Plasma-molten metal and/or liquid interactions for materials processing
25th July, Thrusday, 4:00‐5:00 pm, ChE Seminar hall
ABSTRACT:-
Several grand challenges in energy storage and conversion need the discovery of functional materials that many agree will be composed of complex compositions and nanoscale materials such as nanowires. In this regard, plasma based materials processing has been shown to be promising for combinatorial techniques and scalable processing. For example, our group has shown that gentle plasma excitation of gas phase will allow the use of non-catalytic, low melting metals for catalyzing nanowire growth. Furthermore, the use of plasma oxidation of liquid precursors allows for creation of metastable complex oxide particles with compositional control. A number of examples will be discussed in which the above two techniques are currently being used for accelerating the development of a variety of catalysts including electrocatalysts and materials for storage applications. This talk will highlight our efforts to understand the role of plasmas under two categories: (a) the synergistic effects hydrogen and nitrogen plasma interactions with molten metals; and (b) the oxygen plasma-liquid droplet interactions. To gain insights into these mechanisms we have studied the interaction of hydrogen and nitrogen plasmas with low melting point metals, primarily with gallium. Absorption/desorption experiments as well as theoretical-computational calculations were performed. Experiments have shown an increment of adsorbed gaseous species into the molten metal in the presence of plasmas. In the case of oxygen plasma-liquid droplet interactions for creating complex oxides, the role of solvated electrons, oxygen radicals and heating effects will be discussed. Finally, the use of plasmas for achieving liquid phase epitaxial growth of GaN and related materials will be discussed. Author acknowledge primary funding support from NSF Solar Project (DMS 1125909), and NSF EPSCoR (1355438).
Biosketch:-
Mahendra Sunkara is Director of the Conn Center for Renewable Engineering Research, Professor of Chemical Engineering and Distinguished University Scholar at University of Louisville. Dr. Sunkara received his B. Tech. degree in Chemical Engineering from Andhra University (India) in 1986, a M.S. in Chemical Engineering from Clarkson University in 1988, and a PhD in 1993 from Case Western Reserve. He did his PhD under guidance of Prof. John Angus on chemical vapor deposition of diamond. He worked at Faraday Technology, Inc. in Dayton, OH, from 1993-1996 as a Project Engineer before joining UofL as an assistant professor in 1996.
His personal research interests include large single crystal growth of diamond, gallium nitride and bulk quantities of nanowires, solar cells, Li Ion batteries, and water splitting. He has published over 175 articles in refereed journals, four book chapters, and was awarded over 25 U.S. patents. His articles have been cited over 9,000 times with H-index of 45. He co-authored a book entitled “Inorganic Nanowires: Applications, Properties and Characterization” published by CRC Press. He was awarded the Ralph E. Powe Junior Faculty in Engineering award in 1999 and NSF CAREER award in 1999. In 2002, the Louisville Magazine placed him in the list of top 25 young guns in the city of Louisville. In 2009, he received the UofL President’s distinguished faculty award for research and United Phosphorus CDS Award from the Indian Institute of Chemical Engineers in 2009. He has been named as Fellow of Kentucky Science and Engineering Foundation in 2017. He graduated over 20 M.S/M.Eng and 25 PhD students who found successful careers in academia as faculty at institutions such as Rensselaer Polytechnic Institute, Texas A&M, U of Tulsa, South Dakota School of Mines, IIT - Hyderabad and in Industry such as Intel, HP, Veeco, Lam Research, Applied Materials, and Lexmark, etc. He serves on the editorial boards of Nanotechnology and Nature Scientific Reports.
He founded Advanced Energy Materials, LLC (AdEM) to commercialize his technology on scalable manufacturing of nanowire based materials for catalysts, batteries and absorbents. The company setup commercial production facilities for advanced catalysts and adsorbents for removal of sulfur from diesel and fuels and hydrogenation applications around the world. Prior entrepreneurial activities include founding an IT training and consulting company, Indacle Software, Inc.in 1996 and a lead acid battery manufacturing unit, Chemener Batteries LTd., in India.