Biography: Li Tao is a Young Career Awarded Full Professor in School of Materials Science and Engineering at Southeast University. Prior to 2016, he was a research scientist at Microelectronics Research Center, The University of Texas Austin. He received his Ph.D. from The University of Texas Dallas in 2010 with an inventor recognition award. His interdisciplinary research expertise covers 2D materials and devices, flexible micro/nano electronics, nanofabrication and nanomedicine, with research featured in TIME blog, Nature News and 50+ tech media. He has published 40+ research articles (5 ESI highly cited), including Nature Nanotechnology, Chemical Society Reviews, ACS Nano etc, with Google citations >2600. He has delivered 10+ invited talks in IEEE, MRS and APS, and recently been invited by Elsevier to edit a book. He serves as a committee member for EIPBN (3-beam) conference, associate editor for IET-Micro&Nano Letters, board member for MRS China young scientist branch.
Title of Speech: Emerging 2D Atomic Sheets for Innovative Electronics
Abstract: Two-dimensional (2D) atomic sheets yield collective properties of mechanical flexibility and tunable bandgap for innovative flexible micro-nano devices and systems. This talk will introduce our research progresses in nanoengineering of novel silicene transistors and GHz flexible electronics enabled by 2D atomic sheets. Our recent effort in a unique nanofabrication approach lets silicene transistor make its debut, corroborating theoretically predicted ambipolar transport with Dirac band structure. This requires a careful engineering of the number of layers of silicene and its interface in between source/drain electrodes and capping dielectrics, stabilizing and preserving silicene during transfer and device fabrication. Electrostatic characterization on silicene transistors observed carrier mobility 100-200 cm2/V-s at residual carrier density ~8×109 cm-2 and 10× gate modulation. Similarly, we have demonstrated the first flexible phosphorene devices with carrier mobility 310-1500 cm2/Vs and gate modulation 103-105 on flexible polyimide. It features with an intrinsic fT=20 GHz and sustains ex-situ tensile strain up to 1.5%. Most recently, we discover that field effect transistor with 2D bismuth atomic sheets (bismuthene) can yield photoelectrical and thermoeletronic response. Our research utilizes nanoengineering to address air-stability and interface issues in silicene and phosphorene micro-nano electronics, which provides transferrable knowledge to new 2D Xenes like stanene and germanene.
Biography: Dr. Xiaohong Zhu is currently a full professor at Department of Materials Science, Sichuan University, China. Dr. Zhu received his BSc degree in Materials Physics from Sichuan University in 2000 and PhD degree in Condensed Matter Physics from the Institute of Physics, Chinese Academy of Sciences in 2006. After that, he did 3-year postdoctoral research at CNRS and CEA in France, and then joined Sichuan University as a professor in 2009. From April 2012 to April 2013, he was also a research scholar at the Department of Physics & Department of Materials Science and Engineering, University of California, Berkeley, USA. He was selected as a New Century Excellent Talent in University of China in 2009 and an Outstanding Young Scientific and Technological Leader of Sichuan Province, China in 2011. Dr. Zhu’s research interests include mainly graphene-based electrode materials and novel solid-state electrolytes for energy storage devices (supercapacitors and lithium-ion batteries), piezoelectric ceramics, as well as multifunctional oxide thin films and related electronic devices. Until now, he has authored/co-authored more than 80 SCI-indexed papers and 2 scientific books.
Title of Speech: Graphene-based electrode materials for supercapacitors
Abstract: Graphene has attracted much attention since it was firstly stripped from graphite by two physicists in 2004, and the supercapacitor based on graphene has obtained wide attention and much investment as well. However, there are many problems to solve in practical application of graphene-based supercapacitors, for instance, how to reduce the cost and simplify the fabrication process and how to improve further the electrochemical performance. In this talk, I will present our recent breakthroughs in fabricating graphene-based electrode materials for high-performance supercapacitors. First of all, to avoid graphene restacking, we come up with a pumping paper process, that is, when we use force to draw the paper from a small pore, the paper would fold. So here, we report a novel strategy to prepare wrinkled flower-like graphene through a simple suction filtration process. The wrinkled flower-like graphene shows a high specific capacitance of 272 F g-1 and a perfect capacitance retention of 99.5% after 2,000 times of charging/discharging cycles. Second, graphene/MnO2, graphene/Fe3O4 and graphene/Ni(OH)2 composites with high electrochemical performance are prepared. Last but not least, 3D hierarchical porous carbon-based electrode materials (3DHPCs) with a composite structure are prepared from a biomass waste, sheep manure, by a facile carbonization and activation process without using any additional template. Benefiting from the composite structure, the ions experience a variety of environments, i.e., graphene-like sheets, nanotube- and microtube-like pores coexist in the same material, which, in turn, contribute significantly to the excellent electrochemical properties of supercapacitors, comprising high specific capacitance, outstanding rate capability and excellent long cycle stability. The specific capacitance at large current densities of 1 A g-1 and 50 A g-1 reaches as high as 486 F g-1 and 411 F g-1, respectively, in 6 M KOH electrolyte. Furthermore, the supercapacitor device based on 3DHPCs shows a superior cycle stability with almost 100% retention of the initial specific capacitance after 10,000 cycles; in addition, it yields a Ragone curve with high energy and power density combinations of 57.08 Wh kg-1 at 25.37 kW kg-1.
Biography: Dr. Guang Xu is a full professor and Ph.D advisor at the Faculty of Materials and Metallurgy at Wuhan University of Science and Technology. He received Ph.D in Materials Science and Engineering from Chongqing University in 2002, M.S. in Materials Processing Engineering from the University of Science and Technology of Beijing in 1987 and B.S. in Metals Processing Engineering from the University of Science and Technology of Beijing in 1982. He worked as visiting scholar at Bremen University (German) in 1996 to 1997, McMaster University (Canada) in 2009 to2010, Technische Universitat Bergakademie Freiberg (German) in 2015 and Wollongong University (Australia) in 2016, respectively. He serves as committee member of National Award for Science and Technology Progress. His research interests include the microstructure and property of metals and alloys, the development of high strength steels, the processing technology of materials etc. He undertook and finished many research projects, including the projects from NSFC (Natural Science Foundation of China), Hubei Province Government, Baosteel Group, Wuhan Iron and Steel Company etc. He has published more than 200 academic papers, three monographs, and received 7 invention patents. He acquired the first class awards for Hubei Science and Technology Progress for two times.
Title of Speech: In Situ Observation of Martensitic Transformation of a Fe-C-Mn-Si Bainitic Steel during the Austempering Process
Abstract: The martensitic transformation in a Fe-C-Mn-Si bainitic steel was directly observed by in-situ observation on a high-temperature laser scanning confocal microscope (LSCM) and dilatometry. The phenomenon of continuous martensitic transformation during the austempering process was firstly dynamically observed by LSCM. Differing from the commonly accepted viewpoint on martensite formation in bainitic steels, the martensitic transformation in a conventional medium-carbon bainitic steel was not instantaneous but rather proceeded gradually when the sample was austempered at the temperature below martensite starting temperature (MS). It may be attributed to the buildup of internal stress, thermal activation, stimulating nucleation, and most important, the segregation of Mn. In addition, apart from the continuous martensitic transformation, the bainitic transformation was also directly observed by LSCM during the austempering process below MS. Moreover, from the result of dilatation during the austempering process, it was found that the inflection point in the curve of dilatation versus time was not the demarcation point between the martensitic and bainitic transformation. In-situ observation results confirmed that the martensite still formed after the inflection point. The results of this paper are helpful to further understand bainitic and martensitic transformation during the austempering process at temperature below MS in a Fe-C-Mn-Si bainitic steel.