Core-Shell Electrode Catalyst Chlorine Reduction
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Solution Overview
Problem
Current methods for manufacturing electrode catalysts with a core-shell structure struggle to reliably and simply reduce chlorine content, particularly when using chloride salts of platinum and palladium, which can lead to degradation in fuel cell performance.
Innovation Solution
A production method involving filtration and washing with ultrapure water to reduce chlorine species content, using a reductant such as organic or inorganic acids, and a pretreatment process to enhance the removal of chlorine, resulting in a core-shell electrode catalyst with reduced chlorine levels suitable for mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chloride salts of platinum and palladium are used as raw materials for manufacturing core-shell electrode catalysts, then manufacturing cost is reduced and ease of manufacture is improved, but chlorine content increases causing degradation in fuel cell performance and reliability
Solution Approach 1:
The patent extracts and removes chlorine species from the electrode catalyst through a series of washing steps using ultrapure water. The catalyst precursor is washed multiple times to reduce chlorine content to 1000 ppm or less, thereby eliminating the harmful effect of chlorine while maintaining the core-shell structure and catalytic performance.
Solution Approach 2:
The patent changes the parameter of chlorine content from high (using chloride salts directly) to low (1000 ppm or less) through controlled washing processes. This parameter change is achieved by adjusting the washing conditions including the use of ultrapure water, temperature control, and multiple washing cycles to achieve the desired chlorine reduction.
2Reliability
If extensive washing processes are implemented to reduce chlorine content, then fuel cell performance is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent performs preliminary washing actions during the catalyst synthesis process itself, incorporating washing steps into the manufacturing flow rather than as a separate post-processing stage. This integrates chlorine removal into the core manufacturing process, reducing overall complexity while achieving the required chlorine content reduction.
Solution Approach 2:
The washing process uses ultrapure water that serves multiple functions: it removes chlorine species, maintains catalyst dispersion, and prepares the catalyst for subsequent processing. The process is designed to be self-regulating where the washing conditions automatically optimize chlorine removal efficiency.
3Reliability
If chlorine content is reduced to below 1000 ppm through washing, then catalytic activity is improved, but water consumption and production time increase
Solution Approach 1:
The patent implements continuous washing operations where ultrapure water is continuously circulated through the catalyst precursor suspension. This continuous action maintains efficient mass transfer for chlorine removal without requiring batch processing, thereby reducing total processing time and water consumption while achieving the target chlorine content.
Solution Approach 2:
The patent replaces mechanical filtration and separation methods with a chemical-washing approach using ultrapure water. This substitution eliminates complex mechanical separation equipment and reduces processing steps, achieving chlorine removal through chemical dissolution and diffusion rather than mechanical separation, thereby improving productivity.
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 method effectively reduces chlorine content in electrode catalysts to below 1000 ppm, preventing performance degradation and lowering production costs, making it suitable for mass production and use in fuel cell applications.
Implementation Method 1
a first step (1) of retaining a liquid containing ultrapure water, a reductant and an electrode catalyst precursor
Implementation Method 2
A production method involving filtration and washing with ultrapure water to reduce chlorine species content
Implementation Method 3
preparing a second liquid by filtrating and washing the electrode catalyst precursor contained in the first liquid with ultrapure water
Data Source
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AI summary
Provided is an electrode catalyst production method capable of obtaining, through an easy operation, an electrode catalyst whose chlorine (Cl) species content has been reliably and sufficiently reduced, even when using as an electrode catalyst raw material an electrode catalyst precursor containing a high concentration of chlorine. The method is to produce an electrode catalyst having a core-shell structure including a support, a core part formed on the support and a shell part formed to cover at least a part of a surface of the core part. The method includes a first step (1) of retaining a liquid containing ultrapure water, a reductant such as a hydrogen-containing gas and an electrode catalyst precursor under at least one stage of a predetermined temperature for a predetermined retention time, such electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined first chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy.