Fuel Cell Catalyst Layer Coating to Prevent Titanium Elution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Titanium oxide supports in fuel cell electrode catalyst layers are prone to elution in reductive atmospheres, leading to decreased catalytic activity and increased cell resistance, which affects the long-term durability of the fuel cell.
Innovation Solution
Incorporating a coating oxide of niobium, tantalum, zirconium, or silicon on the surface of the titanium oxide support to prevent titanium elution, with a controlled atomic ratio A2/A1 of 0.35 to 1.70, measured by X-ray photoelectron spectroscopy, and optimizing the coating oxide's form and particle size to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium oxide support is used, then electro-conductivity and potential stability are improved, but long-term durability deteriorates due to titanium elution and re-precipitation
Solution Approach 1:
The core-shell composite structure maintains the electro-conductive titanium oxide core for electrical functionality while the protective oxide shell prevents titanium elution, thereby preserving catalytic activity and ensuring long-term durability without sacrificing electro-conductivity or potential stability.
Solution Approach 2:
The coating oxide is applied in advance to the titanium oxide surface to create a protective barrier before the fuel cell operation begins. This pre-established protection prevents titanium elution during operation, cushioning against the harmful effects of the reductive atmosphere and strongly acidic environment that would otherwise degrade the support and reduce durability over time.
2Duration of action of stationary object
If a coating oxide is applied to prevent titanium elution, then durability is improved, but the atomic ratio control and surface composition complexity increases
Solution Approach 1:
The invention specifies a target atomic ratio range (A2/A1 from 0.35 to 1.70) for the coating oxide to titanium on the surface, providing a clear parameter control guideline. By defining this specific ratio range, the patent balances the need for sufficient coating coverage (to prevent elution) with maintaining catalytic activity, making the manufacturing precision requirement manageable while achieving improved durability.
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
Effectively prevents titanium elution, maintains catalytic activity, and reduces cell resistance, thereby improving the long-term durability and performance of the fuel cell.
Implementation Method 1
a surface of the catalyst/support composite has an oxide of at least one element selected from the group consisting of niobium, tantalum, zirconium, and silicon
Implementation Method 2
The elution of titanium is more likely to occur in particular at an anode, which is in a reductive atmosphere. The titanium that has eluted is diffused and re-precipitated
Implementation Method 3
A1 and A2 being measured by X-ray photoelectron spectroscopy
Data Source
AI summary
An electrode catalyst layer for a fuel cell includes a catalyst/support composite including a support and a catalyst supported thereon. The support contains a titanium oxide. The surface of the catalyst/support composite has an oxide of at least one element selected from the group consisting of niobium, tantalum, zirconium, and silicon. The ratio A2/A1 is from 0.35 to 1.70, wherein A1 is the atomic ratio of titanium on a surface of the catalyst layer and A2 is the atomic ratio of a total of niobium, tantalum, zirconium, and silicon on the surface of the catalyst layer, A1 and A2 being measured by X-ray photoelectron spectroscopy. The titanium oxide preferably has a composition TiOx (0.5 ≤ x < 2).