Sensitive-transfer-transmission separated Ni-MOF / SnO2 high-selectivity hydrogen sulfide room temperature sensor and preparation method thereof

Abstract

The invention belongs to the field of gas sensors, and discloses a sensing-transfer-transmission separated Ni-MOF / SnO2 high-selectivity hydrogen sulfide room temperature sensor and a preparation method thereof. The sensor comprises an insulating substrate, a gold interdigital electrode, a SnO2 electron transport layer and a Ni-MOF sensing layer from bottom to top, wherein the SnO2 electron transport layer is prepared on the gold interdigital electrode through an atomic layer deposition process, the Ni-MOF sensing layer is prepared on the SnO2 layer in an in-situ growth mode, and a heterojunction is formed between the SnO2 layer and the Ni-MOF layer. The sensor combines the conductivity advantage of tin oxide, the specificity sensitivity advantage of the MOF layer and the transduction advantage of the Ni-MOF / SnO2 heterojunction, the defect of intrinsic high resistance when Ni-MOF is used as the sensor is overcome, room-temperature high-selectivity, low-detection-lower-limit and high-response detection of hydrogen sulfide is achieved, the humidity stability of the sensor is greatly improved, and the sensor has a wide application prospect. The method has a wide application prospect in the aspect of gas detection.

Description

Technical Field

[0001] The present invention belongs to the technical field related to nanomaterials and sensors, and more specifically, relates to a Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor for sensing, transduction and separation and a preparation method thereof. Background Art

[0002] Hydrogen sulfide is commonly found in petroleum exploration. High concentrations of hydrogen sulfide can cause serious human poisoning, so hydrogen sulfide detection is of great significance.

[0003] Most existing hydrogen sulfide sensors are metal oxide gas sensors, such as tin oxide gas sensors, but they have poor recognition ability for hydrogen sulfide and low selectivity and cannot accurately detect hydrogen sulfide. At the same time, they need to work under high temperature heating conditions, which poses a safety hazard in special environments.

[0004] The development of new highly selective sensitive materials is particularly critical. Metal-organic framework materials have broad prospects in achieving high selectivity due to their unique structure and functional group characteristics. However, their inherent wide band gap and low conductivity limit their use as chemiresistive sensors. The simultaneous realization of high selectivity, high sensitivity and excellent conductivity at room temperature on a single material will be limited by the intrinsic properties of the material. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with separated sensing, transmission and transport, and a preparation method thereof, wherein the sensor aims to prepare the SnO2 transport layer and the Ni-MOF sensing layer in situ and by growth respectively by atomic layer deposition process, and to form a heterojunction structure between the SnO2 transport layer and the Ni-MOF sensing layer of the sensor for signal transduction. The sensor thus prepared solves the technical problem that the sensors in the prior art cannot achieve low operating temperature, high selectivity, high sensitivity and excellent conductivity at the same time.

[0006] In order to achieve the above-mentioned purpose, in one aspect of the present invention, a Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transduction and transmission separation is provided, which comprises, from bottom to top: an insulating substrate, a gold interdigital electrode, a SnO2 electron transport layer and a Ni-MOF sensing layer; wherein the SnO2 electron transport layer is prepared on the gold interdigital electrode by an atomic layer deposition process, and the Ni-MOF sensing layer is prepared by in-situ growth on the SnO2 layer, and a heterojunction structure is formed between the SnO2 layer and the Ni-MOF layer.

[0007] Preferably, the SnO2 layer is prepared by an atomic layer deposition process, including: using a tin source and a water source as precursor sources, alternately introducing them into an atomic layer deposition chamber, and depositing a SnO2 layer on the gold interdigitated electrodes.

[0008] Preferably, the SnO2 layer has a thickness of 20-50 nm.

[0009] Preferably, the Ni-MOF layer is prepared by in-situ growth on the SnO2 layer, including: dispersing a completely ionizable divalent nickel salt and terephthalic acid in a non-aqueous solvent with inert coordination ability, adjusting the solution pH between 6.5-8.0 to obtain a Ni-MOF growth solution, transferring it to the SnO2 layer and performing a hydrothermal reaction to obtain the Ni-MOF layer.

[0010] Preferably, in the Ni-MOF growth solution, the concentration of the completely ionizable divalent nickel salt is 0.2-10 g / L, the concentration of terephthalic acid is 0.5-5 g / L, and the molar ratio of the completely ionizable divalent nickel salt to terephthalic acid is 1:(1-3).

[0011] In order to achieve the above object, in another aspect of the present invention, a method for preparing a Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation as described in the first aspect of the present invention is provided, comprising the following steps:

[0012] (1) Printing gold interdigital electrodes on the surface of an insulating substrate;

[0013] (2) using a tin source and a water source as precursor sources, alternately introducing them into an atomic layer deposition chamber, and depositing a SnO2 layer on the gold interdigitated electrode;

[0014] (3) Dispersing completely ionizable divalent nickel salt and terephthalic acid in a non-aqueous solvent with inert coordination ability, adjusting the solution pH between 6.5 and 8.0 to obtain a Ni-MOF growth solution, transferring the solution to the SnO2 layer and performing a hydrothermal reaction, and drying to obtain a Ni-MOF / SnO2 thin film device.

[0015] Preferably, in the atomic layer deposition process, the pressure ratio of the tin source to the water source is 1:(1.5-2).

[0016] Preferably, in the atomic layer deposition process, the carrier gas flow rate is 20-50 sccm, the number of pulse cycles is 200-1000, and the deposition temperature is 90-120°C.

[0017] Preferably, the completely ionizable divalent nickel salt is nickel nitrate hexahydrate or nickel chloride hexahydrate; and the non-aqueous solvent having an inert coordination ability is methanol or N,N-dimethylformamide.

[0018] Preferably, the thermal reaction is a hydrothermal reaction at 100-150° C. for 8-12 hours, followed by natural cooling to room temperature.

[0019] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0020] (1) The sensor of the present invention uses SnO2 as the transmission layer instead of the traditional gas-sensitive layer. It is prepared by atomic layer deposition process. In situ growth uses highly specific Ni-MOF as the sensing layer. It is prepared by in situ growth on SnO2, so that a heterojunction structure is formed between the SnO2 layer and the Ni-MOF layer of the sensor. Combining the conductivity advantage of SnO2, the specific sensing advantage of the MOF layer and the signal transduction advantage of the Ni-MOF / SnO2 heterojunction, the disadvantage of the intrinsic high resistance of MOF itself as a sensor is improved, and high selectivity, low detection limit and high response detection of hydrogen sulfide at room temperature are achieved. In addition, the heterojunction hinders the migration of protons in the ionization of water molecules, significantly improving the humidity stability of the sensor, so that the sensor has broad application prospects in gas detection.

[0021] Specifically, the lower tin oxide layer provides a large baseline current as an electron transport layer. The upper Ni-MOF layer serves as a sensing layer, which is based on the metal protein structure of the cell respiratory enzyme. It contains polar ligands and can simultaneously grow in situ to obtain unsaturated Ni metal centers, which can highly selectively recognize hydrogen sulfide; polar ligands can accelerate the ionization of hydrogen sulfide molecules to produce hydrogen sulfide ions, which bind to the unsaturated coordination sites of Ni atoms; water molecules in the air can accelerate the dissociation of hydrogen sulfide ions, so that this unique sensing mechanism can break through the barrier of the oxygen adsorption mechanism and achieve efficient catalysis of hydrogen sulfide gas. The upper Ni-MOF layer also has semiconductor properties and can form a heterojunction with the lower tin oxide layer to achieve signal transduction. At the same time, the gas-sensitive layer makes the gas-sensitive response amplification factor determined by the sensing layer, while the amplification benchmark is determined by the transport layer, which solves the problem of poor conductivity of the original Ni-MOF and achieves a geometric amplification of the net response value. Therefore, the design of this sensor is completely different from the existing oxygen adsorption recognition mechanism of tin oxide as a metal oxide, and proposes the design of the existing traditional resistive gas sensor with integrated sensing.

[0022] (2) The transmission layer and the sensing layer of the sensor of the present invention are prepared as thin films directly on the substrate by in-situ deposition, and are compatible with both atomic layer deposition (physical method) and liquid phase growth (chemical method) processes, thus having the potential advantage of mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A schematic diagram of the preparation process of a Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation according to an example of the present invention;

[0024] Figure 2 This is a scanning electron microscope morphology image of the Ni-MOF gas-sensitive powder prepared in Example 2 of the present invention;

[0025] Figure 3 X-ray diffraction patterns corresponding to the tin oxide gas-sensitive film of Example 1 of the present invention, the Ni-MOF gas-sensitive material of Example 2, and the Ni-MOF / SnO2 film of Example 3;

[0026] Figure 4 This is the room temperature hydrogen sulfide gas sensitive response curve of the tin oxide film prepared in Example 1 of the present invention;

[0027] Figure 5 This is the room temperature hydrogen sulfide gas sensitive response curve of the Ni-MOF film prepared in Example 2 of the present invention;

[0028] Figure 6 The room temperature hydrogen sulfide gas-sensitive response curve of the Ni-MOF / SnO2 film prepared in Example 3 of the present invention, wherein the inset corresponds to the response current detected when the detection time of the main figure is between 0 and 4500 seconds;

[0029] Figure 7 This is a test result diagram of room temperature hydrogen sulfide selectivity of the Ni-MOF film prepared in Example 2 of the present invention;

[0030] Figure 8 This is a test result diagram of room temperature hydrogen sulfide selectivity of the Ni-MOF / SnO2 film prepared in Example 3 of the present invention;

[0031] Fig. 9 This is the humidity sensitivity curve of the Ni-MOF film prepared in Example 2 of the present invention;

[0032] Fig.10 This is the humidity sensitivity curve of Ni-MOF / SnO2 obtained in Example 3 of the present invention;

[0033] Fig.11 This is the room temperature hydrogen sulfide gas-sensitive response curve of the thin film device prepared in Example 4 of the present invention;

[0034] Fig.12 This is the room temperature hydrogen sulfide gas sensitive response curve of the tin oxide film prepared in Example 5 of the present invention;

[0035] Fig.13 This is a scanning electron microscope morphology image of the tin oxide film prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Unless otherwise indicated, the raw materials or reagents used in the present invention are commercially available. All reagents are commercial grade and used according to the received standards. The scientific and technical terms and abbreviations used in the present invention have the meanings commonly understood by those skilled in the art.

[0038] The present invention provides a Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor with sensing, transduction and separation and a preparation method thereof. The sensor obtained by the present invention has the advantages of low operating temperature (no heating required), high selectivity, high sensitivity and excellent conductivity.

[0039] The present invention designs a Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation. Figure 1 As shown in the figure, the entire sensor consists of a four-layer planar structure, from bottom to top: insulating substrates such as alumina ceramics, screen-printed gold interdigital electrodes, atomic layer deposited tin oxide transport film, and highly selective Ni-MOF sensitive film. The interdigital electrodes are obtained by screen printing Au slurry onto insulating substrates such as alumina ceramics, the tin oxide transport film is deposited onto the interdigital electrodes by atomic layer deposition, and the Ni-MOF highly selective sensitive film is obtained by in-situ growth on the tin oxide layer. Real-time detection of hydrogen sulfide can be achieved by applying a test potential on both sides of the interdigital electrodes.

[0040] The core transmission and sensitive films are obtained by the following steps:

[0041] (1) Preparation of tin oxide thin film using atomic layer deposition (ALD) process: Place an aluminum oxide substrate in an ALD chamber, select a tin source and a water source as precursor sources, the carrier gas flow rate is 20-50sccm, the number of pulse cycles is 200-1000, the pressure ratio of the tin source and the water source is controlled to be (1:1.5-1:2), the deposition temperature is 90-120°C, and the deposition thickness is 20-50nm to obtain a uniform tin oxide thin film.

[0042] (2) Preparation of Ni-MOF growth solution: Disperse a completely ionizable divalent nickel salt (such as nickel nitrate hexahydrate (Ni(NO3)2·6H2O) or nickel chloride hexahydrate (NiCl2·6H2O)) and terephthalic acid (PTA) in a non-aqueous solvent with inert coordination ability (such as terephthalic acid (PTA), methanol, etc.), and ultrasonically treat for 5-10 minutes to obtain a clear and transparent solution (Ni(NO3)2·6H2O concentration 0.2-10 g / L, PTA concentration 0.5-5 g / L, and the molar ratio of the completely ionizable divalent nickel salt to terephthalic acid is 1:(1-:3). Subsequently, 0.3-0.6 mol / L sodium hydroxide solution is added dropwise to the above solution under magnetic stirring (volume ratio 1:10), and stirring is maintained for 20-40 minutes to obtain a green emulsion with a pH range of 6.5-8.0.

[0043] (3) In situ growth of Ni-MOF thin film: The ceramic device deposited with the tin oxide thin film is placed in a stainless steel reactor lined with polytetrafluoroethylene, and the green emulsion obtained in step (2) is simultaneously transferred to the stainless steel reactor lined with polytetrafluoroethylene (reactor volume to solution volume ratio (2-5): 1), followed by hydrothermal reaction at 100-150°C for 8-12h, and then naturally cooled to room temperature.

[0044] like Figure 1 As shown, the method for preparing a Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor for sensing, transduction and separation designed by the present invention comprises the following steps:

[0045] (1) The alumina substrate printed with interdigital gold electrodes was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, with each cleaning time of 5-20 minutes. The substrate was placed in a forced air drying oven, dried at 50-80° C. for 10-20 minutes, and then cleaned with oxygen plasma for 30-60 minutes.

[0046] (2) The transmission layer and sensing layer films were prepared on the alumina substrate through a two-step in-situ deposition process of atomic layer deposition and liquid phase growth.

[0047] (3) Drying the device with the grown thin film at 65-80°C for 5-10 min to obtain a Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transduction and separation.

[0048] The above method is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and the scope of protection of the present invention is not limited thereto.

[0049] Example 1: A tin oxide thin film is prepared by atomic layer deposition process, as follows:

[0050] (1) The alumina substrate printed with interdigital gold electrodes was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, for 10 min each time. The substrate was placed in a forced air drying oven and dried at 65°C for 10 min, and then cleaned with oxygen plasma for 30 min.

[0051] (2) Preparation of tin oxide gas-sensitive thin film by atomic layer deposition (ALD) process: an aluminum oxide substrate was placed in an ALD chamber, a tin source and a water source were selected as precursor sources, a carrier gas flow rate of 50 sccm, a pulse cycle number of 250, and a deposition temperature of 110° C. The pressure ratio of the tin source and the water source was controlled to be 1:1.5 and the deposition time was 3 hours and 50 minutes to obtain a uniform tin oxide film of about 30 nm, thus preparing the tin oxide gas-sensitive thin film of Example 1.

[0052] Example 2: Preparation of Ni-MOF gas sensor, as follows:

[0053] (1) The alumina substrate printed with interdigital gold electrodes was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, for 10 min each time. The substrate was placed in a forced air drying oven and dried at 65°C for 10 min, and then cleaned with oxygen plasma for 30 min.

[0054] (2) Preparation of Ni-MOF growth solution: 9.6 mg Ni(NO3)2·6H2O and 16.6 mg terephthalic acid were dispersed in 20 ml N,N-dimethylformamide and ultrasonically treated for 10 minutes to obtain a green clear transparent solution (solution A). 160 mg sodium hydroxide was dispersed in 10 ml deionized water and ultrasonically treated for 10 minutes. Subsequently, 1 ml of 0.4 mol / L sodium hydroxide solution was added dropwise to solution A under magnetic stirring and stirred for 30 minutes to obtain a green emulsion.

[0055] (3) The obtained green emulsion was transferred to a stainless steel reactor lined with polytetrafluoroethylene. After sealing, the reactor was placed in a water heating box at 100° C. for 12 hours, taken out, naturally cooled to room temperature, and the obtained precursor was collected.

[0056] (4) Wash the sample by centrifugation three times with N,N-dimethylformamide, anhydrous ethanol, and anhydrous ethanol, respectively, at a speed of 6000 rpm and each centrifugation for 10 min.

[0057] (5) The precursor was dried in a drying oven at 65° C. for 8 hours, taken out and ground for later use, to obtain a spindle-shaped Ni-MOF gas-sensitive material.

[0058] (6) The gas-sensitive material is dispersed in anhydrous ethanol and ultrasonically treated for 2-5 minutes to obtain a uniform slurry. A planar insulating substrate printed with gold interdigital electrodes is placed on a 50-80°C heating table, and then a fixed amount of slurry is measured with a pipette and dripped onto the substrate. After the ethanol evaporates, the gas-sensitive film is firmly adhered to the substrate, thereby forming a Ni-MOF gas sensor.

[0059] Example 3: After preparing a tin oxide thin film by atomic layer deposition (ALD) process, a Ni-MOF thin film is grown in situ to prepare a Ni-MOF / SnO2 thin film device, as follows:

[0060] (1) The alumina substrate printed with interdigital gold electrodes was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, for 10 min each time. The substrate was placed in a forced air drying oven and dried at 65°C for 10 min, and then cleaned with oxygen plasma for 30 min.

[0061] (2) Preparation of tin oxide thin film using atomic layer deposition (ALD) process: Place an aluminum oxide substrate in an ALD chamber, select a tin source and a water source as precursor sources, set the carrier gas flow rate to 50 sccm, pulse cycle number to 250, control the pressure ratio of the tin source and the water source to 1:1.5, deposit the temperature to 110°C, and deposit for 3 hours and 50 minutes to obtain a uniform tin oxide thin film of about 30 nm.

[0062] (3) Prepare Ni-MOF growth solution: Disperse 9.6 mg Ni(NO3)2·6H2O and 16.6 mg terephthalic acid in 20 ml N,N-dimethylformamide and ultrasonically treat for 10 minutes to obtain a green clear transparent solution (solution A). Disperse 160 mg sodium hydroxide in 10 ml deionized water and ultrasonically treat for 10 minutes. Subsequently, add 1 ml of 0.4 mol / L sodium hydroxide solution dropwise to solution A under magnetic stirring and keep stirring for 30 minutes until the pH of the solution stabilizes at 7.3 to obtain a green emulsion.

[0063] (4) In-situ growth of modified Ni-MOF film: Place the ceramic device with the tin oxide film deposited in a stainless steel reactor lined with polytetrafluoroethylene, and transfer the green emulsion obtained in step (3) to the reactor simultaneously. Place the reactor in a water heating box, keep it at 100°C for 12 hours, and cool it naturally to room temperature.

[0064] (5) After being taken out from the reactor, the mixture was dried at 65° C. for 5 min to prepare the Ni-MOF / SnO 2 thin film device of Example 3.

[0065] Example 4: After preparing a tin oxide film by a magnetron sputtering process, a Ni-MOF film is grown in situ to obtain a corresponding device, as follows:

[0066] (1) The alumina substrate printed with interdigital gold electrodes was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, for 10 min each time. The substrate was placed in a forced air drying oven and dried at 65°C for 10 min, and then cleaned with oxygen plasma for 30 min.

[0067] (2) Preparation of tin oxide thin film by magnetron sputtering process: A tin target was selected as the metal source and DC sputtering was performed. The sputtering power, working pressure and oxygen partial pressure were 100W, 1.5Pa Ar, and 4% respectively. The deposition time was 5min. Finally, a uniform thin film was obtained.

[0068] (3) Post-treatment of the film: The film obtained in step (2) was annealed at 400° C. for 10 h and furnace cooled to finally prepare the tin oxide film of Example 4.

[0069] (4) Prepare Ni-MOF growth solution: Disperse 9.6 mg Ni(NO3)2·6H2O and 16.6 mg terephthalic acid in 20 ml N,N-dimethylformamide and ultrasonically treat for 10 minutes to obtain a green clear transparent solution (solution A). Disperse 160 mg sodium hydroxide in 10 ml deionized water and ultrasonically treat for 10 minutes. Subsequently, add 1 ml of 0.4 mol / L sodium hydroxide solution dropwise to solution A under magnetic stirring and keep stirring for 30 minutes until the pH of the solution stabilizes at 7.3 to obtain a green emulsion.

[0070] (5) In-situ growth of modified Ni-MOF film: Place the ceramic device with the tin oxide film deposited in a stainless steel reactor lined with polytetrafluoroethylene, and transfer the green emulsion obtained in step (3) to the reactor simultaneously. Place the reactor in a water heating box, keep it at 100°C for 12 hours, and cool it naturally to room temperature.

[0071] (6) After being taken out from the reactor, the mixture was dried at 65° C. for 5 min to prepare a device corresponding to Example 4.

[0072] Example 5: Preparation of tin oxide thin film by atomic layer deposition process, as follows:

[0073] (1) The alumina substrate printed with interdigital gold electrodes was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, for 10 min each time. The substrate was placed in a forced air drying oven and dried at 65°C for 10 min, and then cleaned with oxygen plasma for 30 min.

[0074] (2) Preparation of tin oxide gas-sensitive thin film by atomic layer deposition (ALD) process: an aluminum oxide substrate was placed in an ALD chamber, a tin source and a water source were selected as precursor sources, a carrier gas flow rate of 50 sccm, a pulse cycle number of 250, and a deposition temperature of 150° C. The pressure ratio of the tin source and the water source was controlled to be 1:1.5 and the deposition time was 3 hours and 50 minutes to obtain a tin oxide thin film, which was prepared into the gas sensor of Example 5.

[0075] Example 6: After preparing a tin oxide thin film by atomic layer deposition (ALD) process, a Ni-MOF thin film is grown in situ, and the pH of the in situ growth system is controlled to be 13 to obtain a thin film device, as follows:

[0076] (1) The silicon oxide wafer was ultrasonically cleaned with ethanol, acetone, and isopropanol, respectively, each time for 10 minutes. The substrate was placed in a forced air drying oven and dried at 65°C for 10 minutes, and then cleaned with oxygen plasma for 30 minutes.

[0077] (2) Preparation of tin oxide thin film using atomic layer deposition (ALD) process: Place an aluminum oxide substrate in an ALD chamber, select a tin source and a water source as precursor sources, set the carrier gas flow rate to 50 sccm, and the number of pulse cycles to 250. Control the pressure ratio of the tin source and the water source to be 1:1.5, the deposition temperature to be 110°C, and the deposition time to be 3 hours and 50 minutes to obtain a 20 nm uniform tin oxide thin film.

[0078] (3) Prepare Ni-MOF growth solution: Disperse 9.6 mg Ni(NO3)2·6H2O and 16.6 mg terephthalic acid in 20 ml N,N-dimethylformamide and ultrasonically treat for 10 minutes to obtain a green clear transparent solution (solution A). Disperse 160 mg sodium hydroxide in 10 ml deionized water and ultrasonically treat for 10 minutes. Subsequently, add 2 ml of 0.4 mol / L sodium hydroxide solution dropwise to solution A under magnetic stirring and keep stirring for 30 minutes until the pH of the solution stabilizes at 13 to obtain a green emulsion.

[0079] (4) In-situ growth of modified Ni-MOF film: Place the ceramic device with the tin oxide film deposited in a stainless steel reactor lined with polytetrafluoroethylene, and transfer the green emulsion obtained in step (3) to the reactor simultaneously. Place the reactor in a water heating box, keep it at 100°C for 12 hours, and cool it naturally to room temperature.

[0080] (5) After being taken out from the reactor, the mixture was dried at 65° C. for 5 min to prepare the corresponding thin film device of Example 6.

[0081] The materials or thin film devices prepared in the above embodiments are subjected to corresponding structural characterization and performance characterization. When performing performance characterization on thin film devices, a static test system is used for testing: the device is placed in a 20L sealed chamber, a certain concentration of the gas to be tested is introduced into the chamber, and the change in the current value is observed. Selectivity diagram ( Figure 7 , Figure 8 ) is defined as the difference between the current value of the device in the measured gas and the current value in air divided by the current value in air.

[0082] like Figure 3 It shows that the SnO2 prepared by low-temperature atomic layer deposition process corresponding to Example 1 has poor crystallinity and no obvious diffraction peak can be observed; while the diffraction peak of the Ni-MOF / SnO2 film corresponding to Example 3 shows obvious growth orientation difference compared with the Ni-MOF powder, which indicates that a heterojunction is formed between Ni-MOF and SnO2.

[0083] like Figure 4 It is shown that the SnO2 thin film sensor corresponding to Example 1 has no response to 100ppm hydrogen sulfide and is suitable as an electron transport layer material; Figure 5 It is shown that the simple Ni-MOF sensor corresponding to Example 2 can only detect hydrogen sulfide at the ppm level, with poor resolution, and its baseline current is very small, and the gas-sensitive response value is also small; Figure 6 It shows that the Ni-MOF / SnO2 thin film sensor corresponding to Example 3 has a hydrogen sulfide detection range of 10ppb to 100ppm, the baseline current is further improved compared with the SnO2 thin film, and the gas-sensitive response value is geometrically increased compared with the Ni-MOF sensor. Therefore, this indirectly indicates that a heterojunction is formed between Ni-MOF and SnO2, and through this junction effect, the sensor achieves high sensitivity and excellent conductivity.

[0084] like Figure 7 It shows that the Ni-MOF corresponding to Example 3 has fingerprint-level selectivity for hydrogen sulfide. Figure 8 It shows that the Ni-MOF / SnO2 corresponding to Example 3 also has fingerprint-level selectivity for hydrogen sulfide, further proving that Ni-MOF / SnO2 inherits the high selectivity of Ni-MOF through the heterojunction effect.

[0085] like Fig. 9 It is shown that the Ni-MOF corresponding to Example 2 is very susceptible to humidity interference. When the humidity fluctuates in the range of 70-20%, its current changes by 3-4 orders of magnitude; Fig.10 It shows that the Ni-MOF / SnO2 corresponding to Example 3 has good moisture resistance, and its current only changes slightly under the same humidity range. The heterojunction effect can effectively improve the humidity stability of the device.

[0086] like Fig.11 The sensor current is at the picoampere level, indicating the shedding of the SnO2 film; Fig.12 It is shown that the tin oxide gas-sensitive film is prepared by high-temperature atomic layer deposition process, and the sensor exhibits gas-sensitive response to 10ppm hydrogen sulfide, which proves that only low-temperature atomic layer deposition process is suitable for preparing tin oxide electron transport layer; Fig.13 It shows that the tin oxide layer will be corroded in a high pH environment and heterojunction devices cannot be successfully prepared.

[0087] According to the above, morphology test and performance test show that the Ni-MOF / SnO2 device prepared by in-situ growth of Ni-MOF layer on SnO2 layer prepared by atomic layer deposition process, in which the heterojunction formed between Ni-MOF and tin oxide realizes signal transduction, retains the high selectivity of the sensing layer, and realizes geometric amplification of the response value by the transmission layer. At the same time, the heterojunction only allows electron transmission and prohibits proton transmission, thereby greatly improving the humidity stability of the device.

[0088] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technology, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention.

Claims

1. A Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transfer and separation, characterized in that: From bottom to top, this includes: An insulating substrate, gold interdigital electrodes, a SnO2 electron transport layer and a Ni-MOF sensing layer; wherein the SnO2 electron transport layer is produced on the gold interdigital electrodes by an atomic layer deposition process, the Ni-MOF sensing layer is produced by in-situ growth on the SnO2 layer, and a heterojunction structure is formed between the SnO2 layer and the Ni-MOF layer.

2. The Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transmission and separation according to claim 1 is characterized in that: The SnO2 layer is prepared by an atomic layer deposition process, including: using a tin source and a water source as precursor sources, alternately introducing them into an atomic layer deposition chamber, and depositing the SnO2 layer on the gold interdigitated electrodes.

3. The Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transmission and separation according to claim 1 is characterized in that: The thickness of the SnO2 layer is 20-50nm.

4. The Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transduction and separation according to claim 1 is characterized in that: The Ni-MOF layer is prepared by an in-situ growth method on the SnO2 layer, including: dispersing a completely ionizable divalent nickel salt and terephthalic acid in a non-aqueous solvent with an inert coordination ability, adjusting the solution pH between 6.5 and 8.0 to obtain a Ni-MOF growth solution, transferring it to the SnO2 layer and performing a hydrothermal reaction to obtain the Ni-MOF layer.

5. The Ni-MOF / SnO2 highly selective hydrogen sulfide room temperature sensor with sensing, transduction and separation according to claim 1 is characterized in that: In the Ni-MOF growth solution, the concentration of the completely ionizable divalent nickel salt is 0.2-10 g / L, the concentration of terephthalic acid is 0.5-5 g / L, and the molar ratio of the completely ionizable divalent nickel salt to terephthalic acid is 1:(1-3).

6. The method for preparing the Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation according to any one of claims 1 to 5, characterized in that: The steps include: (1) Printing gold interdigital electrodes on the surface of an insulating substrate; (2) using a tin source and a water source as precursor sources, alternately introducing them into an atomic layer deposition chamber, and depositing a SnO2 layer on the gold interdigitated electrode; (3) Dispersing completely ionizable divalent nickel salt and terephthalic acid in a non-aqueous solvent with inert coordination ability, adjusting the solution pH between 6.5 and 8.0 to obtain a Ni-MOF growth solution, transferring the solution to the SnO2 layer and performing a hydrothermal reaction, and drying to obtain a Ni-MOF / SnO2 thin film device.

7. The method for preparing the Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation according to claim 6, characterized in that: In the atomic layer deposition process, the pressure ratio of the tin source to the water source is 1:(1.5-2).

8. The method for preparing the Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation according to claim 6, characterized in that: In the atomic layer deposition process, the carrier gas flow rate is 20-50 sccm, the pulse cycle number is 200-1000, and the deposition temperature is 90-120°C.

9. The method for preparing the Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation according to claim 4, characterized in that: The completely ionizable divalent nickel salt is nickel nitrate hexahydrate or nickel chloride hexahydrate; the non-aqueous solvent with inert coordination ability is methanol or N,N-dimethylformamide.

10. The method for preparing the Ni-MOF / SnO2 highly selective room temperature hydrogen sulfide sensor for sensing, transduction and separation according to claim 4, characterized in that: The hydrothermal reaction is carried out at 100-150° C. for 8-12 hours and then naturally cooled to room temperature.

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