548 results about "Oxygen reduction" patented technology

The invention discloses a self-driven bio-electro-Fenton sewage treatment method based on granular sludge electroactivity domestication. The sewage treatment method comprises the following steps: firstly, inoculating anaerobic granular sludge into an anode chamber of a microbial fuel cell, fixing a clustered carbon fiber electrode in a biological anode chamber as an electrode collector, taking a cathode as an oxygen reduction cathode, and performing electrochemical enrichment to obtain electroactive granular sludge; then, preparing an iron-cobalt diatomic catalyst from the nitrogen-doped graphene oxide, cobalt phthalocyanine and iron phthalocyanine; and finally, adding the iron-cobalt diatomic catalyst into the electroactive granular sludge to form a hybrid structure, controlling dissolved oxygen in a reaction system, and degrading organic pollutants by adopting an SBR (sequencing batch reactor). The biological electro-Fenton technology has a better effect of removing refractory organic pollutants, and compared with a traditional electro-Fenton method, the self-Fenton technology can achieve the activity of molecular oxygen without external electric energy input.

The invention provides a platinum-carbon catalyst taking hollow carbon nanospheres as a carrier and a preparation method of the platinum-carbon catalyst. The method comprises the following steps: adding a polymer monomer into a nano template dispersion liquid with a uniform size; then adding a proper amount of platinum salt into the solution to obtain a mixed solution, and stirring to react for 0.5-30 hours to obtain a reaction product; and annealing the reaction product, and then removing the nano template to obtain the platinum-carbon catalyst. The obtained platinum-carbon catalyst takes the hollow carbon nanospheres as a carrier and has a larger specific surface area, the platinum catalyst is loaded on the surfaces of the carbon nanospheres and can be in better contact with an electrolyte, and the obtained catalyst has good electrochemical activity and shows excellent electro-catalytic hydrogen evolution performance and oxygen reduction performance; and the related preparation method is simple and reliable, is suitable for preparation of an electrocatalytic hydrogen evolution electrode and an oxygen reduction electrode, and has a good application prospect in the fields of proton exchange membrane electrolytic cells, hydrogen fuel cells and the like.

The invention discloses a fluorine-nitrogen-doped carbon-based oxygen reduction electrocatalyst for a zinc-air battery and a preparation method of the fluorine-nitrogen-doped carbon-based oxygen reduction electrocatalyst, and belongs to the technical field of catalysts. According to the method, a fluorocarbon mixture is rapidly treated through Joule heat to achieve efficient fluorine doping, then nitrogen doping is conducted through an ammonia gas plasma technology, and therefore an original carbon precursor is converted into fluorine-nitrogen-doped carbon. The catalyst material is short in preparation time and high in production efficiency, the content configuration of fluorine and nitrogen doped in fluorine-nitrogen-doped carbon finally formed by accurately controlling the temperature and time of Joule heat treatment and the power and time of plasma treatment is controllable, the morphology and the pore structure are controllable, high electro-catalytic performance is guaranteed, and the catalyst material is suitable for industrial production. The preparation method is high in production efficiency and low in cost, and has large-scale amplification potential.

The invention discloses an application of a single-metal Co (at) N-C nanotube with high C and N contents. The Co (at) N-C nanotube is used for a zinc or magnesium metal air battery positive electrode material catalyst. The application of the oxygen reduction catalyst in a primary zinc-air battery, a primary magnesium-air battery and a secondary zinc-air battery is realized. The oxygen reduction catalytic material is characterized by being a monometallic catalyst, and shows relatively high energy density and power density in a metal battery. The half-wave potential of the prepared single-metal catalyst Co (at) NC-1Co (at) NC-1 is 0.85 V, and the half-wave potential exceeds the half-wave potential of commercialized 20% Pt / C; the limit diffusion current density Jd is 5.44 mA cm <-2 >, which is equivalent to that of commercial 20% Pt / C. The power density of a primary zinc air battery taking Co-coated NC-1 as the oxygen reduction catalyst is 202 mW cm <-2 >, and the maximum energy density is 928 Wh kg <-1 > Zn, which is higher than that of a Pt / C-based zinc metal air battery. The catalyst has the advantages of easily available raw materials, simple preparation and low cost, and has potential commercial application value.

The present invention generally relates to a process for synthesizing a graphene oxide quantum dots-iron phthalocyanine (FePc-GOQDs) nanocomposite with enhanced electrochemical properties, particularly for oxygen reduction reactions (ORR). The process begins by dispersing 500 mg of graphene oxide (GO) in a hydrogen peroxide and deionized water solution in a 1:10 volume ratio, followed by hydrothermal treatment at 180° C. for 8 hours to produce GO quantum dots (GOQDs). The resulting material is freeze-dried to obtain GOQDs powder. Subsequently, 60 mg of GOQDs are combined with 10 mg of iron phthalocyanine (FePc) and 20 mL of dimethyl sulfoxide (DMSO), and the mixture is subjected to microwave irradiation at 500 W and 150° C. for 30 minutes. The resulting composite is rinsed repeatedly with deionized water and ethanol, then dried at 120° C. to yield the FePc-GOQDs nanocomposite. This composite demonstrates superior ORR performance due to strong Fe—O bonding and optimized electronic interactions.

The application discloses a platinum-based high-entropy intermetallic compound and a preparation method and application thereof as a hydrogen fuel cell cathode catalyst, and belongs to the field of fuel cells.The preparation method comprises the following steps: S01, adding platinum salt, at least five other metal salts and a nitrogen-rich organic compound into an organic solvent, uniformly mixing, and obtaining a metal precursor mixed solution; S02, adding a carbon carrier into the metal precursor mixed solution, fully mixing, drying, collecting, and obtaining a precursor; and S03, heat treating the dried precursor under a reducing atmosphere, and performing heat preservation treatment, so as to obtain the platinum-based high-entropy intermetallic compound.The preparation method is simple, low in cost and good in repeatability, the prepared catalyst has the advantages of uniform particle size and high oxygen reduction activity, and has a good development prospect in the field of hydrogen fuel cell catalyst applications.

The invention relates to a carbon carrier material for microwave-assisted phosphoric acid treatment and oxygen reduction, a catalyst, a preparation method and application thereof, and the scheme is innovated by the following steps: dipping conductive carbon black (such as ketjen black ECP600JD) and 60-70wt% phosphoric acid solution according to a solid-to-liquid ratio of 1g / (15-18) mL, preheating at 100-250 DEG C in an argon atmosphere, then carrying out a reaction for 10-100 seconds under the assistance of a microwave power of 100-600 W, and carrying out vacuum drying to obtain the carbon carrier material for microwave-assisted phosphoric acid treatment and oxygen reduction. The phosphorus content of the prepared carbon carrier material is 4-6wt%, and the graphitization degree of the carbon carrier material is improved (ID / IG value is 1.15-1.20). And after the platinum-cobalt alloy is further loaded, the particle size of the nanoparticles is uniform, the potential loss is only 3 mV after 5000 accelerated attenuation tests in the proton exchange membrane fuel cell, and the power density attenuation is reduced by 58%. The method has the advantages of quick reaction, low energy consumption, high corrosion resistance and the like, and the stability of the catalyst is remarkably improved.

The invention discloses a preparation method of niobium-tungsten alloy spherical powder and a 3D printing method of the niobium-tungsten alloy spherical powder, and belongs to the technical field of refractory metal material preparation.The preparation method comprises the steps that niobium, tungsten, molybdenum and zirconium refractory metal raw materials are smelted to obtain cast ingots with uniform components, and hydride powder is formed after hydrotreating and mechanical crushing; spherical powder is prepared by adopting a plasma spheroidizing technology, then dehydrogenation is performed for 1-3 hours at the temperature of 450-750 DEG C, magnesium powder is added, treatment is performed for 2-5 hours in an inert atmosphere at the temperature of 800-1100 DEG C, and finally the low-oxygen niobium-tungsten alloy spherical powder with the oxygen content lower than 120 ppm is obtained. Compared with a traditional process, the spheroidizing treatment is innovatively carried out before the dehydrogenation and oxygen reduction process, the deoxidation efficiency is improved through the relatively small specific surface area of spherical powder, and oxygen content control is achieved in combination with magnesium powder heat treatment. The problems of high oxygen content and low powder yield in a traditional process are solved, and material support is provided for high-performance niobium-tungsten alloy components in the fields of aerospace, nuclear power and the like.

The invention belongs to the technical field of steel smelting, and particularly relates to a rare earth steel smelting method based on a thin slab continuous casting and rolling production line. Comprising the following steps: (1) dynamic dephosphorization control: controlling the temperature of molten steel to be 1380-1410 DEG C, the content of FeO in slag to be 15-20%, the alkalinity of the slag to be 1.8-2.2 and the content of phosphorus at the end point to be less than or equal to 0.015% in a window period 0-6 minutes before converter smelting; and (2) converter end point carbon and oxygen regulation: the converter end point carbon content is greater than or equal to 0.08%, the end point oxygen content is less than or equal to 300ppm, and the end point inclusion density is less than or equal to 10 inclusions / mm < 2 >. Through a process chain of dynamic dephosphorization and oxygen reduction, gradient deoxidation and purification, step-by-step slag system optimization, rare earth sequential addition and whole-course protection casting, a forward circulation of molten steel cleanliness and rare earth stability is formed, the rare earth steel continuous casting problem is fundamentally solved, and technical innovation and economic breakthrough are achieved at the same time.

The invention discloses a two-dimensional Pd nanosheet electrocatalyst rich in grain boundary and a preparation method of the two-dimensional Pd nanosheet electrocatalyst, and belongs to the technical field of electrochemical catalysis. The method comprises the following steps: by taking palladium acetylacetonate as a precursor, ascorbic acid and carbon monoxide as reducing agents and oleylamine as a solvent, carrying out heating reaction in a high-temperature reaction kettle; after the reaction is completed, the obtained mixture is cleaned and dried, and finally the ultrathin two-dimensional Pd nanosheet rich in the grain boundary is prepared. According to the preparation method, the active sites of the basal plane can be greatly increased, the electronic structure of the catalyst can be optimized, the catalytic performance and the quality activity can be effectively improved, and the synthesized two-dimensional Pd nanosheet rich in the grain boundary can be used for a fuel cell, a metal-air battery and an efficient electrocatalyst in the electrochemical oxygen reduction process.

The invention discloses application of a carbon nitride photocatalyst based on multiple asymmetric active sites in hydrogen peroxide production. A sulfur-doped carbon nitride nanotube is synthesized through a thermal polymerization method, and then the photocatalytic material S-CNT-Zn with zinc monatomic loaded on the sulfur-doped carbon nitride nanotube is synthesized through an impregnation-calcination method. The preparation process is simple, and the preparation flow is simple. The carbon nitride photocatalyst with multiple asymmetric active sites can break the symmetry of a carbon nitride material, form gradient charge distribution, realize multi-path charge transfer and promote migration and separation of carriers. And the zinc monatomic as an oxygen adsorption site can promote the adsorption of oxygen and reduce the formation energy barrier of the intermediate. When visible light drives oxygen reduction to synthesize hydrogen peroxide, the carbon nitride photocatalyst with multiple asymmetric active sites keeps the stability of the catalyst and higher hydrogen peroxide yield, so that clean, stable and efficient photocatalytic reduction of oxygen to synthesize hydrogen peroxide is realized.

The invention provides a monatomic cobalt-doped graphite phase carbon nitride modified carbon electrode and a preparation method and application thereof, and belongs to the technical field. The prepared monatomic cobalt-doped graphite phase carbon nitride modified carbon electrode comprises a carbon electrode substrate and a cobalt-doped graphite phase carbon nitride catalytic layer. The oxygen-containing functional group of the carbon electrode and monatomic cobalt synergistically regulate and control the selectivity and activity of two-electron oxygen reduction, so that hydrogen peroxide is efficiently and stably generated by electro-catalyzing oxygen. The carbon electrode is applied to an electro-catalytic ozonation technology, H2O2 generated in situ reacts with ozone to generate hydroxyl radicals (OH), and monatomic cobalt and carbon nitride can also directly act on the ozone to generate OH, so that removal of new pollutants difficult to degrade is remarkably enhanced, and a theoretical basis and a technical support can be provided for remediation of the pollutants.

The embodiment of the application relates to an oxygen reduction catalyst for constructing a local alkaline-like microenvironment and a preparation method and application thereof, and belongs to the technical field of material synthesis. The preparation method of the oxygen reduction catalyst for constructing a local alkaline-like microenvironment comprises the following steps: (1) loading Fe on a core MOF material to obtain a core Fe / MOF material, and then constructing metal atoms M with water activation capacity in-situ on a shell MOF material by an epitaxial growth method to obtain a core-shell Fe / MOF@M / MOF precursor material, and Fe and M are limited in the core and the shell respectively; (2) performing in-situ carbon conversion on the Fe / MOF@M / MOF precursor material by pyrolysis to obtain a FeNC@MNC oxygen reduction catalyst for constructing a local alkaline-like microenvironment in natural seawater. The catalyst with water activation capacity provided in the embodiment overcomes the challenges of low ion conductivity and chloride adsorption in natural seawater, enhances the stability and activity of the catalyst in seawater, and realizes efficient and stable oxygen reduction.

The invention relates to a single crystal furnace and a crystal pulling process. The single crystal furnace comprises a furnace body, a crucible and a guide cylinder, the furnace body defines a furnace cavity with an opening in the top end, the opening is used for introducing protective gas into the furnace cavity, the crucible is arranged in the furnace cavity and used for containing silicon liquid, and the guide cylinder is arranged in the furnace cavity and located on the side, in the axis direction of the furnace cavity, of the crucible. The guide cylinder is provided with a channel which is arranged in a penetrating mode in the axis direction of the furnace chamber, protective gas flows towards the crucible through the channel, the inner side wall of the channel is provided with a plurality of guide grooves, the guide grooves are distributed in the circumferential direction of the furnace chamber at intervals and are spirally distributed, and the extending direction of the guide grooves intersects with the axis direction of the furnace chamber. According to the single crystal furnace, the airflow path of the protective gas can be optimized, the airflow of the protective gas generates vortexes, so that the temperature of the liquid level of the silicon liquid is more uniform, the oxygen reduction effect is better, and the impurity removal effect is better.

The invention discloses a single-chamber electro-Fenton antibiotic mineralization device and method based on double anodes, in the device, an air cathode, a first anode and a second anode are sequentially arranged in a single chamber, an electrolyte contains antibiotics, the first anode comprises an electrogenesis biological membrane and in-situ synthesized nano FeS, and the second anode comprises an electrogenesis biological membrane and in-situ synthesized nano FeS; the second anode comprises a degradation biological membrane of a typical antibiotic degradation intermediate, and the surface of the air cathode is coated with an aerobic reduction catalyst. The first anode is used for driving Fe (III) / Fe (II) circulation, generation of OH is accelerated, meanwhile, nano FeS is used for protecting cells from being damaged, and therefore the antibiotic degradation efficiency is improved, and generation of intermediates is promoted; the second anode is used for promoting anode biodegradation to be coupled with cathode chemical oxidation, the intermediate is rapidly mineralized, electrons are released to drive the cathode electro-Fenton reaction, and finally thorough mineralization of the antibiotics is achieved. The device and the method provided by the invention can realize high-efficiency green low-carbon treatment of antibiotic wastewater, and have important application prospects in the aspects of environmental protection and resource utilization.

The invention discloses a preparation method and application of a polyindium phthalocyanine oxygen reduction electrocatalyst covalently suspended on a carbon nano pit, polyindium phthalocyanine is anchored on a defective carbon nano tube etched by CO2, and collaborative optimization of InPc electronic structure regulation and metal-carrier electron interaction is realized. Nano-pit defects are generated on the surface of CNT through CO2-driven oxidation etching, rich edge type carbon atoms with unpaired electrons are exposed in the substrate surface of the CNT, meanwhile, a single-layer InPPc polymer is covalently suspended on the carbon nano-pit defects through axial In-C coordination, axial In-C coordination bonds serve as electron bridges, and therefore, the carbon nano-pit defects can be formed in the surface of the CNT through the axial In-C coordination bonds. And strong interface coupling between the In-N4 center and the v-CNT substrate is realized. According to the electrocatalyst prepared by the method, the ORR catalytic activity and stability of the catalyst are remarkably improved.

The invention relates to a nitrogen-tellurium co-doped carbon-loaded cobalt-lanthanum-gallium triatomic oxygen reduction catalyst as well as a preparation method and application thereof. The catalyst comprises a carbon carrier, doped nitrogen atoms, doped tellurium atoms, supported cobalt atoms, supported lanthanum atoms and supported gallium atoms, wherein the doping proportions of nitrogen atoms and tellurium atoms in the carrier are 3.63 wt%-6.96 wt% and 2.11 wt%-3.83 wt% respectively, the loading capacity of cobalt atoms is 0.86 wt%-1.05 wt%, the loading capacity of lanthanum atoms is 0.38 wt%-0.47 wt%, and the loading capacity of gallium atoms is 0.21 wt%-0.47 wt%; in the preparation method, the nitrogen-tellurium co-doped carbon carrier is fully anchored and coordinated to Co and La atoms through a hydrothermal reaction; and through freeze drying, collapse of a carbon skeleton of the catalyst can be effectively avoided. The obtained catalyst shows good oxygen reduction activity in a solid zinc-air battery, and the peak power density of the catalyst reaches up to 1.68 mW cm <-2 >.

A bimetal active site doped carbon-based catalyst, which is particularly a ZnMn-N-C catalyst. The ZnMn-N-C catalyst is prepared by using 1H-1,2,3-triazole, manganous nitrate and zinc chloride as reaction raw materials, subjecting same to a solvothermal reaction and then to drying to obtain a Mn-MET-ZnCl2 powder, and then sequentially subjecting the powder to primary pyrolysis, a sulfuric acid treatment and secondary pyrolysis. By respectively using 1H-1,2,3-triazole and zinc chloride as a mesopore forming agent and a micropore forming agent, and adjusting the pore-forming sequence and controlling the pore-forming process by means of pyrolysis, a large number of mesopores are preferentially formed, and then a large number of micropores are uniformly distributed in the mesopores, thereby forming a hierarchical pore channel structure and overcoming the problem of the collapse of the pore channel structure during the formation of the structure; and the obtained bimetal site doped carbon-based catalyst ZnMn-N-C has a high specific surface area of 1837.9 m2 / g and exhibits a good ORR activity (E1 / 2=0.867 V vs. RHE), and a primary zinc-air battery assembled by using the catalyst ZnMn-N-C as a positive oxygen reduction catalyst has a high energy density of 889 Wh / kg-1 Zn.

The invention provides a hydrogen fuel cell catalyst as well as a preparation method and application thereof, and relates to the technical field of catalysts, the catalyst comprises an N atom modified carbon carrier and platinum alloy nanoparticles loaded on the surface of the carbon carrier, the platinum alloy nanoparticles are binary or multicomponent alloys formed by Pt and metal M, the molar ratio of platinum to the metal M is (0-10): 1, and the molar ratio of platinum to metal M is (0-10): 1. The weight ratio of the N atom modified carbon carrier to the platinum alloy nanoparticles is (25-80): (75-20). According to the preparation method of the hydrogen fuel cell catalyst, the N-modified carbon-supported PtFe alloy is prepared by a two-step pyrolysis method, so that the use amount of Pt is effectively reduced, the cost is controlled, and the utilization rate of Pt is increased; through the strong coordination capability of the 1, 10-phenanthroline, the formed Fe-N-C layer can restrain the growth and agglomeration of the PtFe alloy nanoparticles, the adsorption to a reaction intermediate is weakened, and the oxygen reduction activity and stability of the alloy catalyst are improved.

The invention discloses a nitrogen / boron-doped non-noble metal-based material, a synthesis method thereof and application of the nitrogen / boron-doped non-noble metal-based material in a microbial fuel cell. According to the method, a carbon fiber brush is used as a substrate, urea and sodium borohydride are used as a nitrogen source and a carbon source respectively, and the nitrogen / boron doped non-noble metal-based material is synthesized through a hydrothermal method. The electrostatic interaction between graphene oxide and FeCoNi-LDH is utilized to realize tight combination, so that FeCoNi-LDH nanosheets are uniformly dispersed on the surface of the carbon fiber brush, and the problems that LDHs are easy to agglomerate and poor in conductivity are solved; in the boron / nitrogen co-doping process, an efficient electron transmission channel is constructed by adjusting the electronic structure of the composite material, and the material is endowed with excellent electron transmission capability and oxygen reduction performance. In an MFC (Microbial Fuel Cell) test constructed by taking a nitrogen / boron-doped non-noble metal-based material as a cathode, the output voltage and the maximum power density are several times of those of commercial Pt / C and a blank carbon fiber brush, and the carbon fiber brush has a wide application prospect in the field of microbial fuel cells.

The invention relates to the technical field of ceramic materials, in particular to high-thermal-conductivity silicon nitride ceramic and a preparation method thereof. The invention provides a preparation method of high-thermal-conductivity silicon nitride ceramic. The preparation method comprises the following steps: (1) carrying out high-energy ball milling on silicon nitride powder; (2) carrying out oxygen reduction treatment on the silicon nitride powder obtained by high-energy ball milling treatment in the step (1); and (3) carrying out hot pressed sintering on the silicon nitride powder obtained by the oxygen reduction treatment in the step (2). The invention provides silicon nitride ceramic with high thermal conductivity and a preparation method thereof. The method comprises the following steps: firstly, carrying out surface activation treatment on silicon nitride powder through high-energy ball milling to remarkably improve the reaction activity; in the hot pressing sintering process, the carbon atmosphere generated by the graphite mold and the heating body is used in cooperation with the flowing nitrogen environment, and efficient oxygen reduction treatment is achieved at the temperature of 1300-1450 DEG C. And then, carrying out short-time sintering densification at 1700-1850 DEG C to finally obtain the silicon nitride ceramic which has excellent thermal conductivity and does not contain the sintering aid.

The utility model discloses a fresh-keeping device for a refrigerator and the refrigerator, and relates to the field of refrigerators. The refrigerator is provided with at least two mutually independent fresh-keeping chambers, the fresh-keeping device comprises at least two oxygen-enriched assemblies, and each oxygen-enriched assembly comprises an oxygen-enriched membrane and a collecting cavity; and an air extractor. At least one oxygen enrichment assembly is a gear-adjustable oxygen enrichment assembly, the number of oxygen enrichment membranes in the gear-adjustable oxygen enrichment assembly is at least two, and each oxygen enrichment membrane is correspondingly provided with a collecting cavity. The gear-adjustable oxygen enrichment assembly further comprises at least two branch channels and a gear adjusting piece, the branch channels correspond to the at least two collecting cavities, one end of each branch channel is connected with the collecting cavity, the other end of each branch channel is connected with the exhaust pipe, and the gear adjusting piece is used for controlling opening and closing of the branch channels and controlling the opening and closing number of the branch channels. According to the fresh-keeping device disclosed by the utility model, a single air extractor is used for efficiently reducing oxygen in a plurality of fresh-keeping chambers, so that the cost is relatively low. And the oxygen reduction capacity of the fresh-keeping chamber can be adjusted, and the requirements for oxygen concentration of different types of food materials can be met.

A membrane electrode for the preparation of hydrogen peroxide by means of oxygen reduction, a preparation method therefor, and a membrane electrode reactor. The membrane electrode comprises a cathode oxygen reduction electrode, a cation exchange membrane and an anode oxygen evolution electrode, which are stacked, wherein the cation exchange membrane is located between the cathode oxygen reduction electrode and the anode oxygen evolution electrode, and every two of the cathode oxygen reduction electrode, the cation exchange membrane and the anode oxygen evolution electrode are physically connected; the cathode oxygen reduction electrode comprises a cathode porous substrate layer and a cathode active layer, the cathode active layer comprising a cathode catalyst and a cation regulating and controlling material; and the anode oxygen evolution electrode comprises an anode porous substrate layer and an anode active layer, the anode active layer comprising an anode catalyst. The membrane electrode is suitable for the preparation of hydrogen peroxide by means of oxygen reduction, and has good hydrogen peroxide selectivity and high Faraday efficiency.

The utility model discloses a fresh-keeping device for a refrigerator and the refrigerator, and relates to the field of refrigerators. The refrigerator is provided with at least two mutually independent fresh-keeping chambers, the fresh-keeping device comprises an oxygen-enriched assembly, the oxygen-enriched assembly comprises an oxygen-enriched membrane, a collection cavity and an oxygen reduction bin, the collection cavity and the oxygen reduction bin are arranged on the two opposite sides of the oxygen-enriched membrane, the oxygen-enriched assembly is used for enabling more oxygen in the oxygen reduction bin to penetrate through the oxygen-enriched membrane and enter the collection cavity relative to nitrogen, and the oxygen reduction bin is provided with at least two ventilation openings; the at least two air vents are used for communicating the at least two fresh-keeping chambers; the air inlet end of the air extractor is communicated with the collecting cavity of the oxygen enrichment assembly; and the switch piece is used for controlling opening and closing of the at least one ventilation opening and adjusting the proportion of the circulation areas of the at least two ventilation openings. According to the fresh-keeping device, the single air extractor and the single oxygen enrichment assembly are used for efficiently reducing oxygen in the at least two fresh-keeping chambers, and the cost is low. And the oxygen reduction capacity of the fresh-keeping chamber can be adjusted, and the requirements for oxygen concentration of different types of food materials can be met.

The invention relates to the technical field of electrocatalytic oxygen reduction, in particular to a three-dimensional covalent organic framework material and a preparation method and application thereof. The preparation method of the novel material comprises the step of enabling a monomer 4, 4 ', 4', 4 '''-(1, 4 (1, 4)-dibenzocyclohexanoic acid-12, 13, 42, 43-tetrayl) tetrabenzaldehyde with a three-dimensional structure to react with 5, 10, 15, 20-tetraaminophenyl cobalt porphyrin, 1, 2-dichlorobenzene, 1-butanol and acetic acid according to a certain proportion to obtain the novel material. The novel material provided by the invention is simple in preparation process and good in stability, has very excellent catalytic capability on the oxygen reduction reaction of the cathode of the fuel cell, is stable in performance, and is a new energy material with great development potential and wide market prospect.

The invention discloses a preparation method and application of an MOF (Metal Organic Framework) derived carbon catalyst for regulating and controlling oxygen reduction catalytic performance based on surface strain. The method comprises the following steps: firstly, constructing a cubic MOF core under the assistance of a cationic surface active agent template through coordination self-assembly of a cobalt ion node and an imidazole ligand; then, an MOF heterogeneous core-shell layer is constructed on the surface of the core through a zinc ion mediated epitaxial growth technology, and a double-layer cubic MOF precursor with a clear core-shell interface is formed. Through carbonization treatment at different temperatures, the core MOF generates controllable surface strain in the carbonization process, metal active site coordination and electronic structures can be adjusted, and the adsorption strength of sites to oxygen reduction intermediates is optimized. A rigid porous carbon frame formed after carbonization of an epitaxial MOF heterogeneous core-shell layer constructs a three-dimensional through mass transfer network through micro-mesoporous synergy, meanwhile, the rigid porous carbon frame and the strained core form a nanoscale space isolation area, and thermal migration of metal active sites and Ostwald curing are effectively inhibited by means of the geometric confinement effect. The activity and the stability of the catalyst are remarkably improved based on multiple synergistic effects caused by evolution of an intrinsic micro-nano structure induced by surface strain. The MOF derived carbon catalyst for regulating and controlling the oxygen reduction catalytic performance based on the surface strain, provided by the invention, is simple in preparation process and low in cost, and shows excellent performance and wide application prospect in a zinc-air battery.

The application discloses a preparation method of Fe single-atom and Cu cluster co-doped nitrogen-carbon material and application of the material in full-pH oxygen reduction electrocatalysis. The ZIF-8 with a three-dimensional and rich pore structure is used as a framework, and Fe@ZIF-8 is prepared by using a solvothermal method. Then, copper acetylacetonate is used as a copper source, and the copper acetylacetonate molecules dispersed in the gas phase are adsorbed on the surface of the ZIF-8 by using the rich pore structure of the ZIF-8 and the low sublimation temperature of the metal acetylacetonate salt. Finally, pyrolysis is carried out under nitrogen or inert atmosphere, so as to form the Fe single-atom and Cu cluster co-doped nitrogen-carbon material. The material is subjected to electrochemical test under acidic, neutral and alkaline conditions, and the material exhibits high oxygen reduction electrocatalysis performance in the full-pH range and has good stability. The material has good performance as a cathode catalyst in a fuel cell, an alkaline / neutral zinc-air battery, and has high application value.

The invention relates to a sintering method for alternately strengthening oxygen reduction in a vacuum and hydrogen environment, which comprises the following steps: uniformly doping organic carbon into a metal powder raw material, utilizing the characteristics of high-temperature volatilization and decomposition of the organic carbon, heating the organic carbon to volatilize or decompose the organic carbon into CO, CO2, H2O and other gases in a presintering stage, and forming through open pores in a metal blank after overflowing. The pore structure provides a channel penetrating into the green body for hydrogen, so that the hydrogen can be directly subjected to reduction reaction with metal oxide in the green body, and the problem that the oxide in the green body is difficult to fully reduce due to limited mass transfer in the traditional process is effectively solved. In the reduction process, vacuum hydrogen circulation deoxidation can be carried out for multiple times according to the requirement of a sintered product on oxygen element; in the high-temperature sintering process, a vacuum dehydrogenation method can be carried out according to the requirement of the sintered product on the hydrogen element, the oxygen and hydrogen element content of the final product is reduced, and the comprehensive performance of the sintered product is improved.

The present invention provides a method for preparing an ultra-low platinum loading fuel cell catalyst. This method first prepares a nitrogen-doped carbon support loaded with single-atom transition non-precious metals, then reduces ultra-small high-entropy alloy nanoparticles by microwave ethylene glycol and loads them on the support, and then anneals in a reducing atmosphere. After natural cooling, the powder is collected to obtain the ultra-low platinum loading fuel cell catalyst. Through the synergistic effect of ultra-small high-entropy alloy nanoparticles and single-atom transition non-precious metals, the present invention greatly reduces the platinum loading while maintaining high-efficiency oxygen reduction performance and stability, and to a certain extent solves the high-cost problem of fuel cell catalysts caused by low platinum utilization rate.

The invention relates to a method for preparing hydrogen peroxide by electrocatalytic oxygen reduction and preparing carboxylic acid by coupling ketone oxidation, belongs to the technical field of electrocatalysis, and solves the problems of relatively high energy consumption and / or relatively low economic value of an anode product in the existing method for preparing hydrogen peroxide by electrocatalytic oxygen reduction. The method comprises the following steps: taking a carbon catalyst electrode as a cathode, wherein catholyte comprises a sodium sulfate solution; a NiCo2O4 electrode is used as an anode, and an anolyte is a solution containing potassium hydroxide and ketone; the catholyte and the anolyte are separated by a proton exchange membrane; the cathode is subjected to an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide, and the anode is subjected to an electrocatalytic ketone oxidation reaction to generate carboxylic acid. The COR reaction is used for replacing the oxygen evolution reaction (OER) of the anode in the prior art, so that energy consumption is reduced, the anode converts ketone into carboxylic acid with high added value, and the economic value of the anode product is improved.