MATERIAL COMPRISING PRECIOUS METAL ISOLATED ATOMS STABLE IN SOLUTION

Abstract

This invention provides isolated noble metal atoms stabilized in a solution and a method in synthesizing such materials. A block copolymer containing siloxane groups and polyether groups is used as a protective agent to stabilize the reduced isolated noble metal atoms. An aqueous solution containing reducing agents is used as a solvent in the preparation of the material. The weight ratio of precious metal to the protective agent is arbitrary. The invention uses special protective agents to avoid the aggregation of primary isolated atoms to nanoparticles in the synthesis process. The reduced atomic material is distinguished from the known metal nanoparticles and can be used in energy materials, pharmaceutical synthesis, medical materials, catalyst preparation etc. The atomic material provides the building block for the synthesis of number-controlled metal clusters or nanomaterials with the same or different metals.

Claims

1. A material comprising solution-stable isolated noble metal atoms and a protective agent.

2. The material of claim 1, wherein the isolated noble metal atoms are platinum group elements or post platinum group elements; the platinum group elements are selected from the group consisting of palladium, rhodium, ruthenium, iridium, ruthenium, and platinum; the post platinum group elements are selected from the group consisting of silver and gold.

3. The material of claim 1, wherein the isolated noble metal atoms are platinum atoms; and .sup.195Pt NMR of the material is between ?2600 and ?2800 ppm.

4. The material of claim 1, wherein the protective agent is a block copolymer containing siloxane groups and hydrophilic polymers.

5. The material of claim 1, wherein the protective agent is a block copolymer containing siloxane groups and polyether groups.

6. The material of claim 1, wherein the block copolymer containing siloxane groups and polyether groups is a polysiloxane-polyglycol copolymer.

7. The material of claim 1, wherein the polysiloxane-polyglycol copolymer is polysiloxane-polyethyleneglycol copolymer having a structural formula as follows ##STR00002##

8. The material of claim 1, wherein the weight ratio of the isolated noble metal atoms to the protective agent is arbitrary.

9. A method for preparing a material comprising isolated noble metal atoms in a solution, comprising: mixing a block copolymer containing siloxane groups and polyether groups, a noble metal compound precursor, a reducing agent, and water sufficiently; and conducting a reaction at ?30-200? C. for 0.5-200 hours to obtain the isolated noble metal atoms in the solution; wherein the molar ratio of the amount of the reducing agent to the noble metal compound precursor is from (1-10.sup.7):1; and the ratio of the amount of the reducing agent to water is from 1:10.sup.5 to 30:1.

10. The method of claim 9, wherein the noble metal precursor is selected from the group consisting of chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, and platinum chloride. Platinum chloride, diethylamine platinum chloride, platinum nitrate, 1,5-cyclooctadiene platinum dichloride, trichloro-(ethylene) potassium platinate, platinum tetraammine platinum, dinitrile phenyl one of platinum chloride, bis(triphenyl phosphite) platinum dichloride, and ammonium tetrachloroplatinate.

11. The method of claim 9 wherein the reducing agent is selected from the group consisting of alcohol compounds, glucose, formic acid, citric acid, tartaric acid, ascorbic acid, hydrazine hydrate, and borohydride.

12. The method of claim 11 wherein the alcohol compounds are selected from the group consisting of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, butanol, tert-butanol, ethylene glycol, and glycerol.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1. UV-visible spectra of Examples 1, 2, 3, 4, 5, and 6.

[0023] FIG. 2. 195 Pt NMR spectrum of Examples 1, 2, 3, 4, 5, and 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The present invention is further described in detail below by taking an isolated platinum atoms material which is stable in solution as an example. The protection of the patent is not limited to the specific embodiments.

Example 1

[0025] Preparation of isolated platinum atoms in solution: 0.6465 g polyethylene glycol-polysiloxane block copolymer, 135 ml ethanol, 10.2 ml water and 4.8 ml chloroplatinic acid solution with a concentration of 0.018404 mol/L are thoroughly mixed, and then the temperature is raised. The chloroplatinic acid was completely reduced under reflux condensation at 105? C. for 3 hours. It was verified by UV-Vis and .sup.195Pt NMR that a isolated platinum atomic material was synthesized. The UV-Vis absorption spectrum (FIG. 1) shows that chloroplatinic acid is completely reduced. (Note: The UV absorption peak at 265 nm represents the absorption peak of PtCl.sub.6.sup.2? ion, and the disappearance of the UV absorption peak indicates that chloroplatinic acid is completely reduced.) .sup.195Pt NMR spectrum (FIG. 2) indicates: platinum atoms in the reduced state form. (Note: K.sub.2PtCl.sub.6 has a .sup.195Pt NMR at 0 ppm, PtCl.sub.4.sup.2? has a peak at ?1617 ppm, and isolated Pt atoms have a .sup.195Pt NMR peak at ?2680 ppm. At the same time, no Knight Shift of platinum nanoparticles is detected: ?35000 ppm to 10000 ppm, which means that H.sub.2PtCl.sub.6 is completely reduced and isolated Pt atoms is formed, and no Pt nanoparticles are produced.)

Example 2

[0026] Preparation of isolated platinum atoms in solution: 0.6465 g polyethylene glycol-polysiloxane block copolymer, 4.05 mg ethanol (the ratio of the amount of ethanol to chloroplatinic acid is 1:1), 145 ml water and 4.8 ml chloroplatinic acid solution with a concentration of 0.018404 mol/L are thoroughly mixed (the ratio of the amount of ethanol to water was 1:10.sup.5), and the temperature was raised. The mixture is refluxed and condensed at 105? C. for 3 hours to completely reduce chloroplatinic acid. It was verified by UV-Vis and .sup.195Pt NMR that a isolated platinum atomic material was synthesized. The UV-visible spectrum is shown in FIG. 1, and the .sup.195Pt NMR spectrum is shown in FIG. 2.

Example 3

[0027] Preparation of isolated platinum atoms in solution: 0.6465 g polyethylene glycol-polysiloxane block copolymer, 148.5 ml ethanol, 1.02 ml water and 0.48 ml chloroplatinic acid solution with a concentration of 0.018404 mol/L are thoroughly mixed (the ratio of the amount of ethanol to water is 30:1), and the temperature was raised. The mixture was condensed and refluxed at 105? C. for 3 hours to completely reduce chloroplatinic acid. It was verified by UV-Vis and .sup.195Pt NMR that a isolated platinum atomic material was synthesized. The UV-visible spectrum is shown in FIG. 1, and the .sup.195Pt NMR spectrum is shown in FIG. 2.

Example 4

[0028] Preparation of isolated platinum atoms in solution: 0.6465 g polyethylene glycol-polysiloxane block copolymer, 882 g ethanol (1.14 L, ethanol addition amount is 10.sup.7 times of that of chloroplatinic acid), 100.2 ml water and 4.8 ml chloroplatinic acid solution with a concentration of 0.018404 mol/L are thoroughly mixed, and the temperature was raised. The mixture was condensed and refluxed at 105? C. for 3 hours to completely reduce chloroplatinic acid. It was verified by UV-Vis and .sup.195Pt NMR that a isolated platinum atomic material was synthesized. The UV-visible spectrum is shown in FIG. 1, and the .sup.195Pt NMR spectrum is shown in FIG. 2.

Example 5

[0029] Preparation of isolated platinum atoms in solution: 1719.92 g polyethylene glycol-polysiloxane block copolymer, 1000 ml ethanol, 100 ml water and 4.8 ml chloroplatinic acid solution with a concentration of 0.018404 mol/L are thoroughly mixed. (the weight ratio of isolated Pt atoms to protective agent is 0.001%). The mixture was condensed and refluxed at 105? C. for 3 hours to completely reduce chloroplatinic acid. It was verified by UV-Vis and .sup.195Pt NMR that a isolated platinum atomic material was synthesized. The UV-visible spectrum is shown in FIG. 1, and the .sup.195Pt NMR spectrum is shown in FIG. 2.

Example 6

[0030] Preparation of isolated platinum atoms in solution: 0.0344 g polyethylene glycol-polysiloxane block copolymer, 135 ml ethanol, 10.2 ml water and 4.8 ml chloroplatinic acid solution with a concentration of 0.018404 mol/L are thoroughly mixed (the weight ratio of isolated Pt atoms to protective agent is 50%). The mixture was condensed and refluxed at 105? C. for 3 hours to completely reduce chloroplatinic acid. It was verified by UV-Vis and .sup.195Pt NMR that a isolated platinum atomic material was synthesized. The UV-visible spectrum is shown in FIG. 1, and the .sup.195Pt NMR spectrum is shown in FIG. 2.