NSTF Catalyst Iridium Sub-monolayer Starvation Tolerance
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Solution Overview
Problem
Conventional fuel cell anodes based on platinum (Pt) particles dispersed on carbon black supports suffer from oxidation and degradation during fuel starvation events, leading to increased resistance and mass transport losses, which are not adequately prevented by the use of iridium oxide particles.
Innovation Solution
A sub-monolayer of iridium is sputter deposited onto the surface of nanostructured thin film (NSTF) catalysts, which reduces the potential for oxygen evolution reaction and minimizes permanent degradation, while eliminating the need for Pt/C catalysts and replacing them with NSTF-supported catalysts, with iridium in the zero oxidation state and a planar equivalent thickness of 1-100 Angstroms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sub-monolayer of iridium is deposited on NSTF catalysts, then oxygen evolution reaction potential is reduced and degradation is minimized, but manufacturing complexity increases
Solution Approach 1:
A sub-monolayer of iridium is deposited onto the NSTF catalyst surface before the catalyst is put into service. This preliminary protective layer is applied in advance to prevent oxidation and degradation that would otherwise occur during fuel starvation events, thereby improving reliability without requiring complex operational controls
Solution Approach 2:
The catalyst combines multiple materials (platinum, cobalt, manganese, and iridium) in a composite structure. The NSTF core provides catalytic activity while the sub-monolayer iridium coating provides protective functionality, creating a composite material that achieves both high performance and enhanced durability through material synergies
2Adaptability or versatility
If Pt/C catalysts are replaced with NSTF-supported catalysts, then voltage reversal tolerance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention transitions from conventional Pt/C catalysts to NSTF-supported catalysts with a sub-monolayer iridium coating, representing a significant parameter change in catalyst composition and structure. This parameter change enables superior voltage reversal tolerance and anode starvation durability, overcoming the limitations of conventional catalysts despite increased manufacturing precision requirements
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 use of a sub-monolayer of iridium significantly reduces oxygen evolution reaction potential and minimizes permanent degradation of fuel cell performance, achieving improved durability and stability during anode starvation conditions.
Implementation Method 1
A sub-monolayer of iridium is sputter deposited onto the surface of nanostructured thin film (NSTF) catalysts
Implementation Method 2
the use of a sub-monolayer of iridium significantly reduces oxygen evolution reaction potential
Data Source
AI summary
In some embodiments, the present disclosure provides a fuel cell catalyst having a catalyst surface bearing a non-occluding layer of iridium. In some embodiments, the present disclosure provides a fuel cell catalyst comprising a catalyst surface bearing a sub-monolayer of iridium. In some embodiments, the present disclosure provides a fuel cell catalyst comprising a catalyst surface bearing a layer of iridium having a planar equivalent thickness of between 1 and 100 Angstroms. In some embodiments, the fuel cell catalyst comprises nanostructured elements comprising microstructured support whiskers bearing a thin film of nanoscopic catalyst particles. The layer of iridium typically has a planar equivalent thickness of between 1 and 100 Angstroms and more typically between 5 and 60 Angstroms. The fuel cell catalyst typically comprises no electrically conductive carbon material and typically comprises at least a portion of the iridium in the zero oxidation state.