Non-Thermal Plasma activation pathways for chemical and materials synthesis

Dr. Lorenzo Mangolini

Professor
University of California, Riverside

Seminar Information

Seminar Series
Mechanics & Materials

Seminar Date - Time
January 30, 2023, 11:00 am
-
12:15

Seminar Location
von Karman-Penner Seminar Room 479
IN PERSON ONLY


Abstract

Low-temperature plasmas are electrically-driven systems inherently characterized by a non-thermal equilibrium between gas and charge carriers. The presence of energetic free electrons enables the activation of processes that would otherwise require operation at high temperatures. This talk will discuss two examples of such processes.

The first example is related to the use of low-temperature plasma to drive heterogeneous chemical reactions for the fixation of nitrogen and the synthesis of ammonia at room temperature. Careful reactor level process characterization, coupled with ab-initio simulations from the group of Bryan Wong at UC Riverside, suggest that activation pathways in plasma processes are completely different from those in the thermally-driven Haber-Bosch process. Two effects contribute to the reasonable yield of ammonia: (a) the formation of atomic nitrogen radicals in the plasma volume and (b) the large flux of atomic hydrogen to the catalyst surfaces. The interaction between atomic nitrogen and the hydrogen passivated surfaces leads to ammonia formation with near 100% probability and with a weak dependence on the catalyst material, consistent with the experimentally observed behavior in plasma reactors.

The second example discusses the synthesis of small nanoparticles using low-temperature plasmas. The non-equilibrium in these systems leads to the electrostatic stabilization of the particles, which are then substantially smaller compared than those obtained from other aerosol synthesis techniques. This is beneficial for several applications, with one being of particular interest: the production of novel energetic materials. Low-temperature plasmas are used to produce ultrafine (<10 nm) silicon particles using silane as precursor. This approach leads to a high hydrogen content and to interesting combustion kinetics. Upon combustion, plasma-produced silicon particles show superior pressurization rates and peak pressures compared to standard energetic materials such as nano-aluminum.

Speaker Bio

Prof. Lorenzo Mangolini received his Ph.D. in Mechanical Engineering from the University of Minnesota, Minneapolis in 2007. After a brief experience in industry, he joined the Mechanical Engineering Department and the Materials Science and Engineering Program at UC Riverside in 2010. His broad interests are centered on the use of low-temperature plasmas for the production of novel functional materials, and most recently for the electrification of the chemical manufacturing industry. He is a recipient of the NSF Career Award and the DOE Early Career Award. He is the co-founder of SiLi-ion Inc., a start-up bringing plasma-produced materials to the lithium-ion battery market.