Ruthenium-Iridium Oxide Catalyst Composition for Stable Acidic OER
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Solution Overview
Problem
Current catalyst materials for the oxygen evolution reaction in acidic water electrolysis, such as PEM water electrolysis, face challenges with slow reaction kinetics, high overpotential requirements, and limited stability due to corrosive conditions, which restrict their efficiency and scalability.
Innovation Solution
A powder-shaped ruthenium iridium oxide catalyst material with a specific weight ratio of iridium to ruthenium not exceeding 4.5, and with a minimum powderability of 30 S/cm, is developed. This material is designed to enhance catalytic activity and stability while minimizing iridium content, thereby reducing costs and enabling lower iridium loading in electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ruthenium oxides are used as catalysts for oxygen evolution reaction, then high intrinsic activity is achieved, but corrosion occurs during O2 formation in acidic media causing quick loss of activity
Solution Approach 1:
The patent applies composite materials by combining ruthenium oxide and iridium oxide in a mixed oxide structure (Ru1-xIrxO2-y). This composite approach leverages the high catalytic activity of ruthenium oxide while incorporating the corrosion resistance of iridium oxide, thereby simultaneously achieving high productivity and reliability in acidic media during oxygen evolution reaction.
2Reliability
If iridium oxides are used as catalysts for oxygen evolution reaction, then resistance under O2 formation conditions in strongly acidic environments is achieved, but lower activity compared to RuO2 is observed
Solution Approach 1:
The patent combines iridium oxide and ruthenium oxide to create a mixed oxide composite where iridium oxide provides the necessary stability and corrosion resistance in strongly acidic environments, while ruthenium oxide contributes high catalytic activity. This composite structure resolves the contradiction by integrating the advantageous properties of both materials.
Solution Approach 2:
The patent employs parameter changes by adjusting the composition ratio of ruthenium to iridium (expressed as x in Ru1-xIrxO2-y) and controlling oxygen stoichiometry (y). By optimizing these parameters, the catalyst achieves both high stability from iridium and high activity from ruthenium, transforming the trade-off into an optimized performance state.
3Reliability
If higher iridium loading is used in electrodes, then catalytic activity and stability are improved, but cost increases and availability limitations are exacerbated
Solution Approach 1:
The patent applies parameter changes by optimizing the iridium content parameter (x in Ru1-xIrxO2-y) to achieve the minimum necessary amount of iridium that still provides sufficient stability. This allows reducing the quantity of expensive iridium while maintaining acceptable performance, directly addressing the contradiction between reliability and quantity of substance.
4Power
If powder conductivity is increased to at least 30 S/cm, then electrochemical performance is improved, but specific compositional constraints must be met
Solution Approach 1:
The patent applies parameter changes by establishing specific compositional parameters (Ru:Ir weight ratio not greater than 4.5, oxygen deficiency indicated by y in O2-y) that naturally result in high powder conductivity of at least 30 S/cm. By controlling these compositional parameters, the patent achieves high electrical conductivity while providing clear, manageable compositional guidelines rather than complex structural requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The catalyst material demonstrates improved catalytic activity and long-term stability under corrosive conditions, allowing for reduced iridium loading in electrodes to less than 0.3 mg/cm², which enhances the efficiency and cost-effectiveness of water electrolysis.
Implementation Method 1
The catalyst material demonstrates improved catalytic activity and long-term stability under corrosive conditions, allowing for reduced iridium loading in electrodes to less than 0.3 mg/cm², which enhances the efficiency and cost-effectiveness of water electrolysis
Implementation Method 2
A powder-shaped ruthenium iridium oxide catalyst material with a specific weight ratio of iridium to ruthenium not exceeding 4.5, and with a minimum powderability of 30 S/cm, is developed
Implementation Method 3
A water electrolysis cell contains a half-cell with an electrode at which the oxygen evolution reaction (English Oxygen Evolution Reaction, OER) takes place, as well as another half-cell with an electrode where the hydrogen evolution reaction (English Hydrogen Evolution Reaction, HER). The two half-cells are separated by a diaphragm, an ion-conductive membrane, or a ceramic
Data Source
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AI summary
The present invention relates to a powdered catalyst material particularly suitable for the oxygen evolution reaction in water electrolysis. The catalyst material comprises an unsupported ruthenium iridium oxide, wherein the ratio of the weight fractions of iridium (Ir) to ruthenium (Ru) based on the total weight of the unsupported ruthenium iridium oxide is not greater than 4.5. The unsupported ruthenium iridium oxide has a powder conductivity of at least 30 S/cm. The invention further relates to a process for producing such a powdered catalyst material, a composition, a catalyst layer, an electrode, and an electrochemical device containing the powdered catalyst material, as well as a process for producing hydrogen using the powdered catalyst material.