708 results about "COBALTOUS NITRATE" patented technology

Disclosed is a process for preparing a doping cobaltosic oxide, which relates to a method for the production of a modified cobaltosic oxide used for a Lithium-ion battery anode material. The method is characterized in that the preparation process comprises: 1) mixing a cobalt nitrate solution containing doped chemical ions with a mixed precipitator solution containing ammonia and sodium hydroxide and making the mixture react for eight to twenty hours at a pH value of between 8.4 to 10 and a temperature of between 40 and 80 DEG C so as to prepare a cobalt hydroxide precipitation containing doped chemical; and 2) washing and drying the cobalt hydroxide precipitation containing the doped chemical and then burning the precipitation for two to six hours at a temperature of between 500 and 800 DEG C so as to obtain the doping cobaltosic oxide. The method of the invention can get even particles with regular shapes after the reaction, the particle sizes of the doping cobalt hydroxide are controllable in a certain range, and the doping cobaltosic oxide can be obtained by calcinations. The method of preparation is characterized in that a magnesium source, an aluminum source, a titanium source, etc. are induced to the cobalt nitrate solution directly, and the process and operation are simple and easy.

The invention provides a preparation method of a nickel-cobalt layered bimetallic hydroxide/graphene electrocatalyst, which belongs to the technical field of electrocatalysts. The method disclosed bythe invention comprises the following steps: graphene and cobalt nitrate are uniformly dispersed in a methanol solvent by ultrasonic waves, so that an ultrasonic solution is obtained; the ultrasonic solution is added into a methanol solution of dimethylimidazole, is uniformly mixed and then is enabled to stand, and centrifuging, washing and drying are then carried out, so that a ZIF-67/graphene composite material is obtained; the ZIF-67/graphene composite material and nickel salt are mixed and dissolved in a solvent, refluxing is carried out for reaction, centrifugal separation is then carriedout, obtained precipitate is washed with absolute ethyl alcohol, and drying is carried out to obtain a NiCo LDH/G composite material with a nanoscale morphology. The method disclosed by the inventionovercomes the defects of high requirement on equipment, need for high temperature and high pressure and need for an expensive surfactant existing in conventional synthesis methods, and compared withthe prior art, the preparation method has the advantages of simple process, low cost, easy reaction process control and the like, and is suitable for industrial mass production.

The invention discloses a Co3O4 nanometer material for a supercapacitor and a preparation method thereof. The method comprises the following steps: on the basis of using cobalt nitrate as a raw material and a mixture of ethylene glycol and water as a solvent, adding a defined amount of glucose, placing the mixture in an autoclave to react at 120-200 DEG C for 10-25 hours, performing suction filtering, drying at 80 DEG C, calcining in a muffle furnace at 300 DEG C to obtain Co3O4 sea urchin-shaped conjoined spheres which have the diameter of 7-15mu m and are of a three-dimensional hierarchical structure. The Co3O4 nanometer material and the preparation method have the characteristics that the operation method is simple, the yield is high, and the product has the three-dimensional hierarchical structure and superior electrochemical performance. The prepared Co3O4 spheres with the three-dimensional hierarchical structure have the characteristics that the stability is higher, the particle size distribution is uniform, the dispersibility is good, the spheres are difficult in agglomeration and pores with the three-dimensional structure are beneficial to the diffusion of the electrolyte, thus the material can be widely applied in the fields of catalysis, lithium batteries and supercapacitors.

The invention relates to a MoSe2/Co0.85Se composite material for electrocatalytic water decomposition. The microtopography of the composite material is that a micron/nano rod of a MoSe2/Co0.85Se compound is loaded with a nano sheet of a molybdenum selenide/cobaltous selenide compound; the micron/nano rod has the length of is 1.5 to 3.5 microns and a diameter of 0.2 to 0.5 micron. A composite-material precursor CoMoO4 is firstly prepared and obtained through a hydrothermal reaction by using cobalt nitrate and sodium molybdate as reactive raw materials; afterwards, the composite material is made through the hydrothermal reaction by using sodium borohydride, selenium powder and the prepared composite-material precursor as raw materials. A preparation method of the MoSe2/Co0.85Se composite material is simple; the raw materials are easily obtained; the cost is low; the industrialized production is easily realized; the prepared and obtained composite material is good in electrocatalytic effect, and further, has favorable stability.

A method of recycling Cobalt from Cobalt-based catalyst for F-T synthesis is carried out as follows, deionized water and waste Cobalt-based catalyst for F-T synthesis are added into a reaction vessel according to the weight ratio of 1 to 5:1, carbon monoxide is introduced into the reaction vessel till the differential pressure is at 0.5 to 5 Megapascal, then the reaction vessel is kept at the stirring speed of 50 to 700 revolution per minute and the heating temperature of 50 to 200 DEG C for constant temperature about 0.5 to 12 hours; Carbon monoxide is discharged from the reaction vessel after reducing temperature, water is discharged from the reaction vessel, alkali liquor is added into the water, then Cobalt is precipitated as Co(OH)2; Nitric acid is added into the precipitation for dissolving the precipitation, then Cobaltous nitrate is obtained after evaporation and crystallization. The method of recycling Cobalt from Cobalt-based catalyst for F-T synthesis has the advantages of the simple method, the environmental friendliness, and the high recovery efficiency and purity.

The invention discloses a simple, easy-to-operate and environmentally friendly method for synthesizing a three-dimensional structure Co-MOF/NF material in situ. With a cobalt nitrate hexahydrate adopted as a cobalt source, terephthalic acid as an organic ligand, N,N-dimethylformamide as a solvent, absolute ethyl alcohol as an additive, and foamed nickel as a substrate, a one-step solvothermal method is adopted to obtain Co-MOF/NF; when being used as supercapacitor self-supporting electrode material, the Co-MOF/NF exhibits ultra-high area ratio capacitance (13.6 F cm<-2>), the performance of the Co-MOF/NF is far superior to the performance of previously reported MOF-based materials. With the method of the invention adopted, problems such as large contact resistance, insufficient applicationof active materials, and complex electrode preparation processes which are caused by the application of powder electrode materials can be solved. The Co-MOF/NF material is a novel energy storage material which has the advantages of ultra-high area specific capacitance, excellent rate performance and low cost.

The invention relates to the field of environmental science and engineering, in particular to a method for preparing a cobalt-doped improved beta-bismuth oxide photocatalyst for degrading organic pollutants in water by means of visible light photocatalytic technology. In the method, the cobalt-doped improved beta-bismuth oxide photocatalyst is synthesized by using a solvothermal method, the molar ratio of bismuth nitrate to cobalt nitrate is controlled at 10:1-16.7:1 during synthesis, and the calcining temperature is controlled at 450-550 DEG C. A visible light source is simulated by using a xenon lamp for a light degradation reaction. The photocatalyst prepared by the method of the invention can remove more than 50% of 2, 4, 6-trichlorophenol (2, 4, 6-TCP) pollutant (10 mg/L concentration) in a water body. Meanwhile, the photocatalyst has simple preparation process, large particle size, convenient recycling, repeated utilization, low manufacturing cost, short period and high efficiency, and thus, the photocatalyst has good industrial application prospect.

The invention provides a zinc cobaltate nanorod /foam nickel composite electrode, a preparation method thereof and application thereof. According to the method, a foam nickel plate is immersed in a mixed solution of zinc nitrate and cobalt nitrate, heating and heat preservation are carried out in order, an oxalic acid solution is added dropwise, reaction is carried out until the foam nickel grows a nanostructured precursor, the foam nickel is removed, and cleaning, drying and calcining are carried out in order to obtain the zinc cobaltate nanorod /foam nickel composite electrode. The composite electrode has properties of one-dimensional zinc cobaltate nano material with a large specific surface area and porous foam nickel, a contact area with an electrolyte is effectively increased, the electrode material is more fully involved in an electrochemical reaction, the composite electrode obtained through the reaction has a good electrochemical property and is applied in a super capacitor, the performance of a present capacitor is greatly raised, production process is simple, and the electrode is easy to be applied to the actual mass production.

The invention discloses a gold-containing catalyst for preparing vinyl chloride by using an acetylene method as well as a preparation method and application of the catalyst. The catalyst contains a gold element, a lanthanum element, a cobalt element, a co-catalytic metal element and a carrier with a porous micro-structure. The gold accounts for 0.3%-2% by mass of the catalyst; the gold element in the catalyst comes from gold chlorides or gold nitrates; the cobalt element comes from chlorides of the cobalt or cobalt nitrates; and the lanthanum element comes from lanthanum chlorides or lanthanum nitrates. The catalyst disclosed by the invention in use is free from inactivation phenomenon caused by sublimation of industrial catalyst mercury chloride, has no pollution to the environment, overcomes defects of high toxicity and high pollution of the conventional industrial catalyst mercury chloride, has the characteristics of simple preparation method, high conversion rate of the acetylene and selectivity of the vinyl chloride, long service life up to 1000 hours or more, high temperature resistance, and high intensity and is renewable, and the conversion rate of the acetylene and selectivity of the vinyl chloride approximate to or exceed the technical indexes of the mercury chloride catalyst.

The invention relates to a preparation method of three-dimensional flower-shaped nickel cobaltate nano-sheet mesoporous microspheres, and relates to the technical field of multi-level structured nano-grade catalyst materials. First, nickel nitrate hexahydrate and cobalt nitrate hexahydrate are adopted as a nickel source and a cobalt source, a deionized water-isopropanol mixed phase with a proper proportion is adopted as a solvent, methanol is adopted as a reactant, and no additional base precipitating agent is adopted; a three-dimensional flower-shaped nano-sheet microsphere precursor is prepared in a Ni<2+>-Co<2+>-NH3-NH4<+>-SG<n->-H2O-IPA-CH3OH system (SG<n-> is CO3<2-> or HCOO<->); the temperature is increased to 300-400 DEG C in an air atmosphere with a speed of 1 DEG C/min, and the precursor is calcined for 2-3h, such that the three-dimensional flower-shaped nickel cobaltate nano-sheet mesoporous microspheres are obtained. According to the invention, co-precipitation of the formulated cobalt and nickel in the raw materials is realized. The prepared three-dimensional flower-shaped nickel cobaltate nano-sheet mesoporous microspheres are spinel cubic phases with high purity, and are formed by ultrathin nano-sheet self-assembly. The microspheres comprise rich mesopores, and have a large specific surface area. The method has the advantages of simple operation, appropriate conditions and easy control.

The invention discloses a preparation method of a composite nanomaterial of a nano ZnO substrate and a graphene nanosheet. Nano ZnO and the graphene nanosheet are composited to form the composite nanomaterial in a sol-gel method and mechanical alloying combined mode, so that the preparation method is simple and easy to realize and short in reaction time; the finished composite nanomaterial is good in chemical stability; graphene has higher conductivity and can adjust an energy band structure of nano ZnO; nano ZnO has a higher seebeck coefficient, and the nano ZnO substrate and the graphene nanosheet are synthesized, so that interface scattering of phonons can be increased significantly; a recombination rate of an electron-hole pair can be reduced; the appearance of nano ZnO can be adjusted; the heat conductivity of nano ZnO can be reduced; and the photocatalytic efficiency of nano ZnO can be improved. Nitrate of to-be-doped ions comprises any one of aluminum nitrate, ferric nitrate, cobalt nitrate, nickel nitrate, silver nitrate and gold nitrate.

The invention provides a preparation method of bimetallic nano-phosphate based on a metal-organic framework, which comprises the following steps of: using cobalt nitrate and 2-methylimidazole as raw materials to prepare a metal-organic framework, and then using another nitrate, that is, nickel nitrate to treat the metal-organic framework to form a layered double hydroxide on the metal-organic framework to maintain the morphology of the metal-organic framework, to achieve a conformal transformation, and to obtain a precursor. According to the bimetallic nano-phosphate based on the metal-organicframework and the preparation method and the application thereof, the obtained precursor is etched by using phosphate, and a hollow core shell structure formed increases the specific surface area ofthe material and the capacitance performance is high accordingly. The preparation method of the bimetallic nano-phosphate based on the metal-organic framework has the advantages that the raw materialsare cheap and easy to obtain, the operation is simple, the high energy consumption is avoided, and the bimetallic nano-phosphate obtained has high capacitance performance and can be used for preparation of capacitor elements.

The invention discloses a preparation method of a nitrogen-doped carbon-coated Co-based MOF derivative material, which comprises the following steps: preparing a metal organic framework compound ZIF-67, dissolving cobalt nitrate and methylimidazole in water in a reaction kettle, reacting at 150-200 DEG C for 2h, and cooling to obtain a metal organic framework compound ZIF-67; preparing a solid mixture: dissolving the metal organic framework compound ZIF-67, polyvinylpyrrolidone and melamine in water to obtain a mixed solution, freeze-drying that mixed solution to obtain the solid mixture; preparing the nitrogen-doped carbon-coated Co-based MOF derivative material: placing the solid mixture in a furnace, purging with argon, calcining at 800-1000 DEG C for 2 h, and cooling to obtain the nitrogen-doped carbon-coated Co-based MOF derivative material. In the process of preparation, the raw materials are easy to obtain and the synthetic route is simple, and the derived materials have good catalytic effect in both anodic and cathodic reactions during the process of electrolyzing water.

The invention relates to a preparation method of a cobalt oxide/graphene composite nano material, which is characterized by comprising the following steps: (1) preparing a 0.01-1.00 mol/L cobalt nitrate-organic fuel mixed solution, wherein the mol ratio of organic fuel to metal ions is 0.9-2; (2) preparing a 0.1-1.0 mg/ml graphene oxide dispersion solution; (3) calculating the volumes of the mixed solution obtained in the step (1) and the graphene oxide dispersion solution obtained in the step (2) according to the mass ratio of cobalt oxide to graphene in the designed product and the required preparation amounts, and mixing the mixed solution and the graphene oxide dispersion solution by ultrasonic to obtain a dispersion solution for atomization; (4) filling the dispersion solution obtained in the step (3) into an ultrasonic atomization device, carrying the generated atomized liquid drops into a 500-1100 DEG C pipe furnace by argon or nitrogen gas at the flow rate of 0.3-1.2 L/minute, and initiating solution combustion reaction; and (5) collecting the solid reaction product. The invention has the advantages of shorter technical procedure, simple synthesis equipment and continuous preparation process, can directly obtain the final powder product by one step, and can easily implement industrialized preparation.

The invention relates to a method for preparing multi-shape controllable nano nikel-cobalt spinel oxide. The method includes the steps that nickel nitrate and cobalt nitrate are dissolved in anhydrous ethanol according to the cobalt-nickel atom ratio to form a solution A; oleylamine is dispersed in an ethanol solution to form a solution B, and the solution B and the solution A are mixed to obtain a mixed solution; the mixed solution is fully and evenly stirred and moved into a dynamic reaction kettle, H2 is replaced in a sealed mode, pressure intensity of H2 is adjusted to 6-15 bar after replacement, and a steel cylinder air outlet valve is closed; the stirring speed of the dynamic reaction kettle is adjusted to 400 r/min, temperature is set to be 150 DEG C, and reaction is carried out for 10 h; a product is cleaned through ethanol and other nonpolar solvents respectively, centrifugal separation is carried out, and a sediment precursor is obtained through drying at the temperature of 60 DEG C; the temperature of the obtained sediment precursor rises in an air atmosphere at the speed of 10 DEG C/min, and the sediment precursor is heated to 200-400 DEG C and kept warm. According to the method, procedures are few, materials are easy to get and low in price, the procedures are safe, nikel-cobalt spinel oxide of different shapes can be obtained by changing a small condition in the procedures, and accordingly preparing of the controllable nano nikel-cobalt spinel oxide is achieved.

The invention specifically relates to an enamel glaze material, an enamel slurry, and a preparation method and an application thereof. The invention relates to the technical field of enamel materials. The invention aims at solving a technical problem of providing an enamel glaze material. The enamel glaze material is prepared by uniformly mixing the following raw materials, by weight: 40-45 parts of quartz sand, 9.5-10 parts of feldspar powder, 24-26 parts of borax, 2.5-3 parts of cryolite, 5.5-7.5 parts of sodium nitrate, 3.5-4 parts of lithium carbonate, 3.5-4.5 parts of fluorite powder, 2-4 parts of calcium carbonate, 3-4 parts of cobalt nitrate, 0.8-1.2 parts of nickel nitrate, 2-2.2 parts of manganese oxide, and 3.4-3.8 parts of zirconium dioxide. The enamel glaze material can be combined well with glass powder to produce the enamel slurry. The enamel slurry can be coated on the surface of a metal substrate to form an enamel coating. The coating has the advantages of smooth glaze surface, good gloss, no bubble, and no scaling. The coating can be firmly combined with a carbon steel substrate, and has good acid resistance.

The invention discloses a preparation method for a cobalt-doped zinc oxide gas-sensitive material and application thereof, which relate to the technical fields of material chemistry and gas-sensitivesensors. Polyvinylpyrrolidone (PVP), zinc acetate and cobalt nitrate hexahydrate are dissolved in 75ml of ethylene glycol, wherein polyvinylpyrrolidone, the molecular weight of which is 400,000, is 0.3g, the molar ratio of cobalt nitrate hexahydrate to zinc acetate is between 0.025 and 0.233, and thereby the cobalt-doped nanoscale spherical zinc oxide gas-sensitive material is prepared. Because amicrowave-and-ultrasonic wave-co-assisted solvothermal method is adopted in the process of preparation, the cobalt-doped nanoscale spherical zinc oxide material has high detection sensitivity and goodselectivity; and the preparation method is simple and harmless to the environment, and effectively overcomes defects existing in the prior art, for example, preparation methods are complex and cost is higher and production process conditions are strict, and sensors have high working temperature, low response and recovery speed and short service lives.

The invention discloses a nitrogen-doped graphene/cobalt ferrite nano composite material and a preparation method thereof. The preparation method comprises the following steps: putting graphite oxide into absolute ethyl alcohol and carrying out ultrasonic treatment; adding cobalt nitrate and iron nitrate into the absolute ethyl alcohol; adding a dissolved metal salt solution into a graphene oxide solution to carry out ultrasonic dispersion again; adding urea into the uniformly-dispersed mixed solution; agitating and dissolving; finally, carrying out a hydro-thermal synthesis reaction on the mixed solution; after the reaction is finished, centrifugally washing and drying a product to obtain a composite material. According to the preparation method, the urea is used for reducing graphene oxide; in the reduction process, nitrogen atoms are doped on the surface of graphene; the doping of nitrogen atoms changes the surface chemical properties of the graphene to make up the surface defects formed by preparing the graphene by a chemical method; the alkalinity provided by the urea enables cobalt ferrite to be formed on the surface of the nitrogen-doped graphene; nano particles of the cobalt ferrite can further prevent layers of the graphene from being accumulated and reunited, and the electrochemical performance of the composite mateial is improved.

The present invention provides a single-mode microwave synthesis method for preparing a cobalt oxide (Co3O4) nanosheet and graphene composite lithium battery cathode material with a layer-to-layer three-dimensional network structure. According to the present invention, cobaltous nitrate, hexamethylenetetramine (HMT) and natural graphite powder are adopted as raw materials, an improved Hummers method is adopted for preparing a graphene oxide; the resulting graphene oxide is added to a mixed solution comprising the cobaltous nitrate and the HMT to generate cobalt hydroxide by using the reactionof the cobaltous nitrate and the HMT under the single-mode microwave; the resulting cobalt hydroxide is subjected to pyrolysis for 2 hours at a temperature of 300 DEG C in the protection of N2; then the resulting product is placed in a muffle furnace to carry out baking for 2 hours at the temperature of 300 DEG C to obtain the sample. According to the single-mode microwave process provided by thepresent invention, the HMT is adopted as the donor for providing the hydroxyl radical, such that the cobaltous nitrate is subjected to the reaction to generate the cobalt hydroxide under the single-mode microwave; the slow decomposition of the HMT and the uniformity of the single-mode microwave reaction are adopted, such that the product has the layer-to-layer three-dimensional network structure.In addition, the electrochemical performance test is performed for the Co3O4 nanosheet and graphene composite lithium battery cathode material with the layer-to-layer three-dimensional network structure, the test result shows that, the Co3O4 nanosheet and graphene composite lithium battery cathode material has excellent lithium storage performance, and broad prospects in the field of development of the lithium ion battery cathode material.

The invention discloses a nitrogen-doped carbon-coated two-phase staggered distribution type nickel-cobalt bimetal selenide electrode material and a preparation method thereof, and belongs to the field of preparation of electrode materials for lithium ion batteries. The preparation method comprises the following steps of: using nickel nitrate and cobalt nitrate as a metal source, using trimesic acid as an organic ligand, preparing a nickel-cobalt bimetal organic framework compound by adopting a solvothermal method; and putting the obtained nickel-cobalt bimetal precursor and melamine commonlyinto a tube furnace at a temperature of 450 DEG C for calcination for 2h to complete the carbonization and nitrogen doping process so as to obtain a nitrogen-doped carbon-coated nickel-cobalt bimetalsimple substance; and using selenium powder as a selenium source to converting the nitrogen-doped carbon-coated nickel-cobalt bimetal simple substance after calcination to the nitrogen-doped carbon-coated two-phase staggered distribution type nickel-cobalt bimetal selenide electrode material. The nitrogen-doped carbon-coated two-phase staggered distribution type nickel-cobalt bimetal selenide electrode material and the preparation method thereof have the high specific capacitance, the excellent rate performance and the cycle stability.

The invention discloses a preparation method of supercapacitor cobaltous oxide electrode material, belonging to the technical fields of electrochemical science and energy. The preparation method is characterized by taking foamed nickel as a substrate, cobalt nitrate and surface active agent as raw materials, and ethyl alcohol or isopropyl alcohol as a solvent, and the cobaltous oxide electrode material can be prepared by a solvothermal method. The preparation method has the advantages of being simple in production technology and equipment and low in preparation cost; the obtained cobaltous oxide electrode material has good stability and high specific capacitance.

This invention provides a preparation method and application of mesoporous Co3O4/ Beta-MnO2 or NiO/ Beta-MnO2 catalysts. The mesoporous Co3O4/ Beta-MnO2 and NiO/ Beta-MnO2 catalysts having an ordered 3D-hexagonal structure, a specified aperture of 3.7-3.8 nm and a high specific surface area of 100-200 sq.m/g are prepared by a hard template method, which comprises the following steps of: immersing KIT-6 into mixed solution of manganous nitrate and cobalt nitrate or mixed solution of manganous nitrate and nickel nitrate, drying, roasting, dissolving, washing and drying. The catalysts of the invention are applicable to the elimination of formaldehyde with a high air velocity of 60,000 to 100,000 h(-1) and at the low concentration of 500 to 1,000 ppm by catalytic combustion. At the temperature of 130 to 140 DEG C, the formaldehyde can be converted into nonpoisonous CO2 and H2O with a conversion rate of 100 percent, and 100 percent of elimination rate of formaldehyde can be kept within 100 hours.

The present invention discloses a nitrogen-doped carbon material encapsulated cobalt catalyst and a method of using the catalyst to prepare secondary amine compounds. The preparation method of the catalyst comprises the following steps: 1) silica sol is added into a 2-methylimidazole solution and dispersed uniformly to obtain liquid sol, a stirring is conducted while adding cobalt nitrate liquid into the liquid sol, a stirring reaction is conducted for 3-10 h, and after the reaction is completed, centrifuging, filtering, washing and drying are conducted to obtain ZIF-67@SiO<2> materials; 2) under nitrogen protection, the ZIF-67@SiO<2> materials are calcined at 400-1,200 DEG C for 6-10 h, the calcined materials are soaked with hydrofluoric acid solution, the soaked calcined materials are water washed to neutral, the washed calcined materials are dried to obtain CN@Co materials. The method of using the catalyst to prepare the secondary amine compounds is as follows: in an organic solvent, nitro-compounds, formic acids, carbonyl compounds and the CN@Co materials are added, nitrogen is ventilated to replace oxygen in the reaction system, and the reaction is conducted at 90-220 DEG C for 15-18 hours in an air isolation condition to obtain the secondary amine compounds. The catalyst can be used in the preparation of the secondary amine compounds, reduces the requirements and costs of the reaction to devices and is relatively high in reaction selectivity and yield.

The invention provides a method for preparing an Nd/Co-codoped BiFeO3 film on an FTO (fluorine-doped tin oxide)/glass substrate surface, which comprises the following steps: after cleaning an FTO substrate, carrying out ultraviolet irradiation, and dissolving bismuth nitrate (8% excessive), ferric nitrate, neodymium nitrate and cobalt nitrate which serve as raw materials in mixed ethylene glycol monomethyl ether and acetic anhydride in a mol ratio of 0.98:(1-x):0.1:x (x=0.01-0.05), thereby obtaining a stable BiFeO3 precursor solution of which the metallic ion concentration is 0.1-0.5mol/L; and after spin coating, drying to obtain a dry film, preannealing, naturally cooling, repeating the process above to obtain the film with expected thickness, and finally, annealing to obtain the crystalline BiFeO3 film. In the invention, the facility requests are simple, the experiment conditions can be easily achieved, the prepared film has good uniformity, the doping amount is easy to control, andthe dielectric properties of the film can be greatly enhanced by doping.

The invention provides a preparation method of nitrogen-doped graphene/nitrogen-doped carbon nanotube/tricobalt tetraoxide composite paper, which comprises the following steps: a) preparing a graphene oxide dispersion solution; b) preparing an oxidized carbon nanotube dispersion solution; c) mixing the graphene oxide dispersion solution and oxidized carbon nanotube dispersion solution with a cobalt nitrate water solution to obtain a slurry, applying the slurry onto a substrate, and drying to obtain the cobalt-ion-containing graphene oxide/oxidized carbon nanotube composite paper; and d) immersing the cobalt-ion-containing graphene oxide/oxidized carbon nanotube composite paper in an ammonia water solution, and carrying out hydrothermal reaction to obtain the final nitrogen-doped graphene/nitrogen-doped carbon nanotube/tricobalt tetraoxide composite paper. The method is simple to operate and mild in reaction conditions, can implement large-scale preparation of soft composite paper with favorable ORR catalytic property, and has favorable application prospects in the field of electrocatalysis.

The invention discloses a cobalt-based MOFs material. The cobalt-based MOFs material is formed by cobalt-nitrate hexahydrate which is reacted with terephthalic acid through a hydrothermal method, andthen is washed and dried through N, N-dimethyl formamide and an absolute ethyl alcohol solvent. A preparation method comprises the following steps: firstly, adding cobalt-nitrate hexahydrate in absolute ethyl alcohol, and performing magnetic stirring, so as to obtain a clear cobalt nitrate solution, adding terephthalic acid in N, N-dimethyl formamide, and performing magnetic stirring, so as to obtain clear a terephthalic acid solution, and performing mixed ultrasonic treatment on the two solutions; secondly, loading the solution subjected to mixed ultrasonic treatment into a reaction kettle, and arranging the reaction kettle into an oven, ensuring that the solution is reacted under a certain condition, and filtering, washing and drying a reaction product in certain condition after the reaction, so as to obtain the cobalt-based MOFs material. When the material is applied to the catalysis of hydrolysis of sodium borohydride, the hydrolysis speed reaches 1700 to 2400 mL min-1g-1, and thecatalytic performance keeps 47 to 50 percent of the original hydrogen yield after circulation. The material has excellent catalytic performance, and has a wide application prospect in the field of thepreparation of new energy resources.