Hydrogen sulfide gas sensor based on quantum dots and preparation method thereof

Abstract

The invention belongs to the field of gas sensors, and particularly discloses a hydrogen sulfide gas sensor based on quantum dots and a preparation method of the hydrogen sulfide gas sensor. The hydrogen sulfide gas sensor comprises an electronic device and a quantum dot film covering a working electrode or a grid electrode of the electronic device, and 0.8 mg / cm < 2 > to 4.0 mg / cm < 2 > of superoxide dismutase is combined on the surface of the quantum dot film; the electronic device is a planar electrochemical three-electrode or high-electron-mobility transistor; according to the hydrogen sulfide gas sensor, 1-ethyl-3-methylimidazole bis (trifluoromethanesulfonyl) imide salt is used as an electrolyte. The superoxide dismutase-based quantum dot gas sensor is designed based on the specific catalytic action of enzyme and a substrate key-lock, the restriction that a traditional gas sensor has selectivity but has no specificity is solved, and specific detection of hydrogen sulfide gas is achieved.

Description

Technical Field

[0001] The present application belongs to the field of gas sensors, and more specifically, relates to a quantum dot-based hydrogen sulfide gas sensor and a preparation method thereof. Background Art

[0002] "Odor, as a chemical signature in the air, carries a variety of useful information about the environment or organisms." However, most existing gas sensors are based on semiconductors. Their detection principle is that under certain conditions (temperature), when the gas reaches the surface of the semiconductor material and chemically reacts with oxygen adsorbed on the surface, it is accompanied by charge transfer, which further causes a change in the semiconductor's resistance. Gas detection is achieved by measuring this change in semiconductor resistance.

[0003] Currently, hydrogen sulfide gas sensors are selective but not specific and cannot detect hydrogen sulfide in complex atmospheres such as ammonia, nitrogen oxides, benzene, and formaldehyde. Summary of the Invention

[0004] The purpose of this application is to provide a quantum dot-based hydrogen sulfide gas sensor that improves the response sensitivity of hydrogen sulfide. The present invention also provides a preparation method thereof.

[0005] The present application provides a quantum dot-based hydrogen sulfide gas sensor, comprising an electronic device and a quantum dot film covering a working electrode or a gate of the electronic device, wherein a 0.8 mg / cm 2 ~4.0 mg / cm 2 The electronic device is a planar electrochemical three-electrode or a high electron mobility transistor (HEMT); The hydrogen sulfide gas sensor uses 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt as an electrolyte. When the hydrogen sulfide gas sensor is operating, the superoxide dismutase exerts its specific catalytic effect at the optimal temperature, causing the hydrogen sulfide dissolved in the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt to undergo an oxidation-reduction reaction, generating a current signal. The hydrogen sulfide concentration in the gas to be measured is obtained based on the current signal.

[0006] Preferably, the superoxide dismutase is SOD1.

[0007] Preferably, the material of the quantum dot film is SnO2, In2O3, SnS2, PbS, Bi2S3 or WO3, and the thickness of the quantum dot film is 400 nm~900 nm.

[0008] The present application also provides a method for preparing a quantum dot-based hydrogen sulfide gas sensor, which comprises: S1. Obtaining an electronic device having a quantum dot film covered on a first electrode; the electronic device is a planar electrochemical three-electrode or high electron mobility transistor, wherein the first electrode is a working electrode or a gate; S2. Incubate the first electrode with a 0.1 g / L to 1.5 g / L superoxide dismutase solution at the optimal temperature for superoxide dismutase for 30 to 70 minutes, allowing superoxide dismutase to bind to the surface of the quantum dot film covering the first electrode, thereby obtaining the hydrogen sulfide gas sensor.

[0009] Preferably, the optimum temperature is 25°C to 37°C.

[0010] Preferably, the superoxide dismutase is SOD1.

[0011] Preferably, the preparation method of the electronic device having a quantum dot film covered on the first electrode is: drop-coating a colloidal quantum dot solution with a concentration of 7 mg / mL to 15 mg / mL on the surface of the first electrode of the semiconductor device to form a quantum dot film, wherein the size of the colloidal quantum dots in the colloidal quantum dot solution is 3.1 nm to 3.7 nm.

[0012] The present application also provides a method for detecting hydrogen sulfide concentration, comprising the following steps: S1. Obtaining an electronic device having a quantum dot film covered on a first electrode; the electronic device is a planar electrochemical three-electrode or high electron mobility transistor, wherein the first electrode is a working electrode or a gate; S2. Incubate the first electrode with a 0.1 g / L to 1.5 g / L superoxide dismutase solution at the optimal temperature for superoxide dismutase for 30 to 70 minutes, allowing superoxide dismutase to bind to the surface of the quantum dot film covering the first electrode, thereby obtaining the hydrogen sulfide gas sensor.

[0013] S3. Calibrate the hydrogen sulfide gas sensor using a standard concentration of hydrogen sulfide gas at the optimal temperature; S4. Detecting the hydrogen sulfide concentration at the optimum temperature using the calibrated hydrogen sulfide gas sensor.

[0014] In general, the above technical solutions conceived by this application have the following technical advantages compared with the existing technologies: 1. A superoxide dismutase-based quantum dot gas sensor was designed based on the specific catalytic "key-lock" interaction between the enzyme and the substrate. This overcomes the limitation of conventional gas sensors, which are selective but lack specificity, and achieves specific detection of hydrogen sulfide gas. The sensor has been verified to have high specificity for hydrogen sulfide gas, with a response sensitivity of 2.39 for 10 ppm hydrogen sulfide, which is sufficient for the detection of hydrogen sulfide in multi-component gases. 2. Using 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as the sensor's electrolyte ensures good solubility of the hydrogen sulfide gas under test while maintaining good conductivity. The slow volatilization of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ensures the activity of superoxide dismutase during the detection process. 3. During the preparation process, a quantum dot film is prepared using a drop-coating method, followed by a solid-phase one-step labeling method for coupling the enzyme to the quantum dots. This process avoids the reliance on organic crosslinkers in traditional crosslinking processes, facilitating rapid transduction of electrical signals. The coupling interface between the quantum dots and the enzyme is regulated to achieve electron transfer at the interface, and the preparation method is simple. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a scanning electron microscope image of the quantum dot gas sensor sensitive film prepared in Example 1; Figure 2 1 is a Fourier transform infrared spectra of the prepared comparative example (PbS) and Example 4 (PbS-SOD1) quantum dot sensor systems; Figure 3 This is a gas-sensitive cyclic voltammetry test curve diagram of the prepared quantum dot sensor Example 4 in hydrogen sulfide gas with different concentrations; Figure 4 The graph is a dynamic response curve of the quantum dot hydrogen sulfide gas sensor to 10 ppm hydrogen sulfide at room temperature using enzyme-labeled quantum dots of different sizes to regulate charge transfer interface in Example 1-4; Figure 5 is the response of the quantum dot gas sensor of Example 4 to hydrogen sulfide gas of different concentrations; Figure 6 The repeatability test results of the gas sensors prepared in Examples 1-4 were tested for 10 ppm hydrogen sulfide six times continuously at room temperature; Figure 7 These are the selectivity test results of the quantum dot gas sensor prepared in Example 4 for 100 ppm ethanol, 100 ppm formaldehyde, 100 ppm ammonia, 100 ppm benzene, 50 ppm nitric oxide, 100 ppm acetone, 100 ppm p-xylene, and 50 ppm nitrogen dioxide at room temperature.

[0015] Figure 8This is the transfer characteristic curve test result of the HEMT gas sensor chip prepared in Example 7.

[0016] Figure 9 This is a test of the output characteristic curve of the HEMT gas sensor chip prepared in Example 7 at different hydrogen sulfide concentrations (0-50 ppm).

[0017] Figure 10 This is a test of the output characteristic curve of the HEMT gas sensor chip prepared in Example 7 at different hydrogen sulfide concentrations (0-50 ppm) when the control gate voltage is -1 V.

[0018] Figure 11 This is a test of the output characteristic curve of the HEMT gas sensor chip prepared in Example 7 at different hydrogen sulfide concentrations (0-50 ppm) when the control gate voltage is -0.5 V.

[0019] Figure 12 This is a test of the output characteristic curve of the HEMT gas sensor chip prepared in Example 7 at different hydrogen sulfide concentrations (0-50 ppm) when the control gate voltage is 0.5 V. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0021] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0022] Additionally, references throughout this specification to "one embodiment," "one embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment," "in one embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0023] The principle of human smell is that gases adsorb onto olfactory receptor cells, which activate and emit electrical signals. These signals are then transmitted to the brain's central nervous system, where they are processed by the nervous system before being recognized by humans. Inspired by this remarkable olfactory perception, research and development have led to the development of physical and chemical sensors integrated with various olfactory biomaterials or biomimetic components. By combining protein expression and purification with computer-aided design and screening techniques, quantum dot gas sensors, using natural olfactory cells, proteins, enzymes, peptides, and other sensitive components, combined with secondary transducers, can achieve specific recognition of target gases, potentially surpassing natural odor perception and finding unprecedented applications in disease diagnosis, environmental monitoring, food analysis, and other fields.

[0024] The purpose of this application is to provide a quantum dot gas sensor based on the superoxide dismutase enzyme [Cu-Zn]-SOD (SOD1), which has been shown to be an effective hydrogen sulfide hydrogen oxidase. SOD1 rapidly converts hydrogen sulfide into sulfate under sulfide-restricted conditions, enabling specific detection of hydrogen sulfide gas. Therefore, the technical problem addressed by this application is to construct a quantum dot gas sensor with biological olfactory sensing specificity that can achieve specific detection of target gases without relying on post-processing algorithms.

[0025] In a first aspect, the present application provides a method for preparing a quantum dot-based hydrogen sulfide gas sensor, comprising: S1. Preparation of colloidal quantum dot materials: The colloidal quantum dots are one or more of PbS, Bi2S3 or WO3; the hot injection temperature is usually 95-120°C, the hot injection reaction time is 30-50s, and then the mixture is cooled to room temperature in a cold water bath; colloidal quantum dots of different sizes are synthesized by regulating the hot injection temperature, and the interface between superoxide dismutase and colloidal quantum dots is regulated; the size of colloidal quantum dots is usually between 3.1nm and 3.8nm. When the hot injection temperature is 95°C, the corresponding quantum dot size is 3.09 nm, when the hot injection temperature is 100°C, the corresponding quantum dot size is 3.50 nm, when the hot injection temperature is 110°C, the corresponding quantum dot size is 3.59 nm, and when the hot injection temperature is 120°C, the corresponding quantum dot size is 3.71 nm. S2. drop-coating the colloidal quantum dot solution onto the surface of a first electrode of an electronic device, and forming a quantum dot film after drying. The quantum dot film has a thickness of approximately 500 nm to 1000 nm. The electronic device is a planar electrochemical three-electrode device or a high electron mobility transistor, and the corresponding first electrode is a working electrode of the planar electrochemical three-electrode device or a gate of the high electron mobility transistor. S3. At the optimal temperature for superoxide dismutase, use solid phase labeling to label superoxide dismutase (e.g., SOD1) at a concentration of approximately 0.8 mg / cm 2 ~4.0mg / cm 2 The surface of the quantum dot film is chemically cross-linked at a density of 100 nm to obtain a hydrogen sulfide gas sensor; specifically, a 0.1 mg / mL to 1.5 mg / mL superoxide dismutase solution is used to incubate the first electrode of the semiconductor device covered with the quantum dot film for 30 min to 70 min, so that the superoxide dismutase is bound to the surface of the quantum dot film; in step S2, the volume ratio of the colloidal quantum dot solution to the superoxide dismutase solution is (1 to 1.5): 1; the optimum temperature generally refers to the activity temperature of the enzyme, and for superoxide dismutase, the temperature is 25°C to 37°C; The test method using the above hydrogen sulfide gas sensor includes: S1. Covering the first electrode of the hydrogen sulfide gas sensor with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and calibrating the hydrogen sulfide gas sensor using hydrogen sulfide gas of a standard concentration at a temperature of 25° C. to 37° C.; during the calibration, utilizing the specific catalytic effect of superoxide dismutase on hydrogen sulfide, causing hydrogen sulfide dissolved in the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt electrolyte to undergo an oxidation-reduction reaction, generating a current signal, thereby corresponding the intensity of the current signal to the concentration of the hydrogen sulfide gas; performing curve fitting on the current signal to obtain a curve showing the corresponding relationship between the current signal and the concentration of the hydrogen sulfide gas; Using 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as the sensor's electrolyte ensures good solubility of the hydrogen sulfide gas under test while also ensuring good conductivity. Furthermore, the slow volatilization of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ensures the activity of superoxide dismutase during the detection process, thus avoiding a decrease in detection sensitivity or deviation of the test results from the curve due to a decrease in superoxide dismutase activity. S2. Detect hydrogen sulfide concentration using the calibrated hydrogen sulfide gas sensor at a temperature of 25°C to 37°C. By finding the corresponding hydrogen sulfide gas concentration on the curve based on the corresponding current signal, specific detection of the hydrogen sulfide concentration in the test gas can be achieved.

[0026] Note that during the detection process, the temperature in step S1 and step S2 should be kept consistent as much as possible to prevent the signal of the hydrogen sulfide to be detected from deviating from the curve.

[0027] In some embodiments, an electrochemical workstation can be used to perform a preliminary electrochemical gas-sensing performance test on the hydrogen sulfide gas sensor. When hydrogen sulfide gas is introduced, it is determined whether a redox peak appears. If a redox peak appears, it proves that the sensor prepared can be used for the detection of hydrogen sulfide gas. If no redox peak appears, the parameters are adjusted and the sensor is re-prepared.

[0028] The following are examples, and the sources of the reagents and instruments involved are as follows: Electrochemical planar three-electrode: purchased from Botan Technology (Weihai) Co., Ltd. Electrochemical workstation CHI760E: purchased from Shanghai Chenhua Instrument Co., Ltd. Superoxide dismutase 1 bovine (SOD1): purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. Phosphate buffered saline (PBS): purchased from Beijing Inokai Technology Co., Ltd. SOD1 solution: place SOD1 lyophilized powder in the corresponding volume of PBS solution and shake for 10 min until fully dissolved to obtain the corresponding concentration of SOD1 solution; Toluene: purchased from Sinopharm Chemical Reagent Co., Ltd. 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (ETMI-TFSI): Shanghai MacLean Biochemical Technology Co., Ltd. V-1530T constant temperature heating platform: purchased from Dongguan V-1530T Automation Technology Co., Ltd.

[0029] High-precision dynamic gas distribution device: homemade in the laboratory.

[0030] Planar electrochemical gas sensing test chamber: homemade in the laboratory.

[0031] If specific experimental steps or conditions are not specified in the examples, the procedures or conditions of conventional experimental steps described in the literature in the field can be followed. All raw materials and instruments used are commercially available, including but not limited to those used in the examples of this application.

[0032] Example 1 Design and preparation method of a quantum dot gas sensor: S1. Synthesis of Colloidal Quantum Dots: PbS colloidal quantum dots were synthesized using the classic organic hot injection method. 1.8 g of lead oxide was placed in a three-necked flask. 6 mL of oleic acid and 20 mL of octadecene were added with high-speed stirring. The mixture was then heated to 90°C under vacuum to prepare a lead oleate precursor. After 8 hours of vacuum, the precursor temperature was raised to 120°C. In a glove box, 280 μL of tetramethylsilane (TMS) was pipetted into 10 mL of octadecene, pre-evacuated, to prepare a sulfur precursor. Under nitrogen, the sulfur precursor was rapidly injected into the lead precursor. After a 30-second reaction, the heating mantle was turned off and removed. The three-necked flask was placed in a pre-prepared cold water bath for rapid cooling. The cooled PbS quantum dot source solution was pipetted into centrifuge tubes in four batches. A certain amount of acetone was added for centrifugal washing, and the supernatant was discarded. The remaining product was dispersed and dissolved in toluene, and then centrifuged and washed again with acetone. The speed of each centrifugation is 8000 rpm, and the time is controlled within 10 minutes. After three centrifugations, the black precipitate obtained is PbS quantum dots. The quantum dots are then stored in a toluene solution and prepared into a 10 mg / mL solution for later use.

[0033] S2. Preparation of quantum dot film: The quantum dot solution was drop-coated onto the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of approximately 550 nm. The scanning electron microscope image is shown in Figure 2. Figure 1 shown.

[0034] S3. Enzyme-QD Coupling: A 1 g / L SOD1 solution was drop-coated onto the prepared QD film and incubated at 37°C for 1 hour to form a stable enzyme-QD interface. The volume ratio of the QD solution to the enzyme solution was approximately 1:1, and the enzyme distribution density was approximately 0.796 mg / cm 2 .

[0035] S4. Measurement of the gas-sensing performance of quantum dot gas sensors: Add 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt electrolyte to completely cover the working electrode of the electrochemical planar three-electrode. Pass a certain concentration of hydrogen sulfide gas diluted with air through a high-precision gas distribution system. Determine the potential of the constant potential current-time test based on the position of the redox peak using the cyclic voltammetry test curve for subsequent testing.

[0036] Example 2 Example 1 was repeated with the same steps, except that the temperature of the precursor was raised to 95° C. before preparing the sulfur precursor.

[0037] Example 3 Example 1 was repeated with the same steps, except that the temperature of the precursor was raised to 110° C. before preparing the sulfur precursor.

[0038] Example 4 Example 1 was repeated with the same steps, except that the temperature of the precursor was raised to 100° C. before preparing the sulfur precursor.

[0039] Example 5 Example 1 was repeated with the same steps, except that in step S3, the concentration of the SOD1 solution was 1.5 g / L and the distribution density of the enzyme was approximately 1.194 mg / cm 2 .

[0040] Example 6 Example 1 was repeated with the same steps, except that in step S3, the constant temperature incubation temperature was 25°C.

[0041] Example 7 Example 1 was repeated using the same steps, except that a high electron mobility field effect transistor (HEMT) was used instead of the planar electrochemical three-electrode in Example 1, and the gate of the high electron mobility field effect transistor (HEMT) was used as the working electrode of the planar electrochemical three-electrode.

[0042] Comparative Example 1 This comparative example provides a quantum dot gas sensor, the difference being that the quantum dot gas sensor is obtained directly through steps S1-S2.

[0043] Comparative Example 2 Example 5 was repeated with the same steps, except that PBS solution was used instead of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in step S4.

[0044] Comparative Example 3 Example 4 was repeated with the same steps, except that PBS solution was used instead of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in step S4.

[0045] Test Example 1 Will Figure 2 The Fourier transform infrared spectroscopy of the quantum dot sensor system of comparative example 1 (PbS) and example 4 (PbS-SOD1) shows that in the infrared spectrum curve of the quantum dot modified layer film, the peaks at 2789-2985 cm -1 The CH stretching vibration peak appeared in the wavenumber range, and at 1406 cm -1 There is a CH bending vibration peak at 1525 cm -1 The carbonyl (C=O) peak was found at the wavenumber position, which was derived from the long-chain oleic acid ligand on the surface carried from the synthesis stage. Compared with the quantum dot film, in the infrared spectrum curve of the SOD1 enzyme modified PbS quantum dot film, the peak at 2900 cm -1The CH stretching vibration peak at 1646 cm-1 has changed and shifted to a certain extent, indicating that the interaction between quantum dots and enzyme molecules has caused changes in surface groups. -1 The characteristic peak of amide i originating from SOD1 appeared at 617 cm -1 The Cu-S peak appears at the wavenumber of 1.5 Å. The above analysis shows that there is a certain interaction between PbS colloidal quantum dots and SOD1. SOD1 may replace the oleic acid ligand originally existing on the surface of the quantum dots through ligand replacement, form a coordination bond between the O of the carboxyl group in the enzyme molecule and the Pb of PbS, and directly bind to the S of PbS in the enzyme molecule, or bind to the quantum dots through possible adsorption, so that the quantum dots can directly label the enzyme molecules.

[0046] Cyclic voltammetry test curves of quantum dot gas sensors in different concentrations of hydrogen sulfide gas: Using a CHI760 electrochemical workstation, the cyclic voltammetry curves of the quantum dot gas sensors of Examples 1-4 were tested at different hydrogen sulfide concentrations. Figure 3 As shown in the figure, the intensity of the redox peak gradually increases with increasing hydrogen sulfide gas concentration (the direction of increasing concentration is indicated by the arrow in the figure), confirming that the prepared quantum dot gas sensor has a good response to hydrogen sulfide gas. However, Comparative Examples 2 and 3, which used PBS as the buffer for the working electrode, did not show good response characteristics.

[0047] Test Example 2: Response of Quantum Dot Gas Sensor to Hydrogen Sulfide Gas The gas sensing performance of the quantum dot gas sensors prepared in Examples 1-4 was tested at room temperature using a Chenhua electrochemical workstation. First, air was introduced into the test chamber, then a certain concentration of hydrogen sulfide diluted with air was introduced, and then air was introduced to obtain a gas-sensitive response curve, as shown in FIG. Figure 4 As shown, the response value of the sensor in Example 1 to 10 ppm hydrogen sulfide was 2.39, confirming that the prepared quantum dot gas can sensitively detect hydrogen sulfide gas at room temperature and has excellent response characteristics. However, Comparative Examples 2 and 3, which used PBS as the buffer solution for the working electrode, did not show good response characteristics.

[0048] On the basis of Example 1, the incubation temperature of step S3 was adjusted between 25°C and 37°C, and the concentration of the SOD1 solution was adjusted between 0.1 g / L and 1.5 g / L (the density of the enzyme on the surface of the quantum dot film was calculated to be approximately 0.796 mg / cm based on the solution concentration, solution volume, and electrode surface area). 2 ~3.981 mg / cm2 ), or adjust the incubation time in step S3 between 30 and 70 minutes. Testing showed that all hydrogen sulfide gas sensors exhibited a specific response to hydrogen sulfide gas. However, when PBS was used as the electrolyte instead of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, it was difficult to determine the specific response characteristics. This may be because 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide has good conductivity and can dissolve hydrogen sulfide. Its slow volatilization rate can maintain the activity of SOD1 and can also absorb moisture from the air, which helps compensate for moisture, maintain the stability of the enzyme-gas reaction interface, and ensure the accuracy of the test results.

[0049] Test Example 3: Response of quantum dot gas sensor to different concentrations of hydrogen sulfide gas: The test of Example 1 was carried out under the same conditions as those of Test Example 2, and hydrogen sulfide gas at different concentrations (50 ppb~10 ppm) was tested at room temperature. Figure 5 As shown, the quantum dot gas sensor exhibits excellent response recovery characteristics to different concentrations of hydrogen sulfide.

[0050] Test Example 4: Repeatability of the quantum dot gas sensor's response to hydrogen sulfide gas: The conditions of Test Example 2 were kept consistent. The sensors prepared in Examples 1-4 were tested for 10 ppm hydrogen sulfide for six cycles. The results were as follows: Figure 6 As shown, it can be found that the sensor has good repeatability and can achieve multiple consecutive repeatability tests.

[0051] Test Example 5 Specificity of Quantum Dot Gas Sensor: Example 1 was tested under the same conditions as Test 2. Nine gases (all with air as the carrier gas) including 100 ppm ethanol, 100 ppm formaldehyde, 100 ppm ammonia, 100 ppm benzene, 50 ppm nitric oxide, 100 ppm acetone, 100 ppm p-xylene, 50 ppm nitrogen dioxide, and 10 ppm hydrogen sulfide were tested at room temperature. Figure 7 As shown, it is found that the response of the gas sensor prepared in Example 1 to hydrogen sulfide gas is much higher than that to the other eight interfering gases, so the sensor shows excellent specificity to hydrogen sulfide gas.

[0052] Test Example 6: Transfer Characteristic Curve Test of Quantum Dot-Based Hydrogen Sulfide Gas Sensor Chip The transfer characteristic curve of the hydrogen sulfide sensor chip in Example 7 in air was tested using a semiconductor parameter tester. Figure 8As shown in the figure, the threshold voltage shifts to the left when the drain voltage is between 0.1 V and 0.5 V. Controlling the gate voltage has a strong ability to regulate the sensor's drain current. By controlling the gate voltage, the sensor's operating current can be varied, thereby adjusting the sensor's sensitivity and signal-to-noise ratio.

[0053] Test Example 7: Output characteristic curve of quantum dot-based hydrogen sulfide gas sensor chip The sensitivity of the sensor is related to the size of the control gate voltage and the source-drain voltage. The test conditions are the same as those in Test Example 6. The hydrogen sulfide sensor chip of Example 7 is tested. Figure 9 As shown in the figure, with a fixed drain voltage of 0.2V, the leakage current of the sensor changes significantly under various hydrogen sulfide concentrations. When the field-effect transistor operates in the subthreshold swing region, in order to study the influence of the control gate voltage on the gas-sensitive performance of the sensor, the relationship between the output characteristic curve of the sensor and the change of hydrogen sulfide gas concentration under different control gate voltages (-1V~0.5V) was subsequently tested.

[0054] Test Example 8: Output characteristic curve of quantum dot-based hydrogen sulfide gas sensor chip The hydrogen sulfide sensor chip of Example 7 was tested, and the gate voltage was controlled to be -1V. Figure 10 As shown, the sensor gate operates in the subthreshold swing region. When the sensor gate is reverse biased, negative voltage applied to the Schottky gate induces more 2DEG in the conductive channel, increasing the sensor drain current ID. This increases the sensor's sensitivity and allows it to distinguish hydrogen sulfide gas at various concentrations.

[0055] Test Example 9: Output characteristic curve of quantum dot-based hydrogen sulfide gas sensor chip The hydrogen sulfide sensor chip of Example 7 was tested. When the control gate voltage was -0.5V, Figure 11 As shown, the current of the sensor chip is relatively large, which can distinguish hydrogen sulfide gas at various concentrations, but the degree of distinction is not large.

[0056] Test Example 10: Output characteristic curve of quantum dot-based hydrogen sulfide gas sensor chip The hydrogen sulfide sensor chip of Example 7 was tested. When the control gate voltage was 0.5V, Figure 12 As shown in Figure 3, the drain current of the sensor tends to saturation. At this time, the drain current of the sensor does not change much in the hydrogen sulfide atmosphere at various concentrations.

[0057] Based on the above performance test results, it is shown that the response of the quantum dot gas sensor prepared in the embodiment of the present application to 10 ppm hydrogen sulfide gas at room temperature is 2.39, and it has excellent selectivity and good repeatability.

[0058] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A hydrogen sulfide gas sensor, characterized in that: The invention comprises an electronic device and a quantum dot film covered on a working electrode or a gate of the electronic device, wherein the surface of the quantum dot film is combined with 0.8 mg / cm 2 ~4.0 mg / cm 2 The electronic device is a planar electrochemical three-electrode or a high electron mobility transistor; The hydrogen sulfide gas sensor uses 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt as an electrolyte; when the hydrogen sulfide gas sensor is working, the superoxide dismutase exerts its specific catalytic effect at an optimum temperature, causing the hydrogen sulfide dissolved in the 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt to undergo an oxidation-reduction reaction, generating a current signal, and the hydrogen sulfide concentration in the gas to be measured is obtained according to the current signal.

2. The hydrogen sulfide gas sensor according to claim 1, characterized in that: The superoxide dismutase is SOD1.

3. The hydrogen sulfide gas sensor according to claim 1, characterized in that: The material of the quantum dot film is SnO2, In2O3, SnS2, PbS, Bi2S3 or WO3, and the thickness of the quantum dot film is 400 nm~900 nm.

4. A method for preparing a quantum dot-based hydrogen sulfide gas sensor, characterized in that: include: S1. Obtaining an electronic device having a quantum dot film covered on a first electrode; the electronic device is a planar electrochemical three-electrode or a high electron mobility transistor, and the first electrode is a working electrode or a gate; S2. At the optimum temperature of superoxide dismutase, incubate the first electrode with a 0.1 g / L to 1.5 g / L superoxide dismutase solution for 30 min to 70 min, so that the superoxide dismutase binds to the surface of the quantum dot film covered on the first electrode, thereby obtaining the hydrogen sulfide gas sensor.

5. The hydrogen sulfide gas sensor according to claim 4, characterized in that: The optimum temperature is 25°C to 37°C.

6. The preparation method according to claim 4, characterized in that: The superoxide dismutase is SOD1.

7. The preparation method according to claim 4, characterized in that: The preparation method of the electronic device with a quantum dot film covered on the first electrode is: drop-coating a colloidal quantum dot solution with a concentration of 7 mg / mL to 15 mg / mL on the surface of the first electrode of the semiconductor device to form a quantum dot film, wherein the size of the colloidal quantum dots in the colloidal quantum dot solution is 3.1nm to 3.7nm.

8. A method for detecting hydrogen sulfide concentration, characterized in that: The following steps are involved: S1. Obtaining an electronic device having a quantum dot film covered on a first electrode; the electronic device is a planar electrochemical three-electrode or a high electron mobility transistor, and the first electrode is a working electrode or a gate; S2. At the optimum temperature of superoxide dismutase, incubate the first electrode with a 0.1 g / L to 1.5 g / L superoxide dismutase solution for 30 min to 70 min, so that the superoxide dismutase binds to the surface of the quantum dot film covered on the first electrode, thereby obtaining the hydrogen sulfide gas sensor. S3. Calibrate the hydrogen sulfide gas sensor using a standard concentration of hydrogen sulfide gas at the optimum temperature; S4. Using the calibrated hydrogen sulfide gas sensor to detect the concentration of hydrogen sulfide at the optimum temperature.

Images