09 Sep, 2019 (Mon)Time:
SpeakerDr. Yan-Kai Tzeng
Department of Physics,
Stanford University, USA
Carbon materials, only one kind of element, can exist in many crystalline phases including diamondoids, fullerenes, carbon nanotubes, graphene, diamond, etc. Diamondoid has quasi-zero-dimensional cages and graphene has a two-dimensional sheet. Diamond is a three-dimensional structure and based on the sp3 hybridization, unlike other bulk carbon materials that are in layered form with a hexagonal crystal structure. Interestingly, impurity defects in diamond have attracted enormous interests in biolabeling, quantum computing, quantum entanglement and encryption, owing to their unique physical mechanical, and electronic properties. Some of impurity defects in diamond, such as negatively charged nitrogen-vacancy (N-V–) or negatively charged silicon-vacancy (Si-V–), have the unique optical property combined with good biocompatibility makes nanoscale diamond a promising fluorescent probe for super-resolution imaging of stimulated emission depletion (STED) and time-gated image of fluorescence lifetime imaging microscopy (FLIM).
Today, diamond can be synthesized by high-pressure-high-temperature (HPHT) and chemical vapor deposition (CVD) methods. The formidable challenges remain in the synthesis of nano-meter size single crystal diamond with desired internal optical defect centers. Here I will present a novel CVD diamond synthesis method using diamondoid seeds, chemically attached to substrate, and a vertical, rather than horizontal, stage-substrate geometry. In addition, this CVD nanodiamond film synthesis was applied to energy applications such as lithium-ion battery for lithium metal anode stabilization and electrocatalyst for CO2 reduction.
Finally, I will then present two to-be-submitted projects, the study of dynamic formation and migration of optical defect center in nano-scale diamond materials via ultra-fast on/off heating and thermal annealing system under high-pressure environment, and improving cycling performance of lithium-sulfur battery through a highly ion-selective pores in large area single-layer graphene separator.
Biography of the speaker:
Yan-Kai Tzeng is a postdoctoral fellow working with Prof. Steven Chu in the Department of Physics, Stanford University, United States. In June 2014, he received Ph. D. degree in Chemistry from National Taiwan University, under the supervision of Prof. Yuan-Tseh Lee and Prof. Huan-Cheng Chang at the Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan. During his Ph. D curriculum, he worked with Prof. Stefan W. Hell as a visiting student at Max-Planck Institute in Göttingen, Germany for one year. His research interests include materials, biophysics, and energy, such as the creation of optical defect-centers in nanomaterials, super-resolution fluorescence bio-imaging, and new technologies for Li-ion battery and electrocatalyst.
OrganizerDr. Z. Chu
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