Porous Iridium Oxide Catalyst for Activity-Durability Balance
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Solution Overview
Problem
Iridium oxide catalysts for water electrolysis and fuel cells face challenges in achieving high activity while maintaining durability, as increasing specific surface area improves catalytic activity but reduces durability, and existing methods result in insufficient activity or durability.
Innovation Solution
An iridium-containing oxide with a unique pore structure, characterized by a total pore volume of 0.20 cm3/g or more and an average pore diameter of 7.0 nm or more, produced through a hydrothermal synthesis method using high-temperature and high-pressure water, which enhances both activity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the specific surface area of iridium oxide is increased to improve catalytic activity, then the catalytic activity is improved, but the durability is reduced
Solution Approach 1:
The patent applies porous materials by creating iridium oxide with a controlled pore structure having a total pore volume of 0.20 cm³/g or more and an average pore diameter of 7.0 nm or more. This porous structure increases the specific surface area for higher catalytic activity while the interconnected pore network provides structural stability and prevents particle aggregation, thereby maintaining durability during prolonged operation.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the pore volume (0.20 cm³/g or more) and average pore diameter (7.0 nm or more) of the iridium oxide structure. These specific parameter ranges optimize both catalytic activity through increased surface area and durability through structural stability, resolving the trade-off between activity and durability.
2Quantity of substance
If the amount of iridium is reduced to lower cost, then the cost is reduced, but the catalytic activity decreases
Solution Approach 1:
The porous structure with total pore volume of 0.20 cm³/g or more and average pore diameter of 7.0 nm or more maximizes the specific surface area per unit mass of iridium oxide. This allows significantly less iridium to be used while maintaining or even enhancing catalytic activity, as the increased surface area provides more active sites for the reaction.
Solution Approach 2:
The patent creates a composite structure where iridium oxide is combined with a porous support matrix or structured framework. This composite approach increases the effective surface area and active site availability, allowing reduced iridium loading while maintaining high catalytic activity through the synergistic effect of the porous architecture.
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 iridium-containing oxide catalysts exhibit high activity and excellent durability, reducing the amount of iridium needed per unit electrode area by half to fifth of conventional amounts and significantly improving reverse potential durability in fuel cells.
Implementation Method 1
water is converted into high-temperature and high-pressure water in a supercritical state or a subcritical state via a pressurizing means and a heating means
Implementation Method 2
A method for producing an iridium-containing oxide according to the present invention includes: a step A of (1) dispersing iridium nanoparticles or iridium hydroxide particles as a raw material in a medium to obtain a dispersion liquid or (2) dissolving an iridium compound as a raw material in a solvent to obtain a solution; a step B of converting water into high-temperature and high-pressure water under high-temperature and high-pressure conditions of a heating temperature of 100° C. or higher and an applied pressure of 0.1 MPa or more; and a step C of mixing the dispersion liquid or the solution obtained in the step A with the high-temperature and high-pressure water obtained in the step B.
Data Source
AI summary
An iridium-containing oxide having a total pore volume of 0.20 cm3/g or more, calculated by a BJH method from nitrogen adsorption/desorption isotherm measurement, and a pore distribution having an average pore diameter of 7.0 nm or more.