Multimetallic Core-Interlayer-Shell Nanoparticles for Fuel Cell Catalysts
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Solution Overview
Problem
The commercialization of polymer electrolyte membrane fuel cells (PEMFC) is hindered by the sluggish kinetics of the cathodic oxygen reduction reaction (ORR) due to the high cost and durability issues of precious metal-based catalysts, particularly platinum (Pt), which deactivates over time due to corrosion and dissolution in the PEMFC's corrosive environment.
Innovation Solution
The development of multimetallic nanoparticles (NPs) with a metal core/interlayer/shell (MCIS) structure, where a nickel (Ni) core is coated with a gold (Au) interlayer and a platinum (Pt) outer shell, optimizing the balance between activity and durability by preventing Au diffusion to the surface and maintaining beneficial electronic interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Pt-transition metal alloys are used to enhance catalytic activity, then the activity is improved, but durability is lost due to dissolution of transition metal and Pt atoms
Solution Approach 1:
The catalyst is segmented into distinct functional layers: a Pt-transition metal alloy core for catalytic activity, a thin Pt interlayer (0.3-1.0 nm) to prevent transition metal dissolution, and an outer Pt shell for durability. This segmentation allows each layer to perform its specific function optimally.
Solution Approach 2:
The invention uses a composite structure combining Pt and transition metals in a core/interlayer/shell configuration. The composite material leverages the high activity of Pt-transition metal alloys while using pure Pt layers to prevent corrosion and dissolution, achieving both activity and durability.
2Reliability
If Au is used as core material to enhance durability, then durability is improved, but cost substantially increases
Solution Approach 1:
Instead of using expensive Au as the core material, the invention uses a cheaper Pt-transition metal alloy core that provides sufficient durability when protected by the Pt interlayer and shell. This replaces the expensive Au core with a more cost-effective alternative.
Solution Approach 2:
The invention changes the core material parameter from Au to Pt-transition metal alloy, and optimizes the Pt layer thickness parameters (0.3-1.0 nm interlayer, thin outer shell) to achieve the desired durability at lower cost.
3Reliability
If Pt shell thickness is increased to improve durability, then durability is improved, but beneficial electronic effect from transition metal is lost
Solution Approach 1:
The invention optimizes the Pt shell thickness parameter to be thin (specifically controlled to maintain electronic interaction), which allows the shell to provide durability protection while still permitting electronic effects from the transition metal core to influence the catalytic activity at the surface.
Solution Approach 2:
Instead of applying a thick Pt shell that would completely block electronic effects, the invention uses a partial thickness that is sufficient for durability but thin enough to allow beneficial electronic interactions to persist, achieving a balance between protection and activity.
4Productivity
If transition metal content is increased to enhance activity, then activity is improved, but dissolution and deactivation increase
Solution Approach 1:
The catalyst structure segments the transition metal into the core region, separated from the corrosive environment by the Pt interlayer and outer shell. This allows high transition metal content in the core for activity while the Pt layers prevent dissolution into the electrolyte.
Solution Approach 2:
The Pt interlayer (0.3-1.0 nm) acts as an intermediary barrier between the transition metal core and the corrosive electrolyte environment. It prevents direct contact and dissolution of the transition metal while allowing electronic interactions to maintain catalytic activity.
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 configuration enhances the durability and activity of the catalysts, retaining greater than 90% of their initial catalytic activity after 10,000 cycles with reduced precious metal content, thereby lowering costs and improving the efficiency of PEMFCs.
Implementation Method 1
An interlayer is disposed on the first layer. The interlayer includes a plurality of gold atoms... preventing Au diffusion to the surface
Implementation Method 2
optimizing the balance between activity and durability by preventing Au diffusion to the surface and maintaining beneficial electronic interactions
Data Source
AI summary
A multimetallic core/interlayer/shell nanoparticle comprises an inner core formed from a first metal. An interlayer is disposed on the first layer. The interlayer includes a plurality of gold atoms. An outer shell is disposed over the interlayer. The outer shell includes platinum and the first metal. A surface of the NP is substantially free of gold. The first metal is selected from the group consisting of nickel, titanium, chromium, manganese, iron, cobalt, copper, vanadium, yttrium, ruthenium, palladium, scandium, tin, lead and zinc.