Metal monatomic sub-nanoscale association degree regulation and control method and application

Abstract

The invention discloses a method for regulating and controlling sub-nano-scale metal monatomic correlation degree and application, and relates to the technical field of catalytic materials. The method for regulating and controlling the sub-nano-scale metal monatomic correlation degree comprises the following steps: anchoring a monatomic-polymer complex on the surface of a carrier to form a passivation region; the size of the passivation area is adjusted so that the correlation degree between the metal single atoms and the surface of the carrier can be adjusted and controlled. By adopting the technical scheme, the organic metal complex of the metal monatomic-polymer is loaded on the surface of the carrier through hydrogen-bond interaction to form a passivation region which cannot be loaded by other precursors; on the premise of saturated loading, the size of a passivated area on the surface of the carrier can be adjusted by changing the chain length of the polymer, so that the metal monatomic loading capacity is changed; the regulation and control method is combined with a method for changing the addition amount of a single atom-polymer precursor, and the association degree regulation and control of metal single atoms on the surface of the carrier can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and specifically relates to a method and application for controlling the sub-nanoscale correlation of single metal atoms. Background Art

[0002] Single-Atom Materials (SAMs) are a new type of functional materials with single metal atoms dispersed on a carrier. They have extremely high atomic utilization and unique electronic structure. They have attracted much attention due to their physical and chemical properties such as maximum atomic utilization, adjustable electronic structure and high catalytic selectivity, and are widely used in catalysis, environmental governance and energy. In particular, breakthrough progress has been made in electrocatalysis (such as hydrogen evolution reaction HER, oxygen reduction reaction ORR and CO2 reduction) in recent years.

[0003] Metal single atoms have multiple discrete and separated energy levels. This unique electronic structure (such as unsaturated coordination, strong metal-support interaction, etc.) can optimize the adsorption energy of reaction intermediates and improve catalytic selectivity. Due to the complete exposure of metal single atoms, single atoms serve as active sites, and the theoretical atomic utilization rate reaches 100%, which significantly reduces the amount of precious metals used, which makes them have efficient catalytic performance; at the same time, this electronic structure is also highly adjustable. By changing the degree of local correlation of metal single atoms and regulating their coordination microenvironment, active centers with specific electronic states can be designed. However, the current method for regulating the correlation of metal single atoms is often to increase the atomic load to reduce the distance between atoms, but this method has obvious disadvantages, that is, it is difficult to ensure that single atoms with extremely large surface energy will not form three-dimensional dense structures (nanoparticles). Therefore, the difficulty in regulating the correlation of single atoms has seriously hindered the research on the properties of single-atom materials.

[0004] In the existing technology, the preparation methods of single-atom materials mainly include chemical vapor deposition (CVD), atomic layer deposition (ALD), ion exchange, and electrochemical deposition. The above methods all have obvious defects in regulating the correlation degree of metal atoms. For example, chemical vapor deposition (CVD) deposits single atoms on the carrier surface by pyrolysis of precursors. The high-temperature process (>500°C) limits the substrate selection (for example, organic polymers cannot be used), the atomic distribution is highly random, and it is difficult to control the spacing; atomic layer deposition (ALD) achieves single-atom level precision by layer-by-layer deposition, but the equipment cost is high and the deposition rate is slow. It is only applicable to specific metal / carrier combinations and it is difficult to achieve dense and uniform arrangement; electrochemical deposition controls the reduction deposition of metal ions on the carrier surface through potential. The deposition process is diffusion-controlled and clusters are easily formed; spacing control depends on precursor concentration and potential parameters, resulting in poor repeatability.

[0005] Clearly, existing preparation methods like CVD and ALD, due to high-temperature limitations, high costs, and uneven distribution, struggle to precisely control the local correlation between metal single atoms. This can easily lead to atomic aggregation to form nanoparticles, severely hindering their performance optimization. Therefore, breaking through the technical bottleneck of ordered subnanometer arrangement and developing new methods for controllable regulation of single-atom spacing and coordination microenvironment have become key challenges in advancing the performance of metal single-atom materials.

[0006] Based on the technical problems existing in the above-mentioned prior art, the present invention provides a low-temperature, substrate-universal metal single atom surface distribution control technology to achieve sub-nanometer-level control of the correlation degree of metal single atoms, specifically including the control of the soft template length, selective passivation of the carrier surface, combined with the change of the precursor addition amount, to achieve the control of the correlation degree of metal single atoms. Summary of the Invention

[0007] The main purpose of the present invention is to provide a method and application for controlling the sub-nanometer correlation of metal single atoms to overcome the shortcomings of the existing technology.

[0008] In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solutions.

[0009] A method for regulating the correlation degree of metal single atoms at the sub-nanometer level comprises anchoring a metal organic complex on the surface of a carrier to form a passivation region; and adjusting the size of the passivation region to achieve regulation of the correlation degree between the metal single atoms and the surface of the carrier.

[0010] As a preferred embodiment, the metal organic complex is prepared by coordination between a metal source and an organic polymer.

[0011] As a preferred embodiment, in the metal-organic complex, the metal single atom is supported on the surface of the organic polymer.

[0012] As a preferred embodiment, the organic polymer contains an organic molecular chain with adjustable length.

[0013] As a preferred embodiment, the carrier is a low-dimensional metal oxide having abundant dangling bonds on the surface and a single crystal plane.

[0014] As a preferred embodiment, the carrier is any one of cobalt oxide nanosheets, manganese oxide nanosheets, and titanate nanotubes.

[0015] By selecting metal salts as metal sources, length-adjustable organic molecular chains as soft templates, and low-dimensional metal oxides with abundant dangling bonds and a single crystal plane on the surface as carriers, the local correlation degree of single metal atoms on the carrier surface can be regulated.

[0016] As a preferred embodiment, the regulation method includes: first, mixing the metal single atoms with the soft template to form a single atom-polymer precursor through coordination; then, anchoring the single atom-polymer precursor to the surface of the carrier to form a passivation area; adjusting the size of the passivation area can achieve the regulation of the correlation between the metal single atoms.

[0017] As the second aspect of the invention, the present invention also provides a method for preparing sub-nanoscale metal single atom materials, by selecting metal salts as metal sources, length-adjustable organic molecular chains as soft templates, and low-dimensional metal oxides with abundant dangling bonds on the surface and a single crystal plane as carriers, and loading metal single atoms on the carriers.

[0018] In some specific embodiments, the present invention uses sodium tungstate as a metal source, PEG as a soft template, and titanate nanotubes as a carrier, and can produce single-atom tungsten modified titanate nanotubes through simple mixing, low-temperature heating and stirring.

[0019] Furthermore, by changing the chain length of PEG and the amount of precursor added, the controllable distribution of metal single atoms can be achieved.

[0020] As a preferred embodiment, the specific steps of the preparation method include:

[0021] S1. mixing the metal single atom with the soft template, adding acid to adjust the pH value, and forming a single atom-polymer precursor through coordination;

[0022] Then, the single atom-polymer precursor is mixed with the carrier and then heated to react. The single atom-polymer precursor is anchored to the surface of the carrier through hydrogen bonding. After drying and calcination, the sub-nanometer metal single atom material is obtained.

[0023] As a preferred embodiment, the soft template and the metal salt undergo a coordination reaction to form a single atom-polymer precursor having a bidentate coordination structure.

[0024] As a preferred embodiment, in S1, the acid solution is any one of sulfuric acid and hydrochloric acid; the adjusted pH is 5.

[0025] As a preferred embodiment, the reaction temperature is 20-25°C.

[0026] As a preferred embodiment, the reaction time is 0.5 to 2 hours.

[0027] Preferably, the acid solution is sulfuric acid with a concentration of 0.1M.

[0028] As a preferred embodiment, in S2, the heating reaction includes mixing the carrier with the single atom-polymer precursor, heating to 60-90°C, stirring for 3-5 hours, and washing with deionized water and ethanol successively until the pH is close to 7.

[0029] As a preferred embodiment, the drying-calcination includes vacuum drying at 60° C., and finally calcining in an inert gas environment at 180-220° C. for 5-7 hours to obtain a metal single-atom material.

[0030] As a preferred embodiment, the metal source is selected from any one of tungstate, chromate or molybdate, but is not limited thereto.

[0031] As a preferred embodiment, the carrier can be selected from any one of cobalt oxide nanosheets, manganese oxide nanosheets, titanate nanotubes, etc., but is not limited thereto.

[0032] As a preferred embodiment, the soft template can be selected from any one of polyethylene glycol and polyvinyl alcohol, but is not limited thereto.

[0033] As a preferred embodiment, the molecular weight of polyethylene glycol PEG is 300-1000.

[0034] As a preferred embodiment, the molar ratio of the metal source to the soft template is 1:0.9-1.1.

[0035] As the third aspect of the invention, the present invention also provides a sub-nanoscale metal single atom material prepared by the above-mentioned preparation method. In the metal single atom material, the metal single atoms are loaded on the surface of the carrier in a "head-to-head" localized self-assembled structure.

[0036] As a preferred embodiment, the loading amount of the metal single atoms is 8 to 15 wt %; wherein the metal single atoms are mainly pentavalent tungsten.

[0037] As a fourth aspect of the invention, the present invention also provides the application of the above-mentioned sub-nanoscale metal single atom material in the field of catalysis.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] 1. The technical solution of the present invention selects an inexpensive metal salt as the metal source, coordinately anchors it to a soft template, and loads it on the surface of titanate nanotubes through hydrogen bonding, forming a passivation area that other precursors cannot load. Under the premise of saturated loading, the size of the passivation area on the surface of the titanate nanotubes can be adjusted by changing the chain length of PEG, thereby changing the loading amount of tungsten atoms. This regulation method is combined with the method of changing the amount of single atom-polymer precursor added to achieve controllable correlation between metal single atoms under conditions of similar loading amounts, thereby changing the loading amount of metal single atoms on the carrier.

[0040] 2. The technical solution of the present invention can achieve regulation of the loading amount by regulating the chain length structure in the soft template, and realize the controllable arrangement of metal single atoms at the sub-nanometer scale. The metal tungsten is loaded on the surface of the carrier in a "head-to-head" localized self-assembly structure, realizing the coordinated optimization of the active site density and spacing.

[0041] 3. Compared with the methods in the prior art, the technical solution of the present invention has the characteristics of simple method and mild conditions. Single-atom tungsten-modified titanate nanotubes can be prepared by simple mixing, low-temperature heating and stirring. By changing the chain length of PEG and the amount of precursor added, the controllable distribution of metal single atoms can be achieved, thereby greatly reducing the manufacturing cost and being suitable for large-scale promotion and utilization, thereby reducing the cost of applying metal single-atom materials in the field of catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A high-angle annular dark field-scanning transmission electron microscopy image of high-loading and high-correlation single-atom tungsten modified titanate nanotubes prepared in Example 3 is shown.

[0044] Figure 2 A high-angle annular dark field-scanning transmission electron microscopy image of low-loading and low-correlation single-atom tungsten modified titanate nanotubes prepared in Example 4 is shown.

[0045] Figure 3 A high-angle annular dark field-scanning transmission electron microscopy image of low-loading and high-correlation single-atom tungsten modified titanate nanotubes is shown in the example.

[0046] Figure 4The XPS spectra of the tungsten 4f shell of the samples with different correlation degrees prepared in Examples 3-5 are shown.

[0047] Figure 5 A schematic diagram of the principle simulation of regulating the correlation degree of metal single atoms in the present invention is shown. DETAILED DESCRIPTION

[0048] The present invention provides a method for regulating the correlation degree of metal single atoms at the sub-nanometer level, comprising anchoring a metal organic complex on the surface of a carrier to form a passivation region; and adjusting the size of the passivation region to achieve the regulation of the correlation degree between the metal single atoms and the surface of the carrier.

[0049] Specifically, it includes the rational selection of metal source precursors, the selection of soft template polymers and the selection of low-dimensional supports with single crystal faces.

[0050] Furthermore, metal salts are selected as metal sources, including but not limited to tungstate, chromate or molybdate. The above metal salts are inexpensive and can significantly reduce the manufacturing cost of the product.

[0051] In some specific implementations, sodium tungstate is taken as an example for description.

[0052] Furthermore, the present invention also selects an organic molecular chain with adjustable length as a soft template.

[0053] In some specific embodiments, the present invention uses polyethylene glycol (PEG300-1000) as an example, dissolving sodium tungstate in water to form a solution, and then mixing the sodium tungstate solution with polyethylene glycol to perform a coordination reaction to obtain a single atom-polymer precursor.

[0054] The coordination reaction includes: the PEG end forms a stable bidentate coordination with the tungstate ion.

[0055] Preferably, the molar ratio of sodium tungstate to polyethylene glycol is 1:1.

[0056] Preferably, the coordination reaction comprises: after stirring at 20° C. for one hour, adding 0.1 M sulfuric acid dropwise to the mixture until the pH reaches 5, to obtain a single atom-polymer precursor.

[0057] Furthermore, a low-dimensional metal oxide with abundant dangling bonds on the surface and a single crystal plane is selected as the support.

[0058] In some specific embodiments, the present invention selects titanate nanotubes.

[0059] Furthermore, the preparation method of titanate nanotubes includes: adopting an alkaline hydrothermal method and then performing an acidification treatment.

[0060] In some specific embodiments, single-atom tungsten-modified titanate nanotubes are used as a carrier, the carrier is mixed with a single-atom-polymer precursor, stirred at 75°C for 4 hours, washed with deionized water and ethanol successively until the pH is close to 7, then vacuum-dried at 60°C, and finally calcined in an argon environment at 200°C for 6 hours to obtain a metal single-atom material.

[0061] The principle is as follows: PEG adheres to the surface of titanate nanotubes through hydrogen bonding, forming a passivated region that is unavailable to other precursors. Under saturated loading, tungsten atoms are loaded in a localized, self-assembled, head-to-head structure, resulting in a high degree of correlation between the single tungsten atoms.

[0062] Furthermore, under the premise of saturated loading, by varying the PEG chain length, the size of the passivated area on the titanate nanotube surface can be adjusted, thereby varying the tungsten atom loading. This method, combined with the method of varying the amount of single-atom-polymer precursor added, can achieve controllable tungsten atom correlation under similar loading conditions.

[0063] See Figure 5 , which is a schematic diagram of the principle simulation of the correlation degree control of metal single atoms in the present invention. As can be seen from the figure, metal tungsten coordinates with the polymer in a "head-to-head" localized self-assembly structure to form a single-atom-polymer metal organic complex, and is anchored on the surface of the carrier (TNTs) to form a passivation area ( Figure 5 Cii); In the case of saturated loading of the precursor, increasing the length of the organic chain will lead to a larger area of passivation on the carrier surface, thereby reducing the loading amount. The metal tungsten in the precursor is always in a "head-to-head" state, thus maintaining the high correlation morphology of the organometallic complex ( Figure 5 Cii to Ciii in .

[0064] Under another condition, keeping other conditions unchanged, reducing the amount of precursor added, the loading amount is also reduced, the organometallic complex is naturally dispersed, does not locally aggregate, and presents a low-aggregation form. The metal tungsten in the precursor no longer presents a "head-to-head" state ( Figure 5 Cii to Ci in , thereby achieving the decoupling of load and correlation.

[0065] Through the above analysis, the present invention adjusts the amount of precursor added or the chain length of the organic polymer to control the size of the passivation area on the carrier surface to achieve the regulation of the local aggregation degree of metal single atoms, rather than relying on reducing the loading amount.

[0066] The control method provided by the present invention is universal. The selected metal source includes but is not limited to any one of sodium tungstate, potassium tungstate, sodium chromate, sodium molybdate, etc.; the selected soft template includes but is not limited to any one of polyvinyl alcohol, polyethylene glycol, etc.; the selected metal oxide carrier includes but is not limited to any one of cobalt oxide nanosheets, manganese oxide nanosheets, titanate nanotubes, etc.

[0067] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0068] The technical solution of the present invention is explained in more detail below with reference to several embodiments.

[0069] Example 1

[0070] This embodiment provides a titanate nanotube having a single exposed crystal face with abundant dangling bonds on its surface as a single atom carrier.

[0071] The specific steps include: 3.6 g of titanium dioxide powder and 50 mL of sodium hydroxide solution (10 M, analytical grade) are placed in a polytetrafluoroethylene beaker and stirred continuously with a magnetic stirrer (500 rpm) for 30 minutes until a homogeneous suspension is formed. The mixture is then transferred to a 100 mL polytetrafluoroethylene-lined autoclave and heated at 150°C in a forced air drying oven for 20 hours, with a heating rate controlled at 5°C / min. After the reaction, the mixture is naturally cooled to room temperature (25±2°C). The hydrothermal product is centrifuged (8000 rpm, 10 minutes), the supernatant is discarded, and the precipitate is repeatedly washed with deionized water until the filtrate reaches a pH of 7 (monitored in real time with a pH meter with an accuracy of ±0.01). The washed titanate precipitate is dispersed in 200 mL of nitric acid solution (0.1 M) and acidified continuously with a constant temperature magnetic stirrer (25°C, 300 rpm) for 24 hours to promote the proton exchange reaction. The acidified product was collected by vacuum filtration, washed again with deionized water until neutral, and then treated in a vacuum drying oven at 60° C. for 12 hours to obtain a titanate nanotube support.

[0072] Example 2

[0073] In this embodiment, a polyethylene glycol-monoatom tungsten precursor is prepared.

[0074] The specific steps include: weighing 1.3mmol sodium tungstate (purity ≥99.9%) and 1.3mmol polyethylene glycol (molecular weight = 600), dissolving them in 15mL deionized water, and stirring continuously for 1 hour in a constant temperature magnetic stirrer (20±0.5℃, speed 500rpm) to form a uniform transparent solution. Use 0.1M sulfuric acid to add dropwise to the above solution through a microburette, and monitor the pH of the solution in real time until the pH of the system stabilizes at 5.0±0.1. Add deionized water to the mixed solution to a total system volume of 20mL, transfer it to a light-proof reactor, maintain 20℃ and a stirring rate of 500rpm, and continue the reaction for 6 hours to obtain a single-atom precursor dispersion.

[0075] Example 3

[0076] This embodiment prepares a single-atom tungsten-modified titanate nanotube with high loading and high correlation.

[0077] The specific steps include: 0.1 g of titanate nanotubes (NTs) were uniformly dispersed in 20 mL of a 1:10 ethylene glycol / deionized water mixture (ethylene glycol purity ≥99.5%) and treated with an ultrasonicator for 30 minutes to form a stable dispersion. 1.5 mL of the tungsten monoatomic precursor solution obtained in Example 2 was added dropwise to the dispersion using a microsyringe pump at a rate of 0.05 mL / min, while magnetic stirring (500 rpm) was simultaneously activated to ensure uniform mixing. The mixture was transferred to a sealed polytetrafluoroethylene reactor and stirred continuously (300 rpm) in an oil bath thermostat (75±0.5°C) for 4 hours to promote the coordination and anchoring of the precursor to the hydroxyl groups on the NTs. The mixture was then allowed to stand at room temperature (25°C) in the dark for 12 hours to complete the Ostwald ripening process. The mixture was centrifuged at 12,000 rpm for 15 minutes, and the supernatant was discarded. The precipitate was washed alternately with deionized water and anhydrous ethanol until the filtrate had a pH of 7±0.2. The dried sample was placed in a tube furnace, and under the protection of high-purity argon, the temperature was increased to 200°C at a rate of 5°C / min and calcined at a constant temperature for 6 hours to remove residual organic matter.

[0078] The corresponding high-angle annular dark field scanning transmission electron microscope image is Figure 1 The tungsten content of the obtained single-atom tungsten modified titanate nanotubes with high loading and high correlation is 11.4 wt%.

[0079] Example 4

[0080] This embodiment prepares a single-atom tungsten-modified titanate nanotube with low loading and low correlation.

[0081] The specific steps include: 0.1 g of titanate nanotubes (NTs) were uniformly dispersed in 20 mL of a 1:10 ethylene glycol / deionized water mixture and sonicated for 30 minutes to form a stable dispersion. 0.5 mL of the monatomic tungsten precursor solution obtained in Example 2 was added dropwise to the dispersion at a rate of 0.05 mL / min using a microsyringe pump, while magnetic stirring (500 rpm) was simultaneously activated to ensure uniform mixing. The mixture was transferred to a sealed polytetrafluoroethylene reactor and stirred continuously (300 rpm) in an oil bath thermostat (75±0.5°C) for 4 hours to promote the coordination and anchoring of the precursor to the hydroxyl groups on the NTs. The mixture was then allowed to stand at room temperature (25°C) in the dark for 12 hours to complete the Ostwald ripening process. The mixture was centrifuged at 12,000 rpm for 15 minutes, and the supernatant was discarded. The precipitate was washed alternately with deionized water and anhydrous ethanol until the filtrate had a pH of 7±0.2. The dried sample was placed in a tube furnace and heated to 200°C at a rate of 5°C / min under high-purity argon protection and calcined for 6 hours to remove residual organic matter. In this example, the amount of precursor added was reduced, resulting in a lower loading and a longer average spacing.

[0082] The corresponding high-angle annular dark field scanning transmission electron microscope image is Figure 2 The tungsten content of the obtained single-atom tungsten modified titanate nanotubes with low loading and low correlation is 6.2 wt%.

[0083] Example 5

[0084] This embodiment prepares a single-atom tungsten-modified titanate nanotube with low loading and high correlation.

[0085] The specific steps include: uniformly dispersing 0.1 g of titanate nanotubes in 20 mL of a 1:10 ethylene glycol / deionized water mixture and ultrasonically treating for 30 minutes to form a stable dispersion. The molecular weight of the PEG used in the preparation of the single-atom tungsten precursor solution in Example 2 was increased to 1000. The PEG-replaced single-atom tungsten precursor solution was then added dropwise to the dispersion at a rate of 0.05 mL / min using a microsyringe pump, while magnetic stirring (500 rpm) was simultaneously activated to ensure uniform mixing. The mixture was transferred to a sealed polytetrafluoroethylene reactor and stirred continuously (300 rpm) in an oil bath thermostat (75 ± 0.5°C) for 4 hours to promote the coordination and anchoring of the precursor with the hydroxyl groups on the titanate nanotube surfaces. The mixture was then allowed to stand at room temperature (25°C) in the dark for 12 hours to complete the Ostwald ripening process. The mixture was centrifuged at 12,000 rpm for 15 minutes, and the supernatant was discarded. The precipitate was washed alternately with deionized water and anhydrous ethanol until the filtrate pH reached 7±0.2. The dried sample was placed in a tube furnace and, under high-purity argon, heated to 200°C at a rate of 5°C / min and calcined at this temperature for 6 hours to remove residual organic matter. In this example, the chain length of the organic matter in the precursor was increased, resulting in a larger passivated area on the titanate nanotube surface and a reduced loading capacity, while the localized loading configuration still exhibited a highly correlated "head-to-head" structure.

[0086] The corresponding high-angle annular dark field scanning transmission electron microscope image is Figure 3 The tungsten content of the obtained single-atom tungsten modified titanate nanotubes with low loading and high correlation is 8.8wt%.

[0087] See Figure 4 The effectiveness of regulating the correlation degree of metal single atoms in the tungsten 4f shell was evaluated by XPS spectroscopy in the three samples obtained in Examples 3-5. The results show that in the two samples with higher correlation degrees (Examples 3 and 5), the valence state of tungsten is mostly pentavalent, while in the sample with lower correlation degree (Example 4), the content of pentavalent tungsten is significantly reduced. This demonstrates that the present invention can achieve changes in the local electronic structure of tungsten by regulating the correlation degree of metal tungsten atoms.

[0088] This invention proposes a low-temperature, substrate-universal single-atom surface distribution control technology. By selecting appropriate metal salts, soft template organic molecular chains, and suitable metal oxide supports, simple mixing, low-temperature heating, and stirring, single-atom materials can be produced. Further adjustments to the soft template length and precursor dosage can achieve a controllable distribution of metal single atoms.

[0089] It should be noted that the above description is only a preferred embodiment of the present application, and the present application is described in detail according to the aforementioned embodiments. The embodiments are not intended to limit the present application. Although technicians in this field can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein with equivalents, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for regulating the correlation between metal single atoms at the sub-nanometer level, comprising anchoring a metal organic complex to the surface of a carrier to form a passivation region; adjusting the size of the passivation region can achieve regulation of the correlation between the metal single atoms and the surface of the carrier.

2. The method for controlling the correlation degree of sub-nanometer metal single atoms according to claim 1, characterized in that: The carrier is a low-dimensional metal oxide having abundant dangling bonds on the surface and a single crystal plane; And / or, the metal organic complex is prepared by coordination between a metal source and an organic polymer; And / or, in the metal-organic complex, the metal single atom is supported on the surface of the organic polymer.

3. The method for controlling the correlation degree of sub-nanometer metal single atoms according to claim 2, characterized in that: The metal source is a metal salt; and / or, the organic polymer contains an organic molecular chain with adjustable length; And / or, the carrier is any one of cobalt oxide nanosheets, manganese oxide nanosheets, and titanate nanotubes.

4. A method for preparing sub-nanoscale metal single-atom materials, by selecting metal salts as metal sources, using polymers containing organic molecular chains with adjustable lengths as soft templates, and low-dimensional metal oxides with abundant dangling bonds on the surface and a single crystal plane as carriers, and loading metal single atoms on the carriers to obtain the metal single-atom materials.

5. The preparation method according to claim 4, characterized in that The specific steps include: S1. mixing a metal single atom with the soft template, adding an acid solution to adjust the pH value, and forming a single atom-polymer precursor by coordination; the soft template and the metal salt undergo a coordination reaction to form a single atom-polymer precursor having a bidentate coordination structure; S2. The single atom-polymer precursor is mixed with the carrier and then heated to react. The single atom-polymer precursor is anchored to the surface of the carrier through hydrogen bonding. After drying and calcination, the sub-nanoscale metal single atom material is obtained.

6. The preparation method according to claim 5, characterized in that In S1, the acid solution is any one of sulfuric acid and hydrochloric acid; the adjusted pH is 5; The reaction temperature is 20-25°C; the reaction time is 0.5-2h; Preferably, the acid solution is sulfuric acid with a concentration of 0.1M; and / or, in S2, the heating reaction comprises mixing the support with the single atom-polymer precursor, heating to 60-90° C., stirring for 3-5 hours, and washing with deionized water and ethanol successively until the pH is close to 7; And / or, the drying-calcination includes vacuum drying at 60° C., and finally calcining in an inert gas environment at 180-220° C. for 5-7 hours to obtain the metal single atom material.

7. The preparation method according to any one of claims 4 to 6, characterized in that The metal source is selected from any one of tungstate, chromate or molybdate; And / or, the soft template is any one of polyethylene glycol and polyvinyl alcohol; and / or, the molecular weight of ethylene glycol is 300 to 1000; And / or, the molar ratio of the metal source to the soft template is 1:0.9-1.

1.

8. A sub-nanoscale metal single atom material prepared by the preparation method according to any one of claims 4 to 7, wherein the metal single atoms are supported on the surface of a carrier in a "head-to-head" localized self-assembled structure.

9. The sub-nanoscale metal single atom material according to claim 8, characterized in that: The loading amount of the metal single atoms is 8-15 wt %; wherein the metal single atoms are mainly pentavalent tungsten.

10. Use of the sub-nanoscale metal single atom material according to any one of claims 8 to 9 in the field of catalytic materials.

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