High Surface Area Graphitized Carbon for Fuel Cell Catalyst Supports
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Solution Overview
Problem
Fuel cell catalyst supports face durability challenges due to corrosion at high cell potentials and temperatures, particularly during start/stop cycles, necessitating highly durable high surface area materials for efficient reactant/catalyst contact.
Innovation Solution
A process for producing high surface area graphitized carbon by graphitizing and oxidizing starting carbon materials, which includes steps like heat-treating and oxidizing carbon black or amorphous carbon to increase surface area and corrosion resistance, forming catalyst support particles suitable for fuel cell applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If carbon black or amorphous carbon is used as catalyst support, then high surface area is achieved for efficient reactant/catalyst contact, but corrosion resistance and durability deteriorate at high cell potentials and temperatures
Solution Approach 1:
The patent applies parameter changes by transforming the carbon material through controlled oxidation and heat treatment processes. The oxidation step (using HNO3, H2SO4, or steam) modifies the surface chemistry and creates porosity, while subsequent heat treatment at 1000-3000°C graphitizes the carbon structure, fundamentally changing its physical and chemical properties to achieve both high surface area and corrosion resistance
Solution Approach 2:
The patent creates a composite structure by combining oxidized carbon with graphitized carbon phases. The resulting material contains both highly porous oxidized regions (providing surface area) and graphitized crystalline regions (providing corrosion resistance), effectively integrating the benefits of both material types into a single composite support structure
2Area of stationary object
If carbon is oxidized to increase surface area, then reactant/catalyst contact is improved, but structural integrity and durability may worsen due to excessive oxidation
Solution Approach 1:
The patent applies preliminary action by performing controlled oxidation on the carbon material before final graphitization. This preliminary oxidation creates the desired surface area and porosity structure, which is then protected and stabilized by the subsequent graphitization process that reinforces the structural integrity of the oxidized regions
Solution Approach 2:
The patent provides beforehand cushioning by using the graphitization process to protect the previously oxidized carbon structure. The graphitization step creates a robust crystalline framework that cushions and protects the vulnerable oxidized regions from further degradation during fuel cell operation, ensuring long-term structural stability
3Reliability
If graphitization is performed to enhance corrosion resistance, then durability is improved, but surface area decreases reducing catalytic efficiency
Solution Approach 1:
The patent applies preliminary action by performing oxidation before graphitization. This sequence ensures that the surface area is maximized through oxidation first, and then the graphitization process is applied to enhance corrosion resistance without significantly reducing the already-established high surface area, as the graphitization occurs on the pre-formed porous structure
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 resulting high surface area graphitized carbon supports maintain performance with minimal voltage loss over extended corrosion testing, demonstrating enhanced durability and corrosion resistance, suitable for use in fuel cell electrodes.
Implementation Method 1
graphitizing a starting carbon material to form graphitized carbon
Implementation Method 2
oxidizing at least a portion of carbon in the graphitized carbon to form high surface area graphitized carbon
Data Source
AI summary
The invention is directed to high surface area graphitized carbon and to processes for making high surface area graphitized carbon. The process includes steps of graphitizing and increasing the surface area of (in either order) a starting carbon material to form high surface area graphitized carbon. The step of increasing the surface area optionally comprises an oxidizing step (e.g., through steam etching) or template removal from composite particles. The invention is also directed to catalyst particles and electrodes employing catalyst particles that are formed from the high surface area graphitized carbon.