MEMS Seminar: Nanotechnology-Based Catalysts for the Electrochemical Synthesis of Low Carbon Fuels and Fertilizers
Wednesday, November 15, 2017 - 12:00pm to 1:00pm
Dr. Adam Rondinone
The arrangement of active sites on a nanostructured catalyst can yield new ways to influence complex reaction mechanisms. The Center for Nanophase Materials Sciences has developed a textured carbon comprised of 50-80nm graphene spikes with ~5% nitrogen dopants for electrochemical catalysis. Two reactions for this electrocatalyst will be discussed: first, when co-doped with ~50nm copper nanoparticles, the electrocatalyst converts CO2 to ethanol with high Faradaic efficiency (63% at -1.2V vs reversible hydrogen electrode (RHE)) and high selectivity (84%) in aqueous bicarbonate and at ambient temperature and pressure. Electrochemical analysis and density functional theory calculations suggest a mechanism in which active sites on the Cu nanoparticles and the carbon nanospikes work in tandem to control the electrochemical reduction of carbon monoxide dimer to alcohol.
Second, the sharp tips of the nanospikes, which typically reach a radius of ~1nm, achieve very high electric fields over a large number of active sites. When coupled to the proper electrolyte, and without a metal co-catalyst, the carbon nanospikes are active for nitrogen electroreduction to ammonia with an average Faradaic efficiency of 9.25% at –1.19 V vs RHE. Theoretical calculations and modeling of the tip-enhanced field indicate an electric field that exceeds 6 V/nm within the Stern layer, a field strength high enough to alter the energy of the lowest unoccupied molecular orbital of dissolved N2 thereby allowing electron injection into the molecule. The reaction rate is also dependent on the counterion type, suggesting a role in increasing N2 concentration within the Stern layer. Preliminary laboratory experiments and modelling data will be presented.
Dr. Adam Rondinone is a senior staff scientist at the Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences. He received his Ph.D. in Chemistry from the Georgia Institute of Technology in 2001, and immediately joined Oak Ridge as a prestigious Wigner Fellow. He is an expert on materials chemistry at the nanoscale and his research is focused on developing novel means to create functional nanomaterials for energy applications. Recent work has explored nanostructured electrochemical catalysts for the conversion of waste to useful products. He has served on various committees in service to ORNL, including two years as a Legislative Fellow in the office of Senator Lamar Alexander working on energy and technology issues. He is also the outreach coordinator for the Center for Nanophase Materials Sciences.
Lunch will be served at 11:30 am.