Pt-Ir Catalyst Electrodes on Nanostructured Whiskers
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Solution Overview
Problem
Proton exchange membrane electrolyzers require high catalyst loadings of platinum group metals due to low oxygen evolution reaction activity and stability, leading to high capital costs and limitations in introducing new catalyst technologies, as they operate at severe conditions that traditional carbon-supported catalysts cannot withstand.
Innovation Solution
Sputtering Pt and Ir onto nanostructured whiskers to form multiple alternating layers, followed by radiation annealing in an oxygen-rich atmosphere, which reduces the need for high catalyst loadings and enhances the stability and activity of the catalysts for hydrogen and oxygen evolution reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high catalyst loadings of platinum group metals are used, then oxygen evolution reaction activity is improved, but capital costs increase
Solution Approach 1:
The catalyst layer is segmented into multiple alternating thin layers of Pt and Ir deposited on nanostructured whiskers, creating a high-surface-area architecture that maximizes catalytic activity per unit mass of precious metal
Solution Approach 2:
Nanostructured whiskers provide a porous, high-surface-area support structure that enables efficient dispersion of platinum group metal catalysts, increasing the effective catalytic surface area and reducing the amount of precious metal required
2Ease of manufacture
If traditional carbon-supported catalysts are used, then manufacturing ease is improved, but stability under severe operating conditions deteriorates
Solution Approach 1:
The support material is changed from carbon to nanostructured whiskers, fundamentally altering the chemical and thermal stability parameters of the catalyst system to withstand severe electrolyzer operating conditions including high potentials and corrosive environments
3Reliability
If radiation annealing is performed in oxygen-rich atmosphere, then catalyst stability is improved, but manufacturing complexity increases
Solution Approach 1:
The alternating Pt and Ir layers are deposited in a controlled sequence before annealing, creating a precursor structure that facilitates oxidation and stabilization during the subsequent radiation annealing process in oxygen-rich atmosphere
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 method allows for efficient hydrogen and oxygen production at reduced catalyst loadings, improving the stability and activity of the catalysts, thus lowering capital costs and enabling the use of alternative catalysts in proton exchange membrane electrolyzers.
Implementation Method 1
sputtering (a form of physical vapor deposition) at least Pt and Ir onto nanostructured whiskers to provide multiple alternating layers comprising respectively in any order Pt and Ir
Implementation Method 2
radiation annealing (e.g., laser annealing) at least some of the multiple alternating layers comprising respectively Pt and Ir at least in part in an atmosphere comprising an absolute oxygen partial pressure of at least 2 kPa
Data Source
AI summary
Methods of making catalyst electrodes comprising sputtering at least Pt and Ir onto nanostructured whiskers to provide multiple alternating layers comprising, respectively in any order, at least Pt and Ir. In some exemplary embodiments, catalyst electrodes described, or made as described, herein are anode catalyst, and in other exemplary embodiments cathode catalyst. Catalysts electrodes are useful, for example, in generating H2 and O2 from water.