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Nanoparticle conversion chemistry: Kirkendall effect, galvanic exchange, and anion exchange
Bryan D Anderson1, Joseph B Tracy
1Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA. jbtracy@ncsu.edu.
Nanoscale
|July 23, 2014
Summary
Conversion chemistry transforms nanoparticles into new materials, often creating voids. Understanding these reactions, including Kirkendall effect, galvanic, and anion exchange, enables precise control over complex nanostructures.
Area of Science:
- Materials Science
- Nanotechnology
- Chemistry
Background:
- Conversion chemistry is a rapidly advancing field.
- Chemical conversion of nanoparticles (NPs) frequently leads to morphological changes, notably void formation.
- These transformations allow for the creation of complex nanostructures unattainable by other methods.
Purpose of the Study:
- To review the principles and examples of three major classes of conversion chemical reactions.
- To elucidate the mechanisms behind void formation during NP conversion.
- To highlight the potential applications of complex nanostructures derived from conversion chemistry.
Main Methods:
- Review of Kirkendall effect in metal NPs.
- Analysis of galvanic exchange reactions involving noble metal salts.
- Examination of anion exchange reactions in metal compound NPs.
Main Results:
- The Kirkendall effect involves differential diffusion rates, causing void formation during metal NP conversion to oxides, phosphides, sulfides, and selenides.
- Galvanic exchange reactions result in alloying and dealloying of metal NPs through redox processes.
- Anion exchange reactions, driven by anion addition, cause significant morphological changes in NPs due to size differences.
Conclusions:
- Conversion chemistry provides a versatile route to synthesize complex NPs with tailored compositions and structures.
- Understanding reaction mechanisms allows for fine-tuned control over NP morphology and properties.
- The resulting nanostructures exhibit promising catalytic, electronic, optical, magnetic, and electrochemical properties for diverse applications.
