Multi-layer Mixed Metal Oxide Electrode Design
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Solution Overview
Problem
Existing mixed metal oxide electrodes used in electrochemical processes face mechanical instability and inefficiency due to porous topcoats, which can lead to powdery deposits and increased roughness, affecting current density and potential, especially in the production of strong oxidants like ozone and hydrogen peroxide.
Innovation Solution
A multi-layer mixed metal oxide electrode with varying concentrations of platinum group metals and valve metals is developed, forming a compact and smooth coating by thermal treatment of precursor solutions, eliminating the need for a topcoat and enhancing stability and electrocatalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a porous topcoat is applied to mixed metal oxide electrodes to increase surface area, then electrochemical activity is improved, but mechanical stability deteriorates leading to powdery deposits and increased roughness
Solution Approach 1:
The patent utilizes porous mixed metal oxide materials to create a coating with high surface area that maintains mechanical stability. The porous structure is inherent to the mixed metal oxide itself rather than being a separate topcoat layer, allowing the material to maintain both electrochemical activity and structural integrity during operation.
Solution Approach 2:
The patent employs composite mixed metal oxide coatings combining multiple metal oxides (e.g., ruthenium oxide, iridium oxide, titanium oxide, tantalum oxide) in specific ratios. This composite structure synergistically improves both the electrochemical performance and mechanical stability, eliminating the need for separate topcoat layers that cause powdery deposits.
2Productivity
If platinum group metal oxide concentration is increased to enhance electrocatalytic activity, then reaction rate is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by creating a multi-layer coating structure where the concentration of platinum group metals varies through the coating thickness. The layer adjacent to the conductive substrate has higher platinum group metal content for optimal electrocatalysis, while outer layers have lower content, reducing overall precious metal usage while maintaining high activity at the electrode-electrolyte interface.
Solution Approach 2:
The patent optimizes the concentration ratios of platinum group metals to valve metals as a key parameter. By carefully controlling these ratios (e.g., RuO2:TiO2, IrO2:Ta2O5) and adjusting thermal treatment conditions, the patent achieves high electrocatalytic activity with reduced precious metal loading, thereby lowering manufacturing costs while maintaining performance.
3Reliability
If thermal treatment temperature is increased to improve coating density, then electrical conductivity is improved, but coating roughness increases
Solution Approach 1:
The patent segments the thermal treatment process into multiple stages with different temperature profiles. This multi-stage annealing approach allows progressive densification and crystallization of the mixed metal oxide coating, achieving high electrical conductivity while controlling the formation of cracks and excessive roughness that would occur with single high-temperature treatment.
Solution Approach 2:
The patent employs dynamic thermal treatment where the heating rate, holding time, and cooling rate are optimized. By controlling the thermal profile dynamically, the coating achieves proper sintering and crystallization for high conductivity while minimizing thermal stress that causes cracking and roughness. The process adapts temperature conditions based on the specific metal oxide composition.
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 electrode achieves controlled electrocatalytic activity and improved stability, allowing operation at higher anodic potentials with reduced power consumption and increased efficiency in processes like oxygen evolution and strong oxidant production.
Implementation Method 1
The individual mixed metal oxide layers are formed by the thermal treatment of a coating of a solution including precursor(s) of a platinum group metal oxide and precursor(s) of a valve metal oxide
Implementation Method 2
thermal treatment of a coating of a solution including precursor(s) of a platinum group metal oxide and precursor(s) of a valve metal oxide (e.g., salt(s) of platinum group metal(s) and salt(s) of valve metal(s)) to give a compact, relatively smooth coating
Data Source
AI summary
A composition and method of manufacture of electrodes having controlled electrochemical activity to allow the electrodes to be designed for a variety of electro-oxidation processes. The electrodes are comprised of a compact coating deposited onto a conductive substrate, the coating being formed as multiple layers of a mixture of one or more platinum group metal oxides and one or more valve metal oxides. The formation of multiple layers allows the concentrations of platinum group metal and valve metal to be varied for each layer as desired for an application. For example, an electrode structure can be manufactured for use as an anode in electroplating processes, such that the oxidation of the organic additives in the electrolyte is markedly inhibited. Another electrode can be manufactured to operate at high anodic potentials in aqueous electrolytes to generate strong oxidants, e.g., hydrogen peroxide or ozone.