Anode Coating for Oxygen Evolution Durability
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Solution Overview
Problem
Industrial electrochemical processes require electrodes with longer operational lifetimes and reduced oxygen evolution potential, especially at high current densities and in aggressive electrolytes, as existing anodes suffer from corrosion and reduced durability.
Innovation Solution
An electrode with a valve metal substrate coated with a catalytic layer of iridium and tantalum oxides, accompanied by an external valve metal oxide layer such as tantalum, tin, or zirconium, and an optional intermediate titanium or tantalum oxide protection layer, enhancing durability and resistance to contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional anodes are used in electrolysis cells, then oxygen evolution can be achieved, but the operational lifetime is limited due to corrosion and reduced durability
Solution Approach 1:
The patent applies composite materials by creating a multi-layer coating structure on the anode substrate. The coating comprises an internal layer of iridium and tantalum oxides (molar composition Ir 60-70%, Ta 30-40%) and an external layer containing 2 to 7 g/m² of tantalum, tin, or zirconium oxides. This composite structure combines the catalytic activity of iridium oxides with the corrosion resistance of tantalum, tin, or zirconium oxides, thereby extending operational lifetime while maintaining reliability in aggressive electrolytic environments.
Solution Approach 2:
The patent implements local quality by assigning different functional properties to different layers of the coating. The internal layer contains high concentrations of iridium and tantalum oxides for catalytic oxygen evolution, while the external layer contains tantalum, tin, or zirconium oxides specifically for corrosion protection and contaminant tolerance. This spatial differentiation of material properties allows each layer to optimize its specific function, resolving the contradiction between durability and corrosion resistance.
2Productivity
If high current densities are applied to increase productivity, then oxygen evolution rate improves, but electrode durability and tolerance to contaminants deteriorate
Solution Approach 1:
The composite coating structure enables high current density operation by combining catalytically active iridium oxides in the internal layer with protective tantalum, tin, or zirconium oxides in the external layer. This allows the electrode to maintain high oxygen evolution rates while the external protective layer shields the catalytic layer from degradation under high current density conditions, thus maintaining both productivity and reliability.
Solution Approach 2:
The patent applies local quality by concentrating catalytic functionality in the internal layer (Ir 60-70%, Ta 30-40% oxides) while placing protective functionality in the external layer (tantalum, tin, or zirconium oxides). This spatial separation allows the internal layer to maximize oxygen evolution at high current densities while the external layer locally provides protection against degradation, resolving the contradiction between productivity and durability.
3Use of energy by moving object
If catalytic coatings are applied to reduce oxygen evolution potential, then energy efficiency improves, but operational duration and contaminant tolerance are reduced
Solution Approach 1:
The patent resolves this contradiction by creating a composite coating where the internal layer (Ir 60-70%, Ta 30-40% oxides) provides catalytic activity for low oxygen evolution potential, while the external layer (2 to 7 g/m² tantalum, tin, or zirconium oxides) provides durability and contaminant tolerance. The synergistic combination allows the electrode to maintain low energy consumption while achieving extended operational duration exceeding 1300 hours.
Solution Approach 2:
The patent implements local quality by assigning catalytic function to the internal layer with high iridium oxide content for reduced oxygen evolution potential, while the external layer with tantalum, tin, or zirconium oxides provides localized protection for operational duration and contaminant tolerance. This functional differentiation allows simultaneous optimization of energy efficiency and operational durability.
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 proposed electrode design significantly increases operational duration and tolerance to contaminants while maintaining low oxygen evolution potential, as demonstrated by extended deactivation times in accelerated lifetime tests.
Implementation Method 1
electrode for oxygen evolution in electrochemical processes comprising a valve metal substrate, a catalytic coating comprising an internal layer of oxides of iridium and tantalum
Implementation Method 2
the addition of an external coating of the oxides of tantalum, or of tin, or of zirconium at the specified loading is capable of remarkably increasing the duration of an electrode used for anodic evolution of oxygen
Data Source
AI summary
The invention relates to a coating for anodes suitable for oxygen evolution in electrochemical processes, comprising one or more catalytic layers and an external layer. Such external layer having a composition based on tantalum oxides or tin oxides or zirconium oxides in an amount of 2 to 7 g/m2.