Pt-on-Carbon Fuel Cell Catalyst With Controlled Pt(111) Orientation
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Solution Overview
Problem
Existing fuel cell catalysts produced by reductively supporting Pt on carrier particles in a liquid phase often fail to exhibit expected catalytic activity, particularly when used as cathode catalysts, leading to lower catalytic performance.
Innovation Solution
A fuel cell electrode catalyst with Pt or Pt alloy catalyst metal particles supported on a carbon carrier, where the peak intensity ratio on the Pt(111) plane is adjusted to between 0.626 and 0.630 through controlled firing conditions, including an oxygen partial pressure of 4.0 Pa or higher and 800 Pa or lower, to enhance catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Pt particles are supported on carrier particles by reductive support in liquid phase, then the catalyst can be produced with simple process, but the catalytic activity does not meet expected performance and may notably lower activity when used as cathode catalyst
Solution Approach 1:
The invention changes the chemical composition parameters of the catalyst by incorporating specific alloying elements (Fe, Co, Ni, Cu, Zn, In, Ga, or Al) into the Pt alloy particles. This compositional modification transforms the catalyst's electronic structure and surface properties, enabling it to achieve high catalytic activity for oxygen reduction reactions while maintaining structural stability during operation.
Solution Approach 2:
The invention creates composite catalyst materials by combining Pt with alloying elements to form Pt alloy particles. This composite structure leverages the synergistic effects between Pt and the alloying elements, where the alloying elements modify Pt's electronic and geometric properties, resulting in enhanced catalytic performance that neither component achieves alone.
2Reliability
If Pt alloy particles are used to increase cathode activity, then catalytic activity can be improved, but firing must be carried out after supporting Pt and alloy metal on carrier particles which adds process complexity
Solution Approach 1:
The invention performs preliminary alloying during the support process itself, where Pt and alloying elements are simultaneously deposited and reduced on the carrier particles. This preliminary formation of Pt alloy particles eliminates the need for subsequent separate firing steps to create the alloy structure, simplifying the overall production process while achieving the desired catalytic activity.
3Reliability
If catalyst metal particles are made smaller to increase surface area, then catalytic activity should improve, but particle size control becomes more difficult and aggregation increases
Solution Approach 1:
The invention uses carrier particles as intermediaries to support the Pt alloy particles. These carrier particles provide a large surface area with controlled pore structures that prevent aggregation of the small catalyst particles. The carrier acts as a physical spacer and anchoring site, enabling the maintenance of small particle sizes (3-5 nm) without aggregation, thus preserving high surface area and 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
The catalyst achieves high catalytic activity without lowering activity during operation, even when used as a cathode catalyst, by optimizing the crystallinity and particle size of the Pt catalyst metal particles.
Implementation Method 1
reducing the catalyst metal precursor and supporting the catalyst metal particles on the carbon carrier
Implementation Method 2
firing the electrode catalyst precursor under conditions with an oxygen partial pressure of 4.0 Pa or higher and 800 Pa or lower, at a temperature of 500°C or higher and 1,100°C or lower
Data Source
AI summary
This fuel cell electrode catalyst has catalytic metal particles made from Pt or a Pt alloy supported on a carbon carrier, wherein when XRD measurements are taken for the electrode catalyst, the peak intensity ratio of the Pt (111) surface represented by the formula Pt(111) peak intensity ratio = Pt(111) peak intensity/(Pt(111) peak intensity + Pt(200) peak intensity + Pt (220) peak intensity) was 0.626-0.630.