432 results about "Nitrogen doping" patented technology

The invention discloses a silicon-carbon negative electrode material, a preparation method thereof and a lithium ion battery, and relates to the technical field of lithium ion battery negative electrode materials. The material sequentially comprises a porous silicon core, a transition layer and a shell from inside to outside, the transition layer is a nitrogen-doped SiC / C composite layer, the shell comprises a graphene / carbon nanotube skeleton and MXene quantum dots, the MXene quantum dots are embedded in the graphene / carbon nanotube skeleton, boric acid ester bonds exist between carbon nanotubes and graphene, and the MXene quantum dots are embedded in the graphene / carbon nanotube skeleton. The silicon-carbon negative electrode material is based on dual-network dynamic bonding and stress gradient regulation and control, the cycle performance of the material can be remarkably improved, and the service life of the material can be remarkably prolonged.

The invention discloses a silk protein-MXene composite film and a preparation method thereof. The silk protein-MXene composite film sequentially comprises a conductive surface layer, a porous response layer and a supporting bottom layer from top to bottom, the invention relates to the technical field of composite films. According to the fibroin-MXene composite film and the preparation method thereof, a three-layer gradient structure is formed by the conductive surface layer, the porous response layer and the supporting bottom layer, good conductivity and electromagnetic shielding effectiveness are ensured by utilizing oriented arrangement of MXene of the conductive surface layer, gallic acid and MXene form a hydrogen bond network, and nitrogen-doped carbon quantum dots coat the surface of MXene to form a physical barrier, so that the electromagnetic shielding effect is improved, and the electromagnetic shielding effect is improved. Through double oxidation resistance of gallic acid and nitrogen-doped carbon quantum dots, a sponge body structure formed by the porous response layer is matched to endow the composite film with high-sensitivity response to external stimulation, the supporting bottom layer is crosslinked by hexamethylene diisocyanate and enhanced by nanocellulose, the tensile strength is improved, and the tensile strength of the composite film is improved. And the contradiction between the mechanical property and the conductivity of the traditional composite film is effectively solved.

The invention provides a super-hydrophobic passion fruit peel carbon aerogel VOCs adsorbent based on low-temperature plasma synergistic nitrogen doping modification and a preparation method thereof, and relates to the technical field of VOCs adsorbents. The super-hydrophobic passion fruit peel carbon aerogel VOCs adsorbent based on low-temperature plasma synergistic nitrogen doping modification is prepared by crushing passion fruit peel, mixing the crushed passion fruit peel with a nitrogen-containing compound to form gel, performing low-temperature plasma modification, performing freeze drying, performing high-temperature carbonization, and performing water washing and drying. The adsorbent is spherical, and the water contact angle is 115.8 degrees to 152.4 degrees. The adsorbent disclosed by the invention has the advantages of super hydrophobicity, high specific surface area, developed microporous structure, excellent VOCs adsorption performance, broad-spectrum adsorption capacity, good reusability and mechanical strength, the preparation method is simple in process, green and environment-friendly, low in cost and good in universality, a new technical scheme is provided for VOCs treatment in a high-humidity environment, and the adsorbent has a good application prospect.

The invention relates to the technical field of agricultural application of nano materials, and discloses a preparation method and application of a photosynthetic accelerant containing carbon quantum dots. Urea and citric acid are adopted as raw materials, and the nitrogen-carbon molar ratio and hydrothermal reaction parameters are optimized, so that efficient doping of nitrogen and accurate regulation and control of the particle size are achieved, and the photosynthetic accelerant containing the carbon quantum dots is obtained. The nitrogen-doped carbon quantum dot photosynthetic promoter with excellent upconversion performance is successfully synthesized, the promoter has good water solubility and biocompatibility, the photosynthetic efficiency of plants can be greatly improved within the concentration range of 0-100 mg / L, a safe application window is defined, and by establishing foliage spraying and water planting dual-mode application specifications, the application range of the nitrogen-doped carbon quantum dot photosynthetic promoter is widened, and the application range of the nitrogen-doped carbon quantum dot photosynthetic promoter is widened. The problems that current crops are insufficient in solar spectrum utilization and low in light energy conversion efficiency are solved in a targeted manner by utilizing an ultraviolet light-photosynthetically active radiation conversion function mediated by the carbon quantum dots and combining the targeted enrichment permeation characteristic of the carbon quantum dots in chloroplast.

The invention provides a preparation method of a gate oxide layer and a gate, and the method comprises the steps: carrying out the rapid thermal annealing treatment of a silicon-based substrate in a nitrogen-containing gas atmosphere, which belongs to a non-destructive nitrogen doping mode, and carrying out the nitrogen pre-doping on the surface of the silicon-based substrate, so as to reduce the doping amount needed by the subsequent plasma nitrogen doping; therefore, the damage of the plasma nitrogen doping process to the SiON gate oxide layer is reduced, and the interface defect between the SiON gate oxide layer and the silicon-based substrate interface is reduced. Besides, after the nitrogen pre-doped layer is formed, the thermal oxidation process is carried out on the silicon-based substrate to form the silicon dioxide gate oxide layer, so that the damage to the SiON gate oxide layer film is reduced, and the interface defect between the SiON gate oxide layer and the silicon-based substrate interface is further reduced; moreover, the laser rapid annealing treatment can remove the intrinsic oxide layer on the surface of the SiON gate oxide layer, repair the damage to the crystal lattice of the SiON gate oxide layer caused by the plasma nitrogen doping treatment process, improve the film quality and repair the interface.

The invention discloses a high-voltage single-crystal positive electrode material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The preparation method comprises the following steps: by taking MOFs (Metal Organic Frameworks) with a porous structure as a template, loading a ternary precursor in pore channels of the template by adopting a solvothermal method to prepare loaded MOFs; mixing the loaded MOFs with a lithium source, carbonizing and calcining in an inert atmosphere for high-temperature solid-phase reaction, carbonizing the template to form a nitrogen-doped porous carbon skeleton, and converting the ternary precursor into single-crystal NCM particles to prepare a calcined product; sequentially carrying out acid pickling, drying and airflow crushing treatment on the calcined product to obtain a composite material; the composite material is sequentially subjected to multi-section penetration type dry coating and sintering treatment, the high-voltage single-crystal positive electrode material is prepared, and the high-voltage single-crystal positive electrode material can balance the capacity, the cycle life and the safety under high voltage.

The invention relates to the technical field of lithium ion batteries, in particular to a chromium-molybdenum double-doped lithium iron phosphate material as well as a preparation method and application thereof. The preparation method is used for solving the problems of low capacity, low electronic conductivity and poor cycling stability of the existing lithium iron phosphate material. According to the preparation method, chromium-molybdenum is doped into lithium iron phosphate, and the bond energy of a Cr-O bond and a Mo-O bond is stronger than that of a Fe-O bond, so that the dissolution loss of Fe < 2 + > in long-term circulation is reduced, and the battery capacity and the intrinsic electron conductivity of the material are improved; lithium iron phosphate is coated with nitrogen-doped carbon nanotubes, and nitrogen is doped in graphite crystal lattices of the carbon nanotubes, so that additional free electrons are provided, the intrinsic conductivity is improved, the resistance is reduced, the rate capability is improved, and the cycle life is prolonged; the polyaniline coating layer forms a barrier layer on the surface of the lithium iron phosphate particles, so that the cycle performance and the battery capacity are improved; the three components cooperate to improve the capacity, conductivity, rate capability and cycling stability of the material.

The invention provides a phosphorus emitter passivation structure and a preparation method thereof, the passivation structure comprises a phosphorus emitter, the phosphorus emitter comprises silicon, phosphorus, hydrogen, carbon and / or nitrogen, the surface of the phosphorus emitter is provided with a nano silicon oxide layer, the phosphorus emitter comprises an electric injection region and a doped region, the electric injection region is provided with a conductive layer at a corresponding position, and the doped region is provided with a conductive layer at a corresponding position. The conductive layer is used for being connected with a metal electrode, a passivation anti-reflection layer is arranged at the corresponding position of the doped region, and the carbon and / or nitrogen concentration of the electric injection region is higher than that of the electric injection region. Partitioned passivation is performed on the surface of the phosphorus emitter, and carbon and / or nitrogen atoms are introduced into the doped region, so that the interface passivation effect is improved; the electric injection region is not subjected to carbon and nitrogen doping and is not provided with a passive film, so that the influence of passivation on the contact resistivity is reduced; a conductive channel is introduced into the electric injection region for electric injection, so that the defect state of the phosphorus emitter can be further eliminated, and the recombination current is reduced.

The invention belongs to the technical field of preparation of wave-absorbing materials, and particularly relates to a cobalt-based nitrogen-doped carbon nano composite material with a hollow cubic structure as well as a preparation method and application thereof. Comprising the following steps: taking ZnCo-ZIF with a nano cubic structure as a core, coating ZnCo-ZIF with polydopamine by adopting a precipitation method to form a precursor with a core-shell structure, and carbonizing the precursor at 800-900 DEG C to obtain the cobalt-based nitrogen-doped carbon nano composite material with the hollow cubic structure. According to the invention, the dielectric loss capability can be enhanced by using the conductivity and interface polarization effect of the coated carbon layer, and the Co particles introduce strong magnetic loss; meanwhile, due to interface polarization caused by abundant heterogeneous interfaces existing between the Co particles and the coating carbon layer, between the magnetic particles and the carbon nanotubes and between the carbon matrix and the carbon nanotubes in the composite material, the impedance matching characteristic can be improved, and high reflection loss and wide effective absorption bandwidth can be achieved under the low matching thickness.

The invention discloses a biomass nitrogen-doped derivative porous carbon material and a preparation method and application thereof, and belongs to the technical field of photo-thermal atmospheric water catching.The preparation method comprises the following steps that a carbon source and a nitrogen source are put into water to be subjected to an ultrasonic reaction, a reactant is subjected to hydrothermal treatment, and a solid product is obtained; carrying out steam etching and high-temperature annealing treatment on the solid product and metal salt in an inert atmosphere, and then sequentially carrying out acidizing treatment, grinding and drying to prepare the biomass nitrogen-doped derived porous carbon material. The biomass nitrogen-doped derivative porous carbon material prepared by the method has a rich pore structure and efficient adsorption-desorption performance, can replace an expensive MOFs material, optimizes the preparation path, improves the nitrogen doping efficiency and the material stability, remarkably reduces the cost and the environmental burden while ensuring the excellent atmospheric water collection performance, and has a wide application prospect. And the method shows more excellent industrialization prospects and sustainable development values.

The invention discloses a nitrogen-doped multilayer rose-shaped hard carbon material as well as a preparation method and application thereof, and belongs to the technical field of battery materials. A precursor of the nitrogen-doped multi-layer rose-shaped hard carbon material is prepared by adopting a solid-liquid self-assembly method, and then the precursor is calcined, so that the final nitrogen-doped multi-layer rose-shaped hard carbon material can be obtained. The prepared nitrogen-doped porous carbon material has more mesopores and defects, is unique in structure and uniform in shape, and can be used as a sodium ion battery negative electrode material. The nitrogen-doped multilayer rose-shaped hard carbon material prepared by the invention is a material with immunity to environmental influence, belongs to a mesoporous carbon material with stable chemical components and controllable shape in the porous field, has the advantages of regular structure, relatively good stability and the like, and has the properties of high capacity, good rate and the like as a negative electrode material.

The invention relates to the technical field of batteries, in particular to a low-hydrogen-evolution graphene material for a lead-acid battery and a preparation method thereof.The method comprises the steps that firstly, ethidene diamine is grafted to the surface of graphene oxide through a carbodiimide / active ester method, and aminated graphene is obtained; performing heat treatment in a nitrogen / ammonia gas atmosphere to realize nitrogen doping; compounding with titanium dioxide, and carrying out hydrothermal reaction to form a stable structure; then, sequentially grafting imidazolium silane and perfluorodecyl silane to carry out hydrophobic modification; and finally, stabilization and low-temperature re-nitridation curing are carried out through titanium tetrabutoxide. The graphene material prepared by the method endows the battery with excellent performance, and is low in direct-current internal resistance and high in capacity retention ratio.

The invention discloses a preparation method and application of nickel-cobalt bimetallic phosphide for in-situ growth of nitrogen-doped carbon nanotubes. The preparation method comprises the following steps: preparing a graphene oxide dispersion liquid; sequentially adding a cobalt source, a nickel source, a segmented copolymer, a phosphorus source and a nitrogen source into the graphene oxide dispersion liquid, and uniformly mixing to obtain a mixed solution; drying the mixed solution to obtain a precursor; and annealing the precursor in an inert atmosphere to obtain the product. According to the nitrogen-doped carbon material coated phosphide nano-particle composite material and the preparation method thereof, by regulating and controlling the ratio of Ni to Co, a carbon source grows on graphene in situ to form a carbon nano-tube, nickel-cobalt bimetal phosphide nano-particles are uniformly distributed on a nitrogen-doped carbon material to form the nitrogen-doped carbon material coated phosphide nano-particle composite material, and the nitrogen-doped carbon material coated phosphide nano-particle composite material is used as a modified diaphragm material of a lithium-sulfur battery. The preparation method disclosed by the invention has the advantages of mild reaction conditions and easiness in amplification and regulation, and the prepared composite material has a relatively high specific surface area and can be applied to the field of energy sources, especially the field of lithium-sulfur batteries.

The invention discloses a method for synthesizing a platinum-based nitrogen-doped graphdiyne catalyst based on an atomic layer deposition technology and application of the platinum-based nitrogen-doped graphdiyne catalyst. Firstly, hexabromobenzene and calcium carbide are subjected to vacuum ball milling, calcination and purification to obtain a graphdiyne carrier, then the graphdiyne carrier and melamine are mixed and calcined to achieve nitrogen doping of the carrier, and then loading of platinum nanoparticles is accurately controlled through an atomic layer deposition technology. According to the method, the characteristics of an atomic layer deposition technology are utilized, deposition parameters and the number of cycles are controlled, uniform distribution and size control of Pt nano-particles on porous graphdiyne are achieved, and a nitrogen-doped graphdiyne carrier and the platinum nano-particles have a synergistic effect. The platinum-based nitrogen-doped graphdiyne catalyst prepared by the invention has the specific surface area of 734.8 m < 2 > g < 1 > and the average pore size of 8.68 nm, and shows excellent electrocatalytic activity and dynamic performance in reaction.

According to the prepared MXene / C electrode material based on PAN carbonization, a nitrogen-doped carbon layer generated through polyacrylonitrile (PAN) in-situ carbonization serves as a supporting spacer to be inserted between MXene nanosheet layers, the MXene nanosheet layers are tightly bridged, the interlayer spacing of MXene is effectively enlarged, re-stacking of nanosheets is inhibited, and in the carbonization process, the MXene / C electrode material can be used for preparing the MXene / C electrode material based on PAN carbonization. Abundant mesopores and fissure holes are generated in the composite material by introducing and decomposing a sacrificial template (PMMA nanosphere), and a three-dimensional through ion transmission channel is constructed; the nitrogen-doped carbon layer not only serves as a supporting spacer to be inserted between MXene nanosheet layers, but also coats the surfaces of the MXene nanosheets,-F end groups on the surfaces of the MXene nanosheets are weakened, and C-O (H) and C-N functional groups are enriched, so that the interface wettability, the conductivity and the anti-oxidation stability of the material are improved, and the material can be widely applied to the technical field of electrochemical energy storage materials.

The invention discloses a method for purifying water by catalyzing ozonation through a nitrogen-fluorine co-doped carbon-loaded cobalt nanomaterial. Co-ZIF-8 and polytetrafluoroethylene (PTFE) are respectively used as a precursor and a fluorine source, and the nitrogen-fluorine co-doped carbon-loaded cobalt nano-catalyst is successfully prepared through an etching synchronous doping strategy. The composite material can be used for catalyzing ozone to degrade organic pollutants in water. Nitrogen doping can promote formation of a metal-nitrogen coordination structure, and decomposition of ozone on the surface of the catalyst is facilitated. Fluorine modification can significantly enhance the hydrophilicity of the composite material and accelerate the solid-liquid reaction of ozone in a solution and a catalyst interface, and the strong electron withdrawing effect of fluorine can effectively adjust the electronic structure of the catalyst and promote the generation of strong oxidizing active oxygen species, thereby achieving efficient and rapid removal of pollutants. The water treatment method solves the problem of low ozone utilization rate in a conventional catalytic ozonation process, has the advantages of high reaction rate and stable treatment effect, and has a good application prospect.

The invention discloses a high-activity nitrogen-doped hard carbon negative electrode material and a preparation method thereof, high specific capacity is obtained, the problem that the initial coulombic efficiency of existing hard carbon is not high is solved, a prepared product is good in conductivity and high in activity, the capacity is high when the product is used as a lithium ion battery, and the obtained material mainly has the following characteristics that (1) the specific capacity is high and is 190-260mAh / g; (3) first coulombic efficiency gt; 80%.

The invention discloses nitrogen-doped carbon quantum dots derived from American cockroach dregs as well as a preparation method and application of the nitrogen-doped carbon quantum dots, and belongs to the technical field of nitrogen-doped carbon quantum dots. The nitrogen-doped carbon quantum dots are prepared from the American cockroach dregs by a one-step hydrothermal method, optimal synthesis parameters are obtained through experimental optimization of synthesis conditions, and the prepared nitrogen-doped carbon quantum dots have excellent optical characteristics and stability; the invention also provides an application of the nitrogen-doped carbon quantum dot in Ag < + > detection, the nitrogen-doped carbon quantum dot has good selectivity, sensitivity and anti-interference performance on Ag < + >, a detection mechanism is an internal filtering effect and light-induced electron transfer, and the nitrogen-doped carbon quantum dot can be used as a preferred fluorescent material of an Ag < + > fluorescent sensor. The nitrogen-doped carbon quantum dots synthesized by the method not only have an Ag < + > sensing function, but also realize high-valued utilization of medicine residues, and also provide a new thought for self-doping of heteroatoms.

The invention relates to the technical field of carbon material preparation, and discloses a dispersed metal monatomic nitrogen-doped spherical mesoporous carbon material and a preparation method thereof, and the preparation method comprises the following steps: introducing a vinyl-containing metal precursor in a prepolymer stage, and grafting a metal center to a polymer skeleton in situ through chemical bonding; then preparing phenolic resin balls by using the amphiphilic block copolymer as a soft template and combining an emulsification curing process; and finally, carbonizing the resin balls, and introducing water vapor with a specific proportion for activation to construct mesoporous and microporous graded channels. According to the invention, agglomeration of metal atoms at a high temperature is effectively inhibited through in-situ chemical bonding, and high-dispersion loading of single atoms is realized; meanwhile, the soft template and water vapor activation have a synergistic effect, so that the material is endowed with a high specific surface area and a developed hierarchical pore structure. When the obtained material is used as a supercapacitor electrode, high specific capacitance, excellent rate capability and good cycling stability are shown.

The invention discloses a method for preparing an ultrahigh-conductivity graphene / copper composite material through nitrogen plasma ball milling, and relates to the technical field of metal-based composite material preparation. The preparation method of the composite material comprises the steps that copper powder and graphene are mixed and placed in plasma ball milling equipment, a plasma generator and a high-energy ball milling device are started for mixing treatment in the nitrogen atmosphere, and composite powder is obtained; and the composite powder is densified through a spark plasma sintering technology, and the block composite material is obtained. Through the synergistic effect of plasma stripping, nitrogen doping and mechanical compounding, high-quality stripping, controllable doping and uniform dispersion of graphene are achieved in one step, interface bonding of graphene and copper is remarkably improved, and the interface electron transmission capacity is effectively enhanced. The graphene / copper composite material prepared by the preparation method disclosed by the invention shows extremely high conductivity while keeping high density.

The application discloses a preparation method of a hard carbon negative electrode of a sodium ion battery suitable for high initial efficiency and super-high specific capacity. The method comprises the following steps: taking a carbon-containing material as a hard carbon precursor, and performing pre-oxidation treatment on the hard carbon precursor through a muffle furnace; adding a nitrogen-containing doping source into the hard carbon precursor, and placing the hard carbon precursor into a vacuum tube furnace containing a protective atmosphere to perform calcination pyrolysis and natural cooling. The application adopts the carbon-containing material as the precursor, adds the nitrogen-containing doping source to prepare nitrogen-doped hard carbon powder through high-temperature pyrolysis, and obtains a self-supporting structure electrode material by compounding the nitrogen-doped hard carbon powder with MXene, so that the space and mass energy densities of the electrode are greatly improved. The MXene on the surface is not only excellent in conductivity and electrochemical stability, but also can effectively block the destruction of electrolyte to the surface structure of the hard carbon, so that the initial charge-discharge efficiency and reversible specific capacity of the hard carbon negative electrode material are greatly improved.

The invention belongs to the technical field of negative electrode materials, and relates to a nitrogen-doped carbon-coated titanium niobate negative electrode material and a preparation method and application thereof. According to the preparation method, a nano structure is regulated and controlled by virtue of a synergistic effect of'rigid frames + dynamic micelles' of a hard template and a soft template, the hard template provides a rigid space confinement by virtue of ordered mesopores, a niobium source precursor and a titanium source precursor are anchored, and titanium niobate is forced to grow in a pore channel along the axial direction; the soft template is self-assembled into micelles in an organic-water system, channels formed in the hard template are filled with the micelles, the deposition interfacial tension of a precursor is adjusted through the hydrophobic-hydrophilic effect, and the micelles and the hard template are jointly induced to form a'nanotube + mesoporous' multilevel structure.

The invention relates to the technical field of catalysts, in particular to a palladium-based catalyst derived from MOFs as well as a preparation method and application of the palladium-based catalyst. The preparation method comprises the following steps: firstly preparing an MOF material, then preparing a palladium-based MOF precursor, mixing the palladium-based MOF precursor with a nitrogen-containing precursor, heating and roasting in an inert atmosphere, and cooling to room temperature. An external nitrogen-containing precursor is introduced in the high-temperature pyrolysis process and is jointly roasted with a palladium-based MOF precursor, the nitrogen doping amount in the carbon carrier is remarkably increased, and high dispersion and electronic structure optimization of Pd particles are achieved by enhancing the anchoring effect and electronic regulation and control of nitrogen species on the Pd nanoparticles; therefore, high activity, high selectivity and high stability are simultaneously obtained in the selective hydrogenation reaction of 2-methyl-3-butyne-2-alcohol.

The application relates to the field of nanometer carbon materials, and discloses a low-resistivity nitrogen-doped carbon material, a preparation method of the low-resistivity nitrogen-doped carbon material, a fuel cell catalyst and a lithium ion battery electrode material. The carbon material is a hollow cage, the molar content of carbon in the carbon material is 89-98% as measured by X-ray photoelectron spectroscopy, the molar content of nitrogen is 0.5-5%, and the molar content of oxygen is 0.5-10%; the carbon material has at least one mesopore distribution peak, the resistivity of the carbon material is not higher than 500 m omega*cm, and the specific surface area of the carbon material is 50-1000 m 2 / g. The low-resistivity nitrogen-doped carbon material has a large specific surface area, increases active sites, has low resistivity, good conductivity, good catalytic performance when applied to a fuel cell catalyst, and good reversible capacity and cycle stability when applied to a lithium ion battery.

The invention belongs to the technical field of nano materials, and particularly relates to a nitrogen doping method and application of gamma-graphdiyne. Graphdiyne oxide is prepared through a hydrothermal method, then melamine serves as a nitrogen source, graphdiyne oxide serves as a framework, in-situ doping of nitrogen elements and reduction of graphdiyne oxide are achieved at the same time through high-temperature calcination, and the gamma-graphdiyne is obtained. The method is simple and easy to implement, the processing period is short, the doping amount is easy to control, dangerous chemicals such as concentrated sulfuric acid and concentrated nitric acid are not involved, the production safety is greatly improved, and the prepared nitrogen-doped gamma-graphdiyne has the advantages of high purity, high specific surface area, nanoscale pore diameter and excellent wave absorbing performance, gas sensitivity and ferromagnetism.

NCM electrode particle, which has an interphase layer and a nitrogen-containing carbon layer; the NCM electrode particle is used in an electrode of a solid-state battery or a semi-solid battery; the NCM electrode particle comprises: an NCM particle (lithium nickel manganese cobalt oxide) with a single-crystal structure; The intermediate phase layer is applied to the outer surface of the NCM particle; the NCM particle coated with the intermediate phase layer forms a primary particle; the intermediate phase layer comprises a glass phase layer and several ceramic particles dispersed therein; the intermediate phase layer serves to protect the NCM particle and increases the lithium-ion conductivity; A nitrogen-containing carbon layer is applied to the outside of the primary particle; the NCM electrode particle is formed by the NCM particle, the intermediate phase layer, and the nitrogen-containing carbon layer; the nitrogen-containing carbon layer serves to increase the electrical conductivity of the NCM electrode particle; and where nitrogen-doped carbon molecules in the nitrogen-containing carbon layer increase the electronic conductivity and lithium-ion conductivity of the NCM particles and modify the electrical potential of the NCM particles; the nitrogen-containing carbon layer is formed by calcining a nitrogen-containing polymer material in an inert atmosphere and applied to the outer surface of the primary particle; carbon and nitrogen in the nitrogen-containing carbon layer form conjugated C=N bonds to modify an energy band and thus reduce the energy required to excite electrons into a conduction band, thereby increasing the electrical conductivity.

The invention relates to the technical field of lithium batteries, and provides a preparation method of a nitrogen-doped porous carbon composite lithium iron phosphate positive electrode material, which comprises the following steps: mixing a lithium source, anhydrous iron phosphate, titanium dioxide and a carbon source, cleaning, drying and crushing waste plastic, stirring, grinding, spray-drying and calcining to obtain a porous carbon coated precursor; and doping a nitrogen source into the porous carbon coated precursor, grinding, carrying out spray drying, and carrying out secondary calcination to obtain the nitrogen-doped porous carbon composite lithium iron phosphate positive electrode material. The nitrogen-doped porous carbon can inhibit the growth of lithium iron phosphate crystal grains, control the particle size of lithium iron phosphate and shorten the diffusion path of lithium ions; the porosity and the specific surface area are improved, and charge conduction and ion transmission are promoted; the nitrogen doping improves the conductivity of the porous carbon coating layer and improves the electron conductivity. A trace amount of Cr, Cd, Zn and other elements in the waste plastic are introduced into lithium iron phosphate through two times of calcination, so that a lithium ion diffusion channel can be expanded or the symmetry of a crystal field can be optimized, and a lithium ion migration barrier can be reduced.

The invention discloses a silicon-carbon composite negative electrode material and a preparation method thereof, the silicon-carbon composite negative electrode material comprises a core-shell active unit, a conductive network layer and a composite coating layer, the core-shell active unit is a structure formed by loading boron-doped silicon quantum dots in hollow carbon spheres; the composite material is prepared from the following components in percentage by mass: 11 to 18 weight percent of boron-doped silicon quantum dots, 24 to 36 weight percent of hollow carbon spheres, 31 to 42 weight percent of polyimide-derived nitrogen-doped carbon nanofibers, 3 to 8 weight percent of fluorophosphate-aluminum oxide composite coating layer and 2 to 5 weight percent of lithium titanate modified montmorillonite, the mass ratio of fluorophosphate to aluminum oxide in the fluorophosphate-aluminum oxide composite coating layer is 3: 1, the particle size of the boron-doped silicon quantum dots is 2-5nm, the doping amount of the boron element is 1-3at%, and the purity is not lower than 99.95%. The core-shell structure is used for buffering silicon expansion, the nitrogen-doped carbon fiber is used for constructing a high-efficiency conductive network, the composite coating layer is used for stabilizing an interface, and the inorganic dispersed phase is used for inhibiting agglomeration, so that the specific capacity, the cycling stability and the first charge-discharge efficiency of the lithium ion battery are remarkably improved.

The invention provides an N-doped TiO2-BiVO4 heterojunction photocatalytic coating as well as a preparation method and application thereof, and belongs to the technical field of photocatalytic materials. Nitrogen doping is achieved through nitrogen source pyrolysis, an N-doped Bi-Ti heterojunction is formed, the molar ratio of Bi to Ti can be optimized, a tight heterojunction interface is formed, a light absorption edge is subjected to red shift to 600 nm, the carrier separation efficiency is improved, N doping is introduced into an intermediate energy level, the light response range is widened through BiVO4, the net degradation rate of formaldehyde within 24 hours reaches 78% through cooperation of the two, and the light response range is widened through BiVO4. Meanwhile, the problems that an existing photocatalytic coating is low in visible light utilization rate and poor in adhesive force are solved.

The invention relates to the field of sodium-ion batteries, in particular to a high-conductivity carbon-coated sodium-electropolyanion positive electrode material and a preparation method thereof. The nitrogen-containing substance and the high-molecular polymer are compounded, and the high-molecular polymer is an excellent carbon skeleton and a precursor, so that a continuous, compact and uniform carbon coating layer is formed, and a main skeleton of carbon is provided; the rich nitrogen source realizes high-level nitrogen doping, and nitrogen atoms and adjacent carbon atoms form conjugated pi bonds, so that charge transfer and structural stability are facilitated, and the intrinsic conductivity of the carbon layer is remarkably improved; a high-efficiency electronic conductive network can be formed by a strategy of compounding a high-molecular carbon skeleton and a nitrogen-rich molecular dopant, the transmission kinetics of electrons and ions is optimized, high conductivity and good structural characteristics are considered, and the conductivity and stability of the polyanion material are synergistically improved.