Organic-Inorganic Hybrid Materials

We are interested in the fabrication of organic-inorganic hybrid materials at the nanoscale. The inorganic materials are generally composed of metal or semiconductor nanoparticles, or coupled nanocomposites (metal-metal, semiconductor-metal, or semiconductor-semiconductor). Metallic and semiconductor nanoparticles often display several advantages compared to bulk materials. Examples include size- and shape- dependent optical, electronic, magnetic and catalytic properties. Generally, nanoparticle properties are affected by the presence of different materials in close proximity to their surface. The underlying theme is to understand how coupled nanocomposite (metal/metal, semiconductor/semiconductor, metal/semiconductor) structure and composition affects their properties, and the properties of molecular compounds at the interface. The molecular compounds comprise organic chromophores, inorganic coordination chromophores, or molecular catalysts.

Elucidating the Mechanisms of Radiative and Non-Radiative Decay at Metallic Nanoparticle/Chromophore Interfaces

It is well known that conducting metal particles affect the emission properties of fluorophores in close proximity. These effects are due to coupling of the metal surface plasmon absorbances with excited-state fluorophores. Surface plasmon resonances of metallic particles depend on the size, shape, composition, and dielectric constants of nearby materials. A fundamental understanding of the effects of metallic structure and composition (e.g. metal nanocomposites) on the emission properties of organic chromophores is being investigated in our lab. The approach is further being extended for detection of small quantities of environmental contaminants.

Nanostructured Composites for Environmental Remediation

Improving charge separation within semiconductors is an important step in multielectron transfer catalysis. Surface modification of a semiconductor with an appropriate material can be used to decrease the rate of charge recombination. A clear understanding of these processes is being used to carefully tailor molecular-materials catalysts toward multielectron transfer reactions. These reactions are essential for environmental remediation of organic pollutants for example, nitrates, perchlorates, chlorinated hydrocarbons, and phenols.

Students in this group are engaged in many areas including nanoparticle fabrication, synthesis and characterization of organic and coordination compounds, fluorescence spectroscopy and microscopy, time-resolved fluorescence, electrochemistry, photocatalysis, and electron microscopy.