Pd-Core Pt-Shell Catalyst for Phosphoric Acid HT-PEMFC Cathodes
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Solution Overview
Problem
Current fuel cell vehicles using polymer electrolyte membrane fuel cells (PEMFCs) face challenges such as high material costs, substantial performance gaps, poor proton transport in dry conditions, and catalyst poisoning by phosphoric acid, leading to decreased ORR activity and durability.
Innovation Solution
The development of a core/shell catalyst comprising a palladium or palladium-M1 alloy core surrounded by a platinum-M2 alloy shell, where M1 is a first-row transition metal and M2 is gold or silver, which is used in conjunction with a phosphoric acid or phosphonated ionomer to enhance ORR activity and durability in high temperature PEMFCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If phosphoric acid is used in PEMFC MEAs, then high temperature operation is enabled, but catalyst poisoning occurs and ORR activity decreases
Solution Approach 1:
A core/shell catalyst structure with Pd or Pd-M1 core and Pt-M2 shell acts as an intermediary system. The shell protects the core from phosphoric acid poisoning while maintaining catalytic activity, effectively mediating between the high temperature requirement and catalyst durability concern
Solution Approach 2:
The invention uses composite catalyst materials combining Pd-based core with Pt-based shell, creating a heterogeneous structure that leverages the high temperature stability of Pd while the Pt shell provides resistance to phosphoric acid poisoning
2Temperature
If phosphoric acid is used in PEMFC MEAs, then high temperature operation is enabled, but ORR activity decreases
Solution Approach 1:
The catalyst structure applies local quality differentiation where the shell composition (Pt-M2) is specifically optimized to resist phosphoric acid adsorption and maintain ORR activity in the phosphoric acid environment, while the core provides high temperature stability
Solution Approach 2:
The Pt-M2 shell acts as an intermediary layer that prevents direct contact between phosphoric acid and the Pd core, maintaining ORR activity by blocking poison sites while allowing oxygen reduction to proceed
3Quantity of substance
If mass loading of catalyst is decreased, then cost is reduced, but HCD performance decreases
Solution Approach 1:
The invention changes the compositional parameters of the catalyst by using Pd-based cores instead of traditional Pt-based catalysts, and optimizing the shell composition with Pt-M2 alloys to achieve higher activity per unit mass, thereby reducing total mass loading while maintaining HCD performance
Solution Approach 2:
The core/shell composite structure maximizes catalytic efficiency by combining the high temperature stability of Pd with the surface properties of Pt, achieving superior activity that allows for reduced mass loading
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 core/shell catalyst exhibits superior ORR activity and durability in the presence of phosphoric acid, even at high temperatures, thereby improving the performance and reducing the cost of PEMFCs.
Implementation Method 1
The core/shell catalyst exhibits superior ORR activity and durability in the presence of phosphoric acid, even at high temperatures
Implementation Method 2
PEMFCs typically require efficient proton transport in their electrocatalyst layers
Data Source
AI summary
A core/shell catalyst, and, a phosphoric acid or a phosphonated ionomer contacting the core/shell catalyst in a fuel cell. The core/shell catalyst comprises a core surrounded by a shell, the core comprising palladium or a palladium-M1 alloy, the shell comprising a platinum-M2 alloy. M1 is chosen from scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper or zinc; and M2 is gold or silver. High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs, with phosphoric-acid-contained polymer matrix) employing a core/shell catalyst, and, a phosphoric acid or a phosphonated ionomer contacting the core/shell catalyst are disclosed.