Laser-Assisted Lattice Recovery of 3D Graphene by Carbon Nanodot Patching

תמונה_סמינרים
17.01.2019
14:30
David Wang Auditorium, 3rd floor Dalia Maydan Bldg
Dr. Arie Borenstein, Invited Speaker

Dr. Arie Borenstein, Invited Speaker

Department of Chemistry and Biochemistry, University of California, Los Angeles
607 Charles E Young Dr E, Los Angeles, CA, USA

Producing highly oriented graphene is a major challenge that constrains graphene from fulfilling its full potential in technological applications. Graphene exhibits excellent electronic and structural properties due to its conjugated sp2 hybridized carbon bonds. The high theoretical in-plane electron mobility (>15,000 cm2 V-1 s-1) was demonstrated in experimental measurements on a perfect single crystal sheet. However, these exciting properties are impeded in practical bulk materials due to lattice imperfections that hinder charge mobility. We present a simple method to improve the structural integrity and reduce defective fragments by utilizing laser irradiation on a composite of two types of carbon nano-materials: carbon nanodots (CNDs) and 3D graphene. The CNDs attach themselves to defect sites in the graphene sheets, and then upon laser-assisted reduction, patch defects in the carbon lattice. Spectroscopic experiments reveal graphitic structural recovery of up to 43%. The electric conductivity of the CND-patched graphene is four times larger than bare graphene. The composites were tested as electrodes in electrochemical capacitors and demonstrate a very fast RC time constant of 0.57 ms, a frequently response fast enough to operate as AC line filters, potentially replacing today’s electrolytic capacitors. Using this methodology, we demonstrate a novel line filter with a response time of 0.654 ms and an areal capacitance of 68.8 mF cm-2. This result emphasizes the decisive role of structural integrity for optimizing graphene in electronic applications.

Prof. Michael Silverstein