480 results about "Hydrogen atmosphere" patented technology

This invention discloses a method for preparing a CuZnAlGa-based layered double hydroxide (TLH)-derived catalyst for methanol production from carbon dioxide-rich syngas. Using Cu, Zn, Al, and Ga metal salts as precursors, Na₂CO₃ and NaOH as precipitants, and a mixed alcohol-water solution as an auxiliary solvent, co-precipitation is performed under controlled temperature and pH to obtain a LDH-like catalyst precursor. After high-temperature calcination and in-situ reduction in a hydrogen atmosphere, a layered framework structure of Cu nanoparticles immobilized by oxides is obtained. The LDH-like structure provides lattice confinement, preventing Cu particle aggregation, and the interaction between Cu and the oxides enhances the catalyst surface's adsorption capacity for CO and CO₂, thereby improving the activity and stability of methanol production from carbon dioxide-rich syngas.

The invention discloses an annular furnace heat-resistant supporting forged chassis and an additive manufacturing process and a fixing device thereof, and belongs to the technical field of plating of metal materials, and the annular furnace heat-resistant supporting forged chassis comprises the steps that heat-resistant alloy steel base metal with specific components is prepared; carrying out laser texturing and nickel-based alloy bottom layer pretreatment on the surface of the steel plate; performing laser cladding on high-silicon high-temperature alloy powder containing niobium and rare earth elements to form a functional cladding layer, and performing gradient cladding on the edge of the atmosphere guide hole; and finally, carrying out heat treatment and assembling with a fan-shaped refractory brick fixing device. A composite oxide film and a multi-scale strengthening system are constructed, hydrogen resistance and brittleness resistance are effectively achieved, interface thermal stress is relieved, cracking and stripping of a cladding layer are avoided, a fixing device adapts to thermal expansion, the atmosphere is dredged, and the annealing uniformity of a steel coil is improved; the problems of creep deformation, hydrogen embrittlement, cladding layer stripping and thermal stress cracking of a traditional supporting component under the conditions of high temperature, heavy load and nitrogen and hydrogen atmosphere are solved.

This invention belongs to the field of high-value utilization technology of biomass resources, and discloses a method for catalyzing the depolymerization of lignin into phenolic compounds using a RuNiZn / Nb2O5 catalyst. The method includes: uniformly mixing the RuNiZn / Nb2O5 catalyst, lignin-containing biomass feedstock, and water; stirring under hydrogen atmosphere to carry out the depolymerization reaction; after the reaction, cooling to room temperature and performing solid-liquid separation; evaporating the solvent to obtain the hydrogenated depolymerization product containing monophenols. In this invention, the RuNiZn / Nb2O5 catalyst employs a technique of replacing precious metals with various non-precious metals, which improves the catalyst's reactivity and reduces the amount of precious metals used. This increases the yield of lignin depolymerization products, provides milder depolymerization reaction conditions, and ultimately significantly reduces the catalyst preparation cost and the energy cost of the lignin depolymerization process.

The invention discloses a perovskite / crystalline silicon laminated solar cell, a preparation method thereof and a photovoltaic module. The perovskite / crystalline silicon laminated solar cell provided by the invention comprises a perovskite top cell, a crystalline silicon bottom cell and a composite layer used for connecting the perovskite top cell and the crystalline silicon bottom cell, the perovskite top cell comprises a composite hole transport layer, the composite hole transport layer comprises a first hole transport layer and a second hole transport layer, and the first hole transport layer is in contact with the composite layer; the first hole transport layer is obtained by sputtering a nickel oxide target material by introducing H2 in an oxygen-free sputtering atmosphere, and the second hole transport layer is obtained by sputtering the nickel oxide target material in a hydrogen-free atmosphere. According to the perovskite / crystalline silicon laminated solar cell provided by the invention, the composite hole transport layer can realize better contact matching with the middle composite layer, better charge extraction and collection are carried out on the perovskite light absorption layer, and meanwhile, the perovskite / crystalline silicon laminated solar cell has better conductivity.

The invention relates to a polysaccharide coated-hydrogen pre-sintered dispersed graphene copper composite material and a preparation method thereof, and the preparation method comprises the following steps: mixing first copper powder with a coating solution, and removing a solvent to obtain coated copper powder; sintering the coated copper powder in a hydrogen atmosphere for the first time to obtain graphene coated copper powder; second copper powder and the graphene-coated copper powder are mixed, and the graphene-copper composite material is obtained through second sintering and forming; the solute of the coating solution comprises polysaccharide and an organic auxiliary agent, and the number of carbon atoms of the polysaccharide is greater than or equal to 10. According to the preparation method, through molecular-level coating of the polysaccharide and the organic additive, the coating layer is converted into a few-layer graphene or high-quality carbon layer which is uniformly attached to the surface of the copper powder in situ during first sintering, so that the high-quality graphene copper composite material is obtained.

The invention relates to the technical field of diamond color center quantum light sources, in particular to a method for preparing a diamond color center in a positioning mode, and the method comprises the following steps that a single-face polished sapphire sheet serves as a substrate, and a microwave plasma chemical vapor deposition method is adopted for preparing a single crystal diamond with a (001) surface; preparing a metal layer on the surface of the monocrystal diamond by adopting a physical vapor deposition method, and dehumidifying and self-assembling to form balls; etching the surface of the monocrystal diamond (001) at a high temperature in a hydrogen atmosphere to form a conical pit structure with a different surface; and selectively growing a diamond color center in the cone pit by adopting a chemical vapor deposition method. Aiming at the problems that the existing ion implantation technology for positioning and preparing the diamond color center is difficult to realize nanoscale accurate control and high in cost, a foundation is laid for the integration and low-cost preparation of the high-purity and high-brightness diamond single photon source.

The invention discloses a rapidly sintered rhenium plate and a preparation method thereof, and relates to the field of powder metallurgy. The preparation method comprises the following steps: putting a mold filled with rhenium powder into spark plasma sintering equipment, vacuumizing, introducing hydrogen-containing mixed gas, carrying out a gradient pressurization-pulse sintering process, heating the rhenium powder to a target temperature at a rate of 80-200 DEG C / min, carrying out heat preservation, synchronously applying axial pressure, controlling the pressure to be 8-12 Mpa when the temperature is less than 1000 DEG C, controlling the pressure to be greater than or equal to 15 Mpa when the temperature is greater than or equal to 1000 DEG C, and carrying out sintering for 2-3 hours; and cooling, demolding, reducing and annealing in a hydrogen atmosphere, and grinding to obtain the rhenium plate. Rapid sintering densification of pure rhenium is achieved through the spark plasma sintering technology, the temperature rising time is greatly shortened, step pressure rising is carried out before the nucleation stage of heating sintering, it is avoided that moving filling of rhenium powder is hindered by high pressure at the low temperature, size homogenization is promoted, and the prepared rhenium plate is good in uniformity and high in density and purity; and the oxygen content is low.

The invention belongs to the technical field of high-activity tungsten powder preparation, and particularly relates to high-specific-surface-area high-activity tungsten powder and a preparation method thereof.The preparation method comprises the steps that diluted hydrochloric acid is added into an ammonium tungstate solution to adjust the pH to be acidic, then hydrogen peroxide is added, and a mixed solution is obtained; carrying out vacuum drying on the mixed solution at the temperature of less than or equal to 80 DEG C to obtain a solid substance; and in the hydrogen atmosphere, the solid matter is reduced, the tungsten powder with the high specific surface area and the high activity is obtained, and the specific surface area is larger than or equal to 10 m < 2 > / g. According to the technical scheme, ammonium chloride and peroxotungstic acid are creatively applied to be subjected to low-temperature heating decomposition to generate a large amount of gas to form a porous framework, and therefore the nano tungsten powder controllable in granularity, good in dispersity, high in specific surface area and high in activity is prepared; the performance of the high-specific-surface-area and high-activity nano tungsten powder can be controlled by simply controlling process conditions; and the application potential of the nano tungsten powder as a novel high-performance tungsten material is increased.

The invention discloses a synthesis method and application of nitrogen-doped carbon-coated Co porous spheres, cobalt nitrate hexahydrate and 4-picolinic acid are dissolved in a mixed solution, the mixed solution comprises dimethylformamide and absolute ethyl alcohol, then the mixed solution is transferred into a reaction kettle for heating reaction, and after the reaction is finished, centrifugal drying is performed to obtain a Co coordination compound precursor; and calcining the precursor in an argon hydrogen atmosphere, and selecting and setting a proper heating rate, a proper calcining temperature and a proper calcining time to obtain the nitrogen-doped carbon-coated Co porous ball. The obtained nitrogen-doped carbon-coated Co porous ball is used as the air cathode of the zinc-air battery, so that high power density and excellent charge-discharge cycle stability are realized.

The invention discloses a preparation method of a hydrogen-responsive composite multilayer magnesium-based film surface self-wrinkle pattern. The preparation method comprises the following steps: A, preparing a polymer elastic layer on the surface of a supporting substrate; b, depositing a plurality of layers of metal-based films on the polymer elastic layer by adopting a magnetron sputtering method; and C, exposing the prepared sample in a hydrogen-containing atmosphere, and forming a wrinkle pattern of which the recognizable size is in a range of 10nm-1000mu m on the surface through hydrogenation reaction at normal temperature. According to the method, the surface of the thin film can be deformed by exposing the thin film to the hydrogen-containing atmosphere environment, so that the three-dimensional wrinkle texture can be quickly realized, and the three-dimensional wrinkle morphology can be accurately regulated and controlled by adjusting the element components, sputtering time, sputtering power, working gas flow and hydrogen treatment parameters of the magnesium or magnesium alloy hydrogen-sensitive reaction film layer. The pattern features of the prepared wrinkle pattern can be recognized through characterization means such as an optical microscope, a scanning electron microscope, an atomic force microscope or a diffraction light-variable device.

A process for producing C2 to C5 hydrocarbons, the process comprising introducing a feed stream comprising hydrogen and a carbon-containing gas selected from the group consisting of carbon monoxide, carbon dioxide, and mixtures thereof into a reaction zone of a reactor, and converting the feed stream into a product stream comprising C2 to C5 hydrocarbons in the presence of a shaped mixed catalyst in the reaction zone. The shaped mixed catalyst comprises a metal oxide catalyst component comprising nickel oxide, gallium oxide, and zirconium oxide; a microporous catalyst component is a molecular sieve having 8-MR (member ring) pore openings; and wherein the mixed catalyst is reduced in a hydrogen-containing atmosphere at a temperature of 450°C to 750°C.

The application provides a calcium-based bifunctional material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a calcium salt solution and an organic template agent, stirring under heating conditions, forming a gel, and then drying and calcining to obtain a calcium carbonate adsorption component; preparing a rare earth metal oxide by using a hydrothermal method, and then loading a transition metal on the rare earth metal oxide by using an impregnation method to obtain a transition metal supported catalytic component; and placing the adsorption component and the catalytic component in a hydrogen-rich atmosphere after physical mixing and calcining to obtain the calcium-based bifunctional material. According to the method, the preparation process of the adsorption component is controlled, the calcium carbonate is first generated by using a sol-gel method and low-temperature calcining, and the calcium carbonate is mixed with the catalytic component and then hydrogen-rich calcining is performed to generate porous calcium oxide, so that the sintering of the calcium oxide in the high-temperature preparation process is avoided; the method has the advantages of simple process, excellent performance, low energy consumption and good industrial application value.

This invention relates to the field of alloy materials and discloses a method for preparing copper-chromium alloys by recycling copper-chromium alloy waste, comprising: 1) degreasing: immersing the copper-chromium alloy waste in an organic solvent to remove oil, cleaning, and drying; 2) embrittlement: placing the copper-chromium alloy waste in a hydrogen atmosphere, heating to above 500°C for at least 1 hour to embrittle, and then cooling; 3) cryogenic crushing: ball milling the copper-chromium alloy waste in liquid nitrogen medium to obtain copper-chromium alloy powder; 4) molding and pre-sintering: molding and pre-sintering the copper-chromium alloy powder to obtain a sintered blank; 5) densification: densifying and sintering the sintered blank to obtain a copper-chromium alloy. This invention sequentially processes copper-chromium alloy waste through degreasing, embrittlement, cryogenic crushing, molding and pre-sintering, and densification to obtain a copper-chromium alloy with high purity, high electrical conductivity, and high strength, achieving efficient recycling and reuse of copper-chromium alloy waste.

The application discloses a preparation method of a key intermediate of dapagliflozin, and belongs to the technical field of preparation of medical intermediates. The preparation method of the key intermediate of dapagliflozin comprises the following steps: 1, 1-ethoxy-4-methylbenzene is prepared by using p-cresol, sodium hydroxide and diethyl sulfate; 2, (4-ethoxybenzyl) phenyl sulfide is prepared by using 1-ethoxy-4-methylbenzene, thiophenol, a palladium catalyst, an alkali and an oxidant; 3, 1-benzyl-4-ethoxybenzene is prepared by using (4-ethoxybenzyl) phenyl sulfide under a hydrogen atmosphere; 4, 4-ethoxy-2'-chlorobenzhydrol is prepared by carrying out chlorination reaction on 1-benzyl-4-ethoxybenzene; and 5, 5-bromo-2-chloro-4'-ethoxybenzhydrol is prepared by carrying out bromination reaction on 4-ethoxy-2'-chlorobenzhydrol. The yield and purity of 5-bromo-2-chloro-4'-ethoxybenzhydrol prepared by the method are higher, the process is safer, and the production cost is reduced.

The application belongs to the technical field of molecular sieve catalytic material preparation, and particularly relates to a method for preparing a zinc-modified HZSM-5 molecular sieve catalyst by a double-bed in-situ reduction method and application thereof. The application forms a double-bed structure by loading ZnO and HZSM-5 molecular sieves in the same reaction tube respectively, and performs in-situ reduction treatment under a hydrogen-containing atmosphere, so that zinc species acts on the HZSM-5 molecular sieve in a mode different from traditional ion exchange methods and impregnation methods, thereby obtaining a zinc-modified HZSM-5 molecular sieve catalyst. The method is clear in steps and simple in operation, and can be used for adjusting the structural properties, acid characteristics and catalytic performance in a methanol-to-aromatics reaction of the HZSM-5 molecular sieve.

The application relates to the technical field of organic silicon synthesis, and particularly discloses a high-selectivity platinum catalyst and a vinyl double-seal head synthesis method. The high-selectivity platinum catalyst comprises a carrier and a platinum active component loaded on the carrier, the platinum active component is obtained by reducing and activating a platinum precursor and a ligand under a hydrogen atmosphere at 250-350 DEG C after coordination modification, and the molar ratio of the ligand to the platinum element in the platinum precursor is 2-3:1. In the application, the platinum active component is obtained by reducing and activating the platinum precursor and the ligand after coordination modification, and the ligand and the platinum element form a specific coordination structure of the platinum active center, guide the direct silicon-hydrogen addition reaction of acetylene and a hydrogen-containing double-seal head, thus the dimethyl chlorosilane intermediate is not needed, the process flow is simplified, and the effects of improving the reaction yield, environmental protection and process economy are achieved.

The invention discloses a method for preparing monophenol compounds from lignin. The method comprises the following steps: mixing a raw material lignin with a solvent, and carrying out a one-step hydrogenation reaction in a hydrogen atmosphere under the action of a nickel-molybdenum-based catalyst to prepare the monophenol compound, the nickel-molybdenum-based catalyst comprises metal nickel and nickel oxide, molybdenum oxide and silicon oxide. The method provided by the invention has the characteristics of low production cost, simple separation, high monophenol compound yield and the like.

The invention discloses a preparation method of high-purity Nb2O5, belongs to the field of preparation of Nb2O5, and solves the problem of low purity of Nb2O5 prepared by the existing method. The preparation method comprises the steps that a metal niobium ingot with the purity larger than or equal to 99.999% is adopted, and vacuum drying is conducted after surface peeling, dilute nitric acid ultrasonic cleaning and high-purity water flushing are conducted; the pretreated niobium ingot is subjected to a hydrogenation reaction in a pure hydrogen atmosphere, niobium hydride is generated and then crushed, and niobium hydride powder is obtained; carrying out dehydrogenation treatment on the niobium hydride powder under a high vacuum condition; dissolving the metal niobium powder with electronic-grade hydrofluoric acid, and filtering to obtain fluorine niobic acid filtrate; performing multi-stage counter-current extraction and reverse extraction on the fluobiobic acid filtrate by adopting an extracting agent to obtain fluobiobic acid reverse extraction liquid; introducing high-purity ammonia gas into the fluobiobic acid strip liquor, and precipitating to generate niobium hydroxide; ageing, filtering and washing with high-purity water for multiple times to obtain a niobium hydroxide filter cake; and calcining the niobium hydroxide filter cake in a high-purity oxygen atmosphere in stages to obtain niobium pentoxide. The niobium pentoxide prepared by the method disclosed by the invention is high in purity.

The application discloses a method for preparing gamma-valerolactone by catalyzing acetylpicoline acid hydrogenation with molybdenum selenide, and aims to solve the problems of low catalytic efficiency and harsh reaction conditions of existing non-noble metal catalyst systems. The method comprises the following steps: placing molybdenum selenide catalyst, acetylpicoline acid and a solvent as raw materials in a high-pressure reaction kettle, replacing the air in the high-pressure reaction kettle with hydrogen gas at room temperature for multiple times, then continuously feeding hydrogen gas until the pressure in the high-pressure reaction kettle reaches 0.5-3.0 MPa, magnetically stirring the reaction under the pressure range, at a temperature of 100-200 DEG C and in a hydrogen atmosphere, and then cooling to room temperature, so as to obtain gamma-valerolactone. The catalyst used in the application is prepared under hydrothermal conditions, and due to the sheet morphology of the molybdenum selenide catalyst, rich edge active sites are presented, so that the conversion rate of acetylpicoline acid and the selectivity of gamma-valerolactone can reach 100% under mild reaction conditions.

The application discloses a method for preparing ketone compounds by catalytic hydrogenation of cellulose based on a crude hydrogen atmosphere. The method uses cellulose as a raw material, water as a solvent, and activated carbon loaded Pd as a catalyst. The total pressure of the hydrogen source gas containing carbon monoxide and carbon dioxide is 0.5-4.0 MPa, the temperature is 230-260 DEG C, and the reaction time is 1-6 h, so that ketone compounds are obtained as main products. The volume percentage content of carbon monoxide and carbon dioxide in the hydrogen source gas containing carbon monoxide and carbon dioxide is 20%-67%. The reaction provided by the application has the characteristics of renewable raw materials, low reaction process cost, environmental friendliness, mild reaction conditions, high product selectivity, and high economic value of product added value.

The application provides a preparation method of a molybdenum-copper composite material part blank, and relates to the technical field of refractory metal preparation and processing. Molybdenum powder and copper particles are alternately and layer by layer laid flat, and then cold isostatic pressing is performed to obtain a powder blank; the thickness of each molybdenum powder layer and each copper particle layer is independently less than or equal to 20 mm; the powder blank is subjected to reduction pre-sintering in a hydrogen atmosphere to obtain a pre-sintered blank; the pre-sintered blank is subjected to internal melting and infiltration sintering in a hydrogen atmosphere to obtain a sintered blank; and the sintered blank is subjected to hot isostatic pressing to obtain a molybdenum-copper composite material part blank. Through the above method, a molybdenum-copper composite material part blank with uniform distribution of molybdenum and copper phases and high density and large size can be obtained.

The application discloses a new method for synthesizing dihydrogibberellin without protecting carboxyl. The application provides a new method for synthesizing dihydrogibberellin without protecting carboxyl, which comprises the following steps: 1) mixing a compound shown in formula II with a catalyst A in an organic solvent B, and carrying out a hydrogen reduction reaction under a hydrogen atmosphere to obtain a compound shown in formula III; 2) mixing the compound shown in formula III with a saturated aqueous solution of a base in an organic solvent C, and carrying out a selective deacetylation reaction to obtain a compound shown in formula IV; and 3) mixing the compound shown in formula IV with triphenyl phosphine and an elimination reagent in an organic solvent D, and carrying out a dehydration elimination reaction to obtain dihydrogibberellin shown in formula V. The application can simplify the synthesis method of dihydrogibberellin and is more beneficial to large-scale production and synthesis.

The invention discloses a preparation method of porous tungsten with high compressive strength, which comprises the following steps: providing tungsten powder, an organic binder and lanthanum nitrate hexahydrate, the addition amount of the organic binder is 0.8 wt.%-1.2 wt.% of the mass of the tungsten powder, and the addition amount of the lanthanum nitrate hexahydrate is 0.1 wt.%-0.4 wt.% of the mass of the tungsten powder based on lanthanum oxide; the preparation method comprises the following steps: dissolving an organic binder and lanthanum nitrate hexahydrate in alcohol to form a mixed solution, mixing the mixed solution with tungsten powder, carrying out ball milling, and drying the ball-milled mixture to remove alcohol; the dried mixture is subjected to crushing, grinding, sieving and hydraulic forming treatment, and a blocky tungsten powder mixture is obtained; the blocky tungsten powder mixture is subjected to degreasing treatment in the hydrogen atmosphere; and the degreased blocky mixture is subjected to sintering treatment. According to the method, simple, low-cost and controllable-performance preparation of the high-performance porous tungsten is achieved, and the requirements of various application scenes are met.

The invention belongs to the technical field of aviation fuel, and particularly relates to a C11-C16 cycloalkane component as well as a preparation method, a preparation device and application thereof. The preparation method of the C11-C16 cycloalkane component provided by the invention comprises the following steps: carrying out a hydrodesulfurization and denitrification reaction on a coal tar light fraction and a hydrodesulfurization and denitrification catalyst in a hydrogen-containing atmosphere to obtain refined light oil; carrying out alkylation reaction on the refined light oil, naphtha and a hydrogen type molecular sieve catalyst to obtain an aryl mixture; carrying out hydrogenation reaction on the aryl mixture and a hydrogenation catalyst in a hydrogen-containing atmosphere to obtain a cycloalkane mixture; and the cycloalkane mixture is subjected to fractionation, such that the C11-C16 cycloalkane component is obtained. According to the preparation method provided by the invention, the coal tar light fraction and naphtha are taken as raw materials and can be directionally converted into C11-C16 cycloalkane components, so that the novel aviation fuel with high density and calorific value is prepared.

The invention provides high-spheroidization-rate medium-carbon steel based on medium-low annealing temperature and a production method thereof.The method comprises the steps of a hot rolling process, specifically, a medium-carbon steel blank is subjected to hot continuous rolling, the hot rolling coiling temperature is controlled to be 650 + / -20 DEG C, and a lamellar pearlite structure is obtained; a cold rolling process: carrying out cold rolling on the hot rolled coil, controlling the total cold rolling reduction rate to be not less than 35%, and introducing high-density dislocation and distortion defects into a pearlite structure; the cold-rolled steel plate is placed in a cover annealing furnace, under the full hydrogen protection atmosphere, the cold point temperature in the furnace is controlled to be 700 + / -10 DEG C, the hot point temperature is 710 + / -10 DEG C, the heat preservation time is 4-8 hours, and the flaky cementite is fully spheroidized; according to the method, the spheroidization rate of the medium carbon steel reaches 90% or above successfully under the upper limit condition of the annealing temperature of 720 DEG C, the contradiction between insufficient equipment capacity and high-end product requirements is solved, and remarkable economic benefits are achieved.

A gallium or indium doped S-1 molecular sieve encapsulated metal catalyst, its preparation method and application, especially in the application of low carbon alkane dehydrogenation. First, a gallium or indium doped S-1 molecular sieve slurry is prepared by a hydrothermal method, then the above catalyst is prepared through the steps of drying, impregnation, drying, dry gel crystallization reaction, calcination under nitrogen atmosphere, oxidation calcination under air atmosphere, and hydrogen atmosphere reduction. As a specific embodiment of catalyst performance evaluation, the above catalyst is evaluated for its performance in low carbon alkane dehydrogenation by taking propane dehydrogenation reaction as a model reaction. In the reaction process, no hydrogen is added, and a high propane conversion rate and propylene selectivity can be obtained, and the catalyst has good stability and good industrial application prospect. The preparation method is simple, and the dry gel material is crystallized, dried, formed, calcined and reduced to obtain the catalyst. In the preparation process, there is no water washing, filtration and other steps, which reduces the discharge of a large amount of wastewater containing metal and template, and is beneficial to industrial scale production.

Ni3GaC 0.5 / Ni3Ga5 / Ni composite microsphere wave-absorbing material, preparation method and application, (1) Ga (NO3) 3 x H2O is dispersed into deionized water, after stirring uniformly, NH3 H2O is slowly added dropwise by using a rubber head dropper, liquid A is obtained; (2) liquid A is placed into a circulating water filter for filtration, and is placed in a vacuum drying box for drying, GaOOH is obtained; (3) the filtered and dried GaOOH is added into C3H6N6 and Ni (OH) 2 and is uniformly mixed, Ni3GaC 0.5 precursor; (4) the Ni3GaC 0.5 precursor obtained in step (3) is calcined under hydrogen atmosphere, after natural cooling to room temperature, Ni3GaC 0.5 / Ni3Ga5 / Ni composite microsphere wave-absorbing material is obtained. The present application has the advantages of simple process, stable raw materials, strong controllability of structure and suitability for large-scale preparation.

The invention discloses a method for processing the surface of a cavity on a silicon substrate, which belongs to the technical field of semiconductor manufacturing and micro electro mechanical systems, and comprises the following steps of: forming a central hole distribution area and an edge hole-free area on the surface of a silicon wafer by using a hard mask and an etching process; placing the isolation pad between the edge non-hole areas of the two silicon wafers, and aligning the central hole distribution areas of the two silicon wafers to form a silicon wafer-isolation pad-silicon wafer stacked structure; the isolation pad does not shield the central hole flow channel; and placing the stacked silicon wafers and the isolation pad in a hydrogen atmosphere for annealing treatment to form a uniform cavity. According to the invention, the defects of many surface defects, high roughness and poor process stability of the silicon substrate cavity caused by the edge effect of the hydrogen flow field in the existing SON process are overcome, the optimized hydrogen flow channel is formed through wafer stacking, the hydrogen density distribution is improved, the reaction probability of oxygen atoms and silicon atoms is reduced, and the stable preparation of the high-quality and high-consistency cavity is realized.

The invention discloses a photocatalyst for hydrogen production by reforming a formaldehyde solution and a preparation method of the photocatalyst, and belongs to the crossing field of catalyst preparation and a hydrogen energy technology. The photocatalyst is a bimetallic structure material with different Mn and Ni molar ratios, and the molecular formula of the photocatalyst is MnxNiy / C3N4. The preparation method comprises the following steps: adding manganese acetate and nickel chloride in different proportions to adjust the feeding ratio of Mn to Ni in the catalyst, uniformly dispersing the mixture in deionized water containing C3N4, dropwise adding a sodium borohydride solution, continuously stirring to obtain a precursor, and calcining in a hydrogen atmosphere to obtain the catalyst. The photocatalyst can synchronously realize formaldehyde degradation and stable hydrogen production, and the hydrogen production rate can reach 134.53 mmol.h <-1 >. G <-1 >. The photocatalyst shows excellent photocatalytic formaldehyde reforming hydrogen production performance under the mild reaction condition without a sacrificial agent, the problem that a traditional catalyst depends on the sacrificial agent can be solved, and the dual benefits of pollutant degradation and clean energy preparation can be achieved through efficient conversion of formaldehyde.

The application discloses a rhodium-catalyzed desymmetrization hydroformylation method for constructing polychiral center carbon ring nucleosides. The method for constructing polychiral center carbon ring nucleosides comprises the following steps: under the condition of an inert atmosphere, an acetylacetone dicarbonyl rhodium metal precursor and a chiral ligand are added into an organic solvent to prepare a catalyst solution, the catalyst solution is mixed with a substrate, and a reaction is carried out under the condition of a hydrogen atmosphere and a carbon monoxide atmosphere; after the reaction is completed, filtration and purification are carried out, and polychiral center cycloalkyl aldehyde is obtained; and the aldehyde group is converted to obtain the polychiral center carbon ring nucleosides. The method for constructing polychiral center carbon ring nucleosides has the advantages of high selectivity, wide substrate compatibility, high reaction efficiency, easy conversion of products, and the like. The whole reaction process can obtain polychiral center cycloalkyl aldehyde in one step with extremely high enantioselectivity and diastereoselectivity, the aldehyde group is converted, polychiral center carbon rings can be obtained with high yield, high dr value and high ee value, and the method is simple and easy to operate.