Co@Pt Core-Shell Nanoparticles for Oxygen Reduction
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Solution Overview
Problem
The growth of non-precious metal (NPM)/precious metal (PM) core-shell nanoparticles is challenging due to the oxidation of NPM surfaces, which hinders the overgrowth of precious metals, limiting their use in catalytic applications such as electrochemical energy conversion and storage.
Innovation Solution
A method for forming Co@Pt nanoparticles through in situ seed-mediated growth using carbon monoxide as both a stabilizing agent and reducing agent, allowing platinum to overgrow on cobalt seeds, resulting in solid core-shell nanoparticles with enhanced catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-precious metal nanoparticles are used as cores for precious metal plating, then cost-effectiveness and specific surface area are improved, but the NPM surface is prone to oxidation which hinders precious metal overgrowth
Solution Approach 1:
The patent performs preliminary protection of the NPM nanoparticle surface by forming a protective layer or controlling the environment before precious metal overgrowth occurs. This prevents oxidation of the NPM surface that would otherwise hinder subsequent PM deposition, enabling successful core-shell structure formation while maintaining high specific surface area
Solution Approach 2:
The patent introduces an intermediary substance or mechanism that mediates between the NPM core and PM shell formation. This intermediary protects the NPM surface from oxidation during the plating process while still allowing controlled PM deposition, resolving the contradiction between surface stability and specific surface area enhancement
2Ease of manufacture
If traditional plating methods are used on NPM nanoparticles, then precious metal coating can be achieved, but oxidation of NPM surface prevents effective overgrowth
Solution Approach 1:
The patent changes critical process parameters such as pH, temperature, potential, or chemical environment to prevent NPM oxidation during plating. By optimizing these parameters, the method achieves both ease of manufacture through simplified processing and manufacturing precision through uniform shell formation without oxidation-induced defects
Solution Approach 2:
The patent employs an inert atmosphere or chemically controlled environment during the plating process to prevent oxidation of the NPM surface. This creates conditions where traditional plating methods can proceed effectively, producing uniform precious metal shells on NPM cores without oxidation interference
3Productivity
If NPM/PM core-shell structures are formed, then catalytic activity can be enhanced through metal interactions, but oxidation hinders the formation of these structures
Solution Approach 1:
The patent performs preliminary surface treatment or environmental control to prevent NPM oxidation before core-shell structure formation. This enables the desired NPM/PM interfaces to form for enhanced catalytic activity through ligand and strain effects, while avoiding oxidation that would prevent proper structure formation
Solution Approach 2:
The patent uses an intermediary agent or controlled environment that facilitates the formation of NPM/PM core-shell structures with proper interfaces for catalytic enhancement. This intermediary prevents oxidation during the formation process while allowing the beneficial metal-metal interactions to develop for improved catalytic activity
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 Co@Pt nanoparticles exhibit significantly improved catalytic efficiency for the oxygen reduction reaction, with mass activity reaching 10 times that of commercial Pt catalysts, and demonstrate stability under potential cycling, maintaining catalytic activity and structure.
Implementation Method 1
using carbon monoxide as both a stabilizing agent and reducing agent
Implementation Method 2
using carbon monoxide as both a stabilizing agent and reducing agent, allowing platinum to overgrow on cobalt seeds
Implementation Method 3
A method for forming Co@Pt nanoparticles through in situ seed-mediated growth
Data Source
AI summary
Core-shell nanoparticles having a solid core comprising a first metal and a shell comprising a second metal disposed at least a portion of the exterior surface of the core. The core-shell nanoparticles comprise a non-precious transition metal and the second metal comprises a precious metal or semi-precious metal. The core-shell nanoparticles can be used to catalyze oxygen reduction reactions. Also provided are compositions comprising the core-shell nanoparticles, methods of making same, and devices of same.