WO2020155672A1

WO2020155672A1 - Material comprising reduced noble metal isolated atom stable in solution, and preparation method

Info

Publication number: WO2020155672A1
Application number: PCT/CN2019/111843
Authority: WO
Inventors: 张宗超; 李会香
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2019-01-31
Filing date: 2019-10-18
Publication date: 2020-08-06
Also published as: CN111496265A; CN111496265B

Abstract

A material comprising a reduced noble metal isolated atom stable in a solution. The material consists of a reduced noble metal isolated atom and a protective agent. A chain compound containing an ether linkage group is used as the protective agent, so that the reduced noble metal isolated atom stably exists, and the material comprising the noble metal isolated atom is prepared in the solution, and the generation of a nanoparticle caused by the accumulation of a primary isolated atom is avoided in the process of synthesis. The reduced isolated atom of the material is different from a metal nanoparticle, and can be applied to the fields of energy materials, pharmaceutical synthesis, medical materials, catalysts preparation and the like. The present invention provides a basic isolated atom material for synthesis of a controllable number of homogeneous or heterogeneous metal clusters. Also involved is a preparation method for the material comprising the reduced noble metal isolated atom stable in the solution.

Description

Reduced precious metal solitary atom material stable in solution and preparation method

Technical field

The invention belongs to the field of new material invention, and the specific material is a reduced precious metal lone atom material that is stable in a protective agent-containing solution.

Background technique

Precious metals and their alloys have become widely used materials in modern industries due to their excellent properties. Due to its high temperature corrosion resistance, high reliability, high precision and long service life, precious metals are widely used in the manufacture of precision instruments for aerospace, marine industry and military industry, such as springs, bellows, conductive hairsprings, and shafts. Tips and other originals. At the same time, due to its material's physiological non-toxicity, good ductility and biocompatibility, precious metals are widely used in the preparation of medical materials. For example, in the dental field, two major dental precious metal alloys, amalgam alloys and casting alloys, medical gold needles, silver needles and hard needles, and electrode materials for medical electronic equipment. Furthermore, precious metals have unique catalytic performance and stability, especially platinum group metals (iridium, rhodium, palladium and platinum), which are widely used in petrochemicals, hydrogen fuel cells and other fields. However, the scarcity of precious metal resources and the backward manufacturing technology make the price of precious metals high, which severely restricts their full utilization in various fields.

The precious metal solitary atoms provide a broad space for the utilization of precious metals. Maria Flytzani-Stephanopoulos et al. (Acc. Chem. Res, 2014, 47, 783.) reported the synthesis of Au monoatomic materials on various carriers and successfully applied them to water gas shift reactions. Tao Zhang et al. (Nature Chem., 2011, 3,634.) reported the synthesis of Pt monoatomic materials on the surface of iron oxide and successfully applied it to the oxidation reaction of carbon monoxide, which increased the conversion frequency of the reaction by 2-3 times. However, the monoatomic materials obtained by the method of solid surface dispersion not only have many problems such as low loading, instability, etc., at the same time, due to the interaction between the solid surface and the precious metal monoatoms, the precious metal monoatoms do not exist in an isolated state. The existence state is bound to the solid surface and has a strong interaction with the oxygen on the carrier. The metal center is not in a completely reduced state (Nature Nanotechnology, 2018, 13,856; Nature Commu., 2019, 10,234), and it is not easy to peel off from the solid surface. Therefore, it cannot be used as a raw material to generate and prepare a wider range of substances. The reduced noble metal atoms have a large degree of freedom in the movement of the solution, and it is easy to aggregate to cause the generation of nanoparticles. Therefore, it has always been a huge challenge in the field of science and technology to disperse the reduced noble metal atoms in a solution to obtain isolated noble metal atoms. Vinylpyrrolidone polymer and isopropylacrylamide polymer etc. (J. Phys. Chem. B, 1999, 103, 3818.; Langmuir 1997, 13, 6465.). High-molecular polymers are widely used in the synthesis of precious metal materials in solution. However, these high-molecular polymers are difficult to prevent the solitary precious metal atoms in the initial reduced state from gathering and growing into nanoparticles. Surfactants are also used in the synthesis of precious metal materials in solution, but they are difficult to remove, and the freedom of precious metal lone atoms wrapped by surfactants is limited (Patent No.: 201611004958.3), and the polymer remaining in the material Polymers and surfactants also affect the application characteristics of the material.

Based on the above research status, we can know how to overcome the shortcomings of relying on solid surface dispersion to prepare lone atom materials, low loading, noble metal lone atoms in the initial reduced state are easy to aggregate and grow, and the protective agent in the system is difficult to remove, so as to obtain an effective The method of preparing stable reduced noble metal solitary atom materials is of great significance.

The invention introduces a stable reduced noble metal lone atom material in solution and a preparation method, which can stably exist in a solvent containing a protective group. This is different from the metal organic compounds reported in the literature. Marc-Etienne Moret, Bele'n Gil, etc. introduced various types of metal complexes (Higher oxidation state organopalladium and platinum chemistry. J. CHEM. SOC. DALTON TRANS, 1993, 3051-3057; Inorg. Chem. 2006, 45 ,7788-7798; J.Am.Chem.Soc.2011,133,3582–3591; Angew.Chem.Int.Ed.2018,57,1-6. Such as {[(C ₆ F ₅ ) ₃ (tht) Pt]Ag(PPh ₃ )}(tht is tetrahydrothiophene). In its structure, Pt and Ag metal bonds exist in the form of ions, namely Pt(II), Ag(I), and there are containing Phosphorus, carbon and other ligands. Metal Pd atom complex

And the structure is

In the complex, there are nitrogen and carbon ligands around the metal center to stabilize the structure.

In summary, in the metal complexes described above, the valence state of the metal is a non-reduced state, and the metal center in its structure forms a metal-carbon bond, a metal-nitrogen or a metal-phosphorus bond with a nitrogen-containing, phosphorous, or carbon-containing ligand. That is, the reported metal complexes are metal organic compounds. This is different from a metal lone atom material that is stable in solution introduced in the invention.

The reduced noble metal lone atom material that is stable in solution in the present invention can be used in the fields of material preparation, industrial catalysis and the like. For example, the reduced Pt solitary material can be used in the hydrosilylation reaction of unsaturated compounds (the hydrosilylation reaction refers to the addition reaction of the compound containing the Si-H bond and the unsaturated organic compound to form an organic silicon compound One type of reaction). The reduced Au solitary material can be used in low temperature conditions such as carbon monoxide oxidation reaction. In addition, the reduced precious metal lone atom material can also be used in material coating.

Summary of the invention

The purpose of the present invention is to provide a reduced precious metal lone atom material that is stable in solution.

The material is composed of reduced precious metal solitary atoms and a protective agent. The protective agent includes but is not limited to chain ether compounds.

The noble metal lone atom mentioned in the invention refers to an independent existence, no metal bond is formed between metals, and the chemical valence of the noble metal is not higher than the positive univalent, which is 0, or a mixture of 0 and positive univalent, preferably 0 price. For metals that do not have a positive monovalent state in common valence states, such as Pt, Pd, etc., the proportion of the metal lone atom in the solution with zero valence is at least 30%. For metals with positive univalent valence in common valence states, such as silver, the proportion of the chemical state of the metal lone atom in the solution is not less than 80%.

The noble metal solitary atoms include one or more of platinum-based elements and post-platinum-based elements, including but not limited to one or more of palladium, rhodium, iridium, ruthenium, osmium, platinum, and gold.

The noble metal lone atom is a platinum atom or a gold atom.

The protective agent includes but is not limited to one or two or more of compounds with ether structure; the protective agent includes but is not limited to one or two or more of compounds with glycol ether structure; includes but It is not limited to one or two or more compounds of glycol ethers and propylene glycol ether structures.

The protective agent includes but is not limited to ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol dimethyl ether One or more of ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, and n-butyl ether.

The molar ratio of the noble metal lone atom to the protective agent is less than or equal to 1:1, and the preferred range is 10 to 10 ⁶ .

The concentration range of the noble metal lone atoms is greater than 0 to 1 mol/L.

The concentration of the noble metal lone atoms ranges from 0.01 to 50 mmol/L.

The composition of the material in the preparation process includes but is not limited to chain ether compounds, high oxidation state precious metal compound precursors, reducing agents, or includes but not limited to chain ether compounds, high oxidation state precious metal compound precursors, reduction Reagent, water; all components are fully mixed according to the required ratio into a liquid system, and a stable precious metal monoatomic solution can be obtained after the reaction.

The material preparation process can include one or two or three of the following three situations to make the mixed system liquid;

The first type: water can be included in the composition, the mass concentration range of water is 0-70%, and water can be used as a solvent composition;

The second type: when the chain ether compound in the composition contains a protective agent that is liquid at room temperature, the liquid chain ether compound can be used as a solvent composition;

The third type: when the reducing agent in the composition contains a reducing agent that is liquid at room temperature, the liquid reducing agent can be used as a solvent composition.

The high oxidation state noble metal compound precursors include, but are not limited to, high oxidation state platinum compound precursors (one or two of positive divalent and positive tetravalent), high oxidation state palladium compound precursors (positive divalent, positive four One or two of the valence), high oxidation state rhodium compound precursor (positive trivalent), high oxidation state iridium compound precursor (one or two of positive trivalent and positive tetravalent), high oxidation state Ruthenium compound precursor (positive trivalent), high oxidation state osmium compound precursor (positive divalent, positive trivalent, positive tetravalent one or two or three) or high oxidation state gold compound precursor (positive trivalent) One or more of them.

The high oxidation state noble metal compound precursors include but are not limited to: chloroauric acid, sodium chloroauric acid, potassium chloroauric acid, ammonium chloroauric acid, chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, and chlorinated Platinum, platinum chloride, potassium chloroplatinate, sodium chloroplatinate, diethylamine platinum chloride, platinum nitrate, 1,5-cyclooctadiene platinum dichloride, trichloro(ethylene) platinum acid Potassium, dichlorotetraammine platinum, dinitrile phenyl dichloroplatinum, bis(triphenyl phosphite) platinum dichloride, ammonium tetrachloroplatinate, ammonium chloropalladate, sodium chloropalladate, chloropalladic acid One or more of potassium, ammonium chlororhodate, sodium chlororhodate, potassium chlororhodate, chloroiridic acid, sodium chloroiridate, potassium chloroiridate, and ammonium chloroiridate.

The reducing agent includes but is not limited to one or a mixture of alcohol compounds, glucose, formic acid, citric acid, tartaric acid, ascorbic acid, hydrazine hydrate, or borohydride.

The alcohol compound reducing agent includes but is not limited to one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, ethylene glycol, glycerol, or Two or more mixtures.

The present invention provides a material of stable reduced noble metal lone atoms in solution. It is composed of reduced precious metal lone atoms and protective agent. A chain compound containing an ether bond group is used as a protective agent to stabilize the existence of the reduced noble metal lone atom. In the present invention, chain ether compounds are used as protective agents for the first time to prepare precious metal solitary atom materials in solution, which avoids the accumulation of primary solitary atoms in the synthesis process to cause the generation of nanoparticles. The reduced solitary atoms of the material are different from metal nanoparticles, and can be used in the fields of energy materials, pharmaceutical synthesis, medical materials, catalyst preparation and other fields. It also provides a basic lone atom raw material for the synthesis of a controllable number of the same or different metal clusters and nanomaterials.

Description of the drawings

Figure 1 shows the UV-Vis spectra of Examples 1, 8, 9, 10

Figure 2 shows the 195PtNMR spectra of Examples 1, 3, 4, 5, 6, 7, 8, 9, 10

Figure 3 shows the UV-Vis spectra of Examples 2, 12

Figure 4 is the UV-Vis spectrum of Example 3

Figure 5 is the UV-Vis spectrum of Example 4

Figure 6 is the UV-Vis spectrum of Example 5

Figure 7 is the UV-Vis spectrum of Example 6

Figure 8 is the UV-Vis spectrum of Example 7

Figure 9 is the ultraviolet-visible spectrum of Example 11

Figure 10 is one of the high-resolution spherical aberration correction scanning transmission electron microscope analysis diagrams of Example 13

11 is the second embodiment of the high-resolution spherical aberration correction scanning transmission electron microscope analysis diagram of Example 13

Fig. 12 is a high-resolution spherical aberration correction scanning transmission electron microscope analysis diagram of Example 14.

detailed description

Hereinafter, the present invention will be further described in detail by taking platinum, gold, and insolated atomic materials that are stable in solution as examples.

The protection content of this patent is not limited by the specific implementation, but by the claims.

Example 1

Preparation of platinum atoms in the solution: Mix 67ml of ethylene glycol diethyl ether, 67ml of ethanol, 10.2ml of water and 4.8ml of chloroplatinic acid solution with a concentration of 0.018mol/L, then heat up, condense and reflux at 75°C for 24 hours. Chloroplatinic acid is completely reduced. The ethanol and ethylene glycol diethyl ether in the solution can be removed by distillation under reduced pressure. The detection of UV and 195Pt NMR showed that the platinum solitary atom material was synthesized. The ultraviolet-visible absorption spectrum (Figure 1) shows that chloroplatinic acid is completely reduced. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl62- ion peak over time, as shown in Figure 1. The ultraviolet absorption peak at 265 nm represents the absorption peak of PtCl62-. Extending, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The 195Pt NMR spectrum (Figure 2) shows that platinum atoms in the reduced state are formed. (Note: The 195Pt NMR of K2PtCl6 is at 0ppm, the peak of PtCl42- is at -1617ppm, and the 195Pt NMR peak of Pt solitary atoms is at -2755ppm. At the same time, the wide peak of Nat shift of platinum nanoparticles is not detected:- 35000ppm to 10000ppm, which means that H2PtCl6 is completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated). After 240h, the analysis results remain unchanged.

Example 2

Preparation of gold lone atoms in the solution: Mix 67ml of ethylene glycol diethyl ether, 67ml of ethanol, 10.2ml of water and 3ml of 0.0243mol/L chloroauric acid solution, then heat up, condense and reflux at 80℃ for 24 hours to make chlorine Gold acid is completely reduced. The ultraviolet-visible absorption spectrum (Figure 3) shows that the chloroauric acid is completely reduced. Analysis after 240h, the result remains unchanged. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the change of the absorption intensity of the AuCl4-ion peak with time, as shown in Figure 3. The ultraviolet absorption peak at 322nm represents the absorption peak of AuCl4-ion. With time The intensity of the UV absorption peak gradually decreases (from top to bottom), indicating that the chloroauric acid is gradually reduced). The ethanol and ethylene glycol diethyl ether in the solution can be removed by distillation under reduced pressure.

Example 3

Preparation of platinum lone atoms in the solution: Mix 60ml propylene glycol dimethyl ether, 60ml ethanol, 10ml water and 4.8ml chloroplatinic acid solution with a concentration of 0.018mol/L, then heat up, condense and reflux at 75℃ for 14 hours to make chloroplatinum The acid is completely reduced. The detection of UV and 195Pt NMR showed that the platinum solitary atom material was synthesized. The ultraviolet-visible absorption spectrum is shown in Figure 4. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl62- ion peak over time, as shown in Figure 4. The ultraviolet absorption peak at 265 nm represents the absorption peak of PtCl62-. Extending, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The 195Pt NMR spectrum is the same as Figure 2. Analysis after 240h, the result remains unchanged. (Note: The 195Pt NMR of K2PtCl6 is at 0 ppm, the peak of PtCl42- is at -1617 ppm, and the 195Pt NMR peak of Pt solitary atoms is at -2755 ppm. At the same time, the wide peak of Nat shift of platinum nanoparticles is not detected:- 35000ppm to 10000ppm, which means that H2PtCl6 is completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated at the same time).

Example 4

Preparation of platinum solitary atoms in the solution: Mix 60ml of ethylene glycol dimethyl ether, 60ml of ethanol, 10ml of water and 4.8ml of 0.018mol/L chloroplatinic acid solution, then heat up, condense and reflux at 75℃ for 16.5h to make Chloroplatinic acid is completely reduced. The detection of UV and 195Pt NMR showed that the platinum solitary atom material was synthesized. The UV-visible absorption spectrum (Figure 5) shows that chloroplatinic acid is completely reduced. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl62- ion peak over time, as shown in Figure 5. The ultraviolet absorption peak at 265 nm represents the absorption peak of PtCl62-. With time Prolonged, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The 195Pt NMR spectrum is the same as that shown in Figure 2. (Note: The 195Pt NMR of K2PtCl6 is at 0ppm, the peak of PtCl42- is at -1617ppm, and the 195Pt NMR peak of Pt solitary atoms is at -2755ppm. At the same time, the wide peak of Nat shift of platinum nanoparticles is not detected:- 35000ppm to 10000ppm, which means that H2PtCl6 is completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated at the same time).

Example 5

Preparation of platinum atoms in the solution: Mix 60ml of diethylene glycol dimethyl ether, 60ml of ethanol, 10ml of water and 4.8ml of chloroplatinic acid solution with a concentration of 0.018mol/L, then heat up, condense and reflux at 75℃ for 3.5h Complete reduction of chloroplatinic acid. The detection of UV and 195Pt NMR showed that the platinum solitary atom material was synthesized. The ultraviolet-visible absorption spectrum (Figure 6) shows that chloroplatinic acid is completely reduced. (Note: During the preparation process, the absorption intensity of the PtCl62- ion peak was analyzed with an ultraviolet spectrum analyzer over time, as shown in Figure 6. The ultraviolet absorption peak at 265nm represents the absorption peak of PtCl62-. With time Extending, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The 195Pt NMR spectrum is the same as that shown in Figure 2. (Note: The 195Pt NMR of K2PtCl6 is at 0ppm, the peak of PtCl42- is at -1617ppm, and the 195Pt NMR peak of Pt solitary atoms is at -2755ppm. At the same time, the wide peak of Nat shift of platinum nanoparticles is not detected:- 35000ppm to 10000ppm, which means that H2PtCl6 is completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated at the same time).

Example 6

Preparation of platinum atoms in the solution: Mix 50ml of ethylene glycol monomethyl ether, 50ml of ethanol, 7ml of water and 3.5ml of chloroplatinic acid solution with a concentration of 0.018mol/L, then heat up, condense and reflux at 75℃ for 9.3h. Chloroplatinic acid is completely reduced. The detection of UV and 195Pt NMR showed that the platinum solitary atom material was synthesized. The ultraviolet-visible absorption spectrum (Figure 7) shows that chloroplatinic acid is completely reduced. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl62- ion peak over time, as shown in Figure 7. The ultraviolet absorption peak at 265 nm represents the absorption peak of PtCl62-. Extending, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The 195Pt NMR spectrum is the same as that shown in Figure 2. (Note: The 195Pt NMR of K2PtCl6 is at 0ppm, the peak of PtCl42- is at -1617ppm, and the 195Pt NMR peak of Pt solitary atoms is at -2755ppm. At the same time, the wide peak of Nat shift of platinum nanoparticles is not detected:- 35000ppm to 10000ppm, which means that H2PtCl6 is completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated at the same time).

Example 7

Preparation of platinum atoms in the solution: Mix 75ml of butyl ether, 35ml of ethanol, 7.5ml of water and 3.5ml of 0.018mol/L chloroplatinic acid solution, then heat up, condense and reflux at 75℃ for 5h to complete the chloroplatinic acid reduction. The detection of UV and 195Pt NMR showed that the platinum solitary atom material was synthesized. The UV-visible absorption spectrum (Figure 8) shows that chloroplatinic acid is completely reduced. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl62- ion peak over time, as shown in Figure 5. The ultraviolet absorption peak at 265 nm represents the absorption peak of PtCl62-. With time Extending, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The 195Pt NMR spectrum is the same as that shown in Figure 2. (Note: The 195Pt NMR of K2PtCl6 is at 0ppm, the peak of PtCl42- is at -1617ppm, and the 195Pt NMR peak of Pt solitary atoms is at -2755ppm. At the same time, the wide peak of Nat shift of platinum nanoparticles is not detected:- 35000ppm to 10000ppm, which means that H2PtCl6 is completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated at the same time).

Example 8

Preparation of platinum atoms in the solution: 469ml ethanol, 6.7ml ethylene glycol diethyl ether (the ratio of ethanol to ethylene glycol diethyl ether is 130:1), and 0.1ml of water (the ratio of ethanol to water is 1500: 1) and 0.48ml concentration of 0.018mol / L chloroplatinic acid solution (mass composition ratio of ethanol to Pt of ^106: 1) mixed thoroughly, then heated, stirred at room temperature for 600 hours so that complete reduction of chloroplatinic acid . The detection of UV and ¹⁹⁵ Pt NMR showed that the platinum solitary atom material was synthesized. Analysis after 240h, the result remains unchanged. The UV-Vis spectrum has the same trend as the lines shown in Figure 1, and the spectrum is similar (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl ₆ ^2- ion peak over time. UV at 265 nm The absorption peak represents the absorption peak of PtCl ₆ ^2- . With the extension of time, the intensity of the UV absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction); its ¹⁹⁵ PtNMR spectrum The figure is the same as Figure 2. (Note: The ¹⁹⁵ Pt NMR of K ₂ PtCl ₆ is at 0 ppm, the peak of PtCl ₄ ^2- is at -1617 ppm, and the ¹⁹⁵ Pt NMR peak of Pt lone atoms is at -2755 ppm. At the same time, no platinum nanoparticles are detected. The extreme shift and wide peak: -35000ppm to 10000ppm, which shows that H ₂ PtCl _{6 is} completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated).

Example 9

Preparation of platinum solitary atoms in solution: mix 7ml ethanol, 67ml ethylene glycol diethyl ether (the ratio of ethanol to ethylene glycol diethyl ether is 0.18:1), and 1ml of water (the ratio of ethanol to water is 0.01: 1) and 4.8 ml of a 0.018mol/L chloroplatinic acid solution (the ratio of ethanol to Pt is 10:1) is thoroughly mixed, then the temperature is raised, and the chloroplatinic acid is completely reduced by stirring at room temperature for 600 hours. The detection of UV and ¹⁹⁵ Pt NMR showed that the platinum solitary atom material was synthesized. Analysis after 240h, the result remains unchanged. The UV-Vis spectrum has the same trend as that shown in Figure 1, and the spectrum is similar. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl ₆ ^2- ion peak over time, as shown in Figure 1. Show. The ultraviolet absorption peak at 265nm represents the absorption peak of PtCl ₆ ^2- . With the extension of time, the intensity of the ultraviolet absorption peak gradually weakened to disappear (from top to bottom), indicating that chloroplatinic acid was gradually reduced to complete reduction). The ¹⁹⁵ PtNMR spectrum is the same as Figure 2. (Note: The ¹⁹⁵ Pt NMR of K ₂ PtCl ₆ is at 0 ppm, the peak of PtCl ₄ ^2- is at -1617 ppm, and the ¹⁹⁵ Pt NMR peak of Pt lone atoms is at -2755 ppm. At the same time, no platinum nanoparticles are detected. The extreme shift and wide peak: -35000ppm to 10000ppm, which shows that H ₂ PtCl _{6 is} completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated).

Example 10

Preparation of platinum atoms in the solution: Mix 6.7ml ethanol, 6.7ml ethylene glycol diethyl ether, 1ml water and 4.8ml chloroplatinic acid solution with a concentration of 0.018mol/L, then heat up, stir at room temperature for 600 hours to make chlorine Platinum acid is completely reduced. The detection of UV and ¹⁹⁵ Pt NMR showed that the platinum solitary atom material was synthesized. Analysis after 240h, the result remains unchanged. The UV-Vis spectrum has the same trend as the spectrum shown in Figure 1, and the spectrum is similar. (Note: During the preparation process, use an ultraviolet spectrum analyzer to analyze the changes in the absorption intensity of the PtCl ₆ ^2- ion peak over time. The value at 265 nm The UV absorption peak represents the absorption peak of PtCl ₆ ^2- . As time goes by, the intensity of the UV absorption peak gradually weakens to disappear (from top to bottom), indicating that chloroplatinic acid is gradually reduced to complete reduction). The ¹⁹⁵ PtNMR spectrum is the same as Figure 2. (Note: The ¹⁹⁵ Pt NMR of K ₂ PtCl ₆ is at 0 ppm, the peak of PtCl ₄ ^2- is at -1617 ppm, and the ¹⁹⁵ Pt NMR peak of Pt lone atoms is at -2755 ppm. At the same time, no platinum nanoparticles are detected. The extreme shift and wide peak: -35000ppm to 10000ppm, which shows that H ₂ PtCl _{6 is} completely reduced and Pt lone atoms are generated, and no Pt nanoparticles are generated).

Example 11

Preparation of iridium atoms in the solution: Mix 67ml ethylene glycol diethyl ether, 67ml ethanol, 10.2ml water and 3ml chloroiridic acid solution with a concentration of 0.0243mol/L, then heat up, condense and reflux at 70℃ for 8 hours to make chlorine Iridium acid is completely reduced. The ultraviolet-visible absorption spectrum (Figure 9) shows that chloroiridic acid is completely reduced. Analysis after 240h, the result remains unchanged. (Note: The UV absorption peak of the green line represents the absorption peak of IrCl ₆ ^- ion. As time goes by, the intensity of the UV absorption peak gradually weakens to disappear (from top to bottom), indicating that chloroiridic acid is gradually reduced completely) .

Example 12

Preparation of gold lone atoms in the solution: Mix 67ml of ethylene glycol diethyl ether, 67ml of ethanol, 10.2ml of water and 3ml of 0.0243mol/L chloroauric acid solution, then heat up, condense and reflux at 80℃ for 24 hours to make chlorine Gold acid is completely reduced. The ultraviolet-visible absorption spectrum (the same trend as the lines shown in Figure 3) shows that the chloroauric acid is completely reduced. Analysis after 240h, the result remains unchanged. ((Note: The ultraviolet absorption peak at 322nm represents the absorption peak of AuCl ₄ ^- ions. During the preparation process, an ultraviolet spectrum analyzer is used to analyze the changes in the absorption intensity of AuCl ₄ ^- ions over time. As shown in Figure 3, As time goes by, the intensity of the UV absorption peak gradually weakens (from top to bottom), indicating that the chloroauric acid is gradually reduced.) The stainless steel sheet (2cm*3cm) is placed in the gold solitary atom solution prepared above , After 2 hours, a stainless steel sheet with gold-plated surface can be obtained.

Example 13

Preparation of gold solitary atom catalyst:

Take 150ml of the gold solitary atom solution prepared in Example 2 and add about 1.7g of titanium oxide to it. After removing the solvent, 1wt% Au/TiO ₂ can be obtained. High resolution spherical aberration correction scanning transmission electron microscope analysis (Figure 10, Figure 11. The magnification is different, and the selected area is different, the result is the same) It can be seen that Au exists in the form of a single atom in the obtained sample.

Example 14

Preparation of platinum solitary atom catalyst:

Take 150ml of the platinum solitary atom solution prepared in Example 1, and add about 1.7g of titanium oxide to it. After removing the solvent, 1wt% Pt/TiO ₂ can be obtained. The high-resolution spherical aberration correction scanning transmission electron microscope analysis (Figure 12) shows that , Pt exists as a single atom in the obtained sample.

Claims

A stable reduced noble metal lone atom material in a solution, characterized in that the material includes a reduced noble metal lone atom and a protective agent, or consists of a reduced noble metal lone atom and a protective agent, and the protective agent includes but is not limited to chain Like ether compounds.
A stable reduced precious metal lone atom material in a solution according to claim 1, wherein the chemical valence of the precious metal lone atom is not higher than the positive univalent, which is 0, or 0 and positive Monovalent mixing, preferably zero valence.
A stable reduced precious metal lone atom material in solution according to claim 1, wherein the precious metal lone atom contains one or more of platinum-based elements and post-platinum-based elements, including but It is not limited to one or more of palladium, rhodium, iridium, ruthenium, osmium, platinum, and gold.
The solitary noble metal atom material in a stable reduced state in a solution according to claim 1, wherein the solitary noble metal atom is a platinum atom or a gold atom.
A stable reduced precious metal lone atom material in a solution according to claim 1, wherein the protective agent includes but is not limited to one or two or more of compounds with ether structure; The protective agent includes, but is not limited to, one or two or more of compounds with glycol ether structure; preferably, it includes but is not limited to one or two or more of compounds with glycol ether and propylene glycol ether structure.
A stable reduced precious metal lone atom material in a solution according to claim 1 or 5, wherein the protective agent comprises but not limited to ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethyl acetate Glycol diethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, One or more of n-butyl ether.
A stable reduced noble metal lone atom material in a solution according to claim 1, wherein the molar ratio of the noble metal lone atom to the protective agent is less than or equal to 1:1, and the preferred range is 10 to 10 6 .
A stable reduced precious metal lone atom material in solution according to claim 1 or 7, characterized in that: the concentration of the precious metal lone atom is greater than 0 to 1 mol/L, and the preferred range is 0.01 to 50 mmol/L L.
A method for preparing a stable reduced precious metal solitary atom material in a solution according to any one of claims 1-8, characterized in that: the composition of the material during the preparation process includes, but is not limited to, chain ether compounds, highly oxidized Precursors of precious metal compounds, reducing agents, or including but not limited to chain ether compounds, precursors of precious metal compounds in high oxidation states, reducing agents, and water;

All the components are fully mixed into a liquid system according to the required ratio, and a stable precious metal monoatomic solution can be obtained after the reaction.
The method for preparing a stable reduced noble metal lone atom material in solution according to claim 9, characterized in that:

The material preparation process can include one or two or three of the following three situations to make the mixed system liquid;

The first type: water can be included in the composition, the mass concentration range of water is 0-70%, and water can be used as a solvent composition;

The second type: when the chain ether compound in the composition contains a protective agent that is liquid at room temperature, the liquid chain ether compound can be used as a solvent composition;

The third type: when the reducing agent in the composition contains a reducing agent that is liquid at room temperature, the liquid reducing agent can be used as a solvent composition.
A method for preparing a stable reduced noble metal solitary atom material in a solution according to claim 9, wherein the high-oxidation state noble metal compound precursor includes but is not limited to the high-oxidation state platinum compound precursor ( Precious metal positive divalent, positive tetravalent one or two), high oxidation state palladium compound precursor (noble metal positive divalent, positive tetravalent one or two), high oxidation state rhodium compound precursor (precious metal positive three Valence), high oxidation state iridium compound precursor (one or two of noble metal positive trivalent and positive tetravalent), high oxidation state ruthenium compound precursor (noble metal positive trivalent), high oxidation state osmium compound precursor ( One or two or more of the noble metal positive divalent, positive trivalent, positive tetravalent) or high oxidation state gold compound precursor (noble metal positive trivalent).
The method for preparing a stable reduced noble metal lone atom material in a solution according to claim 9, characterized in that: the high oxidation state noble metal compound precursor includes but is not limited to: chloroauric acid, sodium chloroaurate , Potassium chloroaurate, ammonium chloroaurate, chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, platinous chloride, platinum chloride, potassium chloroplatinate, sodium chloroplatinate, diethylamine chloride Platinum, platinum nitrate, 1,5-cyclooctadiene platinum dichloride, potassium trichloro(ethylene) platinum, dichlorotetraammine platinum, dinitrile phenyl dichloroplatinum, bis(phosphite trichloride) Phenyl ester) platinum dichloride, ammonium tetrachloroplatinate, ammonium chloropalladate, sodium chloropalladate, potassium chloropalladate, ammonium chlororhodate, sodium chlororhodium, potassium chlororhodate, chloroiridic acid, chloroiridium One or more of sodium, potassium chloroiridate and ammonium chloroiridate.
A method for preparing a stable reduced precious metal lone atom material in a solution according to claim 9, wherein the reducing agent includes but not limited to alcohol compounds, glucose, formic acid, citric acid, tartaric acid, ascorbic acid, One or more mixtures of hydrazine hydrate or borohydride.
A method for preparing a stable reduced noble metal lone atom material in a solution according to claim 13, wherein the alcohol compound reducing agent includes but not limited to methanol, ethanol, propanol, isopropanol, normal One or a mixture of two or more of butanol, isobutanol, sec-butanol, tert-butanol, ethylene glycol, and glycerol.
A method for preparing a stable reduced noble metal lone atom material in a solution according to claim 9, wherein the reaction temperature ranges from room temperature to 200°C, preferably from 50 to 100°C.
A method for preparing a stable reduced noble metal lone atom material in a solution according to claim 9, wherein the reaction time ranges from 0.5h to 600h, preferably 4h to 50h.
A method for preparing a stable reduced noble metal lone atom material in a solution according to claim 9, wherein the ratio of the amount of the reducing agent and the high-oxidation noble metal precursor substance varies in the range of 1 to 10 7 , preferably 10 2 -10 6 .