97results about How to "Excellent gas sensitivity" patented technology

The invention discloses a surface modification method of the tungstic oxide film gas sensor. The process includes: cleaning the Al203 base sheet; spurting the interdigital electrode on the base sheet in the magnetron sputtering device using the platinum as the target and the argon gas as the working gas; spurting the tungstic oxide film on the base sheet with the interdigital electrode using the tungsten as the target and the argon, oxygen as the working gas; spurting the metal layer on the film using the Ti, Ni, Mo, Va, Platinum, Aurum or Pd as the target material and the argon gas as the working gas; heat process to the metal layer in air and get the surface modifying gas sensor. The film is uniform and high purity which is good adhesion to the base bottom and the parameter is easy to control. The gas sensor has the low working temperature and good selectivity, also the response and recovery time are shot.

The invention belongs to the technical field of metal-oxide gas sensors, and particularly relates to design and synthesis of a composite sensitive material ZnO / ZnFe2O4, and an application of the composite sensitive material ZnO / ZnFe2O4 in an acetone gas sensor. In the preparation and preparation processes of the sensitive material, ZnO hollow microspheres are successfully synthesized first by adopting a microwave heating technology, and then a layer of ZnFe2O4 nanosheets grow on the surfaces of the ZnO hollow microspheres by adopting an epitaxial growth method. The whole synthesis process is simple, highly-efficient, energy-saving and suitable for large-scale production. Compared with ZnO hollow microspheres with a single component, the ZnO gas sensor modified by the ZnFe2O4 nanosheets shows more excellent gas sensitivity to acetone. In addition, the gas sensor of this type is small in size, and low in cost, so that the gas sensor based on the ZnO / ZnFe2O4 heterostructure is more applicable to monitoring acetone gas.

The invention discloses a preparation method of a hybridized hierarchical structure sensitive thin-film sensing device based on a two-dimensional material. The sensing device comprises a single crystal semiconductor substrate, an insulation layer, an interdigital electrode layer, a first PDDA film layer, a reduction-oxidation graphene film layer, a second PDDA film layer and a hierarchical structure ZnO-PSS thin film which are sequentially overlapped according to a preparation order. The preparation method mainly comprises the following steps: preparing an interdigital electrode device; preparing a film layer material required by the sensing device, and preparing the hybridized hierarchical structure sensitive sensing device by adopting a layer-by-layer self-assembling method. The preparation method has the advantages of fully utilizing characteristics of large specific area, low electronic noise, good semiconductor property and negative electricity of reduced-oxidized graphene and combining the structure characteristic of a hierarchical structure zinc oxide to prepare a hybridized hierarchical structure sensitive thin film; the process is simple, the repeatability is good, and the prepared sensing device can be used in the field of gas detection.

The invention belongs to the technical field of sensors, and particularly relates to a novel ammonia sensor and a preparation technology thereof. The novel ammonia sensor comprises a gas sensitive material and a substrate, wherein the gas sensitive material uniformly coats the surface of the substrate uniformly, and comprises the component of reducing graphene which is wrapped with a cobaltosic oxide composite nano material; the coating thickness of the gas sensitive material is 1micron-100microns. The ammonia sensor is relatively high in responsiveness of an ammonia gas, and meanwhile has the advantages of relatively good selectivity, flexibility and stability and relatively low operation temperature.

The invention relates to a cobaltosic oxide bead-chain-shaped fiber and a preparation method thereof. The preparation method comprises the following steps: adding a cobalt source to N,N-dimethylformamide (DMF), and fully stirring till the cobalt source is completely solved; and adding polyvinylpyrrolidone (PVP) to the solution, stirring to obtain a spinning solution, spinning the spinning solution by utilizing an electrostatic spinning technique to obtain fibers, and forging fiber samples to obtain the cobaltosic oxide bead-chain-shaped fiber. According to the cobaltosic oxide bead-chain-shaped fiber and the preparation method thereof, the one-step electrostatic spinning technique is utilized; a bead-chain-shaped structure is formed by controlling the property of a precursor raw material; the process is simple; the bead-chain-shaped structure is a one-dimensional structure formed by connecting Co3O4 monocrystal grains of similar granularity, the diameter is distributed uniformly, the shape is regular, the grains are completely exposed and are connected closely, and the specific surface area is relatively large; the cobaltosic oxide bead-chain-shaped fiber and the preparation method thereof have the wide application prospect in the fields of battery electrode materials, chemical catalysts, gas sensing and the like.

The invention provides a noble metal doped SnO2 composite material and a preparation method thereof. The method comprises: (1) SnO2 superfine powder is mixed with noble metal powder with mass fraction ranging from 0.05 to 1.21, deionized water with mass fraction ranging from 20 to 40 percent is added to and stirred with the mixture into slurry, and the noble metal is one of or the mixture of two or more of Pd, Au, Cu and La or Ce; (2) the slurry is evenly coated on a ceramic substrate and is dried in a baking oven; and (3) the ceramic substrate is put into a muffle furnace and is sintered for 1 hour at the temperature from 600 to 700 DEG C, and after the room temperature is realized by furnace cooling, the noble metal doped SnO2 composite material can be obtained. Compared with common SnO2 materials, the noble metals doped in the invention, such as Pd, Au, Cu, La and Ce, and the like, can reduce the activation energy of adsorption of chemical gas, and can obviously improve the sensitivity and the response time of the SnO2 material.

The invention discloses a SnO2-ZnO gas sensitive material with a heterostructure and a preparation method thereof. The preparation method comprises the following steps: (1) adding an organic weak baseinto a stannic chloride ethanol solution, adjusting pH to 8-10 and ageing, thereby acquiring a tin sol; (2) dispersing a ZnO nanowire into the tin sol and adding hexamethylenetetramine, thereby acquiring a prepared reaction solution; (3) putting the prepared reaction solution into a high-pressure reactor, reacting, and then filtering, washing and drying a reaction product, thereby acquiring the SnO2-ZnO gas sensitive material with the heterostructure. The method has the advantages of simple process, mild conditions and easiness in large-scale production. The prepared SnO2-ZnO gas sensitive material has a multilayer heterostructure and is capable of effectively avoiding the agglomeration of ZnO nanowires and SnO2 nanometer grains; the material has a large specific area and forms a mass ofheterojunctions; the reaction activity site density of the material surface is obviously promoted; the response of the gas sensitive material to various gases is effectively promoted; the gas sensitive material is endowed with an excellent gas-sensitive characteristic.

The invention discloses a methylbenzene gas sensor based on an alpha-Fe2O3 / SnO2 heterostructure nanowire array and a preparation method of the methylbenzene gas sensor, and belongs to the technical field of gas sensors. The device is of a flat plate structure, and is composed of two separated copper-gold alloy probes (serving as test electrodes), a sensitive material thin film growing on a Pt-plated silicon wafer, and a mini-type high-temperature ceramic heating piece on the back face of the silicon wafer. The sensor has the advantages of being high in integration level, simple in structure, low in price, small in size, firm, durable and capable of being produced on a large scale. In addition, the test result of the gas-sensitive characteristic shows that the sensor can detect methylbenzene at low working temperature and has extremely-good long-term stability, and therefore the methylbenzene gas sensor can have important application prospects on the aspects of methylbenzene leakage detecting and alarming in industrial production.

The invention discloses a method to prepare ITO nanometer lines and a method to prepare ITO gas sensors. The method to prepare ITO nanometer lines is as follows: a layer of gold film deposits on an underlayer; powdered indium oxide, stannous oxide and plumbago are mixed pro rata, and are arranged in a boat; the underlayer is also arranged on the boat to be heated and thermally insulated together with the mixture. The air pressure inside a silica tube in a heater is kept to be about 300 Pa, and gaseous mixture containing little oxygen is admitted in the silica tube; after the heater is cooled to the room temperature, yellowish products are generated on the underlayer. The method to prepare the sensors is that the nanameter lines are dispersed in the solution for about two hours with ultrasonic wave, and are dried; the sizing agent formed is applied on the ceramic tubes of two electrodes, and needs covering on the electrodes; then the sizing agent is dried or sintered, and is connected with a leading wire. The method to prepare the ITO nanometer lines has the advantages of simplicity, controllability, low cost, and that the materials have excellent gas sensitivity. The method to prepare the gas sensor has the advantages of short response time, short recovery time, stable nature, low noise, and high sensitivity; and the method is applicable for large-scale industrial production.

The invention discloses an ethanol gas sensor based on a ZnO hollow flower ball and CdO nano-particle composite nanomaterial and a preparation method of the ethanol gas sensor and belongs to the technical field of oxide semiconductor gas sensors. The method comprises the steps of firstly taking zinc acetate dihydrate, glycine, sodium sulfate decahydrate and sodium hydroxide as starting raw materials, and a mixed solution of water and ethanol as a solvent and successfully preparing a ZnO hollow flower ball precursor by using a hydrothermal method; and burning in air to obtain ZnO hollow flower ball powder; and taking the ZnO hollow flower ball powder, cadimium nitrate tetrahydrate and thiourea as the starting raw materials, and a mixed solution of dimethylformamide (DMF) and isopropyl alcohol as the solvent, compounding CdO nano-particles on the ZnO hollow flower balls by using the hydrothermal method and then burning in air to obtain the ZnO hollow flower ball and CdO nano-particle composite nanomaterial. The defect that two materials are relatively poor in gas-sensing characteristics is overcome, and improvement of the detection sensitivity of an ethanol gas and reduction of a lower detection limit are achieved.

The invention discloses a metal-silicon dioxide multilayer film hollow nano structure array and a preparation method thereof. The metal-silicon dioxide multilayer film hollow nano structure array comprises a glass substrate, wherein a silicon dioxide film hollow nano structure array and more than one layer of metal film nano structure array are arranged on the surface of the glass substrate sequentially from bottom to top. The preparation method comprises the process steps such as preparation of single-layer ordered polystyrene nanosphere dense arrangement, preparation of single-layer ordered polystyrene nanosphere non-dense arrangement, preparation of a metal nano-pore array mask, preparation of a nano-structure array template, and preparation of a silicon dioxide film hollow nano-structure array and a metal-silicon dioxide multilayer film hollow nano-structure array. The nano-structure array disclosed by the invention has the advantages of large area, high density, good processability and the like; and the preparation method is low in cost and has high efficiency and good compatibility, thereby bringing convenience to the study on the optical properties, magnetic properties, catalytic properties and the like of the nano-structure array.

The invention discloses a preparation method of an alpha-Fe2O3 / TiO2 nano-composite gas sensing material. The preparation method comprises the following steps: dispersing FeCl3.6H2O into a mixed solution of deionized water and ammonia water; stirring for 10 to 20 minutes; transferring the obtained mixed solution into a hydrothermal reactor; adding a prepared TiO2 nanofiber material; heating the hydrothermal reactor to be 95 DEG C for reacting for 4 hours; cooling the hydrothermal reactor to a room temperature; centrifuging sediment in the reactor with an ethanol solution repeatedly; drying at the temperature of 55 to 65 DEG C for 24 hours; calcining the material at the temperature of 500 DEG C for 2 hours to obtain the alpha-Fe2O3 / TiO2 nano-composite gas sensing material. In the preparation method, the alpha-Fe2O3 / TiO2 nano-composite gas sensing material prepared by combination of an electrostatic spinning technology and a hydrothermal method has a one-dimensional dentritic heterostructure, and can show a high gas sensing characteristic.

The invention relates to an oxygen vacancy modified metal oxide gas sensitive material for low-concentration NO2 gas detection at low temperature and a preparation method thereof. The material is obtained by subjecting a metal oxide to surface reduction with a reductant, is porous nanospheres consisting of small particles, and has a diameter of 200-700 nm, and the size of the small particles is 10-20 nm. The invention also provides a method for preparing an oxygen vacancy modified metal oxide gas sensitive material through safe and effective surface reduction of an oxide. The oxygen vacancy modified metal oxide gas sensitive material has high sensitivity and selectivity for low-concentration NO2 gas at low temperature. The method is simple, process parameters are easy to control, and the method is easy to operate and low in cost.

The present invention discloses the preparation process of ITO nanometer line and its gas sensor. The preparation process of ITO nanometer line includes the steps of: depositing one layer of gold film on substrate; setting the mixture of indium oxide, stannous oxide and graphite in certain weight proportion in a boat, setting the substrate on the boat, and heating and maintaining inside quartz tube in a furnace; maintaining the pressure at 300 Pa while introducing mixed gas containing small amount of oxygen; and cooling to room temperature to form yellowish product on the substrate. The preparation process of the gas sensor includes the steps of ultrasonically dispersing the nanometer lines in solution, stoving, coating the slurry on and between two electrodes on ceramic tube, stoving and sintering, and connecting leads. The ITO nanometer line has excellent gas sensing characteristic and the gas sensor has short response time, short restoring time, high sensitivity and other advantages.

The invention provides a carbon nanotube / phthalocyanine / polyaniline three-element composite material, and a preparation method and application thereof, and relates to a three-element composite material, and a preparation method and application thereof. The invention aims to solve the technical problem that polyaniline can not be uniformly distributed on the surface of a carbon nanotube easily in the existing method. The three-element composite material provided by the invention is prepared from a nanotube, tetra-beta-carboxyl metal phthalocyanine, aniline, ammonium persulfate, N,N-dimethylformamide and distilled water. The method provided by the invention comprises the following steps: 1, equally dividing the distilled water into two equal parts, and adding the ammonium persulfate into one part of distilled water to prepare an ammonium persulfate solution; 2, sequentially adding the tetra-beta-carboxyl metal phthalocyanine and the carbon nanotube into the DMF (N,N-dimethylformamide), performing ultrasonic vibration, performing centrifugal separation, washing with water, drying, sequentially adding the aniline and the remaining distilled water, performing further ultrasonic vibration, and slowing adding the ammonium persulfate solution; and 3, performing stirring reaction, filtering, sequentially washing with distilled water and anhydrous ethanol, and drying. The product provided by the invention can be used in the field of chemical sensors.

The invention discloses a nitrogen dioxide gas sensor containing petal-like SnSe2. The nitrogen dioxide gas sensor comprises a gas sensitive material and a heating substrate, wherein the heating substrate is coated with the gas sensitive material, the coating thickness ranges from 1-100 micrometers, and the gas sensitive material is prepared from a petal-like SnSe2 nanomaterial. A preparation process includes the following steps: step 1, mixing 1.6-2.4 mL of C2H8N2 with 30.4-45.6 mL of (CH2OH)2, adding 361-541.6 mg of stannous chloride dihydrate and 126.3-189.5 mg of selenium powder, performing magnetic stirring for 20-30 minutes, pouring the mixture into a reaction kettle for 3-12 hours of reaction at the temperature of 165-180 DEG C, separating an obtained black product by a centrifugalmachine, repeatedly performing washing until the pH of waste liquid is 6.5-7.5, and drying the waste liquid at the temperature of 80 DEG C for 6-12 hours to obtain the petal-like SnSe2; step 2, preparing SnSe2 dispersion liquid; step 3, coating the dispersion liquid onto the heating substrate, and drying the heating substrate in a drying box at the temperature of 80 DEG C to obtain the nitrogen dioxide gas sensor. The nitrogen dioxide gas sensor provided by the invention has the advantages of simple process step, low cost and sensitive response to nitrogen dioxide.

The invention discloses an ammonia gas sensor, which comprises a gas sensitive material and a substrate. The gas sensitive material is painted on the substrate surface and comprises graphene modified titanium dioxide composite nano particles with a bridge connection structure. The composite nano particle comprises graphene and titanium dioxide, and the graphene is arranged between titanium dioxide as a bridge. Graphene accounts for 0.2 to 20 wt% of the composite nano material. The thickness of the gas sensitive material coating is 0.4 to 0.5 [mu]m. The substrate is made of Si or Al2O3 and is provided with an Au electrode. The gas sensitive material of the ammonia gas sensor is composed of graphene modified titanium dioxide composite nano particles with a bridge connection structure, can respond to NH3 gas more selectively, restoratively, and stably, and has a lower work temperature.

The invention discloses a CNTs@alpha-Fe2O3 heterojunction composite material-based acetone gas sensor and a preparation method thereof, and belongs to the technical field of gas sensors. The acetone gas sensor comprises an insulating alumina ceramic tube substrate with two parallel and separate annular gold electrodes on the outer surface, a semiconductor metal oxide gas sensitive material coated on the outer surface of the insulating alumina ceramic tube substrate and the gold electrodes, and a nichrome heating coil arranged in the insulating alumina ceramic tube, wherein each gold electrode is provided with a platinum wire; the sensitive material is a CNTs and alpha-Fe2O3 nano-rod-compounded heterojunction hierarchical structure nanomaterial. The sensor has the advantages of being simple in structure, low in price, relatively small in volume, solid and durable, is suitable for massive production; and the gas-sensitivity characteristic testing result shows that the sensor can detect low-concentration acetone, has excellent long-term stability and has an important application prospect in detection and alarming of acetone leakage in industrial production and medical detection.

The invention relates to a tungsten disulfide formaldehyde gas-sensitive sensor preparation method and application thereof in vehicle microenvironment detection. By constructing a tungsten disulfide-based Ni-In2O3 / WS2 nano composite gas-sensitive sensor and constructing an in-vehicle microenvironment gas component detection sensing array, component recognition and concentration prediction for thein-vehicle microenvironment are realized through a PSO-BP neural network, so, the method and the application thereof have practical significance for guaranteeing body health and safety of drivers andpassengers.

The invention discloses a method for synthesizing a ZnO supported Fe2O3 nanoheterostructured gas sensor on the basis of an MOF (metal-organic framework) template. The method comprises the following steps: (1) an MIL-88A nanorod is obtained with a solvothermal method and sintered, and a porous alpha-Fe2O3 nanorod is obtained; (2) the porous alpha-Fe2O3 nanorod is taken as a substrate, zinc acetatedihydrate is taken as a reaction raw material, fumaric acid is taken as a ligand, methanol and water are taken as a mixed solvent, and soaking is performed multiple times; (3) after a solvothermal reaction, Zn-MOF / alpha-Fe2O3 powder is obtained by centrifugation, washing and drying and is calcined, and ZnO / alpha-Fe2O3 heterostructured nanopowder is obtained; (4) the gas sensor is prepared. The nanoheterostructured material is synthesized successfully with MOFs as a template, the prepared gas sensor is a practical semiconductor type gas sensor with high sensitivity, good stability and low cost,and one new idea is provided for synthesis of LDO (layered double oxide) nanoheterostructures.

The invention provides a method for simply and stably preparing micro-nano hollow copper, and belongs to method for preparing hollow copper. The method includes the steps that firstly, copper sulfate is dissolved in water and placed in a water bath kettle to be heated; secondly, polyvinylpyrrolidone is added to the solution and stirred; thirdly, water is added to sodium hydroxide, and a water solution of sodium hydroxide is prepared, added to the solution in the second step and stirred; fourthly, a pre-mixed hydrazine hydrate solution is added to the solution in the third step and stirred; fifthly, the water bath kettle is adjusted to the proper temperature, sepia Cu particles are generated, solid-liquid two phases containing the Cu particles are centrifuged at a high speed, Cu solid particles are acquired and washed multiple times with anhydrous alcohol and deionized water in a cross mode, and other impurities generated in the reaction process are removed; sixthly, Cu powder containing water or alcohol is placed in a vacuum drying oven to be dried, and then the high-purity Cu micro-nano particles can be acquired. The method has the advantages of being low in cost, simple in preparation process, high in purity, good in repeatability and high in surface chemical activity.

The invention discloses a ZnSe / ZnO based nitrogen dioxide gas sensor and a preparation process thereof. The sensor comprises a gas sensitive material and a heating electrode, wherein the gas sensitivematerial is coated on the surface of the heating electrode, the coating thickness is 50-80 microns, and the gas sensitive material is a heterojunction composite nano-material formed by zinc selenideand zinc oxide. The preparation process comprises the steps of first, placing zinc selenide powder in an ark, putting the ark in a tubular furnace, introducing a dry gas mixture of 20% of oxygen and 80% of nitrogen for heating at the same time, and reacting at a temperature of 400 DEG C-600 DEG C for 0.5h-4h, then naturally cooling to the room temperature to obtain a ZnSe / ZnO heterojunction; second, putting the ZnSe / ZnO heterojunction powder into a mortar, adding deionized water, and grinding until the solution is in uniform suspension; taking the suspension, coating the suspension on the surface of the heating electrode, placing the sensor in a drying oven to dry at a temperature of 80 DEG C so as to obtain a nitrogen dioxide gas sensor. The nitrogen dioxide gas sensor has the advantagesof simple processing steps, low cost and sensitive response to nitrogen dioxide.

The invention discloses a palladium nano particle-modifying indium oxide nanosheet composite material as well as a preparation method and application thereof. Indium nitrate, resorcinol, N,N-dimethylformamide and acetone are used as raw materials to prepare an indium-series organic framework nanosheet of a three-dimensional net structure by utilizing a high-temperature high-pressure method, thenthe palladium ion-modifying indium-series organic framework nanosheet of the three-dimensional net structure is prepared by virtue of an electrostatic absorption process, and finally the nano particle-modifying indium oxide nanosheet composite material is prepared by virtue of air calcining and reductive gas reduction. The palladium nano particle-modifying indium oxide nanosheet composite materialnot only has high specific surface area and good gas sensitive characteristic, but also can be used as a sensing layer of a resistance-type metal oxide gas sensor to realize the ultra-sensitive and high-selective detection for carbon disulfide gas, and moreover, no expensive detection equipment is needed, the detection cost is low, the operation is simple, the detection time is short, and rapidness and high efficiency can be realized.

The invention discloses a resistance type NO2 sensor based on a stannic oxide modified zinc oxide nanometer material, and a manufacture method thereof, and belongs to the technical field of gas sensors. The sensor is of a tubular structure and consists of an Al2O3 ceramic tube substrate, two parallel annular Au electrodes which are mutually discrete and are coated to the outer surface of the Al2O3ceramic tube substrate, a stannic oxide modified zinc oxide nanometer material gas sensitive thin film coated to the outer surface of the Al2O3 ceramic tube and the annular Au electrodes, and a nickel-chromium alloy heating coil which penetrates through the inner part of the nickel-chromium. The stannic oxide modified zinc oxide nanometer material of which the surface is functionalized has excellent gas sensitive characteristics, including high sensitivity and a high response recovery rate, for NO2, and the problem that a pure-state zinc oxide gas sensor has poor sensitivity performance is solved. By use of the sensor, experiment parameters, including reaction temperatures, reaction time, the ratio of a reaction precursor and the like, can be controlled to indicate the regulation and control of the performance, including the composition, the structure and the like, of the functional zinc oxide material, and therefore, the performance of the sensor is improved.

The invention relates to a alpha-Fe2O3 nano microsphere hydrogen sulfide gas-sensing material and a preparation method of a gas-sensing component. The method includes the following steps: taking FeCl3.6H2O as a raw material and [C12-2-C12im]Br2 as an auxiliary reagent; preforming reaction in a stainless steel self-pressure reaction kettle by a hydrothermal method under 150-210 DEG C for 8-12 hours,; naturally cooling to room temperature and then centrifuging; washing a product with ethanol and ultrapure water for multiple times respectively; vacuum drying to obtain an a-Fe2O3 nanosphere; and calcining the a-Fe2O3 precursor at 250 DEG C for 2 hours to obtain the a-Fe2O3 nanosphere hydrogen sulfide gas-sensing material. The method of the invention has the beneficial effects that ionic liquidGemini imidazole surfactant ([C12-2-C12im]Br2) is adopted for the first time for assisted synthesis of the alpha-Fe2O3 nano microsphere hydrogen sulfide gas-sensing material with a self-assembled porous structure, which opens up a brand-new way for the development and real-time detection of new harmful gas gas-sensing materials.

The present invention provides a chemical sensor simultaneously having light sensitivity and gas sensitivity, and relates to a semiconductor device specially adapted for various gases and illuminationdetection. The chemical sensor comprises the sensitive layer of a chemical sensor, a planar Au plating ceramic substrate, a leading wire and a gas sensor base, wherein the sensitive layer of the chemical sensor is a thin film layer obtained by doping a CH3NH3PbI3 perovskite precursor liquid and WO3 nanometer powder, and a heating layer made of a special material and a Au plating electrode are arranged on the planar ceramic sheet. According to the present invention, by preparing the CH3NH3PbI3 perovskite precursor liquid and WO3 nanometer powder mixing chemical sensor, the gas sensitivity of the sensor is improved, the sensitivity to gases is improved, the chemical sensor has good sensitivity to light, and the resistance of the sensor is reduced in the case of strong illumination so as toimprove the sensitivity to gases.

The invention discloses a PMMA-SnO2-based thin-film gas sensor taking methane as detected gas. A PMMA-SnO2 film is prepared by the following steps: with an insulated substrate / PMMA-SnO2 film / electrode structure, mixing PMMA, taken as an adhesive, with an organic solvent with SnO2 quantum dots to form a spinning solution, and performing spinning to form the PMMA-SnO2 film, wherein a gas-sensitive material adopted in the film structure refers to SnO2 nanoparticles, and the diameter of the SnO2 nanoparticles is about 20+ / -5nm. The film is high in conductivity, the preparation process is simple, and the cost is low; and moreover, the requirement on an attached substrate is low, and the film only needs to be spun on the insulated substrate. The most noteworthy is that the thin-film sensor still has high responding sensitivity on methane at a low temperature of 50 DEG C.

Disclosed are a tetra-beta-carboxyl phenoxy metal phthalocyanine / graphene composite material and a method. Graphene is easy to agglomerate and has relative inert surface and poor dispersity, so that defects of poor selectivity and recovery capability, low sensitivity and the like occur when graphene is used as a gas-sensitive material. Further application of a phthalocyanine complex is hindered due to an overhigh resistance value in practical application. The effect between the phthalocyanine complex and graphene is still unclear, and the distribution of the phthalocyanine complex on the surface of graphene is still not uniform. The compositions of the composite material comprise the following components: 0.85%-1.69% of tetra-beta-carboxyl phenoxy metal phthalocyanine, 0.40%-0.56% of graphene, 80.1%-83.1% of N, N-dimethylformamide, 2.61%-3.05% of hydrazine aqueous solution, and 15.2%-17.1% of ammonia water, wherein the percentage is weight percentage. The composite material is appliedto gas sensitive materials.

The invention provides an oil-gas blocking and sealing material. The oil-gas blocking and sealing material is obtained by the following mode with the steps of: a) mixing acrylate monomer, alkyl olefine acid monomer, styrene monomer and a solvent to obtain monomer solution; b) swelling non-polar or weakly-polar rubber particles in the monomer solution to obtain prepolymer; c) mixing the prepolymerand a separating agent, and carrying out grafting polymerization reaction under the initiated polymerization condition to obtain the oil-gas blocking and sealing material. The oil-gas blocking and sealing material provided by the invention not only has excellent sensitive responding characteristic for oils, but also has sensitive responding characteristic for short-chain gaseous hydrocarbon (the number of carbon atoms is less than or equal to 4), and swells self under the triggering condition of oil or gas so as to block or seal oil-gas channels in microcracks.

The invention provides a preparation method of multistage-structured flower-shaped molybdenum dioxide, and relates to a preparation method of molybdenum dioxide. The invention solves the technical problems that flower-shaped molybdenum trioxide prepared by the existing method is poor in sensitivity and the triethylamine gas sensitivity is poor. The method comprises the following steps: 1, dropwisely adding hydrogen peroxide into a molybdenyl acetylacetonate methanol solution, stirring, transferring into a reaction kettle, and performing thermal reaction to obtain a black precursor; and 2, washing the precursor obtained in the step 1 with anhydrous alcohol, and performing vacuum drying at 60-70 DEG C for 8-15 hours to obtain the multistage-structured flower-shaped molybdenum dioxide. According to the invention, the multistage-structured flower-shaped molybdenum dioxide of different sizes can be obtained by regulating the ratio of the reactants through the simple hydrothermal method without subsequent thermal treatment, the monodispersity of the multistage-structured flower is satisfactory, and the obtained multistage-structured flower-shaped molybdenum dioxide material has favorable triethylamine gas sensitivity characteristic.