# US 11,111,587 B2 · Chemically resistant, oxidic electrocatalyst for oxygen evolution during alkaline water electrolysis

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- Number: US 11,111,587 B2
- Document ID: US11111587B2
- Status: Granted
- Kind: B2
- Application number: 16/499,537
- Filed: 2018-03-28
- Published: 2020-02-06
- Granted: 2021-09-07
- Earliest claimed: 2017-03-29
- Assignees: Forschungszentrum Julich GmbH
- Applicants: Forschungszentrum Jülich GmbH
- Inventors: Daniel Bick; Ilia Valov; Theodor Schneller; Rainer Waser
- Web page: https://patentgrep.com/patent/US11111587B2

## CPC

- C25B 11/0773: {of the perovskite type}
- B01J 21/063: {Titanium; Oxides or hydroxides thereof}
- B01J 23/002: {Mixed oxides other than spinels, e.g. perovskite}
- B01J 23/78: with alkali- or alkaline earth metals
- B01J 35/19: {Catalysts containing parts with different compositions}
- C25B 1/04: by electrolysis of water
- C25B 11/051: Electrodes formed of electrocatalysts on a substrate or carrier
- C25B 11/052: Electrodes comprising one or more electrocatalytic coatings on a substrate
- C25B 11/069: consisting of at least one single element and at least one compound; consisting of two or more compounds
- H01M 4/8825: {Methods for deposition of the catalytic active composition}
- H01M 4/885: {followed by reduction of the catalyst salt precursor}
- H01M 4/8882: {Heat treatment, e.g. drying, baking}
- H01M 4/9016: {Oxides, hydroxides or oxygenated metallic salts}
- H01M 12/06: with one metallic and one gaseous electrode
- H01M 2004/8684: {Negative electrodes}
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY

## Abstract

Disclosed is a biphasic electrically conductive perovskite-based mixed oxide of the structure ABO3 with A=Ba, and B=Co, comprising additionally 5-45 at %, preferably 15 to 30 at %, particularly preferably 25 at % Co3O4 (at % Co based on the total number of Co atoms in the perovskite ABO3 and 0.5 to 0.3 at %, preferably 1 to 2.5 at %, particularly preferably 2 at % (wherein the at % are referred to the total number of B cations in the perovskite ABO3) Ti as dopant. Preferably, the mixed oxide has the stoichiometric formula BaCo1−xTixO3−δ:Co3O4 with x=0.005 to 0.03, preferably x=0.01 to 0.025, particularly preferably x=0.02, wherein δ defines the vacancies in the perovskite structure and is in the range of about 0.1 to 0.8, preferably 0.3 to 0.7, particularly preferably about 0.5 to 0.6. Further disclosed are a catalyst and an anode comprising the mixed oxide, the use of the catalyst in alkaline water electrolysis or in metal-air batteries, the use of the mixed oxide for the preparation of an anode for alkaline water electrolysis or metal-air batteries. Further, manufacturing processes for a precursor solution for the mixed oxide and for the inventive anode are disclosed, as well as an amorphous mixed oxide having a Co:Ba ratio of about 2:1 and a TTB (Tetragonal Tungsten-Bronze)-like near structure obtainable by using the mixed oxide according to the invention as catalyst in the oxygen evolution reaction of alkaline water electrolysis, whereby said amorphous product is formed by leaching out Ba.

## Claims

### Claim 1

A perovskite-based, electrically conductive, biphasic mixed oxide having a structure ABO3 with A=Ba and B=Co, comprising additionally 5-45 at %, CO3O4 wherein the at % of Co is based on the total number of the Co-atoms in the perovskite ABO3 and 0.5 to 3 at % Ti as dopant wherein the at % of Ti is based on the total number of Co-cations in the perovskite ABO3.

### Claim 2 (depends on 1)

The perovskite-based, electrically conductive, biphasic mixed oxide according to claim 1 having the structure BaCo1−xTixO3−δ:Co3O4 with x=0.005 to 0.03, wherein δ defines the oxygen vacancies in the perovskite structure and is in the range of about 0.1 to 0.8.

### Claim 3 (depends on 2)

The perovskite-based, electrically conductive, biphasic mixed oxide according to claim 2 having a formula BaCo0.98Ti0.02O3−δ:Co3O4.

### Claim 4 (depends on 1)

A catalyst for the oxygen evolution reaction in an alkaline environment comprising the perovskite-based, electrically conductive, biphasic mixed oxide according to claim 1.

### Claim 5 (depends on 1)

An anode comprising the perovskite-based, electrically conductive biphasic mixed oxide according to claim 1, and an electrically conductive substrate material.

### Claim 6 (depends on 5)

The anode according to claim 5, wherein the substrate material is a silicon wafer provided with a TiO2 adhesive layer and a polycrystalline Pt(111) layer.

### Claim 7 (depends on 4)

A method for catalyzing the oxygen evolution reaction by the catalyst according to claim 4 in an alkaline water electrolysis or in metal-air batteries.

### Claim 8 (depends on 1)

A method for preparing an anode for an alkaline water electrolysis or metal-air batteries, wherein the anode comprises the electrically conductive perovskite-based biphasic mixed oxide according to claim 1.

### Claim 9 (depends on 1)

A method for the production of a precursor for the electrically conductive biphasic mixed oxide according to claim 1 comprising:
a) dissolving organic carboxylic acid, dicarboxylic acid and/or tricarboxylic acid salts and/or other oxide-forming salts of Ba and Co as well as Ti in a non-aqueous solvent,
b) heating the solution under reflux, and
c) filtering,
characterized in that the addition of Co3O4 desired in the electrically conductive biphasic mixed oxide is adjusted by the correspondingly selected excess amount of Co with respect to the stoichiometric perovskite phase.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the salts of Ba and Co are selected from the group consisting of acetates, propionates, oxalates and pentanedionates and the salt of Ti is Ti(IV)-oxide-bis(2,4-pentanedionate).

### Claim 11 (depends on 9)

The method according to claim 9, wherein the non-aqueous solvent is a mixture of propionic acid and propionic anhydride in the ratio (by volume) of 10:1 to 2:1.

### Claim 12 (depends on 9)

A method for the production of an anode, characterized in that the precursor obtained by the method according to claim 9 is
a) applied to an electrically conductive substrate in a wet coating process,
b) dried, and
c) baked,
wherein the steps a) to c) are repeated until the desired layer thickness is achieved.

### Claim 13 (depends on 12)

The method according to claim 12, wherein the wet coating process is selected from the group consisting of spin coating, spray coating and dip coating.

### Claim 14 (depends on 12)

The method according to claim 12, wherein the drying is carried out at 250 to 400° C.

### Claim 15 (depends on 12)

The method according to claim 12, wherein the baking is carried out at 700 to 1000° C.

### Claim 16 (depends on 12)

The method according to claim 12, wherein the substrate is a silicon wafer coated with a TiO2 adhesive layer and a polycrystalline Pt layer.

### Claim 17 (depends on 12)

The method according to one or more of claim 12, wherein the thickness of a catalyst layer according to step c) is about 50 to 150 nm.

### Claim 18 (depends on 1)

An amorphous mixed oxide having a Co:Ba ratio of about 2:1 and a TTB (Tetragonal Tungsten Bronze)-like near structure, obtainable by using the perovskite-based, electrically conductive, biphasic mixed oxide according to claim 1 as a catalyst in the oxygen evolution reaction of alkaline water electrolysis, wherein said amorphous product is formed by leaching out Ba.

### Claim 19 (depends on 3)

A catalyst for the oxygen evolution reaction in an alkaline environment comprising the perovskite-based, electrically conductive, biphasic mixed oxide according to claim 3.

### Claim 20 (depends on 3)

An anode comprising the perovskite-based, electrically conductive biphasic mixed oxide according to claim 3, and an electrically conductive substrate material.