Iridium Nickel Alloy Catalyst Reversible Oxidation
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Solution Overview
Problem
Iridium-based catalysts used in fuel cells and water electrolysis systems suffer from irreversible properties, leading to degradation in hydrogen evolution and oxidation reactions, and carbon corrosion due to reverse voltage conditions, which affects the durability and performance of these systems.
Innovation Solution
An iridium alloy catalyst with reversible catalytic activity, composed of iridium and nickel, supported on a carbon-based material, which can rapidly convert between oxide and metallic forms in response to voltage, maintaining performance across oxygen evolution, hydrogen evolution, and hydrogen oxidation reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iridium oxide (IrO2) is added to suppress carbon corrosion under reverse voltage, then carbon corrosion is suppressed, but the catalyst does not participate in hydrogen oxidation reaction and reduces catalytic active area
Solution Approach 1:
The patent changes the chemical state parameter of iridium by controlling oxidation-reduction conditions. The iridium catalyst can switch between metallic state (for HOR) and oxidized state (for OER and carbon corrosion protection) based on operating conditions, resolving the contradiction between maintaining catalytic activity and preventing corrosion
Solution Approach 2:
The patent introduces dynamic reversibility to the catalyst system. The iridium catalyst dynamically transitions between different chemical states (metallic ↔ oxidized) in response to voltage polarity changes, enabling it to adaptively perform different functions: hydrogen oxidation during normal operation and oxygen evolution during reverse voltage conditions
2Reliability
If a catalyst is designed for water electrolysis to prevent carbon corrosion, then carbon corrosion is prevented, but hydrogen evolution and oxidation reaction performances are degraded when oxidized
Solution Approach 1:
The patent utilizes parameter changes in oxidation state to resolve the contradiction. The iridium catalyst maintains metallic character during hydrogen reactions for high activity, and transitions to oxidized state during oxygen evolution and reverse voltage for durability, thus achieving both performance and reliability
Solution Approach 2:
The patent makes the iridium catalyst universal by enabling it to perform multiple functions: hydrogen oxidation reaction, hydrogen evolution reaction, oxygen evolution reaction, and carbon corrosion protection. This multi-functionality is achieved through reversible transitions between metallic and oxidized states
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 alloy catalyst effectively controls reverse voltage in fuel cells and maintains electrochemical reaction performance, preventing carbon corrosion and ensuring durability in water electrolysis and fuel cell systems by maintaining catalytic activity across different reaction states.
Implementation Method 1
the iridium alloy catalyst may be rapidly converted to an iridium alloy catalyst in an oxide form and an iridium alloy catalyst in a metallic form according to applied voltage
Implementation Method 2
an iridium alloy catalyst having reversible catalytic activity for an oxygen evolution reaction, a hydrogen evolution reaction, and a hydrogen oxidation reaction
Data Source
AI summary
Proposed is an iridium alloy catalyst having reversible catalytic activity for an oxygen evolution reaction (OER), a hydrogen evolution reaction (HER), and a hydrogen oxidation reaction (HOR) by including an iridium alloy including iridium (Ir) and nickel (Ni). The iridium alloy catalyst according to the present disclosure is rapidly converted to an iridium alloy catalyst in an oxide form and an iridium alloy catalyst in a metallic form according to applied voltage by controlling its crystallinity. Thus, even in case an oxide layer is formed after the OER, the oxidation layer disappears during the HER and HOR and the properties of an iridium metal catalyst remain, thereby maintaining HER/HOR performance.