RuIr Core-Shell Catalyst for Low Overpotential OER
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Solution Overview
Problem
Current catalysts for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) face challenges with high overpotential requirements and low durability, particularly in acidic solutions, where Ru-based catalysts show limited activity and Ir-based catalysts are expensive and less durable.
Innovation Solution
An anisotropic nanostructure represented by RuxM1-x, where 0.6≤x≤0.999, with M being Ir, Rh, Pt, or Au, forming a solid solution and having an anisotropic hexagonal close-packed structure, is produced using a method involving a solution containing Ru and M compounds with a reducing agent at 215 to 230°C, resulting in a catalyst with exposed 0001 planes and high crystallite size ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If Ru-based catalysts are used for OER, then high catalytic activity is achieved, but durability drops sharply in acidic solutions
Solution Approach 1:
The patent creates a composite material consisting of Ru core particles coated with an IrOx shell layer. This composite structure combines the high catalytic activity of Ru with the excellent durability and acid resistance of IrOx, resolving the contradiction between activity and durability in acidic solutions.
Solution Approach 2:
The patent applies different materials to different regions of the catalyst structure: Ru is used in the core where high catalytic activity is needed, while IrOx is applied as a protective shell where acid resistance and durability are required. This local differentiation of material properties resolves the contradiction between activity and durability.
2Reliability
If Ir-based catalysts are used for OER, then durability is improved, but cost increases and activity is reduced
Solution Approach 1:
The patent applies IrOx only as a thin shell layer (1-10 nm thickness) on the Ru core, rather than using bulk Ir-based materials. This localized application provides the necessary durability and acid resistance while minimizing the amount of expensive Ir used, thereby reducing cost while maintaining activity.
Solution Approach 2:
The patent uses a small amount of expensive IrOx as a protective shell that can be replaced or regenerated, while the bulk of the catalyst remains Ru which is cheaper. The thin shell protects the Ru core from dissolution, effectively making the expensive component a durable protective layer rather than the bulk material.
3Device complexity
If conventional catalysts are used for water electrolysis, then simplicity is maintained, but overpotential is high and efficiency is low
Solution Approach 1:
The patent employs a Ru@IrOx core-shell composite structure that combines the advantages of both Ru (high activity, low overpotential) and IrOx (stability, acid resistance). This composite approach achieves low overpotential for water electrolysis while maintaining structural simplicity through a straightforward core-shell architecture.
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 a current density of 10 mA/cm2 with low overpotential in acidic solutions, demonstrating high durability and activity for both OER and HER, surpassing conventional catalysts in stability and cost-effectiveness.
Implementation Method 1
Ru and M form a solid solution at the atomic level
Implementation Method 2
a solution containing Ru and M compounds with a reducing agent at 215 to 230°C
Implementation Method 3
The catalyst achieves a current density of 10 mA/cm2 with low overpotential in acidic solutions, demonstrating high durability and activity for both OER and HER
Data Source
AI summary
This invention provides an anisotropic nanostructure represented by the formula:RuxM1-x,wherein 0.6≤x≤0.999, and M represents at least one member selected from the group consisting of Ir, Rh, Pt, Pd, and Au, and wherein Ru and M form a solid solution at the atomic level, and the anisotropic nanostructure has an anisotropic hexagonal close-packed structure (hcp).