Platinum Core-Shell Catalyst Potential Cycling for Durability
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Solution Overview
Problem
The durability and oxygen reduction reaction (ORR) activity of platinum core-shell catalysts, particularly those with a palladium core and platinum shell, are limited due to oxidative dissolution of the palladium core, leading to particle size and morphology changes, which affect the catalyst's performance and longevity.
Innovation Solution
A method involving the controlled application of potentials to platinum catalysts in an acidic solution, where a chemical species applies a potential higher than the onset potential for Pt oxide formation and another species applies a potential lower than the onset potential for Pt oxide reduction, alternately and for a predetermined duration, to mitigate particle agglomeration and enhance electrochemical surface area, thereby increasing ORR mass activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a palladium core-platinum shell catalyst is used to improve ORR activity, then the oxygen reduction reaction activity is enhanced, but the catalyst durability deteriorates due to oxidative dissolution of the palladium core
Solution Approach 1:
The patent removes the problematic palladium core from the catalyst structure and replaces it with a platinum core. This extraction of the harmful component (Pd) while retaining the beneficial shell structure (Pt) resolves the contradiction by eliminating the source of oxidative dissolution while preserving the ORR activity enhancement provided by the Pt shell structure.
Solution Approach 2:
The patent changes the compositional parameter of the core material from palladium to platinum. This parameter change fundamentally alters the electrochemical stability of the core, preventing oxidative dissolution while maintaining the core-shell structure's ability to enhance ORR activity through the platinum shell.
2Power
If the particle size is reduced to increase surface area, then the ORR activity is improved, but the particle agglomeration increases reducing durability
Solution Approach 1:
The patent applies a potential treatment process before the catalyst is deployed in fuel cells. This preliminary action involves cycling the catalyst through potentials that oxidize the platinum core surface and then reduce it, which pre-stabilizes the particle structure and prevents agglomeration during subsequent use, thereby maintaining both high ORR activity and particle size stability.
Solution Approach 2:
The patent employs periodic potential cycling during the treatment process, alternating between oxidation potentials (which remove surface contaminants and stabilize the structure) and reduction potentials (which restore the metallic state). This periodic action effectively prevents particle agglomeration while maintaining high surface area and ORR activity.
3Ease of manufacture
If platinum usage is reduced to lower cost, then the manufacturing cost is decreased, but the ORR activity per unit mass must be increased
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the platinum is concentrated in the outer shell that directly contacts reactants, while the core uses a different material. This localized distribution of platinum maximizes its utilization efficiency and ORR mass activity, allowing reduced overall platinum loading while maintaining or enhancing performance.
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
This method results in a platinum catalyst with enhanced ORR activity per unit mass, reducing the need for platinum usage and improving catalyst durability, making it suitable for industrial-scale production and cost-effective.
Implementation Method 1
a chemical species that applies a potential higher than onset potential of Pt oxide formation
Implementation Method 2
a chemical species that applies a potential lower than onset potential of reduction of Pt oxide
Implementation Method 3
allowing a chemical species that applies a potential higher than onset potential of Pt oxide formation to be present; and allowing a chemical species that applies a potential lower than onset potential of reduction of Pt oxide to be present
Data Source
AI summary
A platinum core-shell catalyst that uses palladium (Pd) as a core metal, or a platinum catalyst containing platinum and a metal besides platinum is manufactured industrially on a mass scale. The platinum catalyst is supported on carbon and has excellent oxygen reduction activity. The platinum catalyst is made for a fuel cell by bringing about the presence of a chemical species imparting higher potential than the initial oxide formation potential of the platinum of the platinum catalyst, and by bringing about the presence of a chemical species imparting lower potential than the initial oxide formation potential of the platinum of the platinum catalyst. The manufacture is carried out in a dispersion solution of the platinum catalyst dispersed in an acidic solution containing protons.