Core-Shell Electrode Catalyst with Controlled Bromine and Chlorine
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Solution Overview
Problem
Conventional electrode catalysts for polymer electrolyte fuel cells (PEFC) with high chlorine content above 100 ppm require complex processes to remove chlorine, making them unsuitable for mass production and increasing manufacturing costs.
Innovation Solution
Development of an electrode catalyst with a core-shell structure, where the concentration of bromine species is controlled to 500 ppm or less and chlorine species to 8,500 ppm or higher, allowing for sufficient catalytic activity without the need for specialized chlorine removal processes, using X-ray fluorescence (XRF) spectroscopy for concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of chlorine in the electrode catalyst is reduced to less than 100 ppm, then the catalytic activity and lifetime of the fuel cell are improved, but the manufacturing process becomes complex and costly due to the need for specialized chlorine removal processes
Solution Approach 1:
The invention changes the chemical parameters of the catalyst preparation process by using specific precursors (chloride-containing platinum precursors and bromide-containing alloy precursors) and controlling the reduction conditions. This allows the final catalyst to have chlorine content below 100 ppm while using cost-effective preparation methods that do not require complex chlorine removal processes. The key parameter change is using bromide salts as alloying element precursors, which enables chlorine to be excluded during the reduction process itself.
Solution Approach 2:
The invention converts the potentially harmful effect of using chloride-containing precursors into a benefit by carefully controlling the reduction process. The chloride ions from the platinum precursor are effectively removed or excluded during reduction, while the bromide ions from the alloy precursor remain and provide the desired alloying effect. This transforms what would normally be a contamination problem into a controlled compositional feature.
2Ease of manufacture
If the content of chlorine in the electrode catalyst is maintained at 100 ppm or more, then the manufacturing process is simplified, but the catalytic activity becomes insufficient and corrosion occurs, shortening the fuel cell life
Solution Approach 1:
The invention changes the chemical parameters by using a specific combination of precursors: chloride-containing platinum precursors (such as H2PtCl6) and bromide-containing alloy element precursors (such as NiBr2, CoBr2, or CuBr2). The key parameter change is the use of bromide salts for the alloying elements, which enables selective exclusion of chlorine during the reduction process while maintaining simple manufacturing procedures without requiring additional chlorine removal steps.
Solution Approach 2:
The invention replaces mechanical or physical chlorine removal processes (such as washing, filtration, or thermal treatment) with a chemical mechanism during the reduction process itself. The bromide ions from the alloy precursors create a chemical environment during reduction that naturally excludes chloride ions from the final catalyst structure, eliminating the need for separate chlorine removal operations.
3Reliability
If complex chlorine removal processes are implemented, then the chlorine content is reduced below 100 ppm, but the manufacturing cost increases and mass production becomes difficult
Solution Approach 1:
The invention changes the preparation parameters by using water-soluble bromide salts of alloying elements (NiBr2, CoBr2, CuBr2, etc.) in combination with chloride-containing platinum precursors. This parameter change enables the chlorine to be naturally excluded during the aqueous reduction process, achieving low chlorine content (<100 ppm) through a simple one-step reduction that is easily scalable for mass production without requiring complex multi-step purification processes.
Solution Approach 2:
The reduction process itself performs the dual function of both synthesizing the catalyst and removing chlorine. The bromide ions from the alloy precursors create a chemical environment during reduction that automatically excludes chloride ions from the final catalyst structure. This self-service mechanism eliminates the need for separate chlorine removal operations, making the process suitable for mass production.
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 catalyst exhibits satisfactory catalytic performance even with high chlorine concentrations, facilitating mass production and reducing manufacturing costs by eliminating the need for complex chlorine removal processes.
Implementation Method 1
the concentration of bromine (Br) species is not higher than 500 ppm when measured by X-ray fluorescence (XRF) spectroscopy, and the concentration of chlorine (Cl) species is not higher than 8,500 ppm when measured by X-ray fluorescence (XRF) spectroscopy
Data Source
AI summary
Provided is an electrode catalyst that can exhibit sufficient performance, is suitable for mass production, and is suitable for reducing production costs, even when containing a relatively high concentration of chlorine. The electrode catalyst has a core-shell structure including a support; a core part that is formed on the support; and a shell part that is formed so as to cover at least one portion of the surface of the core part. A concentration of bromine (Br) species of the electrode catalyst as measured by X-ray fluorescence (XRF) spectroscopy is 500 ppm or less, and a concentration of chlorine (Cl) species of the electrode catalyst as measured by X-ray fluorescence (XRF) spectroscopy is 8,500 ppm or less.