CN100553833C - The method for preparing metallic simple substance nano-crystal material - Google Patents

Abstract

The invention discloses a method for preparing metal elemental nanocrystal materials, which is suitable for the preparation of metal nanocrystal materials such as copper, silver, lead, palladium, tin, antimony and the like. It is synthesized by chemical reaction at normal pressure and 100-300°C with molten composite alkali metal hydroxide solvent. The raw materials used are soluble inorganic metal salts and zinc powder or iron powder. The cost of the synthesis process is low, and the reaction process Various parameters are easy to monitor and control, less environmental pollution, good uniformity of the reaction system, simple process, easy to scale up production; and the obtained metal crystals have good crystallization, clean surface, and uniform size, which is suitable for the study of their intrinsic properties And maximize the function of nanocrystalline materials. Metal nanocrystal materials Metal nanomaterials have the characteristics of metal, electrical and electronic properties, magnetism, chemical properties, thermal properties and luminescence, and are widely used in superconducting, chemical, medical, optical, electronic, electrical and other industries.

Description

Method for preparing metal elemental nanocrystal material

technical field

The invention relates to a preparation method of a nano crystal material, in particular to a method for preparing a simple metal nano material under low temperature and normal pressure conditions by using a composite alkali metal hydroxide solvent synthesis method.

Background technique

Metal elemental nanomaterials have metallic properties (such as high hardness, luster, opacity, easy heat transfer, good electrical conductor, etc.), electrical and electronic properties, magnetic properties, chemical properties, thermal properties, and luminescence, and are widely used in ultra- Guidance, chemical industry, medicine, optics, electronics, electrical appliances and other industries. Metallic silver can be used for biomarkers, sterilization, lubricants, catalysts, modification of plastics, rubber, coatings and paints, and plays an important role in the research fields of surface enhanced Raman spectroscopy, surface enhanced resonance scattering spectroscopy, molecular biology, supramolecular systems It has a very important position and has broad application prospects. Metallic lead has a relatively high life in many media, for example, lead is also quite stable in sulfuric acid and hydrochloric acid below 200 °C. Lead is also of great significance in military affairs. For example, lead is the base metal for making bullets and warheads, and it can make battery plates, etc. Lead has good absorption of X-rays and γ-rays and can be used in medical and nuclear industries. Lead has excellent running-in and self-lubricating properties, and is used in the manufacture of bearing alloys in military and civilian industries. Metal Sn is a soft metal with low shear strength and low melting point, which can be used as anti-friction and anti-wear materials. Moreover, compared with ordinary metal materials, nano-metal materials have many excellent properties. For example, experiments show that the melting point of 2nm Au is only 330°C, which is more than 700°C lower than the melting point of ordinary Au; while the melting point of nano-Ag powder is as low as 100°C. ℃; the heat capacity of nano-Pd (6nm, 80% theoretical density) is about 29%-54% higher than that of coarse crystal, and the thermal expansion coefficient of nano-crystalline Cu (8nm, 90% theoretical density) is more than 1 times higher than that of coarse crystal Cu. In the existing method for synthesizing simple metals, such as Chinese patent CN101024251, a method for preparing nanometer metals by a composite solvent method is disclosed. A chemically pure metal salt is dissolved in ethylene glycol to form a metal salt ethylene glycol solution, and the chemically pure poly Vinylpyrrolidone is dissolved in ethylene glycol to form polyvinylpyrrolidone ethylene glycol solution; ethylene glycol is put into the reaction vessel to heat and keep warm; the aforementioned metal salt ethylene glycol solution and polyvinylpyrrolidone ethylene glycol solution are passed through the syringe at the same time Slowly inject into the reaction container, and continue to heat the reaction solution after the injection is completed. The synthesis process of this method involves the mixing of multiple organic polar solvents, resulting in high synthesis costs and easy pollution to the environment. Liu Hong, Hu Chenguo and Wang Zhonglin reported in 2006 a method for the synthesis of complex oxides (Nano Letters, 6, 1535) by the composite alkali metal hydroxide medium method, which uses molten composite alkali metal hydroxide as the reaction Solvents, metal inorganic salts and oxides are used as reaction raw materials to synthesize complex oxides and other oxygen-containing compounds at low temperature and normal pressure. There is no report on the preparation of simple metal nanocrystals by the method of composite alkali metal hydroxide media.

Contents of the invention

The invention aims at the deficiency in the existing technique of synthesizing single metal nano crystal material, and provides a method for synthesizing simple metal nano crystal material by using compound alkali metal hydroxide solvent.

In order to achieve the above object, the present invention adopts sodium hydroxide and potassium hydroxide in the composite alkali metal hydroxide of melting as reaction solvent, reacts with chemically pure metal salt and zinc powder or iron powder reaction as the raw material of synthetic metal elemental nanocrystal material, Metal elemental nanoparticles and nanowires are obtained after chemical reaction. The present invention is prepared according to the following sequential steps:

Step 1, prepare reaction solvent, the solid sodium hydroxide that is 10～90% by weight is mixed evenly with the potassium hydroxide that is 10～90% by weight; The characteristic of this reaction solvent is solid at normal temperature, but is heated to It turns into a molten state at 100-300°C. Since the reaction solvent is a strong polar solution, many chemical reactions that can only occur with aqueous solutions or organic solvents at low temperature and high pressure can be achieved in this solvent only at low temperature and normal pressure. occur.

Step 2, preparation of reaction raw materials, optional 10-90% by weight of soluble metal salt powder containing one or two kinds of silver or palladium or copper or lead or antimony or tin, and 10-90% by weight of zinc Powder or iron powder are mixed to obtain reaction raw materials; metal soluble salts can be one of chloride salts, nitrates, sulfates, carbonates, and acetates.

Step 3, heating reaction, put the reaction raw materials with a weight percentage of 0.5% to 50% and the reaction solvent with a weight percentage of 50% to 99.5% together into the reaction container, cover and seal, and then put the reactant container into the already Heating to the heating equipment at 100-300°C, preheating and melting for 20-60 minutes, after the solid composite hydroxide in the reactor is completely melted, open the reaction vessel and stir with a stirrer to make the reactants in the molten state Evenly distribute in the reaction solvent, close the container again, and heat at a constant temperature at 100-300°C for 1-100 hours;

Step 4, cooling, cooling the reaction vessel after the constant temperature reaction to room temperature.

Step 5, washing, first dissolve the reaction product with cold or hot deionized water or a dilute acid with a pH value of 1 to 5, and then filter it with a centrifuge with a rotating speed of 1000 to 20000 rpm or with a suction filtration device, and then Redistribute the centrifuged or filtered product in cold or hot deionized water, ethanol, or dilute acid, and then repeat dehydration and washing for 3 to 5 times until the pH of the reaction product is neutral.

Then the crystal phase of the reaction product was identified by X-ray diffraction (XRD), and its shape and size were characterized by scanning electron microscope or transmission electron microscope.

The reaction container in the above step 3 is an organic polymer preparation container or a noble metal container that is inert to alkali metal hydroxide.

The heating equipment in the above-mentioned step 3 is a muffle furnace or a resistance furnace or an oven.

The present invention has following beneficial effects:

1. The cost is low. The composite hydroxide solvent method is used to synthesize metal single substance nanocrystal materials only need to be chemically synthesized under normal pressure, and the synthesis temperature is 100-300°C, and no high-pressure and high-temperature reaction system is required; moreover, the raw materials used are cheap Inorganic metal salt and zinc powder or iron powder, because it is a one-step synthesis, that is, the raw materials and reaction solvent are added to the reactor at one time and then placed in a constant temperature furnace for heating and reaction. The operation procedure is simple, the controllable parameters in the synthesis process are less, and the synthesis cost is low. .

2. Various parameters (temperature, pressure, etc.) in the reaction process are easy to monitor and control, which makes it easier for us to study the reaction mechanism, find out the most critical influencing factors, and provide a process basis for us to effectively control the grain size.

3. Less environmental pollution. Compared with other synthetic methods, because no surfactant or templating agent is introduced in the synthetic process of the present invention, pollution can be basically eliminated, which is beneficial to environmental protection.

4. The product is clean. Because no surfactant or template is introduced in the synthesis process of the present invention, the surface of the nanocrystalline material is clean, which is suitable for carrying out research on its intrinsic properties and maximizing the function of the nanocrystalline material, and it is also easy to carry out surface modification.

Description of drawings

Fig. 1 is the XRD of the copper nanostructure prepared in Example 1 of the present invention; Fig. 2 is the scanning electron micrograph of this copper nanostructure;

Fig. 3 is the XRD of the silver nanostructure that the embodiment of the present invention 2 prepares; Fig. 4 is the scanning electron micrograph of this silver nanostructure;

Fig. 5 is the XRD of the lead nanostructure prepared in Example 3 of the present invention; Fig. 6 is the scanning electron microscope image of the lead nanostructure;

FIG. 7 is the XRD of the tin nanostructure prepared in Example 4 of the present invention; FIG. 8 is the scanning electron microscope image of the tin nanostructure.

FIG. 9 is the XRD of the antimony nanostructure prepared in Example 5 of the present invention; FIG. 10 is the scanning electron microscope image of the antimony nanostructure.

Figure 11 is the XRD of the palladium nanostructure prepared in Example 6 of the present invention; Figure 12 is the scanning electron microscope image of the palladium nanostructure.

Detailed ways

Example 1:

The specific synthetic method of copper nanocrystal material

The raw materials for synthesizing copper nanocrystalline materials are KOH, NaOH, copper chloride (CuCl ₂ .2H ₂ O), and iron powder, and the step-by-step reactions that occur are as follows:

(a) CuCl ₂ .2H ₂ O→Cu ⁺ +2Cl ^- +2H ₂ O

(b) Fe+2NaOH→FeO+H ₂ +Na ₂ O

(c)H ₂ +Cu ²⁺ +2OH ^- →Cu+2H ₂ O

The specific operation steps are as follows:

Step 1. KOH=57% and NaOH=43% are weighed and mixed according to the weight percentage as the reaction solvent.

Step 2: Weight percentage of copper chloride (CuCl ₂ .2H ₂ O) = 23% and weight percentage of zinc powder = 77% were weighed as reactants. The weight percent of reactants to reactants+reaction solvent was 8.1%.

Step 3, put the reaction raw materials of the above step 2 and the reaction solvent in the above step 1 into a polytetrafluoroethylene reaction container, the weight percentage of the reactant is 8.1%, then the polytetrafluoroethylene container is sealed and put into the temperature Inside a constant temperature muffle furnace at 200°C. After the reaction vessel is kept warm in the furnace for 40 minutes, the reaction vessel is opened and stirred to uniformly mix the molten reaction solvent and the reactants. The reaction vessel was sealed again with a cover, and kept at a constant temperature of 200° C. for 16 hours.

Step 4, the reaction vessel is taken out from the muffle furnace, and naturally cooled to room temperature.

Step 5, dissolving the reaction product with deionized water; separating and washing with a centrifuge to obtain nano-metal copper. Repeat the above steps 5-10 times until the pH value of the reaction product is neutral.

As shown in Figure 1, X-ray diffraction (XRD) result, it shows that synthetic product is the copper of single-phase cubic crystal structure; As shown in Figure 2, scanning electron microscope observation shows, copper crystal width is 50 nanometers to 200 nanometers, Wire-like structures with a length of 2 microns to 5 microns.

Example 2:

Synthesis of silver nanocrystal structures

The raw materials for synthesizing silver nanocrystal materials are KOH, NaOH, silver nitrate (AgNO ₃ ), zinc powder, and the step-by-step reactions that take place are as follows:

(a)AgNO ₃ →Ag ⁺ +NO ₃ ^-

(b)Zn+2NaOH→ZnO+H ₂ +Na ₂ O

(c)H ₂ +2Ag ⁺ +2OH ^- →2Ag+2H ₂ O

The specific operation steps are as follows:

Step 1. KOH=57% and NaOH=43% are weighed and mixed according to the weight percentage as the reaction solvent.

Step 2, weight percentage of silver nitrate (AgNO ₃ ) = 72.2%, and weight percentage of zinc = 27.8% were weighed as reactants.

Step 3, put the reaction raw materials in the above step 2 and the reaction solvent in the above step 1 into a polytetrafluoroethylene reaction container, the weight percentage of the reactant is 4.6%, then the polytetrafluoroethylene container is sealed and put into the temperature Inside a constant temperature muffle furnace at 200°C. After the reaction vessel is kept warm in the furnace for 40 minutes, the reaction vessel is opened and stirred to uniformly mix the molten reaction solvent and the reactants. The reaction vessel was sealed again with a cover, and kept at a constant temperature of 200° C. for 6 hours.

Step 4, the reaction vessel is taken out from the muffle furnace, and naturally cooled to room temperature.

Step 5, dissolving the reaction product with deionized water; separating and washing with a centrifuge to obtain nano-metallic silver. Repeat the above steps 5-10 times until the pH value of the reaction product is neutral.

As shown in Figure 3, the X-ray diffraction results show that the obtained powder is silver with a single-phase cubic crystal structure; as shown in Figure 4, scanning electron microscopic observation shows that the silver crystal is a granular structure with a size of 50-100 nanometers.

Example 3:

Synthetic method of lead (Pb) nanocrystal material

The raw materials for synthesizing lead nanocrystal materials are KOH, NaOH, lead nitrate (Pb(NO ₃ ) ₂ ), zinc powder, and the step-by-step reactions that take place are as follows:

(a)Pb(NO ₃ ) ₂ →Pb ²⁺ +2NO ₃ ^-

(b) Zn+2NaOH→ZnO+H ₂ +Na ₂ O

(c)H ₂ +Pb ²⁺ +2OH ^- →Pb+2H ₂ O

The specific operation steps are as follows:

Step 1. KOH=57% and NaOH=43% are weighed and mixed according to the weight percentage as the reaction solvent.

Step 2. Weighing as reactants according to lead nitrate (Pb(NO ₃ ) ₂ ) weight percentage = 42%, zinc weight percentage = 58%.

Step 3, put the reaction raw materials in the above step 2 and the reaction solvent in the above step 1 into a polytetrafluoroethylene reaction container, the weight percentage of the reactant is 4.1%, then the polytetrafluoroethylene container is covered and closed and put into the temperature Inside a constant temperature muffle furnace at 200°C. After the reaction vessel is kept warm in the furnace for 40 minutes, the reaction vessel is opened and stirred to uniformly mix the molten reaction solvent and the reactants. The reaction vessel was sealed again with a cover, and kept at a constant temperature of 200° C. for 16 hours.

Step 4, the reaction vessel is taken out from the muffle furnace, and naturally cooled to room temperature.

Step 5, dissolving the reaction product with deionized water; separating and washing with a centrifuge to obtain nano-metal lead. Repeat the above steps 5-10 times until the pH value of the reaction product is neutral.

As shown in Figure 5, X-ray diffraction results show that the obtained powder is lead with a single-phase cubic crystal structure; as shown in Figure 6, scanning electron microscope observation shows that the lead crystal width is 500 nanometers to 5 microns, and the length is several 10 microns rod-like structure.

Example 4:

Synthetic method of tin nanocrystal material

The raw materials for synthesizing tin nanocrystals are KOH, NaOH, tin chloride (SnCl ₂ .2H ₂ O), and zinc powder, and the step-by-step reactions that take place are as follows:

(a) SnCl ₂ .2H ₂ O→Sn ²⁺ +2Cl ^- +2H ₂ O

(b) Zn+2NaOH→ZnO+H ₂ +Na ₂ O

(c)H ₂ +Sn ²⁺ +2OH ^- →Sn+2H ₂ O

The specific operation steps are as follows:

Step 1. KOH=57% and NaOH=43% are weighed and mixed according to the weight percentage as the reaction solvent.

Step 2. Weighing as reactants according to tin chloride (SnCl ₂ .2H ₂ O) weight percentage = 77.7%, zinc weight percentage = 22.3%. The weight percent of reactant to reactant+reaction solvent was 5.2%.

Step 3. Put the reaction raw materials in the above step 2 and the reaction solvent in the above step 1 into a polytetrafluoroethylene reaction container, then cover and seal the polytetrafluoroethylene container and place it in a constant temperature muffle furnace with a temperature of 200°C . After the reaction vessel is kept warm in the furnace for 40 minutes, the reaction vessel is opened and stirred to uniformly mix the molten reaction solvent and the reactants. The reaction vessel was sealed again with a cover, and kept at a constant temperature of 200° C. for 6 hours.

Step 4, the reaction vessel is taken out from the muffle furnace, and naturally cooled to room temperature.

Step 5, dissolving the reaction product with deionized water; separating and washing with a centrifuge to obtain nano-metal tin. Repeat the above steps 5-10 times until the pH value of the reaction product is neutral.

As shown in Figure 7, X-ray diffraction results show that the obtained powder is tin with a single-phase cubic crystal structure; as shown in Figure 8, scanning electron microscope observation shows that the tin crystal is a cubic particle structure of 2 to 3 microns.

Example 5:

Synthesis method of antimony nanocrystal structure

The raw materials for synthesizing antimony nanocrystalline materials are KOH, NaOH, antimony chloride (SbCl ₃ ), and zinc powder, and the step-by-step reactions that occur are as follows:

(a) SbCl ₃ →Sb ³⁺ +3Cl ^-

(b) Zn+2NaOH→ZnO+H ₂ +Na ₂ O

(c)3H ₂ +2Sb ³⁺ +6OH ^- → 2Sb+6H ₂ O

The specific operation steps are as follows:

Step 1. KOH=57% and NaOH=43% are weighed and mixed according to the weight percentage as the reaction solvent.

Step 2, weighing antimony chloride (SbCl ₃ ) weight percent = 68.2%, zinc weight percent = 31.8% as reactants.

Step 3, put the reaction raw materials in the above step 2 and the reaction solvent in the above step 1 into a polytetrafluoroethylene reaction container, the weight percentage of the reactant is 5.8%, then the polytetrafluoroethylene container is sealed and put into the temperature Inside a constant temperature muffle furnace at 200°C. After the reaction vessel is kept warm in the furnace for 40 minutes, the reaction vessel is opened and stirred to uniformly mix the molten reaction solvent and the reactants. The reaction vessel was sealed again with a cover, and kept at a constant temperature of 200° C. for 24 hours.

Step 4, the reaction vessel is taken out from the muffle furnace, and naturally cooled to room temperature.

Step 5, dissolving the reaction product with deionized water; separating and washing with a centrifuge to obtain nano-metal antimony. Repeat the above steps 5-10 times until the pH value of the reaction product is neutral.

As shown in Figure 9, the X-ray diffraction results show that the obtained powder is antimony in a single-phase trigonal crystal system; as shown in Figure 10, scanning and transmission electron microscopic observations show that the antimony crystal is a sheet structure with a thickness of 10 to 20 nanometers .

Embodiment 6:

Synthesis of palladium nanocrystal structures

The raw materials for synthesizing palladium nanocrystal materials are KOH, NaOH, palladium (Pd(NO ₃ ) ₂ .2H ₂ O), and zinc powder, and the step-by-step reactions that take place are as follows:

(d)Pd(NO ₃ ) ₂ .2H ₂ O→Pd ²⁺ +2NO ₃ ^- +2H ₂ O

(e)Zn+2NaOH→ZnO+H ₂ +Na ₂ O

(f)H ₂ +Pd ²⁺ +2OH ^- →Pd+2H ₂ O

The specific operation steps are as follows:

Step 1. KOH=57% and NaOH=43% are weighed and mixed according to the weight percentage as the reaction solvent.

Step 2. Weighing as reactants according to palladium nitrate (Pd(NO ₃ ) ₂ .2H ₂ O) weight percentage = 80.3%, zinc (Zn) weight percentage = 19.7%.

Step 3, the reaction raw material of above-mentioned step 2 and the reaction solvent in above-mentioned step 1 are placed in polytetrafluoroethylene reaction vessel, the weight percent of the weight of reactant and reactant+reaction solvent is 3.4%, then polytetrafluoroethylene The ethylene container was sealed with a cover and placed in a constant temperature muffle furnace at a temperature of 200°C. After the reaction vessel is kept warm in the furnace for 40 minutes, the reaction vessel is opened and stirred to uniformly mix the molten reaction solvent and the reactants. The reaction vessel was sealed again with a cover, and kept at a constant temperature of 200° C. for 24 hours.

Step 4, the reaction vessel is taken out from the muffle furnace, and naturally cooled to room temperature.

Step 5, dissolving the reaction product with deionized water; separating and washing with a centrifuge to obtain nano metal palladium. Repeat the above steps 5-10 times until the pH value of the reaction product is neutral.

As shown in Figure 11, X-ray diffraction results show that the obtained powder is palladium with a single-phase hexagonal structure; as shown in Figure 12, scanning electron microscope microscopic observation shows that the palladium crystal has a structure of 10 to 40 nanometer particles.

Claims (3)

1. A method for preparing metal elemental nanocrystal material, is characterized in that: comprise the following steps: Step 1, preparing a reaction solvent, uniformly mixing 10-90% by weight of solid sodium hydroxide and 10-90% by weight of potassium hydroxide; Step 2, preparation of reaction raw materials, 10-90% by weight of soluble metal salt powder containing any one or two of silver or palladium or copper or lead or antimony or tin, and 10-90% by weight of zinc Powder or iron powder is mixed to obtain the reaction raw materials; Step 3, heating reaction, put the reaction raw materials of step 2 with a weight percentage of 0.5% to 50% and the reaction solvent of step 1 with a weight percentage of 50% to 99.5% together into a reaction container, cover and seal, and then put Put the reactant container into the heating equipment that has been heated to 100-300°C, and preheat and melt for 20-60 minutes. After the solid composite hydroxide in the reactor is completely melted, open the reaction container and stir it with a stirrer. Make the reactants evenly distributed in the molten reaction solvent, close the container again, and heat at a constant temperature at 100-300°C for 1-100 hours; Step 4, cooling, the reaction vessel after constant temperature reaction is cooled to room temperature; Step 5, washing, first dissolve the reaction product with cold or hot deionized water or a dilute acid with a pH value of 1 to 5, then centrifuge with a centrifuge at a speed of 1000 to 20000 rpm, or use suction filtration The equipment is filtered, and then the centrifuged or filtered product is redispersed in cold or hot deionized water, ethanol, or dilute acid, and then repeated dehydration and cleaning 3 to 5 times until the pH of the reaction product is neutral. 2. The method for preparing metal elemental nanocrystalline materials according to claim 1, characterized in that: the reaction container in the step 3 is an organic polymer preparation container or a precious metal container that is inert to alkali metal hydroxides. 3. The method for preparing metal elemental nanocrystalline material according to claim 1, characterized in that: the heating equipment in the step 3 is a muffle furnace or a resistance furnace or an oven.

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