GATED ELECTRODES FOR ELECTROLYSIS AND ELECTROSYNTHESIS

• US 20080116080A1
• Filed: 11/20/2007
• Published: 05/22/2008
• Est. Priority Date: 11/20/2006
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Shen, Likun, Mishra, Umesh K., Lal, Rakesh K.
• Granted Patent: US 8,147,659 B2
• Time in Patent Office: Days
• US Class Current: 205/334
• CPC Class Codes: C25B 1/55 Photoelectrolysis
• CPC Class Codes: C25B 11/075 consisting of a single catalytic element or catalytic compound
• CPC Class Codes: Y02P 20/133 Renewable energy sources, e.g. sunlight

Abstract

A gated electrode structure for altering a potential and electric field in an electrolyte near at least one working electrode is disclosed. The gated electrode structure may comprise a gate electrode biased appropriately with respect to a working electrode. Applying an appropriate static or dynamic (time varying) gate potential relative to the working electrode modifies the electric potential and field in an interfacial region between the working electrode and the electrolyte, and increases electron emission to and from states in the electrolyte, thereby facilitating an electrochemical, electrolytic or electrosynthetic reaction and reducing electrode overvoltage/overpotential.

Claims

1. A gated electrode structure for altering electrode overvoltage, comprising:

(a) at least one working electrode for transferring charge to or from an electrolyte; and

(b) at least one gate electrode appropriately spaced from the working electrode, so that a relative bias between the gate electrode and the working electrode alters electric charge, field and potential in an interfacial region between the working electrode and the electrolyte and modifies the working electrode'"'"'s potential.

2. The gated electrode structure of claim 1, comprising of an array of two or more of the working electrodes.

3. The gated electrode structure of claim 1, wherein the working electrode is a cathode, and a potential on the gate electrode is a static or dynamic bias which affects the electric charge, field and potential at the cathode.

4. The gated electrode structure of claim 1, wherein an appropriate gate potential is applied relative to the working electrode to modify the electric field and potential along one or more surfaces of the working electrode and to increase charge transfer between the working electrode and states in the electrolyte, thereby facilitating electrochemical, electrolytic or electrosynthetic reactions in the electrolyte.

5. The gated electrode structure of claim 1, wherein the gate electrode can act as both a gating electrode and a counter electrode.

6. The gated electrode structure of claim 1, wherein the gate electrode encircles the working electrode.

7. The gated electrode structure of claim 1, wherein the working electrode or gate electrode are overhanging or suspended.

8. The gated electrode structure of claim 1, wherein the working electrode and gate electrode are made on two different substrates and suitably appositioned.

9. The gated electrode structure of claim 1, wherein the gate electrode and working electrode are coplanar and interdigitated.

10. The gated electrode structure of claim 9, wherein the gate electrode and working electrode are on a semiconductor substrate.

11. The gated electrode structure of claim 10, wherein the semiconductor substrate is polarized.

12. The gated electrode structure of claim 9, wherein the working electrode comprises one or more stripe electrodes.

13. The gated electrode structure of claim 1, wherein the gate electrode and the working electrode are separated by an insulating layer to form a Metal-Insulator-Metal (MIM) or Metal-Insulator-Semiconductor (MIS) structure, and the working electrode is a metal or a semiconductor.

14. The gated electrode structure of claim 1, wherein the relative bias between the working electrode and gate electrode is floating, static or time-varying.

15. The gated electrode structure of claim 1, wherein the electrodes are interchanged to function either as an anode, cathode, or gate, including a remote gate.

16. The gated electrode structure of claim 15, wherein more than one of the electrodes functions as a gate, and each of the gates are at different potentials.

17. The gated electrode structure of claim 15, wherein more than one of the electrodes functions as a cathode.

18. The gated electrode structure of claim 15, wherein more than one of the electrodes functions as an anode.

19. The gated electrode structure of claim 15, where the bias applied to any of the electrodes is steady state or time varying.

20. An electrochemical or photo-electrochemical cell using the gated electrode structure of claim 1 to reduce overvoltages.

21. A method for altering electrochemical, electrolytic, or electrosynthetic reactions and altering overvoltages, comprising:

(a) modifying an electric field and potential in an interfacial region between an electrolyte and one or more electrodes to create conditions to facilitate transfer of electrons between the electrolyte and the electrodes.

22. The method of claim 21, wherein the electric charge, field and potential are modified by using a gated electrode comprising at least one gate and at least one working electrode, and a relative bias is applied between the gate and the working electrode.

23. The method of claim 22, wherein the modifying step comprises using a fringing field between the gate and the working electrode, which form a Schottky contact or heterojunction.

24. Electrochemistry, electrolysis or electrosynthesis performed using the method of claim 21.

25. A cell with a plurality of gated electrodes to reduce overvoltages at both an anode and a cathode of the cell, wherein an electrolytic reaction occurs at one of the gated electrodes and an electrosynthetic reaction occurs at another of the gated electrodes.