CN115652260A - Preparation method of monatomic germanium and few-atom cluster - Google Patents
Preparation method of monatomic germanium and few-atom cluster Download PDFInfo
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Abstract
The invention discloses a preparation method of a monatomic germanium and few-atom cluster, which comprises the following steps: (1) Performing sputtering and heating cycle treatment on the single crystal substrate in an ultrahigh vacuum environment to obtain a clean and flat surface; (2) Evaporating and depositing bismuth atoms on the clean and flat surface obtained in the step (1) in an ultrahigh vacuum environment to obtain a two-dimensional ordered periodic hole film; (3) And (3) evaporating and depositing germanium atoms on the two-dimensional ordered periodic hole film obtained in the step (2) in an ultrahigh vacuum environment, and simultaneously keeping the growth temperature and fully diffusing to obtain the monoatomic germanium distributed in a honeycomb shape and the germanium clusters distributed in a triangular lattice shape. The invention can grow high-quality monatomic germanium and few-atom germanium clusters, and presents two-dimensional order, monatomic germanium is in honeycomb arrangement, and few-atom clusters are in triangular lattice arrangement.
Description
Technical Field
The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a monatomic germanium and small-atom cluster.
Background
Catalysis is an important research area in science and engineering. When the catalyst size is reduced to single atoms and clusters containing only a few atoms, the significant electronic structural changes brought about by quantum size effects can result in single atom catalysts and atomic cluster catalysts exhibiting activities, selectivities and stabilities that differ from those of conventional nanocatalysts. The research of the material not only provides an ideal model and a research platform for understanding the mechanism of catalytic reaction from a molecular (atomic) level, but also is expected to become a novel catalyst with industrial catalytic application potential.
On the one hand, the noble metal catalyst is not suitable for large-scale industrial application due to high cost. Other high efficiency catalysts that are relatively abundant and inexpensive are of concern. For example, diatomic iron-nickel alloy is used for efficient hydrogen evolution, and a ruthenium monoatomic alloy catalyst is used for an efficient oxygen evolution catalyst, so that industrialization of hydrogen production by water electrolysis is promoted. Monatomic iron is also used in hydrogen fuel cells. On the other hand, from the viewpoint of preparing a monatomic catalyst and an atomic cluster catalyst, the realization of dispersed monatomic or small atomic clusters can be realized only under the condition of low metal loading, which affects the large-area preparation of the catalyst and greatly limits the catalytic efficiency. Meanwhile, the increase of metal loading can lead metal atoms to be aggregated into larger nano particles, so that the catalytic effect of single-atom catalysis and atom cluster is not achieved. To achieve high loading of single atoms and clusters requires careful design of the support surface, providing both good binding sites to anchor the metal atoms and blocking regions to limit the formation of metal nanoparticles.
Germanium, which is located in the fourth main group of the periodic table, is relatively abundant in the earth's crust and has exhibited excellent catalytic properties in catalyzing polyester production, PET polycondensation, and synthesizing diamond. However, the experimental preparation method of the monatomic germanium, particularly the monatomic germanium with two-dimensional order and high surface density and the monatomic germanium cluster, has no related report so far, and greatly limits the further research on the catalytic property of the monatomic germanium. As a novel monatomic material, the obtainment of monatomic germanium and few-atom germanium clusters with two-dimensional order is a precondition and condition for the research and practical application of the catalytic properties of the monatomic germanium and few-atom germanium clusters. Therefore, it is important to find a method for preparing high-quality monatomic germanium and low-atomic germanium clusters.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a preparation method of a monatomic germanium and a few-atom cluster, which can grow the high-quality monatomic germanium and the few-atom germanium cluster and is represented as two-dimensional order, wherein the monatomic germanium is arranged in a honeycomb manner and the few-atom cluster is arranged in a triangular lattice manner.
In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows: the preparation method of the monatomic germanium and few-atom cluster is provided, and comprises the following steps:
(1) Performing sputtering and heating cycle treatment on the single crystal substrate in an ultrahigh vacuum environment to obtain a clean and flat surface;
(2) In an ultrahigh vacuum environment, evaporating and depositing bismuth atoms on the clean and flat surface obtained in the step (1) to obtain a two-dimensional ordered periodic hole film;
(3) And (3) evaporating and depositing germanium atoms on the two-dimensional ordered periodic hole film obtained in the step (2) in an ultrahigh vacuum environment, and simultaneously keeping the growth temperature and fully diffusing to obtain the monoatomic germanium distributed in a honeycomb shape and the germanium clusters distributed in a triangular lattice shape.
Further, in the step (1), the degree of vacuum was 10 -5 mabr, performing argon ion sputtering on the surface of gold (111), heating for circulation, wherein each sputtering is performed for 20-30min, and the heating is performed at 500 ℃ for 30min, and the circulation is performed for 3-5 times.
Further, in steps (2) and (3), bismuth atoms and germanium atoms are deposited on the substrate by thermal resistance heating evaporation.
Further, in the step (2), the degree of vacuum is 10 -10 mabr with bismuth atom purity of 99.999%, and depositing at 0.01-0.02ML/min evaporation rate and 25-28 deg.C for 60-70min.
Further, the solution was deposited at an evaporation rate of 0.01ML/min and a temperature of 27 ℃ for 10min.
Further, in the step (3), the degree of vacuum is 10 -10 mabr with a germanium atom purity of 99.999% deposited at an evaporation rate of 0.01-0.02ML/min and at a temperature of 25-28 deg.C for 10-15min.
Further, the deposition was carried out at an evaporation rate of 0.01ML/min and a temperature of 27 ℃ for 10min.
Further, in the step (3), the growth temperature was 27 ℃.
Furthermore, in the honeycomb-shaped distribution of the monatomic germanium and the triangular lattice distribution of the germanium cluster, the interval of the periodic structures of the honeycomb-shaped distribution of the monatomic germanium and the triangular lattice distribution of the germanium cluster is 3.48nm.
In summary, the invention has the following advantages:
according to the invention, through ultrahigh vacuum deposition, the monoatomic layer bismuth film with two-dimensional ordered periodic holes covered on the gold surface is used as a growth sheet, high-quality monoatomic germanium and few-atomic germanium clusters are grown, the monoatomic germanium is in honeycomb arrangement and the few-atomic clusters are in triangular lattice arrangement and are expanded in a two-dimensional plane. The pores on the surface of the growth template provide effective limited space for the growth of the atomic germanium clusters, balance the interaction of germanium atoms and germanium atoms, germanium atoms and substrate gold atoms, and germanium atoms and substrate bismuth atoms, finally form stable clusters with few atoms, show abundant surface electronic states, and provide a foundation for potential catalytic application of the clusters. In addition, the aggregation of the monatomic germanium to the small-atom cluster is blocked by the hole-hole potential barrier, so that a site for stabilizing the monatomic germanium is provided, and the formation of germanium nanoparticles is avoided; and the hole structure of the template is two-dimensional ordered, so that the grown monoatomic germanium and few-atomic germanium clusters are two-dimensional ordered. The ordered high surface density monatomic germanium and the germanium cluster with few atoms lay a foundation for the research of the electronic property and the catalytic property based on germanium elements and the development of related devices. Meanwhile, due to the abundant surface electronic state, the preparation method is simple, the raw materials are easy to obtain, and the method has great application potential for the design and manufacture of novel catalysts.
Drawings
FIG. 1 is a schematic diagram of a preparation process of the present invention;
FIG. 2 is a scanning tunneling microscope image of the honeycomb distribution of monatomic germanium and the triangular lattice distribution of germanium clusters obtained in example 2;
FIG. 3 is a graph showing the periodic variation of the germanium clusters of the single-atom germanium and the triangular lattice distribution obtained in example 2;
FIG. 4 is a scanning tunneling microscope atomic resolution image of a honeycomb distribution of monatomic germanium and a triangular lattice distribution of germanium clusters obtained in example 2;
fig. 5 is an atomic structure model diagram of the germanium clusters with the monoatomic germanium and the triangular lattice distribution obtained in example 2.
Detailed Description
Example 1
A method for preparing a cluster of monatomic germanium and few atoms, as shown in fig. 1, comprises the following steps:
(1) At 10 -5 In a mabr ultrahigh vacuum environment, performing heating circulation after argon ion sputtering on the surface of gold (111), wherein each sputtering is performed for 20min, heating is performed at the temperature of 500 ℃ for 30min, and the heating circulation is performed for 3 times to obtain a clean and flat surface;
(2) At 10 -10 Evaporating and depositing bismuth atoms on the clean and flat surface obtained in the step (1) in a mabr ultrahigh vacuum environment, wherein the purity of the bismuth atoms is 99.999%, and depositing for 60min at the evaporation rate of 0.01ML/min and the temperature of 25 ℃ to obtain a two-dimensional ordered periodic hole film;
(3) At 10 -10 And (3) under the ultrahigh vacuum environment of mabr, evaporating and depositing germanium atoms on the two-dimensional ordered periodic hole film obtained in the step (2), wherein the purity of the germanium atoms is 99.999%, depositing for 10min at the evaporation rate of 0.01ML/min and the temperature of 25 ℃, and simultaneously keeping the growth temperature of 27 ℃ and fully diffusing to obtain the monatomic germanium in honeycomb distribution and the germanium cluster in triangular lattice distribution.
Example 2
A method for preparing a cluster of monatomic germanium and few atoms, as shown in fig. 1, comprises the following steps:
(1) At 10 -5 Performing treatment on the surface of gold (111) in a mabr ultrahigh vacuum environmentHeating for circulation after argon ion sputtering, wherein each sputtering is carried out for 25min, the heating is carried out for 30min at the temperature of 500 ℃, and the circulation is carried out for 4 times, so as to obtain a clean and flat surface;
(2) At 10 -10 Evaporating and depositing bismuth atoms on the clean and flat surface obtained in the step (1) in a mabr ultrahigh vacuum environment, wherein the purity of the bismuth atoms is 99.999%, and depositing for 70min at the evaporation rate of 0.01ML/min and the temperature of 27 ℃ to obtain a two-dimensional ordered periodic hole film;
(3) At 10 -10 And (3) evaporating and depositing germanium atoms on the two-dimensional ordered periodic hole film obtained in the step (2) in an ultrahigh vacuum environment by using a mabr, wherein the purity of the germanium atoms is 99.999%, the germanium atoms are deposited for 10min at the evaporation rate of 0.01ML/min and the temperature of 27 ℃, the growth temperature is kept at 27 ℃, and the germanium atoms are fully diffused to obtain the monatomic germanium distributed in a honeycomb shape and the germanium clusters distributed in a triangular lattice shape.
Example 3
A method for preparing a cluster of monatomic germanium and few atoms, as shown in fig. 1, comprises the following steps:
(1) At 10 -5 In a mabr ultrahigh vacuum environment, performing heating circulation after argon ion sputtering on the surface of gold (111), wherein each sputtering is performed for 30min, heating is performed at the temperature of 500 ℃ for 30min, and the heating circulation is performed for 5 times to obtain a clean and flat surface;
(2) At 10 -10 Evaporating and depositing bismuth atoms on the clean and flat surface obtained in the step (1) in a mabr ultrahigh vacuum environment, wherein the purity of the bismuth atoms is 99.999%, and depositing for 70min at the evaporation rate of 0.02ML/min and the temperature of 28 ℃ to obtain a two-dimensional ordered periodic hole film;
(3) At 10 -10 And (3) evaporating and depositing germanium atoms on the two-dimensional ordered periodic hole film obtained in the step (2) in an ultrahigh vacuum environment by using a mabr, wherein the purity of the germanium atoms is 99.999%, the germanium atoms are deposited for 15min at the evaporation rate of 0.02ML/min and the temperature of 28 ℃, the growth temperature is kept at 27 ℃, and the germanium atoms are fully diffused to obtain the monatomic germanium distributed in a honeycomb shape and the germanium clusters distributed in a triangular lattice shape.
Examples of the experiments
Scanning tunneling microscope images, periodic variation graphs, atomic resolution images and atomic structure model graphs of the mono-atomic germanium clusters in the honeycomb distribution and the germanium clusters in the triangular lattice distribution obtained in example 2 are respectively obtained and are respectively shown in fig. 2 to 5.
As can be seen from figures 2-4, the invention forms the monatomic germanium with honeycomb distribution and the germanium cluster with triangular lattice distribution, and the two-dimensional ordered monatomic germanium and the germanium cluster with few atoms have the period of 3.48nm through measurement. As can be seen from fig. 5, the germanium monoatomic atoms formed by the present invention occupy the pore gaps of the porous structure on the gold surface, and the germanium clusters with few atoms are spaced and occupied in the bismuth pore structure.
While the present invention has been described in detail with reference to the illustrated embodiments, it should not be construed as limited to the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive work within the scope of the appended claims.
Claims (9)
1. A preparation method of a monatomic germanium and small atom cluster is characterized by comprising the following steps:
(1) Performing sputtering and heating cycle treatment on the single crystal substrate in an ultrahigh vacuum environment to obtain a clean and flat surface;
(2) Evaporating and depositing bismuth atoms on the clean and flat surface obtained in the step (1) in an ultrahigh vacuum environment to obtain a two-dimensional ordered periodic hole film;
(3) And (3) in an ultrahigh vacuum environment, evaporating and depositing germanium atoms on the two-dimensional ordered periodic hole film obtained in the step (2), and simultaneously keeping the growth temperature and fully diffusing to obtain the monatomic germanium distributed in a honeycomb shape and the germanium cluster distributed in a triangular lattice shape.
2. The method of claim 1, wherein the degree of vacuum in step (1) is 10 -5 mabr, performing argon ion sputtering on the surface of gold (111), heating for circulation, wherein each sputtering is performed for 20-30min, and the heating is performed at 500 ℃ for 30min, and the circulation is performed for 3-5 times.
3. The method of claim 1, wherein in steps (2) and (3), the bismuth atoms and germanium atoms are deposited on the substrate by thermal resistive heating evaporation.
4. The method of claim 1, wherein the degree of vacuum in step (2) is 10 -10 mabr with bismuth atom purity of 99.999%, and depositing at 0.01-0.02ML/min evaporation rate and 25-28 deg.C for 60-70min.
5. The method of claim 4 wherein the monatomic germanium and small atomic cluster is deposited at an evaporation rate of 0.01ML/min and a temperature of 27 ℃ for 10 minutes.
6. The method of claim 1, wherein the degree of vacuum in step (3) is 10 -10 mabr with a germanium atom purity of 99.999% deposited at an evaporation rate of 0.01-0.02ML/min and at a temperature of 25-28 deg.C for 10-15min.
7. The method of claim 6 wherein the monatomic germanium and small atomic cluster is deposited at an evaporation rate of 0.01ML/min and a temperature of 27 ℃ for 10 minutes.
8. The method of claim 1, wherein in step (3), the growth temperature is 27 ℃.
9. The method according to claim 1, wherein the spacing between the periodic structures of the honeycomb-shaped distribution of the monatomic germanium and the triangular lattice distribution of the germanium clusters is 3.48nm.
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