Sun Research Group

We utilize the so called “bottom-up” approach for the synthesis of monodisperse nanoparticles. Recent focus has been on the synthesis of magnetic nanoparticles of Co, MFe2O4 and FePt by reduction of metal salts and/or thermal decomposition of organometallic precursors. The size, composition, and shape of these nanoparticles can be tuned by controlling reaction parameters, such as the reactant ratio and concentrations, temperature and time. We are also exploring other synthetic approaches to prepare multi-component and multi-functional nanoparticles of the alloy-type (e.g. CoFe), core/shell type (e.g. CoFe/Fe3O4), and dumbbell-like (e.g. Au-Fe3O4) materials. Through proper surface modification, these nanoparticles can be dispersed in various media, or they can self-assemble into superlattice structures. The effects of particle size, shape, composition and interparticle spacing on physical and chemical properties of the nanostructures constitute issues of the critical importance that are addressed by our research.

Recent advances in the synthetic control of nanoparticle monodispersity suggest that the fabrication of nanoparticle-based bio-probes with ultra-high sensitivity should be possible. We are working to make a series of biocompatible superparamagnetic nanoparticles that show the maximum magnetic moment (M) under physiological conditions, and subsequently establish their bio-recognition capabilities. We will integrate the functionalized nanoparticles into bio-systems for highly sensitive and efficient biomedical applications.

The rapid progress in the construction of nanoparticles with controllable size, shape, and electronic properties has made it possible to rationally design and synthesize nanoparticle-based catalysts. Our goals are to prepare transition metal based nanoparticles with controlled size, composition, and shape and to study their self-assembled structures for controlled oxygen reduction and organics oxidation.

Nanocomposites refer to engineered materials consisting of at least one nanoscale constituent. By independently tuning the size and composition of each component, followed by engineering the assembly, the nanostructures and their properties can be tailored to store high density magnetic energy. The self-assembly approach is being used to prepare multi-component systems to provide both a model for fundamental understanding of physical properties within the nanostructures and a practical route to novel devices for magnetic energy storage applications. The figure here shows two examples of nanocomposites we made in our lab: FePt-Fe3O4 and core/shell structured Fe/Fe3O4.