Graphene and semiconductor nano particle compound system and synthesizing method thereof
Technical Field The invention relates to a semiconductor nano-material composite system and method for synthesizing the same, in particular to a large specific surface area of the electrical and thermal performance excellent graphene and the photosensitive property of the semiconductor nano-particles of a nano-material and its synthetic method, which belongs to the technical field of preparing semiconductor material. Background Art Graphene (Graphene) is composed of a single layer of carbon atoms of the carbon nano-structure material two-dimensional , has a large specific surface area and excellent electrical and thermal performance. High mobility of Graphene can exceed 104 cm2/V·s, promising high speed in the future nano-electronic device, in biological chemical sensor application. However, because the structure of the semiconductor energy band zero band gap and monoatomic layer thickness the photoelectric characteristic of limiting the same, single graphene, is almost a transparent to visible light, only a very small light conductance. Therefore, to improve the carbon nanotube, photoelectric characteristic of graphene is a need to solve the problem. Semiconductor nano-crystal, also referred to as nano-particles, are of great interest in studying another nanometer material. The size distribution of a few nanometer to several tens of nanometer range. Semiconductor nano-particles in the biological fluorescent labeling, electroluminescent, photoelectric device has an important potential application. Semiconductor nano-particle with discrete electronic energy and size dependent energy gap of spacing and, therefore it has good optical properties. CdSe, PbSe semiconductor nano-particles, such as of the small band gap to enable to realize found exciton multiplication phenomenon, it is expected to be in the high-efficiency solar cell application. Semiconductor nano-particles are made of inorganic semiconductor core and the shell body of the organic ligands, coated organic ligands in nanoparticulate synthetic and storing the role of preventing the agglomeration and stability. However, the presence of these insulating organic ligand, greatly reduces the coupling between the nano-crystal, semiconductor nano-particle assembly and lead to the presence of a significant amount of disorder in the system, if the energy unordered more than of the coupling, the entire system will be in a state similar to insulator Anderson-Mott. Therefore, semiconductor nanoparticles having a very low conductivity and photoconductive, this severely limits the application of the photoelectric area nano-particles. Semiconductor nano-particle to use solar photovoltaic device has become an important research direction, therefore, to improve the electrical conductivity of the semiconductor nano-particle system to their application of the photoelectric transformation is of great significance. Carbon nanotube, graphene and semiconductor nano-particle is a common advantage is made into a thin film and device area is relatively large. In the thin film of the carbon nanotube, the carbon nanotube film directionally assembled caused great concern of people, because the directivity, high-density can be made into high-performance, of the device are good. In the chemical vapor deposition (CVD) in the process of synthesizing carbon nanotubes, using control air flow, the temperature gradient, and the field of single crystal quartz substrate has been able to produce the directional of a carbon nanotube array. Recently, large-scale preparation of Graphene has also made some significant progress, chemical reduction of the oxidized graphite can be through electrostatic action in stable dispersion in the aqueous solution. CVD method for directly synthesizing single-layer and several laminated Graphene transparent conductive thin film, progress has been obtained. For realizing these progress based on oriented carbon nanotube, graphene provide the possibility of the composite system. Because the photosensitive property of the semiconductor nano-particles, providing a conductive carbon nano-material and over leakage path and improve the mobility, carbon nano-material and semiconductor nano-particle composite system cause strong interest in the material. Covalent connection needs to oxidation treatment to the carbon nanotube, the carbon nanotube to sp2 the destruction of the structure, would seriously reduce the conductivity of the carbon nanotube. The nano-particles and a carbon nano-tube of non-covalently complexed and work is only limited to, synthetic, structure and optical performance characterization, initial stage. How to design and synthesis of carbon nano-material and semiconductor nano-particle non-covalent complex, the manufacturing model with high transformation efficiency photoelectric device, applied to the photovoltaic device and the medium not yet solve many problems. Directional assembling carbon nanotubes and nano crystal non-covalent composite system also not carried out. Chemical reduction of aqueous solution of preparation Graphene Graphene and CVD breakthrough only recently, semiconductor nano-particles and Graphene non-covalently bound, no progress in the preparation of the composite system. The semiconductor nano-particles realizing Graphene there are also the composite system to be solved in two mutually soluble in the solution of the problem of and interaction. How to improve the carbon nano material and semiconductor nano-particle interface geometry contact and energy matching in order to be able to provide more effective charge migration also to be considered. Realize field effect modulation carbon nano material to control the carbon nano material in the carrier concentration, the problem of carrier types are to be resolved. Content of the invention The purpose of this invention aims at providing a graphene with the semiconductor nano-particle composite system and method for synthesizing the same, in the two mutually soluble in the solution of the problem of and interaction, improve the graphene (or carbon nanometer materials) and semiconductor nano-particle interface geometry contact and energy matching, in order to provide more efficient charge migration. 1st purpose of this invention, will be realized through the following technical scheme: Graphene and semiconductor nano-particle composite system, characterized in that the composite system comprises a single-layer or multi-layer of the semiconductor nano-particles and graphite laminar , wherein the graphite flake layer size is between 20 nm -600 the m, the size of the semiconductor nano-particles is between 2 nm -100 nm, the semiconductor nanoparticles graphite laminar combined into covalent structure, non-covalent structure, or covalently with the non-covalent integrated structure. Furthermore, the aforesaid graphene and semiconductor nano-particle composite system, wherein the graphite laminar the reduction through chemical oxidation by the graphite powder having a hydroxyl group or carboxyl group of preparation of the dispersion of the graphene, or the thermal expansion of the graphite is graphite the cleavage inserts the levelalkene laminar , or carbon source under the catalysis of the metal film made of high-temperature decomposition of graphene thin film. Furthermore, the aforesaid graphene and semiconductor nano-particle composite system, wherein the used for chemical oxidation-reduction of the natural graphite powder comprises a graphite powder, flake graphite powder, artificial graphite powder and the expansion graphite powder; the intercalation of the cleavage for thermal expansion of the graphite comprises sulfuric acid intercalation graphite, intercalated graphite of sodium hydroxide, potassium hydroxide and alkali metal intercalation graphite graphite the potassium inserts the level ; under the catalysis of the metal film of the high-temperature decomposition of carbon source is a hydrocarbon, including CH4, C2 H2, phenyl-ethanol. Furthermore, the aforesaid graphene and semiconductor nano-particle composite system, wherein the semiconductor nano-particles have a π containing ligand of the key, the ligand is pyridine, pyrenebutyric, or a derivative of one of the two, or in the semiconductor nano-particles used for chemical modification with the graphene covalently bound amino. 2nd purpose of this invention, will be realized through the following technical scheme: Graphene and semiconductor nano-particle synthesis method of the composite system, characterized in that the semiconductor nano-particles containing pyridine of the key by π, pyrenebutyric, or a derivative of one of the two, in the solution in the graphene to carry out non-covalent composite. Wherein the semiconductor nanoparticles by chemical liquid phase synthesis, then with the pyridine, pyrenebutyric, or a derivative of one of the two, the ligand to the semiconductor nano-particles and a replacement. 2nd purpose of this invention, can also be realized through the following technical scheme: Graphene and semiconductor nano-particle synthesis method of the composite system, characterized in that in the stated graphite laminar through a chemical oxidation-reduction method on the modified hydroxy group or carboxyl, and the surface of the semiconductor nano-particles of amino-modified, by hydroxyl or carboxyl group is covalently bonded to the amino group, form graphene with the semiconductor nano-particle composite system. Graphene of this invention with the semiconductor nano-particles and the composite system application after the implementation of the method for synthesizing the same, can effectively improve the graphene and semiconductor nano-particle interface geometry contact and energy matching, provides graphene and semiconductor nano-particles feasible method for the synthesis of the composite system, based on the composite system of the industrial application of the photoelectric device to create the precondition. Description of drawings Figure 1 is the reduction-oxidation chemical preparation graphene and semiconductor nano-particles of the composite system non-covalent composite chemical equation; Figure 2 is the reduction-oxidation chemical preparation graphene and semiconductor nanoparticles covalently of the composite system composite chemical equation; Figure 3a is the reduction-oxidation chemical preparation graphene of scanning electronic micrograph; Figure 3b is the reduction-oxidation chemical preparation of graphene atomic force micrograph; Figure 4 is absorption spectrum of graphene of this invention the composite system of the semiconductor nano-particles; Figure 5 is a transmission electron microscope picture of graphene of this invention with the semiconductor nano-particle composite system. Mode of execution This invention has offered a kind of graphene and semiconductor nano-particle composite system and its synthetic method, which aims at solving the two mutually soluble in solution and interact with, improve the graphene (or carbon nanometer materials) and semiconductor nano-particle interface geometry contact and energy matching, in order to provide more efficient charge transporting property. On the whole, this compound system comprises a single-layer or multi-layer of the semiconductor nano-particles and graphite laminar , combined into covalent structure, non-covalent structure, or covalently with the non-covalent integrated structure. Wherein: The graphite flake layer size is between 20 nm -600 the m, graphite powder can be made by chemical oxidation-reduction preparation and having a hydroxyl or carboxyl dispersion graphene, can be obtained by thermal expansion of the graphite is graphite the cleavage inserts the levelalkene laminar , can also be a carbon source under the catalysis of the metal film made of high-temperature decomposition of graphene thin film. Moreover, the used for chemical oxidation-reduction of the natural graphite powder comprises a graphite powder, flake graphite powder, artificial graphite powder and the expansion graphite powder; the intercalation of the cleavage for thermal expansion of the graphite comprises sulfuric acid intercalation graphite, intercalated graphite of sodium hydroxide, potassium hydroxide and alkali metal intercalation graphite graphite the potassium inserts the level ; under the catalysis of the metal film of the high-temperature decomposition of hydrocarbon to carbon, including CH4, C2 H2, phenyl-ethanol, can also be a hydrocarbon, such as CO. The semiconductor nano-size of the particles is between 2 nm -100 nm, chromium-selenide (CdSe) can be adopted, tellurium chromium (CdTe), lead selenide (PbSe), lead telluride (PbTe), lead sulfide (PbS), chromium sulfide (CdS), zinc selenide (ZnSe), zinc sulfide (ZnS), zinc oxide (ZnO) and titanium oxide (TiO2), and the like. The semiconductor nano-particles have a π containing ligand of the key, the ligand may be pyridine, pyrenebutyric, or a derivative of one of the two, or chemically modified with the graphene covalently bound amino. To further facilitate understanding of the present invention synthetic method of the composite system, the following will be to chemical reduction oxidation method for preparing semiconductor nano particles of graphene and of the two synthetic embodiment and other method for preparing semiconductor nano particles of graphene and of a number of synthetic embodiment, detailed as follows: Embodiment 1 As shown in Figure 1 of the present invention prepared by oxidizing chemical reduction of graphene and semiconductor nano-particles of the composite system non-covalent composite chemical equation, can be understood as: through the concentrated sulfuric acid (1) graphite powder, high potassium sulfate, after oxidation of phosphorus pentoxide, using de-ion water washing to the neutral, and then through the concentrated sulfuric acid, potassium permanganate in-depth oxidation, by adding a large amount of deionized water and a certain amount of hydrogen peroxide to terminate the reaction, once again through deionized water washing to the neutral. The oxidation of the graphite. Oxidized graphite 1a after ultrasonic, reduction of hydrazine hydrate, ammonia water stable, single-layered graphene 1b (as shown in Figure 3a and Figure 3b shown, is the invention chemical reduction-oxidation graphite preparation graphene of scanning electronic microscope photographs and atomic force micrograph). Synthesis of (2) CdSe nano-particles, mainly adopts the chromium oxide, octadecyl phosphate (ODPA), (TOPO) is dissolved in three octyl phosphorus oxygenoctyl phosphorus with the selenium powder and then (TOP) is 280 the half-hour reaction under [...]. To obtain three is chromium selenide octyl phosphorus oxygen as ligand 2 (CdSe-TOPO). Selenylation chromium 2 to pyridine as ligand CdSe-TOPO is obtained by a non-water-pyridine in the 118 [...] , under the protection of nitrogen reaction 24 hours, the reaction product after hexane precipitation, further after centrifugation in the 65 [...] in pyridine as solvent reaction 1 hour, the process is repeated 3 times. Pyridine as ligand to chromium selenide 2a (CdSe-Py). Graphene and nano-particles obtained of the composite system, is to utilize the graphene of the six-membered ring in the key π π CdSe-Py pyridine in mutual role of the key. Main process after diluting the obtained graphite alkene, CdSe-Py the pyridine solution added at the same time, continuing to stir, graphene-nano particles obtained composite system 3. Embodiment 2 As shown in Figure 2 of the present invention prepared by oxidizing chemical reduction of graphene and semiconductor nano-particles of the composite system non-covalent composite chemical equation, it can be interpreted as a: graphite powder through the concentrated sulfuric acid, the high potassium sulfate, after oxidation of phosphorus pentoxide, using de-ion water washing to the neutral, and then through the concentrated sulfuric acid, potassium permanganate in-depth oxidation, by adding a large amount of deionized water and a certain amount of hydrogen peroxide to terminate the reaction, once again through deionized water washing to the neutral. The oxidation of the graphite. Graphite oxide after ultrasonic, reduction of hydrazine hydrate, ammonia water stable, having a hydroxyl or carboxyl group by a single graphene 1. Replacement by ligands, CdSe semiconductor nano-particles will be 2 using sulfur and amino 2b is connected, then the oxidized graphite preparation of chemical reduction of graphene mixed, through amino 2b and carboxyl dehydration reaction, graphene of preparing the semiconductor nanoparticles covalently composite system. Embodiment 3 Cleavage of thermal expansion of the graphite preparation the intercalation of graphene and semiconductor nano-particle non-covalent composite: Intercalation graphite cleavage graphite alkene laminar , which is characterized in that a micro nanometer level (100 nm -800 the m) natural, or flake graphite, and sulfuric acid or alkali are mixed and are put in the high-pressure reactor or flasks, in the 250 [...] -400 the intercalation between [...] , the reaction time is more than 36 hours, to form intercalated graphite material. After the mechanical polishing, the the 900-1800 between [...] , in under the conditions of high vacuum and hydrogen, for fast or slow thermal expansion, preparing the graphite alkene laminar. Then the pyridine of the key having a π, pyrenebutyric (Pyrene), or a derivative of one of the two semiconductor nano-particle to carry out non-covalent composite. Embodiment 4 Chemical vapor deposition process of preparing semiconductor nano-particles with the graphene of non-covalent composite: Graphene of chemical vapor deposition, chemical vapor deposition is characterized in that the preparation of the graphene thin film is a metal thin film (Fe, Ni, Co, Ag, cu) as the catalyst, its thin film can adopt the electron-beam evaporation, magnetron sputtering can also be used for preparing, growth first carries on annealing treatment. Hydrocarbon (CH4, C2 H2, ethanol, benzene) as the carbon source, high temperature (750 the the [...] -950 [...]) preparation of catalytic decomposition of graphene thin film. Then the pyridine of the key having a π, pyrenebutyric, or a derivative of one of the two semiconductor nano-particle to carry out non-covalent composite. Through the above-described synthesis of the embodiment of, graphene of this invention with the semiconductor nano-particle composite structure and of the composite system have been made by the method for synthesizing a comprehensive and detailed description. To prove it has remarkable progress of the nanometer material performance. As shown in Figure 4 and Figure 5, graphene and the present invention is semiconductor nanoparticle absorption spectrum of the composite system and transmission electron microscope chart , wherein the diagram 4 horizontal coordinate for the spectrum in wavelength, ordinate is the light absorptivity, the three coordinates from top to bottom the light absorptivity change curve, graphene and respectively representing semiconductor nano-particle optical absorption of the composite system, the light absorption of the pure graphite alkene, pure semiconductor nano-particle optical absorption. Figure 5 is the quantum dot (Figure of graphene and semiconductor nano-particle of the composite system transmission electron microscope chart , can clearly see the graphene is provided with a great amount of the densely black straight hairlines). From this it can be seen, the present invention can effectively improve the graphene (or carbon nanometer materials) and semiconductor nano-particle interface geometry contact and energy matching, provides the preparation graphene and semiconductor nano-particles effective method of the composite system, based on the composite system of the industrial application of the photoelectric device to create the precondition. The invention discloses a graphene and semiconductor nano particle compound system and a synthesizing method thereof in the field of nano materials. The compound system comprises a single or multiple graphite sheet layers and semiconductor nano particles, wherein the graphite sheet layers and the semiconductor nano particles are carried out noncovalent compounding with graphene in solution by pyridine, pyrene or a derivative containing a pi bond or hydroxyl or carboxyl is modified on the graphite sheet layers by a chemical oxidation reduction method, and the amino modification is carried out on the surface of the semiconductor nano particles; and the graphene and semiconductor nano particle compound system is formed by the covalent combination of the hydroxyl or carboxyl and amino. The invention can really improve the interface geometrical contact and energy matching of the graphene and the semiconductor nano particles and creates beneficial condition for the industrial application of a photoelectric device based on the compound system. 1. Graphene and semiconductor nano-particle composite system, characterized in that the composite system comprises a single-layer or multi-layer of the semiconductor nano-particles and graphite laminar , wherein the graphite flake layer size is between 20 nm -600 the m, the size of the semiconductor nano-particles is between 2 nm -100 nm, the semiconductor nanoparticles graphite laminar combined into covalent structure, non-covalent structure, or covalently with the non-covalent integrated structure. 2. Graphene and semiconductor nano-particle composite system according to Claim 1, characterized in that the stated graphite laminar is a chemical oxidation-reduction preparing the graphite powder having a hydroxyl or carboxyl group of the dispersion of the graphene, or the thermal expansion of the graphite is graphite the cleavage inserts the levelalkene laminar , or carbon source under the catalysis of the metal film made of high-temperature decomposition of graphene thin film. 3. Graphene and semiconductor nano-particles according to Claim 2 the composite system, characterized in that the means for chemical oxidation-reduction of the natural graphite powder comprises a graphite powder, flake graphite powder, artificial graphite powder and the expansion graphite powder. 4. Graphene and semiconductor nano-particles according to Claim 2 the composite system, characterized in that cleavage of thermal expansion for the intercalation of sulfuric acid intercalated graphite comprises graphite, intercalated graphite of sodium hydroxide, potassium hydroxide and alkali metal intercalation graphite graphite the potassium inserts the level. 5. Graphene and semiconductor nano-particles according to Claim 2 the composite system, characterized in that under the catalysis of the metal film of the high-temperature decomposition of carbon source is a hydrocarbon, including CH4, C2 H2, phenyl-ethanol. 6. Graphene and semiconductor nano-particle composite system according to Claim 1, characterized in that the semiconductor nano-particles have a π containing ligand of the key, the ligand is pyridine, pyrenebutyric, or a derivative of one of the two. 7. Graphene and semiconductor nano-particle composite system according to Claim 1, characterized in that the semiconductor nano-particles used for chemical modification with the graphene covalently bound amino. 8. Claim 1 the graphene and semiconductor nano-particle synthesis method of the composite system, characterized in that the semiconductor nano-particles containing pyridine of the key by π, pyrenebutyric, or a derivative of one of the two, in the solution in the graphene to carry out non-covalent composite. 9. Graphene and semiconductor nano-particle synthesis method of the composite system according to Claim 8, characterized in that the semiconductor nano-particle by chemical liquid phase synthesis, then with the pyridine, pyrenebutyric, or a derivative of one of the two, the ligand to the semiconductor nano-particle replacement. 10. Graphene and semiconductor nano-particle synthesis method of the composite system according to Claim 1, characterized in that in the stated graphite laminar through a chemical oxidation-reduction method on the modified hydroxy group or carboxyl, and the surface of the semiconductor nano-particles of amino-modified, by hydroxyl or carboxyl group is covalently bonded to the amino group, form graphene with the semiconductor nano-particle composite system.