CN112858400A - Sensor for detecting hydrogen sulfide gas at room temperature - Google Patents
Sensor for detecting hydrogen sulfide gas at room temperature Download PDFInfo
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- CN112858400A CN112858400A CN202110058589.0A CN202110058589A CN112858400A CN 112858400 A CN112858400 A CN 112858400A CN 202110058589 A CN202110058589 A CN 202110058589A CN 112858400 A CN112858400 A CN 112858400A
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- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
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Abstract
The invention relates to the field of constructional engineering and discloses a sensor for detecting hydrogen sulfide gas at room temperature. The preparation method comprises a reduced graphene oxide nanosheet 1, a copper-doped zinc oxide nanorod 2, an Au (50nm)/Ti (5nm) coating 3 and a glass substrate 4. When the sensor surface is exposed to H2When S is in gas, H2S molecules are adsorbed on the surface of the nanocomposite sensor, pre-adsorbed oxygen and H2The interaction between S releases free electrons. These free electrons neutralize holes in Reduced Graphene Oxide (RGO), reducing the size of the charge conduction channel, resulting in an increase in the width of the space charge region, thereby increasing the resistance of the sensor. Thereby reacting H2Concentration of S gas. The hydrogen sulfide gas sensor has the advantages of high sensitivity, strong selectivity to hydrogen, stable performance and short response time.
Description
Technical Field
The invention relates to the field of constructional engineering, in particular to a sensor for detecting hydrogen sulfide gas at room temperature.
Background
Hydrogen sulfide is a toxic, colorless, aromatic gas, and excessive inhalation can lead to neurobehavioral toxicity, respiratory failure, and also death. Therefore, the high-performance, high-reliability and good-selectivity H detector capable of working at low temperature and detecting low-concentration gas is developed2S gasThe sensor is of great significance.
To achieve these goals, metal oxide semiconductor-based gas sensors have been extensively studied, and there remains a need for H2S gas sensing is constantly improving. Among various semiconductor materials in practical application, zinc oxide has the advantages of low cost, no toxicity, unique electrochemical property, nano size, various shapes, simple integration and the like, and shows that the zinc oxide is applied to H2S gas-sensitive field. In addition, metal impurities are doped in the ZnO nano structure, so that the electronic property of ZnO and the adsorption position of gas molecules can be changed, and better gas-sensitive characteristics can be obtained. Some early studies have shown that for copper-doped and tin-doped ZnO films, 20ppm H is measured at operating temperatures of 250 ℃ and 200 ℃2S has a significant response. However, zinc oxide based gas sensors have higher power consumption due to their high operating temperature (typically over 200 ℃) and poor chemical properties. High operating temperatures also place considerable limitations for enabling wider real-time applications due to integration difficulties and the risk of gas explosion. Temperature drift caused by high temperature often causes the resistance of the sensor to fluctuate, thereby affecting the measurement accuracy. These limitations have recently inspired researchers to achieve high performance H working at room temperature2And (S) a gas sensor.
In order to solve these problems, modifications of metal oxides, such as transition metal doping, surface functionalization, and synthesis of nanocomposites, are required. RGO, modified graphene, along with the original or doped metal oxide, has recently been considered to create a new method of sensing gases in gas sensors. For example, some typical metal oxides, such as SnO2、ZnO、Cu2O and WO3Have been effectively combined with RGO to improve gas sensing performance. However, for reduced graphene oxide/hexagonal WO3Nanosheets and SnO2Detection of H by quantum wire/reduced graphene oxide nano composite material2The study of S gas is relatively limited. All of these combinations are observed to improve gas sensing performance by some fundamental phenomena, such as creating more surface defect sites by forming a p-n junction between RGO and metal oxide andthe schottky barrier height is increased.
Although one dopes RGO/ZnO heterostructures and Cu with ZnO H2A great deal of research is carried out on the detection potential of S gas, but the gas-sensitive characteristic of modifying RGO on a Cu-doped ZnO nano structure is rarely reported. Therefore, the invention discloses room temperature H of the RGO modified Cu doped ZnO nano-structure double-layer gas sensor2S sensing characteristics. The copper-doped zinc oxide nano-structure is grown by a hydrothermal method; the simple method of depositing RGO in the form of air-spray technology distinguishes it from other chemical methods reported previously. The physical and gas-sensitive properties of undoped and Cu-doped ZnO nanostructures were studied systematically. Due to the combined action of the Cu dopant and the RGO, the sensor has significant H at room temperature2S sensing capability.
Disclosure of Invention
Technical problem to be solved
In order to solve the technical problems, the invention provides a sensor for detecting hydrogen sulfide gas at room temperature, which has the characteristics of high sensitivity, strong selectivity, short response time and low power consumption, can work at low temperature and can detect low-concentration gas, and solves the problems of low sensitivity and high power consumption of the existing hydrogen sulfide sensor.
(II) technical scheme
The technical scheme of the invention is based on the hydrothermal synthesis of non-doped zinc oxide (ZnO) and copper-doped zinc oxide (CZO) nano-structure, and the sensitive room-temperature hydrogen sulfide (H) is developed2S) a gas sensor. The sensor is characterized by comprising a reduced graphene oxide nanosheet 1, a copper-doped zinc oxide nanorod 2, an Au (50nm)/Ti (5nm) coating 3 and a glass substrate 4.
Preferably, the Au (50nm)/Ti (5nm) film 3 is deposited on the surface of the glass substrate by a radio frequency magnetron sputtering method.
Preferably, the ZnO film seed layer on the surface of the Au (50nm)/Ti (5nm) film 3 is hydrothermally synthesized.
Preferably, both of the nanostructured films exhibit a hexagonal wurtzite structure with polycrystalline nature.
Preferably, the water isThe hot reaction solution was prepared by mixing 25mM zinc nitrate and 25mM aqueous HMT solution (pH) in a Teflon container1/47) To prepare the compound.
Preferably, the nanoparticle ZnO and Cu-doped ZnO deposits need to be uniformly dispersed throughout the seed layer coated glass substrate.
Preferably, the sensor surface is exposed to H2When S is in gas, H2S molecules are adsorbed on the surface of the nanocomposite sensor, pre-adsorbed oxygen species and H2The interaction between S releases free electrons. Resulting in an increase in the width of the space charge region and thus an increase in the resistance of the sensor.
Preferably, the attachment of RGO nanoplates in the sensor not only reduces the overall resistance of the sensor, but also increases the overall adsorption sites for oxygen.
Preferably, the Cu-doped ZnO nanorod surface morphology provides additional active surface sites, increases chemisorption, and improves sensor sensitivity.
Preferably, the 3CZO/RGO nanocomposite sensor has good long-term stability.
Preferably, the hydrogen sulfide gas sensor, when exposed to hydrogen sulfide gas, proceeds according to the following reaction formula:
H2S+3O-→H2O+SO2+3e-
(III) advantageous effects
Compared with the prior art, the invention provides the sensor for detecting the hydrogen sulfide gas at room temperature.
1. The sensor for detecting hydrogen sulfide gas at room temperature is used for detecting 100ppm H at 24 DEG C2The gas sensitive response of S gas is as high as 0.87%, and the response recovery time is shorter than 14S and 32S.
2. The sensor has the characteristics of high selectivity, short response time and low power consumption.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
FIG. 2 Synthesis procedure of Cu doped ZnO/RGO nanocomposite sensor.
FIG. 3 shows the nano-composite sensor at 24 ℃ to 150ppm H2Typical response transient for S gas.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to prepare the gas sensor, a Ti (5nm)/Au (50nm) film is deposited on the surface of a glass substrate by adopting a radio frequency magnetron sputtering method. The metal film was then patterned to form interdigitated electrodes (IDEs) with 22 fingers and 100mm gaps. Fig. 2 shows a schematic diagram of the manufacturing process steps for forming interdigitated gold electrodes. Then, an undoped ZnO thin film was grown as a seed layer on the entire surface by hydrothermal synthesis. The hydrothermal reaction solution was prepared by mixing 25mM zinc nitrate and 25mM HMT in water (pH) in a Teflon container1/47) To prepare the compound. The pH was adjusted to 7 by adding a precise amount of ammonium hydroxide as a pH control agent to the aqueous solution. The synthesis was carried out at 90 ℃ for 3 hours. Next, 3 wt% Cu doped ZnO (3CZO) nanostructures were grown hydrothermally on the ZnO seed layer. The hydrothermal reaction solution was the same as the zinc oxide seed layer synthesis reaction solution, but an appropriate amount of copper nitrate was added to obtain 3 wt% copper doping. The substrate coated with the seed layer was immersed upside down in the reaction solution. The hydrothermal reaction was carried out at 90 ℃ for 3 hours. The coated substrate was then rinsed with deionized water and dried with an air gun to avoid surface contamination. In order to increase the film thickness and surface morphology, the rinsing and drying process was repeated a second time on the same substrate during the above hydrothermal deposition of ZnO and 3CZO nanostructures. Finally, the annealing was carried out in a furnace at 400 ℃ for one hour. In addition, Graphene Oxide (GO) flakes dispersed in deionized water and ethanol were deposited onto undoped and Cu-doped ZnO nanostructures by spraying. During the spraying process, the substrate temperatureThe temperature was maintained at 170 ℃. Finally, undoped and copper doped ZnO films of GO coating were exposed to hydrazine hydrate vapor for 3 hours in a sealed glass beaker at a temperature of 90 ℃ to obtain reduced GO. FIG. 1 illustrates the structure of the above copper doped ZnO/RGO nanocomposite sensor.
And (4) testing the concentration of hydrogen sulfide gas, and fixing ZnO/RGO and 3CZO/RGO sensors on a ceramic micro-heater by using heat conducting paste. In order to accurately measure the temperature of the gas sensor, a high-sensitivity temperature sensor is mounted on the surface of the micro-heater. The response of the two nanocomposite sensors to the target gas was measured at 24 ℃. Here, the gas response percentage is defined as S ═ Rg-R0)/R0]X 100% where R0 is the resistance of the sensor in ambient air and Rg is the sensor resistance in the target gas. The response time and recovery time are defined as the exposure of the sensor to the measured gas (i.e., H), respectively2S and air) the time required for 90% of the total resistance change.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (13)
1. A sensor for detecting hydrogen sulfide gas at room temperature. The graphene oxide nano-sheet comprises a reduced graphene oxide nano-sheet 1, a copper-doped zinc oxide nano-rod 2, an Au (50nm)/Ti (5nm) film 3 and a glass substrate 4.
2. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the reduced graphene oxide nanosheets 1 are dispersed in deionized water and ethanol by spraying, and then deposited onto undoped and Cu-doped ZnO nanostructures.
3. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the Au (50nm)/Ti (5nm) film 3 is formed by depositing on the surface of a glass substrate by a radio frequency magnetron sputtering method.
4. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: and the ZnO film seed layer on the surface of the Au (50nm)/Ti (5nm) film 3 is synthesized by hydrothermal synthesis.
5. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the hydrothermal reaction solution was prepared by mixing 25mM zinc nitrate and 25mM aqueous HMT solution (pH1/47) in a Teflon container.
6. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the ZnO film presents a surface appearance of a nano rod shape.
7. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the ZnO and RG nano-structure is doped with Cu, so that more active centers are provided, and the chemical adsorption is increased.
8. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the two nano-structure films both have a hexagonal wurtzite structure and have polycrystalline properties.
9. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein: the nano-particle ZnO and Cu-doped ZnO sediments are uniformly dispersed on the whole seed layer coating glass substrate.
10. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein the sensor surface is exposed to H2When S is in gas, H2S molecules are adsorbed on the surface of the nanocomposite sensor, pre-adsorbed oxygen species and H2The interaction between S releases free electrons.
11. The sensor for detecting hydrogen sulfide gas at room temperature as claimed in claim 1, wherein the reduction gas-sensitive mechanism of the Cu-doped ZnO/RGO nano composite material in the sensor is mainly influenced by factors such as specific surface area, surface defects and heterojunction formation.
12. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, wherein the attachment of RGO nanosheets in the sensor not only reduces the overall resistance of the sensor, but also increases the overall adsorption sites for oxygen.
13. The sensor for detecting hydrogen sulfide gas at room temperature according to claim 1, which has good long-term stability.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113533300A (en) * | 2021-07-22 | 2021-10-22 | 岭南师范学院 | Graphene plasmon gas sensor and manufacturing method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113533300A (en) * | 2021-07-22 | 2021-10-22 | 岭南师范学院 | Graphene plasmon gas sensor and manufacturing method thereof |
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