Pd-Shell Catalyst Synthesis via Cu-UPD Displacement
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Solution Overview
Problem
Conventional core-shell catalysts produced using Cu-UPD have low initial catalytic activity and require lengthy pre-conditioning operations due to incomplete core-shell structures and inefficient platinum distribution, leading to suboptimal performance in fuel cells.
Innovation Solution
A method involving palladium-containing particles, where a platinum outermost layer is formed by direct contact with a platinum compound solution followed by copper underpotential deposition (Cu-UPD) to achieve high coverage and activity, eliminating the need for pre-conditioning by ensuring complete core-shell structure formation at the outset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Cu-UPD method is used to form core-shell catalyst, then platinum coverage is improved, but initial catalytic activity deteriorates due to incomplete shell formation
Solution Approach 1:
The patent applies preliminary action by first forming a complete platinum shell through direct deposition before Cu-UPD. This ensures the core-shell structure is already formed with high platinum coverage at the outset, eliminating the need for subsequent pre-conditioning operations to achieve adequate coverage and activity.
Solution Approach 2:
The patent uses copper as an intermediary material in the Cu-UPD process. Copper is deposited first as a sacrificial layer, then selectively replaced by platinum through displacement reaction. This intermediary approach allows controlled platinum deposition while ensuring complete shell formation, resolving the contradiction between coverage and initial activity.
2Reliability
If pre-conditioning operation is performed to increase catalyst activity, then catalytic performance is improved, but production time is extended
Solution Approach 1:
The patent performs the shell formation action in advance during the synthesis process itself, creating a complete and stable core-shell structure before the catalyst is put into service. This preliminary structuring eliminates the need for time-consuming pre-conditioning operations, as the catalyst achieves high activity immediately upon production.
3Quantity of substance
If platinum amount is reduced by using core-shell structure, then cost is decreased, but initial activity deteriorates due to incomplete shell coverage
Solution Approach 1:
The patent applies local quality by ensuring uniform and complete platinum shell coverage around the core particles through the direct deposition method followed by Cu-UPD. This localized control of platinum distribution ensures that even with reduced overall platinum loading, every active site on the core surface is adequately covered, maintaining high initial catalytic activity while minimizing platinum usage.
4Ease of manufacture
If Cu-UPD is used for shell formation, then manufacturing complexity is reduced, but copper residue in membrane electrode assembly increases
Solution Approach 1:
The patent employs the discarding and recovering principle by using copper as a temporary sacrificial layer during synthesis. The copper is deliberately deposited via Cu-UPD, then completely replaced by platinum through displacement reaction. The copper is subsequently removed from the system, ensuring minimal copper residue in the final catalyst product while maintaining the simplicity of the Cu-UPD manufacturing process.
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 method results in fine catalyst particles with high initial activity and durability, maintaining mass activity and electrochemical surface area without the need for pre-conditioning, while reducing platinum usage and minimizing copper residues in the membrane electrode assembly.
Implementation Method 1
covering at least part of a surface of the palladium-containing particle with platinum
Implementation Method 2
covering at least part of a surface of the first composite body with copper using copper underpotential deposition
Implementation Method 3
the copper in the second composite body is substituted with platinum derived from a third solution in which a platinum compound is dissolved
Data Source
AI summary
Disclosed is a method for producing a fine catalyst particle comprising a palladium-containing particle and a platinum outermost layer covering the palladium-containing particle, wherein a first composite body containing palladium and platinum is formed by mixing the palladium-containing particle with a first solution in which a platinum compound is dissolved, and then covering at least part of a surface of the palladium-containing particle with platinum; wherein a second composite body containing palladium, platinum and copper is formed by mixing the first composite body with a second solution in which a copper compound is dissolved, and then covering at least part of a surface of the first composite body with copper using copper underpotential deposition; and wherein the copper in the second composite body is substituted with platinum derived from a third solution in which a platinum compound is dissolved.