Titanium Oxide Carrier Powder with Chained Crystallite Structure
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Solution Overview
Problem
Existing methods for manufacturing titanium oxide catalysts for fuel cells predominantly produce the anatase phase, which is thermodynamically unstable and low in conductivity, limiting the performance and durability of solid polymer electrolyte fuel cells.
Innovation Solution
A carrier powder with a titanium oxide composition that has a ratio of anatase to rutile phases of 0.2 or lower, formed by fusion bonding crystallites into a chain structure, enhancing conductivity and stability, and supporting metal fine particles on this carrier to create a high-performance catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If titanium oxide is manufactured using conventional chemical flame methods, then the manufacturing process is simple, but the resulting titanium oxide is predominantly anatase phase which is thermodynamically unstable and low in conductivity
Solution Approach 1:
The patent applies parameter changes by controlling the oxidation atmosphere during heat treatment. Specifically, performing heat treatment in an oxygen atmosphere at 400-600°C promotes the formation of rutile phase and increases conductivity, while avoiding reduction atmospheres that would stabilize the anatase phase. This parameter change (oxidizing atmosphere) resolves the contradiction by achieving both thermodynamic stability and high conductivity without complicating the manufacturing process.
Solution Approach 2:
The patent creates a composite structure by forming a coated layer on the titanium oxide core particles. This coated layer, formed through heat treatment in oxygen atmosphere, has different properties (rutile phase, high conductivity) than the core, creating a composite material that combines the advantages of both phases while maintaining manufacturing simplicity.
2Area of stationary object
If titanium oxide with high anatase phase content is used as carrier, then the specific surface area is large, but the conductivity and thermodynamic stability are poor
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core maintains high surface area (anatase phase) and the shell provides high conductivity and stability (rutile phase). The coated layer formed on the surface through oxygen atmosphere heat treatment has different local properties than the core, allowing the particle to simultaneously achieve high surface area, conductivity, and thermodynamic stability.
3Ease of manufacture
If conventional heat treatment is performed in reducing atmosphere, then the manufacturing process is straightforward, but the titanium oxide remains in anatase phase with low conductivity
Solution Approach 1:
The patent applies inversion by reversing the conventional heat treatment atmosphere from reducing to oxidizing. Instead of using hydrogen or nitrogen atmosphere that stabilizes anatase phase, the patent uses oxygen atmosphere at 400-600°C, which inverts the phase formation mechanism to produce rutile phase with high conductivity and stability, while maintaining straightforward manufacturing conditions.
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 solution results in a fuel cell with improved durability, catalytic activity, and long-term stability, achieving higher conductivity and reduced costs, making it suitable for widespread use.
Implementation Method 1
the carrier fine particles comprise a chained portion structured by fusion bonding a plurality of crystallites into a chain
Implementation Method 2
a ratio of anatase phase/rutile phase of the titanium oxide of the carrier powder is 0.2 or lower
Data Source
AI summary
A carrier powder is thermodynamically stable and conductivity can be easily provided thereto. A carrier powder includes an aggregate of carrier fine particles; wherein: the carrier fine particles include a chained portion structured by fusion bonding a plurality of crystallites into a chain; the carrier fine particles contain titanium oxide; and a ratio of anatase phase/rutile phase of the titanium oxide of the carrier powder is 0.2 or lower.