Preparation method of two-dimensional amorphous Pt nano-sieve
Technical Field
The invention belongs to the technical field of preparation of two-dimensional metal materials, and particularly relates to a preparation method of a two-dimensional amorphous Pt nano-sieve.
Background
In recent years, two-dimensional nanomaterials have attracted extensive attention of researchers because they exhibit many unique physicochemical properties due to their quantum effects, small-size effects, surface effects, and macroscopic quantum tunneling effects. The noble metal nano material has potential application value in the fields of catalysis, electrochemistry, new energy, medicine, optics and the like due to the surface plasma effect, the quantum effect and the biocompatibility of the noble metal nano material. However, the scarcity of noble metals and their expensive price greatly hinders their widespread use. The performance of the noble metal nano material is closely related to the shape, the size and the shape of the noble metal nano material, so that the size and the shape of the noble metal nano material can be controlled to synthesize the noble metal nano material and the performance research of the noble metal nano material is a research hotspot in the field of the nano material at present. For non-layered materials represented by metals, the non-directionality of metal bonds causes metal atoms to be closely packed in three dimensions in space, and the intrinsic driving force of two-dimensional anisotropic growth is lacked. Thus, efficient, controllable preparation of two-dimensional metal nanomaterials is currently still a challenging topic.
The two-dimensional amorphous metal nanosheets have unique properties due to asymmetry of long-range rotation and translation and disorder of atomic arrangement. For example, the surface of the two-dimensional amorphous material has a large number of randomly oriented bonds, so that the two-dimensional amorphous material has abundant defects and coordination unsaturated sites, and has better catalytic performance than a crystalline material. In addition, the method for manufacturing the nanometer-sized holes in the two-dimensional metal material can effectively improve the specific surface area and the number of active sites of the material, so that the material has a good mass transfer effect, and the excellent electrocatalysis performance is shown. However, the noble metal nanomaterials synthesized by the conventional methods are generally crystalline due to the strong isotropy of the metal bonds. Therefore, the synthesis of two-dimensional amorphous noble metal nanomaterials with precisely controllable elemental composition, material size and morphology remains a significant challenge.
Disclosure of Invention
The invention overcomes the defects of the prior art, successfully prepares the two-dimensional amorphous Pt nano-sieve, overcomes the defects of the element composition, the size and the shape of the noble metal nano-material synthesized by the traditional method, and aims to improve the performance of the electrocatalyst of the two-dimensional amorphous metal nano-plate.
The invention is realized by the following technical scheme.
A preparation method of a two-dimensional amorphous Pt nano-sieve specifically comprises the following steps:
a) mixing Pt (acac)2、Co(acac)3Adding NaBr and the mixture into an ethanol solution, and stirring the mixture at room temperature until the mixture is fully mixed and dissolved;
b) drying the mixed solution to obtain a light yellow solid product;
c) grinding the light yellow solid product into powder, and carrying out heating annealing in a tube furnace;
d) cleaning and drying the heat-treated product to obtain a product expressed as Pt/Co NSs;
e) and (3) putting the Pt/Co NSs into concentrated nitric acid for soaking and corroding, and then cleaning and drying to obtain the a-Pt NMs.
Preferably, the volume ratio of the absolute ethyl alcohol to the ultrapure water in the ethanol solution used in the step a is 6: 1.
Preferably, Pt (acac)2、Co(acac)3The molar weight x/y/z ratio of the NaBr to the NaBr is 1:0.01-1: 1-100.
Preferably, the stirring and mixing time of the step a is 8-12 h.
Preferably, the step b is to dry the mixed solution in an oven, wherein the oven temperature is 40-80 ℃.
Preferably, the grinding time in the step c is 0.5 to 1 hour.
Preferably, the heating annealing in the step c is carried out at the temperature of 150 ℃ and 300 ℃ for 1-3 h in an air atmosphere, and the temperature rise rate is 5 ℃/h.
Preferably, the water used for washing in steps d and e is deionized water, and the drying manner is freeze drying.
Preferably, the soaking corrosion time in the step e is 0.5 to 12 hours.
Compared with the prior art, the invention has the following beneficial effects:
the a-Pt NMs synthesized by the method can be used for fuel cells and high-efficiency electrocatalysts in the electrochemical water decomposition process. Compared with the prior art, the amorphous structure in the ultrathin two-dimensional amorphous porous nano structure enables the material to have rich defects and coordinated unsaturated positions, so that the local electronic environment can be adjusted, and the catalytic performance superior to that of a crystalline material is provided. On the other hand, the unique porous structure of the two-dimensional nanosieve allows the material to have a large specific surface area, which can provide more "space" for charge transport and mass transfer, while having many defect atoms (i.e., edge sites) around the pores with high reactivity, which can improve electrocatalytic activity. In conclusion, the advantages of the two are combined, so that the prepared two-dimensional amorphous Pt nano-sieve has excellent electrocatalysis application prospect. The method has high yield and easy operation, and is favorable for further scientific research, popularization and application of the two-dimensional amorphous noble metal nano material.
Drawings
FIG. 1 is a scanning electron microscope image of the Pt/Co NSs prepared in example 1.
FIG. 2 is a transmission electron microscope image of the Pt/Co NSs prepared in example 1.
FIG. 3 is a selected area diffraction pattern of the Pt/Co NSs prepared in example 1.
FIG. 4 is a transmission electron microscope image of a-Pt NMs prepared in example 1.
FIG. 5 is a selected area diffraction pattern of a-Pt NMs prepared in example 1.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention is described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.
Example 1
A two-dimensional amorphous Pt nano-sieve: the preparation method of the a-Pt NMs comprises the following steps:
first 8 mg Pt (acac)2、0.5mg Co(acac)3The resulting solution was stirred with 10 mg NaBr in 7 mL of ethanol at room temperature for 12 hours. In the ethanol solution, the volume ratio of ethanol to deionized water is 6: 1.
Then, the above solution was transferred to an oven to be dried at 60 ℃ to obtain a pale yellow solid product. And grinding the dried product into powder, heating to 230 ℃ in a tube furnace at the speed of 5 ℃/min, preserving heat for 1.5 h, and naturally cooling to room temperature. Wherein the gas atmosphere is air. The product Pt/Co NSs is obtained. And (3) immersing Pt/Co NSs into concentrated nitric acid to corrode for 3 h, washing a sample by using deionized water, and freeze-drying to obtain a product a-Pt NMs.
FIG. 1 is a scanning electron microscope image of the Pt/Co NSs prepared in example 1, from which it can be seen that the sample prepared in example 1 is nanosheet in morphology.
FIG. 2 is a TEM image of the Pt/Co NSs prepared in example 1, and it can be seen that the sample morphology obtained in example 1 is nanosheet, consistent with the scanning results.
FIG. 3 is a selected area diffraction pattern of the Pt/Co NSs prepared in example 1, from which it can be seen that the resulting Pt/Co NSs are polycrystalline structures.
FIG. 4 is a TEM image of a-Pt NMs prepared in example 1, and it can be seen that the prepared sample has a porous structure.
FIG. 5 is a diffraction pattern of selected areas of a-Pt NMs prepared in example 1, from which it can be seen that the resulting sample is amorphous.
As can be clearly seen from the above graph, the ultrathin two-dimensional amorphous porous nanostructure of the present embodiment not only has a large specific surface area, but also has excellent charge transport capacity and a large number of active sites, so that the prepared two-dimensional amorphous Pt nanosieve has excellent electrocatalytic performance.
Example 2
The preparation of the a-Pt NMs comprises the following steps:
first 8 mg Pt (acac)2、4 mg Co(acac)3The resulting solution was stirred with 15 mg of NaBr in 14 mL of ethanol at room temperature for 12 hours. In the ethanol solution, the volume ratio of ethanol to deionized water is 6: 1.
Then, the above solution was transferred to an oven to be dried at 60 ℃ to obtain a pale yellow solid product. And grinding the dried product into powder, heating to 230 ℃ in a tube furnace at the speed of 5 ℃/min, preserving heat for 1.5 h, and naturally cooling to room temperature. Wherein the gas atmosphere is air. The product Pt/Co NSs is obtained. And (3) immersing Pt/Co NSs into concentrated nitric acid to corrode for 3 h, washing a sample by using deionized water, and freeze-drying to obtain a product a-Pt NMs.
Example 3
The preparation of the a-Pt NMs comprises the following steps:
first 8 mg Pt (acac)2、0.5 mg Co(acac)3The resulting solution was stirred with 10 mg NaBr in 7 mL of ethanol at room temperature for 12 hours. In the ethanol solution, the volume ratio of ethanol to deionized water is 6: 1.
Then, the above solution was transferred to an oven to be dried at 60 ℃ to obtain a pale yellow solid product. And grinding the dried product into powder, heating to 230 ℃ in a tube furnace at the speed of 5 ℃/min, preserving heat for 3 h, and naturally cooling to room temperature. Wherein the gas atmosphere is air. The product Pt/Co NSs is obtained. And (3) immersing Pt/Co NSs into concentrated nitric acid to corrode for 3 h, washing a sample by using deionized water, and freeze-drying to obtain a product a-Pt NMs.
While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.