Coated Membrane Catalyst Layers for Low-Iridium Water Electrolysis
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Solution Overview
Problem
Existing water electrolysis systems face inefficiencies due to the slow reaction kinetics and high overpotential of the oxygen evolution reaction (OER) at the anode, necessitating high iridium content which is limited and costly, and the use of electrically non-conductive support materials that hinder performance.
Innovation Solution
A coated membrane with a catalyst-containing coating on its front side, comprising a support material with a BET surface area of up to 80 m²/g and iridium oxide or hydroxide, limited to 0.4 mg/cm², and a core-shell structure to enhance activity and conductivity, reducing iridium loading while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high iridium content is used to achieve sufficiently high conversion rates for the oxygen evolution reaction, then the reaction efficiency is improved, but the cost and availability limitations are worsened
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst layer by incorporating metal carbides (such as ruthenium carbide, rhodium carbide) and metal nitrides (such as ruthenium nitride, rhodium nitride) alongside iridium oxide. This parameter change allows the system to achieve high conversion rates with reduced iridium content, as the carbide and nitride components contribute to catalytic activity while requiring less precious metal
Solution Approach 2:
The patent employs composite catalyst materials consisting of iridium oxide combined with metal carbides and metal nitrides on a conductive support. This composite approach distributes the catalytic function across multiple material components, reducing dependence on high iridium content while maintaining high conversion rates for the oxygen evolution reaction
2Reliability
If electrically non-conductive support materials are used, then the stability under corrosive conditions is improved, but the electrical conductivity and reaction efficiency are worsened
Solution Approach 1:
The patent uses composite support structures that combine electrically conductive materials (such as titanium, stainless steel, or conductive oxides) with corrosion-resistant properties. This composite approach ensures both electrical conductivity for efficient electron transport and stability under the highly corrosive acidic conditions of the oxygen evolution reaction
Solution Approach 2:
The patent applies different material properties to different parts of the electrode structure. The support material is designed to provide conductivity where needed (in the bulk and electron transport paths) while maintaining corrosion resistance at the catalyst-support interface and in contact with the electrolyte, achieving local optimization of both conductivity and stability
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 solution achieves a highly active oxygen evolution reaction with a low iridium content, improving electrical conductivity and reducing the overpotential, thus enhancing the efficiency of water electrolysis.
Implementation Method 1
The catalyst compositions for the oxygen evolution reaction and the hydrogen evolution reaction, for example, are applied as anode and cathode on the front and back of the membrane
Implementation Method 2
a core-shell structure to enhance activity and conductivity
Implementation Method 3
the polymer membrane acts as a proton transport medium
Data Source
Figure 1~2
AI summary
The invention relates to a coated membrane containing - a membrane with a front and a rear face, - a catalyst-containing coating which is provided on the front face of the membrane, - said catalyst containing - a support material which has a BET surface area of maximally 80 m2/g, and - an iridium-containing coating which is provided on the support material and which contains an iridium oxide, an iridium hydroxide, or an iridium hydroxide oxide or a mixture of at least two of said iridium compounds, wherein - the catalyst contains iridium in a quantity of maximally 60 wt.%, and - the coating provided on the membrane front face has an iridium content of maximally 0.4 mg iridium / cm2.