The central theme of my research is to design and synthesize novel nanostructured materials. Specifically, I employ chemical synthesis for the fabrication of various Inorganic nanomaterials including noble metal nanostructures with controlled morphologies and functionalities, as well as nanocomposites consisting of metals-metal oxides (or metal-semiconductor). The resulting nanomaterials are exploited for DNA-mediated assembly and application including photocatalysis, surface plasmon resonance and surface enhanced Raman scattering, organic photovoltaic cells and chemical and biosensing.
Inorganic Nanoparticle Synthesis
It is well known that the physical properties of nanoscale materials are highly dependent on their morphology. This relationship implies that for every nanoparticle composition there may be an infinite number of optical, electronic, and catalytic behaviors. Unfortunately there is currently no systematic way to design and then rationally access a particular nanoparticle architecture.
Elucidating these pathways would allow us to better use our current materials, and more effectively create new ones. Just as organic chemistry research has developed a mechanistic framework and synthetic toolbox that has produced different materials from plastics to pharmaceuticals, similar concepts must be developed for nanochemistry to harness the similar potential for inorganic nanomaterials. Through the discovery of nanoparticle reaction mechanisms, I work to develop a set of physical, analytical, and synthetic principles to rationally synthesize complex, highly-tailored nanoparticles for different applications.
Shape-selective growth of noble metal (such as Au, Ag) nanocrystals has received tremendous attention in recent years, not only because of the beauty of manipulating the geometries and sizes of these nanocrystals, but also due to the wide variety of applications that are coupled to their morphologies. In this area, we focus on the study of various thermodynamic and kinetic factors that affect the growth modes of noble metal nanocrystals. Examples of these factors include the selection of solvents, the introduction of foreign species such as surfactants or metal ions, the control over the reducing agents and/or the pH value, etc. By examining various aspects of solution-based synthetic approaches, we hope to gain further fundamental understanding of the growth mechanism and generalize certain design rules for noble nanocrystals.
For Au and Ag nanocrystals, they have a fascinating property called localized surface plasmon resonance (LSPR). This phenomenon arises due to the interaction between the electrons of the nanocrystals and electromagnetic waves, causing oscillation of the electrons in resonance with the frequency of the incident light. By tuning the shapes of Au, Ag, and even Pd nanocrystals, their LSPR can be tailored to any specific wavelength ranging from visible to near infrared. Based on the tunable LSPR, applications such as bioimaging, chemical sensing, and photothermal therapy have been exploited for Au and Ag nanocrystals.
Inorganic Nanoparticle Synthesis
It is well known that the physical properties of nanoscale materials are highly dependent on their morphology. This relationship implies that for every nanoparticle composition there may be an infinite number of optical, electronic, and catalytic behaviors. Unfortunately there is currently no systematic way to design and then rationally access a particular nanoparticle architecture.
Elucidating these pathways would allow us to better use our current materials, and more effectively create new ones. Just as organic chemistry research has developed a mechanistic framework and synthetic toolbox that has produced different materials from plastics to pharmaceuticals, similar concepts must be developed for nanochemistry to harness the similar potential for inorganic nanomaterials. Through the discovery of nanoparticle reaction mechanisms, I work to develop a set of physical, analytical, and synthetic principles to rationally synthesize complex, highly-tailored nanoparticles for different applications.
Shape-selective growth of noble metal (such as Au, Ag) nanocrystals has received tremendous attention in recent years, not only because of the beauty of manipulating the geometries and sizes of these nanocrystals, but also due to the wide variety of applications that are coupled to their morphologies. In this area, we focus on the study of various thermodynamic and kinetic factors that affect the growth modes of noble metal nanocrystals. Examples of these factors include the selection of solvents, the introduction of foreign species such as surfactants or metal ions, the control over the reducing agents and/or the pH value, etc. By examining various aspects of solution-based synthetic approaches, we hope to gain further fundamental understanding of the growth mechanism and generalize certain design rules for noble nanocrystals.
For Au and Ag nanocrystals, they have a fascinating property called localized surface plasmon resonance (LSPR). This phenomenon arises due to the interaction between the electrons of the nanocrystals and electromagnetic waves, causing oscillation of the electrons in resonance with the frequency of the incident light. By tuning the shapes of Au, Ag, and even Pd nanocrystals, their LSPR can be tailored to any specific wavelength ranging from visible to near infrared. Based on the tunable LSPR, applications such as bioimaging, chemical sensing, and photothermal therapy have been exploited for Au and Ag nanocrystals.
DNA-mediated Self-assembly of Inorganic Nanoparticles
The 3D assembly of nanoparticle (NP) building blocks into macroscopic superlattice with well-defined order and symmetry and crystallinity is proved to be promising and useful although it remains one of the most important challenges in materials science and chemistry. Superlattices consisting of metal NPs have emerged as a new platform for the bottom-up design of plasmonic metamaterials. Many of the current methods to fabricate metamaterials in the optical range use serial lithographic-based approaches which are time-consuming, expensive and not programmable. DNA-mediated assembly of NPs has the potential to help overcome these challenges.
Spherical gold NPs are commonly used to make 3D superlattice but there are very few examples of superlattice with anisotropic NP component. In general, any anisotropic NPs capable of DNA fictionalization could be used to impart directional bonding interactions at nanoscale through anisotropic interactions resulting from particle shape to make interesting novel architectures. Herein, we have examined the concept of inherent shape-directed crystallization of NPs to make 1-dimentional superlattie with gold nanoprism and 3-dimentional superlattie with gold nanocube in the context of DNA-mediated NP assembly.
The 3D assembly of nanoparticle (NP) building blocks into macroscopic superlattice with well-defined order and symmetry and crystallinity is proved to be promising and useful although it remains one of the most important challenges in materials science and chemistry. Superlattices consisting of metal NPs have emerged as a new platform for the bottom-up design of plasmonic metamaterials. Many of the current methods to fabricate metamaterials in the optical range use serial lithographic-based approaches which are time-consuming, expensive and not programmable. DNA-mediated assembly of NPs has the potential to help overcome these challenges.
Spherical gold NPs are commonly used to make 3D superlattice but there are very few examples of superlattice with anisotropic NP component. In general, any anisotropic NPs capable of DNA fictionalization could be used to impart directional bonding interactions at nanoscale through anisotropic interactions resulting from particle shape to make interesting novel architectures. Herein, we have examined the concept of inherent shape-directed crystallization of NPs to make 1-dimentional superlattie with gold nanoprism and 3-dimentional superlattie with gold nanocube in the context of DNA-mediated NP assembly.
