419results about How to "Improve gas sensing performance" patented technology

The invention discloses a binary carbon material-conductive polymer composite nano gas-sensitive thin film and a preparation method thereof. The binary carbon material-conductive polymer composite nano gas-sensitive thin film is a composite thin film formed by self-assembling a binary carbon material and a conductive polymer material through chemical polymerization, the binary carbon material is a combination of any of a graphene material and a carbon nanotube as well as a carbon nanofiber, nano porous carbon or nano graphite. The composite nano thin film with excellent gas-sensitive characteristic can be prepared by fully utilizing the excellent conductivity and high specific surface area of the carbon nano material and the peculiar response characteristic of the conductive polymer, playing the synergistic and supplementary roles generated among different materials and combining an orderly controllable self-assembled film forming method. The binary carbon material-conductive polymer composite nano gas-sensitive thin film and the preparation method thereof can open up a new approach for the sensitive thin film for a gas sensor which is high in performance, low in cost and capable of working at room temperature.

The invention provides a ZnO/SnO2 nano composite gas-sensitive material with a flower-shaped grading structure. The ZnO/SnO2 nano composite gas-sensitive material is prepared by the following steps: dripping a sodium hydroxide water solution into an ethanol solution of cetyl trimethyl ammonium bromide and stannous chloride dihydrate under electromagnetic stirring; after dripping, preparing a precursor solution by the continuous electromagnetic stirring; adding the precursor solution into a reaction kettle, reacting at 130 DEG C; carrying out centrifuging on a reactant, washing and drying to obtain a flower-shaped stannous oxide sacrifice template; adding the flower-shaped stannous oxide sacrifice template into a zinc acetate solution; agitating and carrying out ultrasonic treatment; removing a solvent to obtain a ZnO/SnO2 precursor; and carrying out heat preservation on the ZnO/SnO2 precursor for 2-4 hours in an air atmosphere of 700 DEG to obtain the composite gas-sensitive material. According to the ZnO/SnO2 nano composite gas-sensitive material with the flower-shaped grading structure, the controllable preparation of the composite gas-sensitive material on the appearance and components can be realized; the mass percent content of zinc oxide in the composite gas-sensitive material is 5%-15%; a flower shape is assembled by sheet-shaped tin dioxide and zinc oxide nano particles; the ZnO/SnO2 nano composite gas-sensitive material has a good gas sensitive performance and has a wide application prospect in the aspect of manufacturing a novel high-efficient gas sensor.

The invention relates to a method for preparing ferroferric oxide nano-piece through a microwave method, which belongs to the field of preparation of nano-material through a wet chemical method. The method comprises the following steps of: preparing a ferric salt solution by using ethylene glycol by using a soluble trivalent ferric salt as a raw material , adding the sodium acetate and a surfactant in the ferric salt solution, evenly stirring, and irradiating by using microwave to generate ferroferric oxide, filtering and washing the product, drying the product at a constant temperature in air to obtain the ferroferric oxide nano-piece material. The ferroferric oxide nano-piece material synthesized by the method has a thickness of 100nm below as well as the length and width of 1-10microns. The invention has the advantages of high purity of the prepared ferroferric oxide nano-piece, simple synthetic line, short period of microwave reaction of only tens of minute and easy control of the whole process, meets the demands of practical production, and has god application prospect in the fields of catalysis, biological medicine, energy and environment and the like.

The invention belongs to the technical field of preparation of tin dioxide powder, and relates to a preparation method of silver-doped nano tin dioxide powder. The preparation method comprises the following steps of: firstly adding citric acid solution, a surface active agent and ammonia water sequentially into mixed solution of soluble tin salt and soluble silver salt, and adjusting the pH value of a reaction system to 2.5-11, and under the action of constant-temperature magnetic stirring, generating precursor sol; then, adding the precursor sol into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle in a drying oven, carrying out hydrothermal reaction, taking out the hydrothermal reaction kettle after hydrothermal reaction, cooling, and sampling; and finally, cleaning, drying and grinding to prepare a finished nano tin dioxide powder product. The tin dioxide powder prepared by the method has the advantages of fewer granularity, narrow distribution range and good dispersity; and a gas sensor based on the tin dioxide powder material has good detection performance for fault gas in transformer oil.

The invention discloses [alpha]-phase ferric oxide porous core-shell microspheres and a controllable synthetic preparation method thereof. The [Alpha]-phase ferric oxide microspheres having porous core-shell structures can be prepared through a hydrothermal method with an inorganic soluble ferric salt being a raw material, deionized water and anhydrous alcohol being solvents and at a certain temperature for a certain time. The microspheres are 3 [mu]m in the average diameter. Cores and shells are composed of nano particles, wherein the average diameter of the nano particles is 200 nm and the average thickness of the shells is 100nm. A plurality of pores with pore diameters being 40nm are uniformly distributed on the surface of each shell with of a plurality of pores with pore diameters being 40nm. The preparation method is free of any dispersing agent and surfactant, and subsequent processes are convenient since a template is not needed. The preparation method is simple in technology, short in reaction time, large in output, is environmental-friendly and cheap in raw materials, is beneficial to large scale industrial production and the porous core-shell microspheres can be used for a lithium ion battery electrode material and a gas-sensitive material.

The invention discloses a preparation method for SnO2/ZnO compound micro-nano fibers. The preparation method comprises the following steps: firstly preparing Zif-8 by zinc salt and 2-methylimidazole; adding ammonium citrate dibasic, octadecylamine and ethyecellulose to prepare the Zif-8 solution; preparing tin salt solution by tin salt and polyvinylpyrrolidone, and slowly dropwise adding to the Zif-8 solution, to obtain precursor spinning solution, and executing the electrostatic spinning and heat treatment to obtain a final product. The body of the prepared SnO2/ZnO compound micro-nano fibers is formed by SnO2 and ZnO nano-particle combination, and the surface has the SnO2 nano-particles. According to the preparation method, a zinc-based metal organic framework material is introduced into the SnO2 micro-nano fibers, the synthetic process is simple, the reaction parameters are easily set, and the ingredients of the obtained product are adjustable. The obtained SnO2/ZnO compound micro-nano fibers have the important application value in the fields, such as air-sensitive and photocatalysis.

The invention discloses a preparation method of a titanium dioxide-tin dioxide nano-sosoloid material. The preparation method comprises the following steps: enabling a soluble tin (IV) salt, citric acid and a titanium (IV) salt to react in ethylene glycol till the a transparent precursor sol is formed; enabling the precursor sol to perform a closed reaction for 6-20 hours in a reaction kettle at the temperature of 150-220 DEG C; and washing and drying a reaction product. According to the preparation method disclosed by the invention, hydro-thermal treatment is directly performed on the precursor sol obtained by a sol-gel method, rutile type nano-tin dioxide-titanium dioxide (Ti1-xSnxO2, x is not less than 0.15 and less than 1) sosoloid material with the different titanium-tin weight ratio can be directly prepared without high-temperature sintering, the average particle size is 9-11nm, the particle size distribution is uniform, the specific surface area is large, the photocatalytic ability or the gas-sensing property can be improved, the agglomeration of nano-particles caused by sintering can be avoided, and the process energy consumption can also be effectively reduced; and furthermore, the technical principle is simple, the operation is simple and convenient, and the requirements on equipment are low.

The invention discloses a planar flexible room-temperature NO<2> sensor based on a three-dimensional MXene folded ball/ZnO composite material and a preparation method thereof, and belongs to the technical field of gas sensors. The sensor is composed of a polyimide flexible substrate having an Au interdigital electrode and three-dimensional MXene folded ball/ZnO composite material sensitive electrodes prepared on the interdigital electrode and the substrate. According to the planar flexible room-temperature NO<2> sensor based on the three-dimensional MXene folded ball/ZnO composite material andthe preparation method thereof provided by the invention, with the MXene material as a basis, the MXene is treated via an ultrasonic spraying method to prepare the anti-aggregating three-dimensionalMXene folded ball, thus achieving the advantages of being anti-aggregating, and maintaining a large specific surface area of the MXene; meanwhile, the oxidation is composited, and a ZnO nanoparticle is increased on a surface of the three-dimensional MXene folded ball, so that a sensing site is increased; and compared with a two-dimensional MXene and pure three-dimensional MXene folded ball, the sensor prepared based on the three-dimensional MXene folded ball/ZnO composite material obtains higher NO<2> sensing property, and has very good selectivity, resilience and bendability.

The invention discloses a multi-stage structure nanometer In2O3/graphene composite and a preparation method and application thereof. The composite is of a brick-shaped structure. The preparation method includes the steps of making indium salt capable of being dissolved in ethylene glycol, reduced graphene oxide and precipitator ammonium hydroxide have a chemical reaction under the microwave heating conditions on the gas-liquid interface formed by an ethylene glycol solution and ammonium hydroxide steam, bringing away the reaction product through a rolling ethylene glycol solution, and continuing to generate a new product. The composite has the advantages that original nanometer particles of nanometer In2O3/graphene prepared through a microwave gas-liquid interface method are small and uniform; the brick-shaped nanometer structure is formed with the original nanometer particles through self-assembling, and the multi-stage structure nanometer In2O3/graphene composite has good gas-sensitive performance for nitric oxide gas at the temperature of 100 DEG C and is high in selectivity.

The invention relates to a gas sensor based on a mesoporous indium oxide gas-sensitive material and a preparation method. The mesoporous indium oxide gas-sensitive material is used as a sensing layer of the sensor. According to the invention, mesoporous indium oxide prepared by using a nanometer casting method is used as the gas-sensitive material, the concentration of prepared coating slurry is 0.02 to 0.2 g/mL, and the thickness of the sensing layer of the gas sensor prepared through coating is 500 nm to 300 mu m. The preparation method for the gas sensor is simple to operate and easy to realize; the gas sensor has a large gas-sensitive specific surface area, greater than 150 m<2>/g; the preparation method is favorable for improving gas-sensitive performance of the prepared gas sensor, and the prepared gas sensor has optimal ethanol sensing performance of greater than 18, optimal acetone sensing performance of greater than 15 and optimal methanol sensing performance of greater than 12, all higher than the performance of frequently used industrial gas sensors.

The invention discloses a preparation method of an aluminum-doped tin dioxide flower-like micro-sphere/nano-rod gas sensitive material, which is characterized by comprising the following steps of (1) dissolving tetrachlorostannane pentahydrate and aluminum trichloride hexahydrate at a certain proportion into absolute ethyl alcohol, and dissolving a certain amount of sodium hydroxide into deionized water; (2) mixing the solution under the effect of a magnetic stirrer, and stirring at a medium speed for 20-30 minutes; (3) transferring the stirred solution into a reaction kettle, reacting for a certain time at the set temperature, and naturally cooling to room temperature; (4) performing centrifugal washing and drying to obtain doped tin dioxide powder. The gas sensitive material is of two micro structures including flower-like micro-sphere and nano-rod. The manufactured aluminum-doped SnO2 surface type gas sensing element has excellent sensitivity against hydrogen at a relatively low working temperature of 200-300 DEG C, and the highest sensitivity reaches 97.6% (the upper limit of sensitivity is 100%). By adopting the method disclosed by the invention, the prepared gas sensitive material is simple to prepare and has excellent gas sensitivity, thereby being an ideal hydrogen sensitive material.

The invention belongs to the technical field of a nanometer material, and provides a nitrogen dioxide gas sensor based on a SnSe2/SnO2 heterojunction as well as a preparation process and application thereof. The nitrogen dioxide gas sensor based on the SnSe2/SnO2 heterojunction mainly consists of a gas sensitive material and a heating base plate, wherein the gas sensitive material is coated on thesurface of the heating base plate; the coating thickness is 1 mum to 100 mum; the gas sensitive material is a heterojunction composite nanometer material formed by ingredients of tin diselenide and tin dioxide. A hot oxidization method is used for obtaining the novel heterojunction composite nanometer material; the raw materials can be conveniently obtained; the price is low; the heterojunction preparation process is simple; the scheme beings to a two-dimensional semiconductor heterojunction preparation scheme with the advantages of low equipment investment and simple technical flow process.The work temperature of nitrogen dioxide made of the tin diselenide and tin dioxide heterojunction composite nanometer material is 120 DEG C; the material and silicon base microelectron phase integration can be realized.

The invention discloses a palladium-doped stannic oxide wrapped carbon nano tube which is prepared by using a gel-sol method. The carbon nano tube is structurally prepared by wrapping the surface of the carbon nano tube with palladium-doped stannic oxide crystal (Pd/SnO2), and the method comprises the following steps: dispersing the carbon nano tube into super-pure water in an ultrasonic mode, adding a stannic chlori precursor, dispersing in the ultrasonic mode again, subsequently adding a sodium tetrachloropalladate solution, uniformly stirring, mixing, adjusting the pH value to be 7-9, preserving for 0.2-36 hours at 30-200 DEG C so as to obtain milk white gel, washing and drying the gel, subsequently calcining at 200-700 DEG C so as to prepare the palladium-doped stannic oxide wrapped carbon nano tube. Due to adoption of noble metal and doping of the carbon nano tube, the gas-sensitive property of a stannic oxide-based gas sensor is greatly improved, the response and recovery time is shortened, and the low operation temperature is optimal.

The invention provides a composite gas sensitive material, a gas sensor and a preparation method thereof and relates to the technical field of nanocomposite materials. A preparation method of the composite gas sensitive material comprises the steps of using a template agent for assembling a graphene material into a three-dimensional framework structure, making a metal salt react with an organic ligand on the surface of the three-dimensional framework structure, and enabling metal organic framework crystals to grow; removing the template agent and then carrying out calcining. A pore structure of the prepared composite gas sensitive material includes micropores, mesopores and macropores. The preparation method of the gas sensor comprises the steps of attaching a dispersion liquid of the composite gas sensitive material to an electrode surface and carrying out drying. The composite gas sensitive material improves the gas sensitive performance of the gas sensor.

The invention provides an overlong vanadium pentoxide nanowire harness with a hierarchical structure and a preparation method thereof. The length of the wire harness is not shorter than 10 cm; the diameter of the wire harness is 1-3 microns; the wire harness comprises parallel overlong nanowires; the diameters of the nanowires are 20-30 nm and the lengths of the nanowires are longer than 100 microns to 1 mm. The preparation method comprises the following steps: preparing a vanadium pentoxide sol by using a melting and quenching method; putting 40 ml sol to a reaction kettle; reacting the sol for 2-4 days under a condition of 160-200 DEG C so as to obtain a suspension containing overlong vanadium pentoxide nanowires; enabling a slender glass fiber to extend into the vanadium pentoxide nanowire suspension; lifting the slender glass fiber at a constant speed so as to obtain the wire harness; drying the obtained wire harness; carrying out heat treatment on the wire harness under an air atmosphere under a condition of 400-600 DEG C; and finally obtaining the overlong vanadium pentoxide nanowire harness with the hierarchical structure. A gas sensitive device assembled by using materials has the advantages of rapid response, good stability, sensitivity of 2.6 and low working temperature of 60 DEG C.

The invention relates to a preparation method for a hierarchical hollow cubic stannic oxide nanometer particle composed of ultrafine nano-rods and belongs to the technical field of nanometer material preparation. The method comprises the following steps: taking solid cubic zinc hydroxystannate as a precursor, covering a layer of stannic oxide nano-rods on the surface of the zinc hydroxystannate after the hydrothermal reaction for a period of time, and meanwhile, decomposing the inner zinc hydroxystannate, thereby acquiring the hierarchical hollow cubic stannic oxide nanometer particle composed of the ultrafine nano-rods in the shape similar to the shape of zinc hydroxystannate. Compared with the traditional template method, the preparation method has the advantages of low cost, few steps and simple operation; the prepared hollow stannic oxide nanometer particle has an obvious hierarchical structure and a mesoporous structure, is difficult to agglomerate, is excellent in crystallinity and is high in specific surface area; the hierarchical hollow cubic stannic oxide nanometer particle is composed of a large quantity of orderly arrayed nano-rods and the size of the nano-rods is close to the debye length; the air-sensitive characteristic is excellent; and the hierarchical hollow cubic stannic oxide nanometer particle has a potential application value in the field of air-sensitive sensors.