Synthesis Method for Hydrogen Gas-Driven Deposition of Iridium on Platinum Surfaces, Iridium-Coated Platinum Nanoparticles, and Their Use in Electrochemical Devices

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This invention describes a method for coating platinum nanoparticles with a thin layer of iridium using hydrogen gas as the driving force in an acidic liquid reaction medium. Iridium cations in the solution are reduced and deposited onto platinum surfaces when hydrogen gas is introduced, resulting in iridium-coated platinum nanoparticles containing between 1 and 40 weight percent iridium. The process can also be applied to non-platinum support materials that have platinum-coated surfaces. The resulting core-shell nanoparticles are designed for use in electrochemical devices such as fuel cells and water electrolyzers.

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• As electrocatalysts in proton exchange membrane (PEM) water electrolyzers, where iridium-coated platinum nanoparticles serve as oxygen evolution reaction (OER) catalysts at the anode.
• As cathode or anode catalyst materials in hydrogen fuel cells (PEM fuel cells), combining the catalytic activity of platinum with the stability benefits of iridium.
• As catalyst coatings on non-platinum support materials (e.g., carbon or metal oxide supports with platinum surface layers) to reduce overall precious metal loading while maintaining performance.
• In electrochemical hydrogen production systems requiring highly active and corrosion-resistant nanoparticle catalysts operating under acidic conditions.
• In the manufacture of membrane electrode assemblies (MEAs) for electrochemical devices where precise control of iridium shell thickness (via weight percent tuning) is needed to optimize cost and performance.

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• Reduces the total iridium loading required compared to pure iridium catalysts, lowering material costs while retaining catalytic activity.
• The hydrogen-driven deposition method provides a simple, scalable, and chemically mild route to conformal iridium coatings without the need for external electrical power or complex reducing agents.
• Precise control of iridium content (1–40 wt%) allows fine-tuning of the catalyst's electrochemical properties and cost profile for specific applications.
• The core-shell architecture leverages platinum's high catalytic activity while the iridium shell improves corrosion and oxidation resistance under harsh acidic electrochemical conditions.
• Applicability to non-platinum support materials with platinum-coated surfaces broadens the design space for catalyst architectures and enables further reduction of precious metal use.
• The acidic aqueous reaction medium is compatible with industrial catalyst manufacturing processes, facilitating straightforward scale-up.

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Patent Abstract

The application relates to iridium-coated platinum nanoparticles with an iridium content of the iridium-coated platinum nanoparticles of 1 to 40 wt% based on the total weight of the iridium-coated platinum nanoparticles, as well as a method for hydrogen-driven deposition of iridium on platinum surfaces, in particular of platinum nanoparticles, characterized in that the surface of platinum nanoparticles in an acidic liquid reaction medium in the presence of H2 gas is brought into contact with Ir cations. Furthermore, the application relates to the use of iridium-coated Pt nanoparticles and support materials not consisting of platinum with iridium-coated Pt surfaces in electrochemical devices.