anions, increasing the iron molybdate's resistance (Ra). In an ethanol environment, ethanol molecules react with the chemically adsorbed oxygen anions, releasing the captured electrons back into the iron molybdate's conduction band, decreasing the iron molybdate's resistance (Rg). Ethanol gas detection is achieved by the difference between Ra and Rg, and sensitivity S is typically defined as the ratio of Ra to Rg: S = Ra / Rg. Because the number of oxygen anions on the iron molybdate surface is low at room temperature, the sensitivity of iron molybdate for ethanol gas detection is reduced. In other words, increasing the number of oxygen anions on the iron molybdate surface is crucial for improving the sensitivity of iron molybdate for ethanol gas detection. Summary of the Invention
[0003] To address the above issues, the present invention provides a titanium dioxide nanostructure-enhanced ethanol gas sensor, comprising a substrate, an interdigitated electrode layer, a gas-sensitive material layer, and titanium dioxide nanostructures. The interdigitated electrode layer is disposed on the substrate, and the gas-sensitive material layer is disposed on the interdigitated electrode layer. The gas-sensitive material layer is made of molybdate, and the titanium dioxide nanostructures are doped within the gas-sensitive material layer. During use, the gas-sensitive material layer is irradiated with ultraviolet light.
[0004] The core concept of this invention is to use titanium dioxide nanostructures to absorb and radiate ultraviolet light, forming a stronger ultraviolet light field in the gas-sensitive material layer, promoting the separation of electrons and holes, so that more oxygen molecules are adsorbed on the molybdate surface in an oxygen environment, forming more oxygen negative ions; when combining with ethanol gas molecules, the ethanol gas molecules can release more free electrons, thereby causing a greater resistance change and achieving more sensitive ethanol gas sensing.
[0005] Furthermore, the molybdate is iron molybdate, and specifically, the iron molybdate is stacked in the form of nanosheets to enhance the absorption and scattering of incident ultraviolet light, thereby forming a stronger ultraviolet light field in the iron molybdate.
[0006] Furthermore, the titanium dioxide nanostructure is titanium dioxide nanoparticles.
[0007] Furthermore, the diameter of the titanium dioxide nanoparticles is less than 100 nanometers.
[0008] Furthermore, the titanium dioxide nanostructure is titanium dioxide nanofiber.
[0009] Furthermore, the titanium dioxide nanofibers partially extend out of the gas-sensitive material layer.
[0010] Furthermore, the material of the substrate is aluminum oxide.
[0011] Furthermore, the material of the interdigital electrode layer is platinum.
[0012] Furthermore, titanium dioxide nanostructures are doped into the gas-sensitive material layer by a grinding method.
[0013] Beneficial effects of the present invention:
[0014] (1) The present invention sets a titanium dioxide nanostructure in the gas-sensitive material layer to enhance the absorption and scattering of ultraviolet light, generate a stronger ultraviolet light field in the gas-sensitive material layer, and promote the separation of electrons and holes in molybdate, thereby making it easier for oxygen molecules to become oxygen anions on the surface of the gas-sensitive material layer, ultimately improving the sensitivity of ethanol gas molecule detection.
[0015] (2) The present invention utilizes titanium dioxide nanofibers to promote the propagation of ultraviolet light in the titanium dioxide nanofibers, increases the time that ultraviolet light stays in the titanium dioxide nanofibers, thereby gathering a stronger ultraviolet light field in the gas-sensitive material layer, promoting the separation of electrons and holes, and making it easier for oxygen molecules to become oxygen negative ions on the surface of the gas-sensitive material layer, ultimately achieving higher sensitivity detection of ethanol gas molecules.
[0016] (3) The present invention uses a grinding method to dope titanium dioxide nanostructures into the gas-sensitive material layer. The method is simple and allows the titanium dioxide nanostructures (especially titanium dioxide nanofibers) to have different directions relative to the gas-sensitive material layer, which is more conducive to the use of ultraviolet light.
[0017] Based on the above effects, the present invention has good application prospects in the field of ethanol sensing technology.
[0018] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of a titanium dioxide nanostructure-enhanced ethanol gas sensor.
[0020] Figure 2 This is an SEM image of nanosheet-stacked iron molybdate nanostructures, where the scale bar represents 1 micron.
[0021] Figure 3 Schematic diagram of another titanium dioxide nanostructure-enhanced ethanol gas sensor.
[0022] In the figure: 1. substrate; 2. interdigitated electrode layer; 3. gas-sensitive material layer; 4. titanium dioxide nanostructure. DETAILED DESCRIPTION
[0023] In order to make the objectives, technical solutions and advantages of this application more clear, the application is further described in detail below with reference to the accompanying drawings and examples.
[0024] The present invention provides a titanium dioxide nanostructure enhanced ethanol gas sensor, such as Figure 1 As shown, it includes a substrate 1, an interdigitated electrode layer 2, a gas-sensitive material layer 3, and a titanium dioxide nanostructure 4. The material of the interdigitated electrode layer 2 is platinum, the material of the substrate 1 is aluminum oxide, and the interdigitated electrode layer 2 is placed on the substrate 1. The gas-sensitive material layer 3 is placed on the interdigitated electrode layer 2. The material of the gas-sensitive material layer 3 is molybdate, and the molybdate is an iron molybdate nanostructure, and its scanning electron microscope image is shown as follows: Figure 2 As shown, the iron molybdate nanostructures are stacked in the form of nanosheets, with the scale bar representing 1 micron. Titanium dioxide nanostructures 4 comprise titanium dioxide nanoparticles with a diameter less than 100 nanometers, enabling them to absorb and scatter ultraviolet light. Titanium dioxide nanostructures 4 are doped within gas-sensitive material layer 3. During use, ultraviolet light is applied to gas-sensitive material layer 3. Interdigitated electrode layer 2 is connected to an external circuit to measure the difference in resistance of gas-sensitive material layer 3 in air and ethanol gas, enabling ethanol gas detection.
[0025] The core concept of the present invention is to use titanium dioxide nanostructures 4 to absorb and radiate ultraviolet light, forming a stronger ultraviolet light field in the gas-sensitive material layer 3, promoting the separation of electrons and holes in the gas-sensitive material layer 3, so that more oxygen molecules are adsorbed on the surface of the iron molybdate nanostructure in an oxygen environment, forming and gathering more oxygen anions; when combining with ethanol gas molecules, the ethanol gas molecules can react with more oxygen anions, thereby releasing more free electrons, thereby causing a greater resistance change and achieving more sensitive ethanol gas sensing.
[0026] The present application uses nanosheet-like stacked iron molybdate nanostructures as the gas-sensitive material layer 3. Since the nanosheet-like stacked structures have different directions and are tilted, they are conducive to confining ultraviolet light within the gas-sensitive material layer 3, thereby allowing the gas-sensitive material layer 3 to absorb more ultraviolet light, resulting in more electron and hole separation within the gas-sensitive material layer 3. The hydrothermal method is used to synthesize nanosheet-like stacked iron molybdate nanostructures, the core steps of which include: (1) preparing an iron nitrate solution; (2) preparing a sodium molybdate solution; (3) while ensuring continuous magnetic stirring, slowly introducing the iron nitrate solution into the sodium molybdate solution to obtain a yellow suspension; (4) placing a pH meter in the yellow suspension and recording the initial pH value; (5) diluting concentrated nitric acid and water in a ratio of 1:4, dripping it into the yellow suspension, and adjusting the pH index to 1; (6) placing the yellow suspension in a polytetrafluoroethylene reactor to react for 12 hours, and then cooling it to room temperature; (7) filtering, washing, and drying to obtain the iron molybdate nanosheet-like stacked structure.
[0027] Preferably, if Figure 3 As shown, the titanium dioxide nanostructures 4 are titanium dioxide nanofibers, partially extending beyond the gas-sensitive material layer 3. When ultraviolet light irradiates the titanium dioxide nanofibers, it couples into them and propagates along them. Due to the strong ultraviolet field on the titanium dioxide nanofiber surface, a stronger ultraviolet field is concentrated within the gas-sensitive material layer 3, promoting the separation of electrons and holes in the iron molybdate nanostructures. Oxygen molecules in the air more readily bind to the iron molybdate nanostructures, generating more oxygen anions. When exposed to ethanol gas, the binding of ethanol molecules with oxygen anions releases more electrons, further altering the resistance of the iron molybdate nanostructures and achieving higher sensitivity for ethanol gas molecule detection. The ends or middle of the titanium dioxide nanofibers extend beyond the gas-sensitive material layer 3, facilitating the coupling of ultraviolet light into the titanium dioxide nanofibers and their propagation along them, further separating electrons and holes within the gas-sensitive material layer 3.
[0028] Preferably, titanium dioxide nanoparticles and titanium dioxide nanofibers are doped in the gas-sensitive material layer 3 at the same time, and the titanium dioxide nanoparticles and titanium dioxide nanofibers generate strong coupling at the gap, forming a stronger ultraviolet light field between the titanium dioxide nanoparticles and the titanium dioxide nanofibers, causing more separation of electrons and holes between them, and generating more oxygen negative ions outside the gas-sensitive material layer 3, and the ethanol gas releases more electrons, thereby changing the resistance of the gas-sensitive material layer 3 more, and achieving more sensitive detection of ethanol gas molecules.
[0029] The method for doping titanium dioxide nanoparticles or titanium dioxide nanofibers or both into the gas-sensitive material layer 3 adopts a grinding and screen printing method, and its core steps include: (1) placing the iron molybdate nanostructure in an agate mortar for preliminary grinding, and the preliminary grinding is performed using a grinding rod; (2) adding titanium dioxide nanoparticles or titanium dioxide nanofibers or both into the iron molybdate nanostructure for deep grinding, and during the deep grinding, pouring pine oil into the mixture and grinding until it becomes viscous; (3) using a screen printing plate to print the obtained viscous material onto the interdigital electrode layer 2; (4) placing the obtained sample into a baking machine to allow the organic solvent to volatilize and the iron molybdate nanostructure to have good contact with the interdigital electrode layer 2; (5) aging the sample to improve the density and performance stability of the gas-sensitive material layer 3. In this method, the iron molybdate nanostructure is first coarsely ground, and then titanium dioxide nanoparticles or titanium dioxide nanofibers are added, which is conducive to the uniform doping of titanium dioxide nanoparticles or titanium dioxide nanofibers in the iron molybdate nanostructure, thereby allowing more ultraviolet light to be gathered in the gas-sensitive material layer 3 and separating more electrons and holes.
[0030] Preferably, in the interdigitated electrode layer 2, a UV-reflecting portion is provided between adjacent interdigits. The UV-reflecting portion has the same height as the interdigits, and the material of the UV-reflecting portion is calcium fluoride. When the present invention operates at room temperature, calcium fluoride has poor conductivity and can act as an insulator to isolate adjacent interdigits. Alternatively, the material of the UV-reflecting portion can be other materials that reflect UV light and are also insulators. This, on the one hand, reflects UV light, increasing the intensity of UV light within the gas-sensitive material layer 3 and allowing for more electron-hole separation within the gas-sensitive material layer 3. On the other hand, the amount of gas-sensitive material filling between adjacent interdigits is reduced, and the resistance of this portion of gas-sensitive material changes less. Providing the UV-reflecting portion between adjacent interdigits reduces the resistance of the gas-sensitive material originally located there, causing only the resistance of the surface layer of the gas-sensitive material layer 3 to change, thereby improving the sensitivity of ethanol gas sensing.
[0031] More preferably, a UV reflective layer is provided on substrate 1, followed by an interdigitated electrode layer 2, and finally a gas-sensitive material layer 3 doped with titanium dioxide nanostructures 4 is provided on interdigitated electrode layer 2. The UV reflective layer reflects ultraviolet light, concentrating it within gas-sensitive material layer 3, promoting the separation of electrons and holes within gas-sensitive material layer 3 and improving the sensitivity of ethanol gas sensing. Providing the UV reflective layer directly on substrate 1, rather than providing UV reflective portions between adjacent interdigitated electrodes, offers the advantage of simplified fabrication.
[0032] In summary, the present invention provides a titanium dioxide nanostructure-enhanced ethanol gas sensor, comprising a substrate 1, an interdigitated electrode layer 2, a gas-sensitive material layer 3, and titanium dioxide nanostructures 4. The interdigitated electrode layer 2 is disposed on the substrate 1, the gas-sensitive material layer 2 is disposed on the interdigitated electrode layer 2, the gas-sensitive material layer 2 is made of molybdate, and the titanium dioxide nanostructures 4 are doped within the gas-sensitive material layer 3. During use, ultraviolet light is applied to the gas-sensitive material layer 3. The present invention provides the titanium dioxide nanostructures 4 within the gas-sensitive material layer 3 to enhance the absorption and utilization of ultraviolet light, generate a stronger ultraviolet light field within the gas-sensitive material layer 3, and promote the separation of electrons and holes, thereby making it easier for oxygen molecules to convert into oxygen anions on the surface of the gas-sensitive material layer 3. This ultimately improves the sensitivity of ethanol gas molecule detection and has good application prospects in the field of ethanol gas sensing.
[0033] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.
Claims
1. A titanium dioxide nanostructure enhanced ethanol gas sensor, characterized in that: The invention comprises a substrate, an interdigitated electrode layer, a gas-sensitive material layer, and a titanium dioxide nanostructure, wherein the interdigitated electrode layer is placed on the substrate, the gas-sensitive material layer is placed on the interdigitated electrode layer, the material of the gas-sensitive material layer is molybdate, the molybdate is iron molybdate, the titanium dioxide nanostructure is doped in the gas-sensitive material layer, the titanium dioxide nanostructure is titanium dioxide nanofiber, the titanium dioxide nanofiber partially extends out of the gas-sensitive material layer, and in the interdigitated electrode layer, an ultraviolet light reflecting portion is arranged between adjacent interdigits, the height of the ultraviolet light reflecting portion is the same as the height of the interdigits, and the material of the ultraviolet light reflecting portion is calcium fluoride.
2. The titanium dioxide nanostructure-enhanced ethanol gas sensor according to claim 1, wherein: The iron molybdate is accumulated in the form of nanosheets.
3. The titanium dioxide nanostructure-enhanced ethanol gas sensor according to claim 1, wherein: The material of the substrate is aluminum oxide.
4. The titanium dioxide nanostructure-enhanced ethanol gas sensor according to claim 1, wherein: The material of the interdigital electrode layer is platinum.
5. The titanium dioxide nanostructure-enhanced ethanol gas sensor according to any one of claims 1 to 4, characterized in that: The titanium dioxide nanostructure is doped into the gas-sensitive material layer by a grinding method.