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NanoColloquium: Jin Zhang - Unique Optical Properties and Applications of Nanomaterials in Solar...
Unique Optical Properties and Applications of Nanomaterials in Solar Energy Conversion and Cancer Therapy
Department of Chemistry and Biochemistry
UC Santa Cruz
Light refreshments available beginning at 2:30
Abstract: Nanomaterials are of strong interest for both fundamental and technological purposes. At the fundamental level, nanomaterials possess novel physical and chemical properties that differ from those of isolated atoms or molecules and bulk matter due to quantum confinement effects and exceedingly larger surface area relative to volume. Semiconductor nanoparticles or quantum dots (QDs) have potential application in electronic and photonic devices and offer the opportunity to study the effects of quantum confinement.
Our lab has been actively engaged in the study of doped and undoped semiconductor nanomaterials for solid state lighting, biodetection, and energy conversion applications. In addition, we have been studying metal oxide nanostructures for solar energy applications based on photovoltaics (PV), photocatalysis, or photoelectrochemistry (PEC). One example is hydrogen generation from photoelectrochemical splitting of water based on 0D and 1D WO3, ZnO, and TiO2 nanostructures doped with nitrogen or sensitized with quantum dots. The combination of N-doping and QD sensitization of TiO2 has been found to be promising for PV and PEC applications due to strong synergistic effects attributed to enhanced hole transport. Preliminary ultrafast studies of the charge carrier dynamics support the model proposed.
Likewise, metal nanostructures also exhibit interesting properties and potential applications in various fields. We have very recently found that gold nanoparticles can substantially improve PEC performance of QD-sensitized TiO2 photoanodes, possibly due to enhanced absorption of QDs caused by increased light scattering of Au NPs. In addition, we have studied the optical and structural properties of different metal nanostructures including aggregates, nanorods, and hollow nanospheres with the goal to optimize their optical properties including SERS (surface-enhanced Raman scattering) activities. We have demonstrated SERS from single, hollow gold nanospheres (HGNs) and exceptional sample homogeneity leads to a nearly tenfold increase in signal consistency over standard silver substrates. SERS offers a unique combination of molecular specificity and extremely high sensitivity for analytical applications. The rationally designed HGNs have turned out to be useful for cancer imaging and therapy applications through a process called photothermal ablation therapy (PTA).
Speaker Bio: Jin Zhong Zhang received his B.Sc. degree in Chemistry from Fudan University, Shanghai, China, in 1983 and, through the CGP (Chemistry Graduate Program), his Ph.D. in physical chemistry from University of Washington, Seattle, USA in 1989. His Ph.D. work focused on experimental and theoretical studies of molecular reaction dynamics in the gas phase. He was a postdoctoral research fellow at University of California Berkeley from 1989 to 1992, where he studied reaction dynamics in solutions using ultrafast laser and computer simulation techniques. In 1992, he joined the faculty at University of California Santa Cruz, where he is currently full professor of chemistry and biochemistry. Zhang’s recent research interests focus on design, synthesis, characterization, and exploration of applications of advanced materials including semiconductor, metal, and metal oxide nanomaterials, particularly in the areas of solar energy conversion and biomedical detection/therapy. He has authored over 160 publications including a published book on “Self-assembled Nanostructures” (2002, Kluwer-Plenum) and a new book on “Optical Properties and Spectroscopy of Nanomaterials (2009, World Scientific). Zhang has been serving as a senior editor for the Journal of Physical Chemistry published by American Chemical Society since 2004 and on the editorial boards of several other international journals. He is adjunct and guest professor of several universities in China. He was elected Fellow of AAAS in 2007 and Fellow of APS in 2009.
This Event is For: Graduate • Faculty • Post-Docs