25th anniversary article: Ion exchange in colloidal nanocrystals

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Ion exchange has emerged as a powerful method for synthesizing complex nanocrystal structures.
• Early research focused on II-VI semiconductors, but the technique now encompasses a broader range of materials, including I-III-VI and III-V semiconductors.

Purpose of the Study:

• To review the progress and advancements in ion exchange for nanocrystal synthesis.
• To explore the synthetic strategies, underlying principles, and diverse nanostructures achievable through ion exchange.
• To provide a perspective on the future outlook and emerging applications of ion exchange-derived materials.

Main Methods:

• Surveying synthetic approaches, primarily focusing on cation replacement strategies.
• Analyzing thermodynamic factors, ion-transfer agent interactions, and diffusion mechanisms.
• Utilizing advanced electron microscopy and image reconstruction for structural analysis.

Main Results:

• Demonstrated control over ion exchange extent, yielding doped nanoparticles, alloys, core-shells, and segmented nanostructures.
• Expanded the scope of ion exchange to include low-toxicity and challenging semiconductor materials.
• Provided a compilation of literature data on solubilities, ion properties, and Lewis acid/base strengths to aid fundamental understanding.

Conclusions:

• Ion exchange is a versatile and increasingly important technique for creating novel nanocrystal architectures.
• A deeper understanding of fundamental principles is driving progress and enabling the synthesis of complex materials.
• Emerging applications are expected to benefit significantly from the unique properties of ion exchange-derived nanomaterials.