107results about How to "Achieve controlled growth" patented technology

A preparation method of a grapheme and ferriferrous oxide composite nanometer material belongs to the technical field of functional materials. The preparation method comprises the following steps: at first, oxidized grapheme is prepared by an improved chemical method; and then oxidized grapheme and ferric ions are adopted as raw materials, and are compounded through adopting a solvothermal technology to carry out one-step in-situ reduction to obtain the grapheme and ferriferrous oxide composite nanometer material. The preparation method solves the problems in the prior art that the interface binding force of grapheme and a magnetic material is insufficient, the appearances, the sizes and the magnetism of magnetic material particles are uncontrollable, and the magnetic material particles cannot be dispersed in water; the prepared composite nanometer material shows a microspheric appearance, has a loose surface and is high in specific surface area; through the change of the ratio of grapheme to the ferric ions, final magnetic property and electrical property of the composite material can be adjusted; and the controllable growth of the grapheme and ferriferrous oxide composite material is realized. The prepared grapheme and ferriferrous oxide nanometer microsheric material with magnetic and electric properties can be used in fields such as biological medicine, energy, invisibility and electronic materials.

The invention relates to a preparation method of magnetic graphene, in particular to a chemical preparation method of magnetic graphene. The preparation method aims at solving the problems of the existing synthesis method that the reaction process is toxic and harmful to the environment, large-scale production cannot be realized, the morphology, size and magnetism of magnetic nanoparticles in the magnetic graphene are not controllable and the magnetic graphene cannot be dispersed in water. The chemical preparation method comprises the steps of: 1) preparing aminated Fe3O4 magnetic nanoparticles; 2) preparing graphene; and 3) preparing magnetic graphene through chemical reaction. The chemical preparation method of the magnetic graphene has the advantages that the high temperature and the high pressure are not required, the equipment is simple, the process cost is low, the environment is protected, no pollution is caused, the grain size of the synthesized magnetic nanoparticles is uniform, the controllable growth of the magnetic nanoparticles can be realized by changing reaction conditions, the solubility of the synthesized magnetic graphene is 0.8-1.2mg / ml, the magnetic graphene can be stably dispersed in water and sediment does not occur within 1-2 months. The graphene prepared by adopting the method can be used in biomedical, energy, electronic fields and the like.

The invention discloses a multi-walled carbon nanotube-loaded nano ferrofferic oxide (Fe3O4) catalyst and a preparation method and an application thereof. In the multi-walled carbon nanotube-loaded nano ferrofferic oxide catalyst, ferroferric oxide is distributed on the surface of the outer wall of the multi-walled carbon nanotube. The preparation process is simple, the cost is low, and easiness in industrialized popularization is realized. In the synthesized catalyst, the crystallinity of the Fe3O4 nano particles is high, the particle size is controllable, and the particles distribution is narrow. The catalytic activity of the multi-walled carbon nanotube-loaded nano ferrofferic oxide (Fe3O4) catalyst multi-walled carbon nanotube-loaded nano ferrofferic oxide (Fe3O4) catalyst (Fe3O4-MWCNTs) is high and the Fe3O4-MWCNTs is easy for being repeatedly used through magnetic separation. The Fe3O4-MWCNTs which is prepared by the method can be used as peroxide mimic enzyme and can be used as catalyst for organic pollutants which are difficult to degrade and for organic synthesis.

The invention belongs to the technical field of preparation of nano-functional materials, in particular to a method for preparing a nitrogen doped carbon nanotube three-dimensional composite materialby in-situ growth of a few layers of titanium carbide, immersing ternary layered Ti3AlC2 ceramic powder in hydrofluoric acid solution, heating and stirring, centrifugally cleaning with ultrapure waterand absolute ethanol, drying to obtain two-dimensional layered titanium carbide nano-powder, adding it into tetramethylammonium hydroxide solution, heating and stirring, centrifuging with deionized water to obtain a few layers of titanium carbide nano-sheet dispersion; Adding cobalt salt into a dispersion of a few layers of titanium carbide nano-sheets for reaction, adding dicyandiamide, heatingand stirring until dicyandiamide is completely dissolved, freezing, and freeze-drying to obtain precursor powder; Nitrogen-doped carbon nanotubes (CNTs) three-dimensional composites were prepared by in-situ growth of a few layers of titanium carbide after grinding the precursor powder and heat treatment. A three-dimensional composite material is prepared by a simple pyrolysis method using a few layers of titanium carbide as a carrier, cobalt as a catalyst, dicyandiamide as a carbon and nitrogen source, and the electrochemical performance of the few layers of titanium carbide can be improved.

The invention provides a preparation method of a NiCo2S4 nano-material. The preparation method comprises the following steps: firstly, mixing a soluble cobalt source, a soluble nickle source, urine and a solvent to obtain a reaction precursor solution; then placing a conductive substrate in the obtained reaction precursor solution, performing reaction under the microwave action, and then performing heat treatment to obtain a NiCo2O4 nanosheet; and enabling reaction between the obtained NiCo2O4 nanosheet and a sulfide to obtain the NiCo2S4 nano-material. The preparation method is simple in process, low in cost and energy consumption, short in reaction time, and favorable for large-scale industrial expansion; the NiCo2S4 semiconductor nanosheet is uniform in shape and large in specific area; controllable growth of a nano-structure thin film can be realized, so that full contact with an electrolyte is realized; quick ion diffusion and effective charge transmission are guaranteed; the NiCo2S4 nano-materia can be directly used as a counter electrode of a dye-sensitized solar cell and has a huge application prospect.

The invention discloses a nanometer silver wire and a preparing method thereof. Cl- ions are led in the preparing process of the nanometer silver wire. The morphology and the size of the nanometer silver wire are controlled through the concentration of the Cl- ions, and the leading range of the Cl- concentration ranges from 15 mmol / L to 60 mmol / L. By means of the method, silver nitrate serves as the raw material, and a polyhydric alcohol method is used for reducing Ag+ in the silver nitrate, and the high-length-diameter-ratio nanometer silver wire is obtained. The diameter of the nanometer silver wire is smaller than 100 nm, and the length-diameter ratio of the nanometer silver wire is 1000. The disclosed method has the beneficial effects that raw materials are simple, the cost is low, operation is simple, the preparing efficiency is high, and the yield is high; and good application and industrial prospects are achieved.

The invention discloses a titanium dioxide (TiO2) nanoflower film photoanode and a preparation method thereof. The photoandoe consists of common glass, a fluorine (F) doped tin dioxide (SnO2) transparent conductive film and a TiO2 nanoflower film. The preparation method comprises the following step of: directly synthesizing the TiO2 nanoflower film serving as the photoanode of a dye-sensitized solar cell on a FTO glass substrate by taking a mixture of concentrated hydrochloric acid, deionized water, toluene and butyl titanate as a reaction precursor and by hydro-thermal synthesis technology, wherein the shape of nanoflowers and the diameter and the length of nanorods consisting of the nanoflowers can be controlled by changing the ratio of the concentrated hydrochloric acid to the deionized water to the toluene and the concentration of the butyl titanate in the reaction precursor. By using higher light utilization efficiency and excellent electron transfer characteristic of TiO2 nanowires, the photoanode has the advantages of ensuring higher light trapping efficiency of electrodes, improving the transportation capacity of photon-generated carriers, reducing the recombination process of the photon-generated carriers, and consequently improving the photoelectric conversion efficiency of the dye-sensitized solar cells.

The invention discloses a TiO2 nanowire array film light anode and a preparation method thereof. The structure of the light anode comprises common glass, an F-doped SnO2 transparent conducting film and a TiO2 nanowire array film. The preparation method comprises the following step of directly synthesizing the TiO2 nanowire array film which is used as a light anode of a dye-sensitization solar battery on a FTO (Tin Oxide) glass substrate by using the mixture of concentrated hydrochloric acid, deionized water and tetrabutyl titanate as a reaction precursor in a hydrothermal synthesis technique. The method controls the diameters and densities of nanowires by changing the ratio of the concentrated hydrochloric acid to the deionized water in the reaction precursor and the concentration of the tetrabutyl titanate, controls the lengths of the TiO2 nanowires by changing reaction time, and ensures that the electrode has higher light capturing efficiency, improves the transporting capacity of photon-generated carriers and reduces the compounding process of the photon-generated carrier by utilizing higher light utilization rate and favorable electron shifting properties of the TiO2 nanowires, thereby improving the photoelectric conversion efficiency of the dye-sensitization solar battery.

The invention relates to a titanium carbide in-situ growth CNTs three-dimensional composite with polydopamine serving as a transition layer and a preparation method thereof. The method includes the steps that Ti3C2 nano-powder and dopamine hydrochloride are dispersed into ultrapure water respectively, even mixing is conducted, and stirring is conducted under the shading condition; a Tris- buffer solution is added, and stirring continues under the shading condition; the obtained mixed solution is subjected to separation, washing and drying, and Ti3C2@PDA nano-powder is obtained; the Ti3C2@PDA nano-powder is added into ultrapure water, Co(NO3)2.6H2O is added after uniform dispersion, and stirring is conducted for a reaction; urea is added after the reaction is finished, stirring is continuously conducted under a constant temperature to evaporate water, and precursor powder is obtained; the precursor powder is subjected to heat treatment, and the titanium carbide in-situ growth CNTs three-dimensional composite with polydopamine serving as the transition layer is obtained. The Ti3C2@PDA@CNTs three-dimensional composite is successfully prepared through a simple pyrolysis method.

The invention discloses coal ash microsphere loaded one-dimensional nanometer titanium dioxide (TiO2) composite photocatalyst and a preparation method thereof. The coal ash microsphere loaded one-dimensional nanometer TiO2 composite photocatalyst consists of a coal ash microsphere and a one-dimensional nanometer TiO2 film covered on the surface of the coal ash microsphere, wherein the coal ash microsphere is in a thin-wall hollow structure; the external diameter of the coal ash microsphere is 100-200 micrometers; the thickness of the wall is 2-6 micrometers; the thickness of the one-dimensional nanometer TiO2 film is about 0.5-3 micrometers; and the TiO2 is in the one-dimensional nanometer structure. The composite photocatalyst disclosed by the invention is easy to disperse, recover and use in liquid medium, has a higher reaction activity and has a wide application prospect on the water body purification aspect, and a purpose of effectively removing organic pollutants in the water body can be achieved.

The invention belongs to the technical field of preparation of nano functional materials and particularly relates to a 3D composite having CNTs (carbon nanotubes) growing on Ti3C2 in situ and a preparation method of the 3D composite. Firstly, Ti3C2 nano powder is added to ultrapure water to be dispersed uniformly, then Co(NO3)2.6H2O is added, and a liquid phase reaction is conducted; after the liquid phase reaction ends, urea is added to a reaction liquid, the mixture is continuously stirred at the constant temperature to evaporate moisture, and precursor powder is obtained, wherein the mass ratio of Ti3C2 nano powder to Co(NO3)2.6H2O to urea is (0.2-1.0): (0.1-0.4): (3.0-30.0); the precursor powder is ground fine and subjected to heat treatment, and the 3D composite having the CNTs growing on Ti3C2 in situ is obtained. Ti3C2 serves as a carrier, cobalt serves as a catalyst, urea serves as a carbon source, the 3D composite is prepared with a simple pyrolysis method, and the electrochemical performance of the Ti3C2 can be improved.

The present invention provides a preparing method of ZnO quantum dot. Firstly, processing surface treatment to a substrate, then forming a layer nano-sphere assembled by itself by czochralski method in deionized water, the nano-sphere is used as a template for preparing ZnO quantum dot; further, depositing a layer ZnO film which thickness is 5nm-50nm by electron beam evaporation under the conditions of temperature between 25-100 DEG C, 10<-4>-10<-6> Torr vacuum; finally, dipping in toluol, and vibrating 2-5 min by ultrasonic to remove the nano-sphere in the template. The ZnO quantum dot prepared by the method has large growth area, regular arrangement, even distribution. The preparing method simply, economically and effectively produces ZnO quantum dot having larger range, and order. The ZnO oxide semiconductor energy gap is wide, direct wide band gap is transmitted, and exciton binding energy is large, the ZnO quantum dot material becomes expectations of high quantum dot laser and nan0-laser by adding the quantum confinement effect of the quantum dot.

The invention provides an Ag-carbon nano fiber composite material as well as a preparation method and application thereof. The preparation method provided by the invention adopts a one-step method and has moderate conditions; special instruments and equipment are not needed, high temperature and high pressure are not needed, the operation is simple and feasible and the efficiency is high; hydrothermal reaction does not need a template; a monosaccharide is used as a carbon source and reduction reaction between the monosaccharide and a catalyst precursor Ag3PO4-AgCl is realized; the in-situ catalytic growth of carbon nano fibers is realized, Ag nanoparticles are highly dispersed in situ and loaded on the carbon nano fibers and Ag nano-wires are filled into cavities of the carbon nano fibers in situ. A result of the embodiment shows that the Ag-carbon nano fiber composite material is used for photo-catalytically degrading an organic pollutant methylene blue under visible light; after the methylene blue is adsorbed for 2h under a dark state, the concentration of the methylene blue is reduced to 55 percent of initial concentration; after the methylene blue is photo-catalytically degraded for 2h under the visible light, the removal efficiency of the methylene blue can reach 95 percent or more.

The invention provides a preparation method and application of a two-dimensional ultra-thin CuBr nano sheet, and belongs to the technical field of two-dimensional nano material preparation. Accordingto the preparation method, Van der Waals epitaxial growth is carried out on mica by a simple chemical vapor deposition method, and thus lattice mismatch between a substrate and a material is avoided;and BiBr3 is used as a reaction source, a copper foil is used as a confinement mean, the triangular single crystal nano sheet with a thickness of 0.9 nm-200 nm and a size of 2-150 [mu]m is obtained byadjusting parameters such as a source quantity, a reaction temperature and a reaction time, the controlled growth of the CuBr nano sheet is realized, and the prepared CuBr is good in mono-crystallineproperties, and has no lattice mismatch with a substrate.

The invention discloses a method for preparing a cuprous oxide thin film. The method includes the following steps of using a cleaned copper sheet as an anode, a platinum sheet as a cathode, and a 0.1-0.5mol / L sodium hydroxide aqueous solution as an electrolyte, and performing electrolysis reaction for 1-3 minutes under electrolysis conditions of 8-10V of direct current voltage and 0.5-1.0A of direct current; using a 0.01-0.05mol / L sodium hydroxide aqueous solution as an electrolyte, and performing electrolysis reaction for 40-120 minutes under electrolysis conditions of 2-5V of direct current voltage and 0.01-0.05A of direct current; finally, performing annealing. The method is simple in operation, easy to control, applicable to large-area production, and capable of achieving controllable growth of a structure and thickness of the cuprous oxide thin film, the prepared cuprous oxide thin film has a nanocrystalline structure with a crystalline grain size of 100-150nm, and improvement of photoelectricity converting efficiency of solar cells is facilitated.

The invention discloses a molecular beam epitaxial (MBE) growth method of a Bi element regulated and controlled GaAs-based nanowire crystal structure. A Bi element is introduced as an activating agent during the growing process of nanowires in an MBE growth chamber, the ionicity of GaAs is reduced, and the formation of a nanowire zinc blende structure is promoted. The method is characterized in that the Bi evaporator source temperature is regulated during the process of nanowire growth according to the beam equivalent partial pressure of a Ga element so as to control the beam equivalent partial pressure of the Bi element and to ensure that the ratio of the beam equivalent partial pressure of the Bi element to that of the Ga element is x, and the value of x can influence the regulating and controlling ability of the Bi element to the nanowire crystal structure and influence the feature and the phase structure purity of the nanowires. The method has the benefits that the growth of the GaAs-bases nanowires with the zinc blende crystal structure can be easily realized without changing the growth process conditions of MBE, and thus the method is beneficial to the controlled growth of the GaAs-based nanowires with the wurtzite and zinc blende structure and the formation of a homogeneous heterophase heterogeneous structure of the nanowires, and provides an excellent material for preparing nanoscale photoelectronic devices.

The invention discloses a method for controllable synthesis of a zinc oxide nanotube and / or nanowire, which comprises the following steps of: preparing a zinc oxide film to be used as a seed layer; then placing a substrate plated with the seed layer into reaction liquid, wherein the reaction liquid is formed through mixing a compound aqueous solution which can be ionized to generate OH<-> in water and a soluble-zinc-salt aqueous solution; and controllably obtaining a zinc oxide nanotube and nanowire through adjusting and controlling the concentration of reactants. The method disclosed by the invention has the advantages of reducing the complexity of synthesis and controllably obtaining different zinc oxide nano materials purely through controlling concentration. The obtained zinc oxide nanotube has the outer diameter of 17-50nm, the inner diameter of 3-21nm and the density of 10-100pieces / mum<2> or so; and the obtained zinc oxide nanowire has the diameter of 80-500nm and the density of 40-80 / mum<2> or se. In the method, the synthesis is carried out at normal pressure, and aqueous solution reaction is applied; and the method is simple and easy and can be used for growing the zinc oxide nanotube and nanowire on scale.

The method for preparing strip 3-D array carbon nano tube includes the following steps: using a mask with pattern formed from strip and vacuum evaporating a metal aluminium film layer whose thicknessis 100-500 nanometers on a clean substrate, using plasma to bombard with substrate with evaporated aluminium film pattern in ammonia gas for 5-20 min to make pretreatment, placing said substrate intoreactor formed from quartz tube and tubular electric furnace, introducing mixed gas of hydrogen gas and argon gas, then rising temp. of electric furnace to 850-1000 deg.C, and retaining constant temp., adding phthalocyanine iron, high-temp. cracking for 5-30 min. ,then introducing air and cooling so as to obtain the invented product with important application value for constructing field emissionplane display, vacuum microelectronic source and new-type functional microelectronic device, etc.

The invention relates to a method for preparing a two-dimensional semiconductor alloy. The general formula of the two-dimensional semiconductor alloy is MoS2(1-x)Se2x, wherein x is more than 0 and less than or equal to 1. The method comprises: heating molybdenum sulfide and molybdenum selenide placed in quartz tubes respectively in an oxygen-free environment till volatilizing, keeping a volatilization temperature, and performing chemical vapor deposition on the volatilized molybdenum sulfide and molybdenum selenide on a silicon substrate under the action of introduced protective gas flow to form the two-dimensional semiconductor alloy material. The provided two-dimensional semiconductor alloy MoS2(1-x)Se2x can realize continuous adjustment of band gaps by adjusting the value of xl and the band gap adjustment of the two-dimensional semiconductor alloy MoS2(1-x)Se2x is realized by controlling the volatilization quantity of the molybdenum sulfide and the molybdenum selenide.

The invention relates to a growth method for a ZnO nanotube array. The method includes the steps that under the alkaline condition, the ZnO nanotube array is prepared through a hydrothermal synthesis method with a Zn piece as a substrate and a reaction source; and according to the formation of the ZnO nanotube array, ZnO nanometer pieces are firstly formed on the substrate and then grow into nanometer sticks, the centers of the nanometer sticks are eroded, and finally, the nanometer sticks are eroded into nanotubes. The hydrothermal method is low in growth temperature and cost, easy to operate and beneficial to large-scale growth; the controllable growth of the ZnO nanotube array can be successfully achieved by only regulating the growth time; and hope is brought to the low-cost large-scale production technology meeting the development requirement of novel devices and industries, and an effective backup method is provided for the size-controllable growth of other nanometer materials.

The invention provides a high-entropy single-crystal metal oxide with a cation disordered salt rock structure and a preparation method and application thereof. The preparation method of the metal oxide comprises the following steps of: mixing at least five transition metal compounds and lithium source powder, and carrying out ball milling to obtain a precursor; fully mixing the precursor with fused salt, tabletting, sintering at high temperature in an inert atmosphere, and rapidly cooling to obtain a product; and separating the product, washing the product with a solvent, and drying the product to obtain the high-entropy single-crystal metal oxide with a cation disordered rock salt structure. The transition metal compounds comprise at least one compound selected from Mo < 6 + >, V < 5 + >, Nb < 5 + > and Ti < 4 + >. The metal oxide obtained by the preparation method provided by the invention is a sphere-like single crystal, is of an Fm-3m type structure, is used as a secondary battery positive electrode material, and shows relatively high energy density and good cycling stability.

The invention provides a transition metal chalcogenide nanowire and a preparation method and an application thereof. The preparation method comprises that under vacuum conditions, a metal, semi-metalor semiconductor substrate is kept to be heated to 250 DEG C-350 DEG C, transition metal atoms and chalcogenide atoms are evaporated onto the substrate, a transition metal chalcogenide film is prepared, the transition metal chalcogenide film is heated and annealed, and thus the transition metal chalcogenide nanowire is prepared. The prepared nanowire has the advantages of regular shape, definite width, uniform distribution of density of states, no impurity ions, simple operation and high preparation efficiency, and can be used for studying quantum physical phenomena in one-dimensional systems,wires in nanoscale circuits, and metal-monatomic layer semiconductor contact.

The invention discloses a method for preparing a magnetic iron containing graphene-manganese dioxide nano material. The method comprises the following steps: firstly, preparing graphite oxide into graphene, respectively dissolving graphene and ferric chloride hexahydrate in a manganese sulfate solution, adding a potassium permanganate solution and acid, and performing ultrasonic treatment to obtain the magnetic iron containing graphene-manganese dioxide nano material. The manganese dioxide nano crystal in the magnetic iron containing graphene-manganese dioxide nano material is relatively large in specific surface area, the reaction area of active substances is increased, and graphene and ferroferric oxide can be introduced as efficient carriers, so that the use efficiency of manganese dioxide can be improved, and agglomeration can be prevented; when the material is used as an electrode material, the internal resistance of an electrode can be greatly reduced, electrons can be smoothly transferred in the material, the conductivity of the composite material can be greatly improved, and the material is an excellent electrode material.

The invention relates to a preparation method for an ultra-long TiO2 nanowire array thin-film photo-anode, and belongs to the field of dye-sensitized solar cells. The problem that photon-generated carrier composite losses of an existing dye-sensitized solar cell TiO2 nanocrystalline photo-anode are large is solved. The preparation method comprises the steps that a solvothermal synthesis reaction is carried out at a time, an ethyl alcohol, hydrochloric acid and TiCl4 mixed solution is used as a precursor, and an ultra-long one-dimensional TiO2 nanowire array thin film is made to grow on a piece of FTO conductive glass. The TiO2 nanowire array thin film photo-anode is directly applied on the dye-sensitized solar cell; according to the one-dimensional structure, the electron transport speed is high, the photon-generated carrier composite losses are small, and the performance of the dye-sensitized solar cell is improved.

The invention discloses a preparation method of alkali type magnesium chloride whisker, and more particularly relates to a method for preparing the alkali type magnesium chloride whisker in a microemulsion way. The method comprises the steps of: preparing microemulsion by cetyl trimethyl ammonium bromide, alcohol cosurfactant, oil and magnesium chloride solution according to the mass ratio of 1.1: 6.3: 20: 0.492 at the room temperature; then, adding ative magnesium oxide powder into the microemulsion; and finally, preparing the dispersed alkali type magnesium chloride whisker. Compared with the highest level sedimentation method or hydrothermal method at home and abroad, the method improves the length-diameter ratio of the whisker, realizes the controllable growth of the size of the whisker, and achieves the aims of energy conservation, emission reduction, large-scale production and wide application; furthermore, the production cycle of the whisker can be shortened to be 1 / 2-1 / 6, and the yield is improved to be about 3-20 times.

The invention provides a method for preparing a high temperature superconducting nano structure array, comprising the following steps that: methods such as the pulse laser precipitation method are used, a CeO2 or YSZ buffer layer ultrathin membrane is grown on a monocrystalline substrate; the prepared CeO2 or YSZ membrane sample is a 'growth state' membrane sample; the 'growth state' membrane sample is made into a substrate with the CeO2 or YSZ nano structure buffer layer; and a high temperature superconducting membrane is grown on the substrate with the CeO2 or YSZ nano structure buffer layer by the methods such as the pulse laser precipitation method. The invention provides a simple and feasible experimental method to prepare the buffer layer, the high temperature superconducting nano structure and the array thereof, and realizes the controllable growth of the buffer layer, the high temperature superconducting nano structure and the array thereof.

The invention provides a novel avalanche-diode photoelectric detector comprising an N type electrode, an N type heavily doped layer, a single crystal substrate, a metal multifunctional layer, an InGaAs absorption layer, a P type heavily doped InGaAs layer and a P type electrode. The photoelectric detector has the wide application range. Controllable growth of the novel avalanche photo diode (APD)on various substrates is realized, the substrates are made of various materials, and the visible light APD and infrared APD are realized by replacing different substrates, so that the production costsare lowered. The single crystal substrate has good lattice integrity and lattice collisions are easy to occur, so that more avalanche electrons are excited and the efficiency of the APD is increased.The novel APD has the simple structure; the metal multifunctional layer plays a role in realizing epitaxy of the buffer layer, the charge control layer, and the reflective layer and reducing a barrier of entrance of electrons into a multiplication layer; and the reflective layer is able to reflect light that is not absorbed by the absorption layer completely to the absorption again, so that the absorption efficiency is improved.

The invention relates to the technical field of two-dimensional materials, in particular to a preparation method of a black phosphorus film. The preparation method is characterized in that a growth substrate, a phosphorus-containing precursor and a mineralizer are placed in a vacuum closed reaction chamber, wherein the growth substrate and the phosphorus-containing precursor are placed in different areas in the vacuum closed reaction chamber; the reaction chamber is heated and subjected to heat preservation, so that the mineralizer reacts with part of phosphorus-containing gas from the phosphorus-containing precursor, and an induced nucleating point or an induced nucleating layer for inducing black phosphorus crystallization is formed on the growth substrate; and the temperature of the reaction chamber is reduced, the phosphorus-containing gas is deposited on the growth substrate and epitaxially grows under the induction of the induction nucleating point or the induction nucleating layer to form the black phosphorus film. The black phosphorus film has high quality, high crystallinity and strong repeatability, is suitable for large-area and batch production of the black phosphorus film, and meets the industrial requirements in practical application.

The invention discloses a preparation method for a HfS2 single crystal nanosheet, and belongs to the field of preparation of semiconductor materials. The method comprises the following steps: (1) putting an S source and an Hf source in an upstream area of a quartz tube, placing an embedded quartz tube of which an inner diameter is smaller than that of the quartz tube in a downstream area, and placing a mica substrate into the embedded quartz tube; (2) performing vacuumizing on the interior of the quartz tube, introducing an inert gas to make pressure in the tube keep an atmospheric pressure environment, and introducing a carrier gas flow and a protective gas; and 3) heating the S source and the Hf source to evaporation, performing a reaction for 5-15 minutes under conditions that the temperature is 800-980 DEG C, a distance d between the mica substrate and the lower wall of the embedded quartz tube is 0.5-2.5mm, performing natural cooling on the quartz tube to a room temperature, and taking out the substrate. According to the invention, parameters such as the distance d between the mica substrate and the lower wall of the embedded quartz tube and a deposition temperature are optimized, thus controllable growth of the HfS2 nanosheet with a thickness of 0.8-15nm and a side length of about 5 micrometers is realized.