Redox-switchable materials

• US 7,435,362 B2
• Filed: 12/30/2002
• Issued: 10/14/2008
• Est. Priority Date: 12/28/2001
• Status: Expired due to Fees

• Current Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Original Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Inventors: Bell, Thomas W., Gillett, Stephen L., Muraoka, Masahiro
• Primary Examiner(s): Zimmer; Marc S
• Application Number:
  US10/500,433
• Publication Number:
  US 20050227071A1
• Time in Patent Office: 2,115 Days
• Field of Search: None
• US Class Current: 252/582
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01M 14/005 Photoelectrochemical storage cells light sensitive devices H01G9/20, semiconductors sensitive to light H01L31/00
• CPC Class Codes: H10K 10/701 Organic molecular electronic devices
• CPC Class Codes: H10K 85/331 Metal complexes comprising an iron-series metal, e.g. Fe, Co, Ni
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

The invention relates to redox-switchable material comprising a redox-active moiety adsorbed, bonded or both, to a semiconductor material. Among the preferred redox-active moieties disclosed herein are ferrocenes, acridines, and quinones though any such moiety may be employed. The redox-switchable material of this invention may be used to selectively remove one or more selected solutes from an aqueous solution wherein adsorption/complexation of the solute is influenced by the oxidation state of the redox-active moiety. In an alternative embodiment, inclusion moieties that are covalently bound to the redox-active moiety are employed to achieve selective complexation of the desired solute. Other possible applications of the disclosed materials are photoerasable writing media, electrochromic or photochromic materials, catalysis, and solar energy storage.

Claims

1. A redox-switchable material which comprises:

a solid semiconductor; and

a redox-active moiety adsorbed, bonded or both to the surface of the solid semiconductor,

wherein the redox-active moiety also comprises a selective complexing moiety.

2. The material of claim 1 wherein the selective complexing moiety is a cryptand.

3. The material of claim 1 wherein the selective complexing moiety is a crown ether.

4. The material of claim 1 wherein the redox-active moiety comprises a ferrocene.

5. The material of claim 1 wherein the redox-active moiety comprises an acridine.

6. The material of claim 1 wherein the redox-active material comprises a quinone.

7. A reversible redox system which comprises a redox-switchable material of claim 1 in contact with a source of electrons.

8. The reversible redox system of claim 7 also in contact with an electron acceptor.

9. A photoerasable writing media comprising the redox-switchable material of claim 1.

10. A electrochromic or photochromic material which comprises the redox-switchable material of claim 1.

11. A catalyst which comprises the redox-switchable material of claim 1.

12. A method for storage of light energy which comprises the step of employing a redox-switchable material of claim 1 which comprises a redox-active moiety adsorbed, bonded or both to the surface of a photoactive solid semiconductor to mediate or catalyze a chemical reaction.

13. The method of claim 12 wherein the redox switchable moiety is selected from the group consisting of a cryptand and a crown ether.

14. The material of claim 1 wherein the semiconductor is hydrophobic.

15. The material of claim 14 wherein the redox-active moiety is covalently bonded to the surface of the hydrophobic semiconductor.

16. The material of claim 15 wherein the redox-active moiety is covalently bonded to the surface of the hydrophobic semiconductor through a linker group.

17. The material of claim 16 wherein the linker group is a hydrocarbon linker group.

18. The reversible redox system of claim 7 further comprising a light source to irradiate the semiconductor to generate electron-hole pairs.

19. The reversible system of claim 7 in contact with an aqueous solution containing an oxidizing agent wherein the redox-active moiety in its oxidized state can be photoreduced upon irradiation of the semiconductor and in its reduced state can be oxidized by the oxidizing agent.

20. The system of claim 19 wherein the oxidizing agent is oxygen.

21. The system of claim 20 wherein the oxygen is present during photoreduction of the redox-active moiety.

22. The method of claim 12 wherein the redox-active moiety comprises a ferrocene.

23. The method of claim 12 wherein the semiconductor is hydrophobic.

24. The method of claim 23 wherein the redox-active moiety is covalently bonded to the surface of the hydrophobic semiconductor.

25. A redox-switchable material which comprises:

a solid semiconductor; and

a redox-active moiety adsorbed, bonded or both to the surface of the solid semiconductor, wherein the semiconductor is hydrophobic.

26. The material of claim 25 wherein the redox-active moiety is covalently bonded to the surface of the hydrophobic semiconductor.

27. The material of claim 26 wherein the redox-active moiety is covalently bonded to the surface of the hydrophobic semiconductor through a linker group.

28. The material of claim 27 wherein the linker group is a hydrocarbon linker group.

29. The material of claim 25 wherein the hydrophobic solid semiconductor comprises particles of semiconductor coated with surfactant.

30. The material of claim 25 wherein the hydrophobic solid semiconductor comprises particles of semiconductor covalently bonded to hydrophobic moieties.

31. A reversible redox system which comprises a redox-switchable material in contact with a source of electrons and further comprising a light source to irradiate the semiconductor to generate electron-hole pairs, wherein the redox-switchable material comprises:

a solid semiconductor; and

a redox-active moiety adsorbed, bonded or both to the surface of the solid semiconductor.

32. The reversible system of claim 31 in contact with an aqueous solution containing an oxidizing agent wherein the redox-active moiety in its oxidized state can be photoreduced upon irradiation of the semiconductor and in its reduced state can be oxidized by the oxidizing agent.

33. The system of claim 32 wherein the oxidizing agent is oxygen.

34. The system of claim 33 wherein the oxygen is present during photoreduction of the redox-active moiety.