TWI412638B - Method for making metal sulfide nano crystal - Google Patents

Abstract

The present invention relates to a method for making metal sulfide nano crystals. The method includes the following steps: providing some powder of metal salts disposed in a container; adding excessive mercaptan into the container and stirring uniformly; heating the container to a temperature of about 100 centigrade to about 300 centigrade, and a chemical reaction happens between the metal salt and the mercaptan for about 5 minutes to about 1 hour to form metal sulfide; adding a solvent and stirring uniformly, the metal sulfide nano crystals are formed after centrifugal dealt.

Description

Method for preparing metal sulfide nanocrystal

The invention relates to a method for preparing metal sulfide nanocrystals.

Metal sulfide nanocrystals are a very important semiconductor material, which has peculiar optical, electrical, magnetic, mechanical and positive catalytic properties due to its small size effect, surface and interface effects, quantum size effects, and macroscopic quantum tunneling effects. It has potential application value in many fields. Therefore, metal sulfide nanocrystals can be widely used in the fields of light-emitting diodes, solar cells, electric signal amplifiers, and bioluminescent labels. Therefore, the synthesis of metal sulfide nanocrystals has become a hot spot of extensive research.

At present, various experimental means have been used for preparing metal sulfide nanocrystals. For example, a hot injection method, a metal organic salt pyrolysis method, a metal organic salt pyrolysis-oxidation method, or the like. These methods generally require rapid injection of reactants at high temperatures and are carried out under the protection of an inert gas, and are expensive organic metal salts as raw materials, high in cost, complicated in operation, and unfavorable for industrial mass production.

In view of this, it is necessary to provide a method for preparing a metal sulfide nanocrystal which is simple in process, low in cost, and suitable for mass production.

A method for preparing a metal sulfide nanocrystal, comprising: providing a predetermined amount of a metal inorganic salt powder into a container; supplying an excess of mercaptan to the container and stirring uniformly; heating the container to 100 degrees Celsius to 300 ° C, the metal inorganic salt and mercaptan are reacted for 5 minutes to 1 hour to form metal sulfide nanocrystals; and a polar solvent is added, stirred uniformly, and then centrifuged to obtain Metal sulfide nanocrystals.

Compared with the prior art, the preparation method of the metal sulfide nanocrystal provided by the invention uses the metal inorganic salt as a raw material, the cost is low, the protective gas and the high temperature are not needed in the reaction process, the operation is simple, and the method is suitable for large-scale produce.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing a method for preparing a metal sulfide nanocrystal according to a first embodiment of the present invention.

Fig. 2 is a transmission electron micrograph of lead sulfide nanocrystals prepared in the first embodiment of the present invention.

Figure 3 is an X-ray diffraction (XRD) spectrum of the lead sulfide nanocrystal of Figure 2.

4 is a transmission electron micrograph of lead sulfide nanocrystals provided by a second embodiment of the present invention.

Figure 5 is a transmission electron micrograph of a cuprous sulfide nanocrystal prepared in accordance with a third embodiment of the present invention.

Figure 6 is an X-ray diffraction (XRD) spectrum of the cuprous sulfide nanocrystal of Figure 5.

Figure 7 is a transmission electron micrograph of lead sulfide nanocrystals prepared in accordance with a fourth embodiment of the present invention.

Figure 8 is a transmission electron micrograph of lead sulfide nanocrystals prepared in a fifth embodiment of the present invention.

Hereinafter, a method for preparing a metal sulfide nanocrystal of an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, the present invention provides a method for preparing a metal sulfide nanocrystal, which comprises the steps of: providing a predetermined amount of metal inorganic salt powder into a container; and S2: providing an excess of mercaptan. In the container, and stir evenly; S3: heating the container to 100 degrees Celsius to 300 degrees Celsius, reacting the metal inorganic salt with the mercaptan for 5 minutes to 1 hour; S4: adding a polar solvent, stirring uniformly, and centrifuging to obtain a metal sulfide nanocrystal.

In step S1, the metal in the metal inorganic salt is the same as the metal in the metal sulfide to be obtained. The metal inorganic salt may be a metal sulfate, acetate, nitrate, chloride or the like, such as silver nitrate, copper sulfate, copper chloride, lead acetate, ferrous sulfide or zinc sulfate. The amount of the metal inorganic salt powder is related to the amount of the metal sulfide nanocrystal to be obtained, and the molar ratio of the metal inorganic salt to the metal sulfide nanocrystal should be 1:1.

In step S2, the mercaptan should be in a liquid state at normal temperature, and generally it may be any one of octyl mercaptan to octadecyl mercaptan. The thiol should be in excess relative to the metal inorganic salt powder. If the valence state of the metal in the metal inorganic salt is +n, the molar ratio of the thiol to the metal inorganic salt should be greater than n. For example, if the metal inorganic salt is lead acetate, since the valence of lead in lead acetate is +2, the molar ratio of thiol to lead acetate should be greater than 2. Preferably, the molar ratio of thiol to metal inorganic salt is greater than or equal to 10 to ensure a sufficient excess of mercaptan. Further, other solvents such as octadecene, diphenyl ether, oleic acid, oleylamine, trioctylphosphine, trioctylphosphine oxide and the like may be heated after the addition of the mercaptan. The volume ratio of the thiol to other solvents may be 1:10 to 4:1. The stirring may be performed by mechanical stirring, magnetic stirring or ultrasonic vibration to uniformly disperse the metal inorganic salt in the mercaptan.

In step S3, the container can be placed on a heating furnace for direct heating. In the process of reacting the metal inorganic salt with the thiol, a metal thiolate intermediate is first formed, and the metal thiolate intermediate is further decomposed to form a metal sulfide under continuous heating. Since the mercaptan is in excess, an excess of mercaptan is encapsulated on the surface of the metal sulfide nucleus as a surfactant to prevent the metal sulfide nucleus from growing, thereby forming a nanoscale metal sulfide, ie, metal sulfide naphthalene. Mi Jing. This process will be done in one vessel and once under heating.

After the step S3, a step of cooling the liquid in the vessel to room temperature is further included.

In step S4, since the mercaptan is in excess, the surface of the metal sulfide nanocrystal is coated with a mercaptan, Therefore, the metal sulfide nanocrystals are hydrophobic. Therefore, after the polar solvent is added, the metal sulfide nanocrystals are not dispersed in the polar solvent, and the metal sulfide nanocrystals can be separated by centrifugation to achieve the purpose of washing the metal sulfide nanocrystals. It can be understood that in this step, the polar solvent can be added multiple times, and the metal sulfide nanocrystals are washed multiple times by multiple centrifugation processes to ensure relatively pure metal sulfide nanocrystals.

The change of reaction conditions has a great influence on the morphology, size and the like of the product. For example, the concentration of the metal inorganic salt in the mercaptan, the composition of the solvent, the reaction temperature, the reaction time, and the like. The invention is further illustrated by the following specific examples:

Embodiment 1:

In this embodiment, the metal inorganic salt is lead acetate, the mass is 0.4 g, the solvent is dodecyl mercaptan, the volume of dodecanol is 10 ml, and the molar ratio of dodecyl mercaptan to lead acetate is about 30. After the lead acetate powder was mixed with dodecyl mercaptan, it was stirred by magnetic stirring for 5 minutes. Since lead acetate is insoluble in dodecyl mercaptan, after stirring, the lead acetate powder is uniformly dispersed in dodecyl mercaptan to form a suspension. Then, after heating to 220 ° C and reacting dodecyl mercaptan with lead acetate, lead acetate and dodecanol form a lead thiolate, at which time a clear solution is formed. Then, heating is continued for another 10 minutes or so, and the lead thiolate is decomposed to form lead sulfide, and the solution becomes a suspension again. After cooling to room temperature, a polar solvent alcohol was added and washed three times to obtain a metal sulfide nanocrystal. 2 is a transmission electron micrograph of the lead sulfide nanocrystal obtained in the first embodiment. It can be seen from the photograph that the shape of the lead sulfide nanocrystal is a regular octahedron or a quadrangle, and the size is relatively uniform. The length is about 40 nm. The lead sulfide nanocrystals were subjected to an XRD test, and as a result, as shown in Fig. 3, it was found that the product was a lead sulfide having a high purity.

Embodiment 2:

In this embodiment, the metal inorganic salt is lead acetate, the mass of which is 1 gram, the solvent is dodecyl thiol, twelve The volume of the mercaptan is 10 ml, and the molar ratio of dodecyl mercaptan to lead acetate is about 12. Other conditions are the same as in the first embodiment. Please refer to FIG. 4 , which is a transmission electron micrograph of the lead sulfide nanocrystal obtained in the second embodiment. It can be seen from the photograph that the lead sulfide nanocrystals are all regular octahedrons, and the size is relatively uniform, and the hexagon is shaped. The side length is about 80 nm. From this, it can be seen that the larger the concentration of the metal inorganic salt in the mercaptan, the larger the size of the obtained metal sulfide nanocrystal.

Embodiment 3:

In this embodiment, the metal inorganic salt is copper acetate, the mass of which is 0.2 g, the solvent is dodecyl mercaptan, and the volume of dodecanol is 10 ml. Other conditions are the same as in the first embodiment. Referring to FIG. 5, a transmission electron micrograph of the copper acetate crystal obtained in the third embodiment, it can be seen from the photograph that the copper acetate crystals are both approximately circular and uniform in size. The copper acetate nanocrystals were subjected to an XRD test, and as a result, as shown in Fig. 6, it was found that the product was copper acetate having a high purity. It can be seen that by adding different metal inorganic salts, different metal sulfide nanocrystals can be obtained, and the size is also related to a specific metal inorganic salt.

Embodiment 4:

In this embodiment, the metal inorganic salt is lead acetate, the mass of which is 0.4 g, the solvent is dodecyl mercaptan and oleic acid, the volume of dodecanol is 8 ml, and the volume of oleic acid is 2 ml. Other conditions are the same as in the first embodiment. Referring to FIG. 7, which is a transmission electron micrograph of the lead sulfide nanocrystal obtained in the fourth embodiment, it can be seen from the photograph that the lead sulfide nanocrystals are all polyhedrons, and the size is relatively uniform, and the particle size is about 60 nm. Meter. It can be seen that the morphology of the metal sulfide nanocrystals can be changed by changing the addition of different solvents.

Embodiment 5:

In this embodiment, the metal inorganic salt is lead acetate, the mass of which is 0.4 g, the solvent is dodecyl mercaptan and oleic acid, the volume of dodecanol is 5 ml, the volume of oleic acid is 5 ml, and the reaction temperature is 240 degrees Celsius. . Other conditions are the same as in the fourth embodiment. Please refer to FIG. 8 , which is a transmission electron micrograph of the lead sulfide nanocrystal obtained in the fifth embodiment. It can be seen from the photograph that the lead sulfide nanocrystals are all cubes and the dimensions are relatively uniform, and the side length of the cube is approximately 40 nm. It can be seen that the morphology of the metal sulfide nanocrystals can also be changed by adjusting the amount of other solvent than the added mercaptan.

The preparation method of the metal sulfide nanocrystal provided by the invention takes the metal inorganic salt as a raw material, has low cost, does not need to use a shielding gas in the reaction process, is simple in operation, and is suitable for mass production.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

Claims (9)

A method for preparing a metal sulfide nanocrystal, comprising: providing a predetermined amount of a metal inorganic salt powder into a container; supplying an excess of mercaptan to the container and stirring uniformly; heating the container to 100 degrees Celsius to At 300 degrees Celsius, the metal inorganic salt and the thiol are reacted for 5 minutes to 1 hour to form a metal sulfide nanocrystal; and a polar solvent is added, stirred uniformly, and then centrifuged to obtain a metal sulfide nanocrystal. The method for producing a metal sulfide nanocrystal according to claim 1, wherein the metal inorganic salt is a metal sulfate, acetate, nitrate or chloride. The method for producing a metal sulfide nanocrystal according to claim 1, wherein a molar ratio of the mercaptan to the metal inorganic salt is 10 or more. The method for preparing a metal sulfide nanocrystal according to claim 1, wherein another solvent is further added after heating the mercaptan, and the other solvent comprises octadecene, diphenyl ether, oleic acid, oleylamine. , trioctylphosphine or trioctylphosphine oxide. The method for preparing a metal sulfide nanocrystal according to the fourth aspect of the invention, wherein the volume ratio of the mercaptan to the other solvent is 1:10 to 4:1. The method for producing a metal sulfide nanocrystal according to claim 1, wherein the thiol is any one of octyl mercaptan to octadecyl mercaptan. The method for producing a metal sulfide nanocrystal according to claim 1, wherein after the metal inorganic salt and the thiol are reacted, a step of cooling the container to room temperature is further included. The method for preparing a metal sulfide nanocrystal according to claim 1, wherein the stirring method comprises mechanical stirring, magnetic stirring or ultrasonic vibration. The method for preparing a metal sulfide nanocrystal according to claim 1, wherein the After adding a polar solvent and stirring uniformly, the step of centrifuging is repeated.