L10-CoPt/Pt Core-Shell Nanoparticles for Durable PEMFC ORR Catalysis

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Proton exchange membrane fuel cells (PEMFCs) face challenges in stabilizing transition metals in alloys under oxidizing and acidic conditions, leading to limited durability and activity of catalysts, which hinders the scaling up of fuel cell production due to the scarcity of platinum.

Innovation Solution

The development of core/shell structured L10-CoPt/Pt nanoparticles with a tetragonal intermetallic hard-magnet CoPt core and a 2-3 atomic layer thick Pt shell, achieved by converting soft-magnet Al-CoPt into hard-magnet L10-CoPt and subsequent acid etching and annealing, enhances the stability and activity of the catalyst.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If Pt is alloyed with transition metal to enhance catalysis, then ORR activity is improved, but stability of the alloy under oxidizing and acidic conditions deteriorates

Engineering Contradiction:

ImproveORR activityVSAvoidstability of alloy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The catalyst is segmented into a core/shell structure where the transition metal (Co) is confined to the core and protected by a Pt-rich shell. This segmentation allows the transition metal to provide catalytic activity while being shielded from the harsh oxidizing and acidic environment, thus maintaining both high ORR activity and long-term stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite core/shell structure combining transition metal (Co) core with Pt shell. The composite structure leverages the high catalytic activity of transition metal while utilizing Pt's chemical stability to protect the core from degradation under fuel cell operating conditions.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If Pt is alloyed with transition metal to reduce Pt abundance issues, then Pt usage is reduced, but durability of catalyst deteriorates

Engineering Contradiction:

ImprovePt usage amountVSAvoidcatalyst durability

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

By segmenting the catalyst into core/shell structure with Pt-rich outer shell, the Pt is strategically positioned where it is most needed for catalysis while minimizing total Pt content. The transition metal core provides additional catalytic sites without requiring Pt, thus reducing overall Pt usage while maintaining durability through the protective shell.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The catalyst exhibits local quality differentiation where the Pt-rich shell provides chemical stability and durability in the harsh fuel cell environment, while the transition metal core provides enhanced catalytic activity. This local differentiation allows reduced Pt content overall while maintaining durability where it is most critical.

Inventive Principle:

Principle #3Local quality

3Reliability

If soft-magnet Al-CoPt is converted to hard-magnet L10-CoPt, then magnetic properties are improved, but structural transformation complexity increases

Engineering Contradiction:

Improvemagnetic stabilityVSAvoidstructural transformation process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The Al-CoPt intermetallic compound is synthesized first with a predetermined composition and structure that will transform into L10-CoPt upon annealing. This preliminary preparation of the precursor material simplifies the overall process by pre-organizing the atoms in a configuration that readily transforms to the desired hard-magnetic L10 structure during the annealing step.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The transformation from soft-magnet Al-CoPt to hard-magnet L10-CoPt is achieved by changing thermal parameters (annealing temperature and time). This parameter change triggers the structural transformation and magnetic property enhancement without requiring complex mechanical or chemical processing steps.

Inventive Principle:

Principle #35Parameter changes

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 L10-CoPt/Pt nanoparticles demonstrate superior oxygen reduction reaction (ORR) activity and durability, exceeding the U.S. Department of Energy's 2020 targets with a mass activity of 2.26 A/mgpt and 19% loss after 30,000 cycles, while maintaining stability and performance in membrane electrode assembly (MEA) conditions.

Implementation Method 1

a tetragonal intermetallic hard-magnet CoPt core

Methodology Applied

Scientific EffectTetragonal intermetallic structure stabilization:

Implementation Method 2

The L10-CoPt/Pt nanoparticles demonstrate superior oxygen reduction reaction (ORR) activity

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

acid etching the hard-magnet L10-CoPt

Methodology Applied

Scientific EffectAcid etching:

Implementation Method 4

annealing the acid etched hard-magnet L10-CoPt to generate a L10-CoPt/Pt catalyst

Methodology Applied

Scientific EffectAnnealing: Annealing

Data Source

PatentUS12142404B2Hard-magnet L10-CoPt nanoparticles advance fuel cell catalysis

Publication Date: 2024.11.12 BROWN UNIVERSITY

AI summary

A method includes converting ˜9 nm soft-magnet Al—CoPt into a hard-magnet L10-CoPt, acid etching the hard-magnet L10-CoPt, and annealing the acid etched hard-magnet L10-CoPt to generate a L10-CoPt/Pt catalyst.