Flow-Based Cathode with Immobilized Non-Platinum Transition Metal Redox Catalyst

Patent metadata

Field	Value
Publication number	US-2019131650-A1
Application number	US-201816170231-A
Country	US
Kind code	A1
Filing date	Oct 25, 2018
Priority date	Oct 31, 2017
Publication date	May 2, 2019
Grant date	—

Abstract

Cathodic half-cells for the electrocatalytic reduction of oxygen are disclosed. Within the half-cell, a redox catalyst containing one or more non-Pt transition metals attached to a solid support (i.e., a “heterogenized” non-Pt transition metal-containing catalyst) is separate from and not in direct contact with the cathode electrode. In use, both the cathode electrode and the redox catalyst are in contact with an electrolyte solution that also contains a redox mediator. The oxidized form of the redox mediator is reduced at the cathode electrode, and the resulting reduced form migrates to the redox catalyst, where the mediator is oxidized back to its oxidized form, while oxygen is simultaneously reduced. The oxidized form of the redox mediator then migrates back to the cathode electrode, where the process is repeated. The disclosed cathodic half-cells can be used in combination with an anode half-cell in a variety of different electrochemical cells, such as in fuel cells or in electrosynthetic cells.

First claim

1 . A cathode half-cell comprising:
a heterogeneous redox catalyst comprising one or more non-Pt transition metals attached to a solid support, and a cathode electrode; wherein the cathode electrode and the heterogeneous redox catalyst are both in contact with an electrolyte solution, and wherein the heterogeneous redox catalyst is not in direct contact with the cathode electrode; and wherein the electrolyte solution contains a soluble redox mediator capable of transporting electrons between the cathode electrode and the redox catalyst.

2 . (canceled)

3 . The cathode half-cell of claim 2 , wherein the electrolyte solution is acidic.

4 . The cathode half-cell of claim 1 , wherein the electrolyte solution comprises a redox mediator comprising at least one carbon atom and that is capable of transferring or accepting electrons and protons while undergoing reduction or oxidation.

5 . The cathode half-cell of claim 1 , wherein the one or more non-Pt transition metals include one or more first-row transition metals.

6 . The cathode half-cell of claim 1 , wherein the one or more non-Pt transition metals are selected from the group consisting of cobalt (Co), manganese (Mn), iron (Fe), copper (Cu), vanadium (V), molybdenum (Mo), tungsten (W), nickel (Ni), and chromium (Cr).

7 . The cathode half-cell of claim 1 , wherein the solid support comprises a carbon-based material, silica, a metal oxide, a chalcogenide, a nitride, an oxynitride, a carbide, or a boride.

8 . The cathode half-cell of claim 1 , wherein the heterogeneous redox catalyst comprises a non-Pt transition metal-macrocycle complex or a non-Pt transition metal-pseudomacrocycle complex attached to the solid support.

9 . (canceled)

10 . The cathode half-cell of claim 8 , wherein the non-Pt transition metal-macrocyclic complex or non-Pt transition metal-pseudomacrocycle complex comprises multidentate N-, O-, B-, C-, and/or S-donor ligands.

11 . The cathode half-cell of claim 10 , wherein the non-Pt transition metal-macrocycle complex is an N4 complex.

12 . (canceled)

13 . The cathode half-cell of claim 1 , wherein the heterogeneous redox catalyst comprises one or more non-Pt transition metals on a nitrogen-doped carbon support (an M-N-C catalyst).

14 . The cathode half-cell of claim 13 , wherein the nitrogen-doped solid support comprises one or more nitrogen-containing precursors deposited on the solid support alongside the one or more non-Pt transition metals.

15 .- 19 . (canceled)

20 . The cathode half-cell of claim 1 , further comprising a reactor that is separated from the cathode electrode within which the heterogeneous redox catalyst is located.

21 .- 28 . (canceled)

29 . The cathode half-cell of claim 1 , wherein the cathode half-cell comprises a redox mediator comprising at least one carbon atom and is capable of transferring or accepting electrons and protons while undergoing reduction or oxidation, and wherein the reduced form of the redox mediator is selected from the group consisting of a substituted dihydroxybenzene and a substituted hydroxylamine.

30 . The cathode half-cell of claim 29 , wherein the substituted dihydroxybenzene is a substituted 1,2-dihydroxybenzene or a substituted 1,4-dihydroxybenzene.

31 . The cathode half-cell system of claim 29 , wherein in one or more of the hydrogen atom substitutions in the substituted dihydroxybenzene, the hydrogen atom is substituted with a substituent group that is independently selected from the group consisting of an alkyl with less than ten carbons, an aryl, fused aryl, a heterocycle, an alkenyl, an alkynyl, a cycloalkyl, an amine, a protonated amine, a quaternary amine, sulfate, a sulfonate, a mercaptoalkylsulfonate, sulfonic acid, phosphate, a phosphonate, a phosphinate, a ketone, an aldehyde, an oxime, a hydrazine, a nitrone, an ether, an ester, a halide, a nitrile, a carboxylate, an amide, a thioether, a fluoroalkyl, a perfluoroalkyl, a pentafluorosulfanyl, a sulfonamide, a sulfonic ester, an imide, carbonate, a carbamate, a urea, a sulfonylurea, an azide, a sulfone, a sulfoxide, an amine oxide, phosphine oxide, a quaternary phosphonium, a quaternary borate, a siloxane, or a nitro and combinations of two or more thereof, wherein at least one of the substituents is charged to increase the aqueous solubility of the dihydroxybenzene.

32 . (canceled)

33 . The cathode half-cell of claim 29 , wherein in one or more of the nitrogen-bound hydrogen atom substitutions in the substituted hydroxylamine, the hydrogen atom is substituted with a substituent group that is independently selected from the group consisting of an alkyl with less than ten carbons, an aryl, a cycloalkyl, and a bicycloalkyl, wherein both nitrogen-bound hydrogen atoms can be substituted with the same or different substituents, and wherein the two substituents may be linked, forming a heterocycle.

34 . The cathode half-cell of claim 33 , wherein one or more of the substituent groups further comprises an alkyl with less than ten carbons, an aryl, a heterocycle, an alkenyl, an alkynyl, a cycloalkyl, an amine, a protonated amine, a quaternary amine, sulfate, a sulfonate, a mercaptoalkylsulfonate, sulfonic acid, phosphate, a phosphonate, a phosphinate, a ketone, an aldehyde, an oxime, a hydrazine, a nitrone, an ether, an ester, a halide, a nitrile, a carboxylate, an amide, a thioether, a fluoroalkyl, a perfluoroalkyl, a pentafluorosulfanyl, a sulfonamide, a sulfonic ester, an imide, carbonate, a carbamate, a urea, a sulfonylurea, an azide, a sulfone, a sulfoxide, an amine oxide, phosphine oxide, a quaternary phosphonium, a quaternary borate, a siloxane, a nitro, or combinations of two or more thereof on the same or on different positions on the substituent, and wherein at least one of the substituents is charged to increase the aqueous solubility of the hydroxylamine.

35 . An electrochemical cell comprising the cathode half-cell of claim 1 and an anode half-cell comprising an anode electrode.

36 .- 47 . (canceled)

48 . A method of producing a desired chemical product, comprising contacting the electrocatalyst of the anode half-cell of the electrochemical cell of claim 35 with a reductant that is a precursor of the desired chemical product, and contacting the cathode half-cell of the electrochemical cell of any of claim 35 with O 2 , whereby the precursor is oxidized to the desired product, and O 2 is reduced.

49 . A method of producing electricity, comprising contacting the electrocatalyst of the anode half-cell of the electrochemical cell of claim 35 with a fuel, and contacting the cathode half-cell of the electrochemical cell of claim 35 with O 2 , whereby the fuel is oxidized, the O 2 is reduced, and electricity is produced.

Assignees

• Wisconsin Alumni Res Found

Inventors

• Stahl Shannon S
• Biswas Sourav
• Anson Colin W
• Preger Yuliya
• Root Thatcher

Classifications

• H01M2300/0005

  Acid electrolytes · CPC title

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M4/8605

  Porous electrodes · CPC title

• H01M2004/8689

  Positive electrodes · CPC title

• H01M4/9083

  on carbon or graphite · CPC title