AVS 59th Annual International Symposium and Exhibition
    Oxide Heterostructures-Interface Form & Function Focus Topic Monday Sessions
       Session OX+SS+TF+MI-MoA

Paper OX+SS+TF+MI-MoA2
Manipulating Ferroelectric Surfaces for Direct NOx Decomposition

Monday, October 29, 2012, 2:20 pm, Room 007

Session: Chemistry of Oxide Surfaces and Interfaces
Presenter: E.I. Altman, Yale University
Authors: M.W. Herdiech, Yale University
A. Kakekkhani, Yale University
S. Ismail-Beigi, Yale University
E.I. Altman, Yale University
Correspondent: Click to Email
Current technology for removing nitrogen oxides from engine exhausts relies on nearly stoichiometric air to fuel ratios. Under these conditions, the concentrations of CO and unburned hydrocarbons in the exhaust stream are high enough to efficiently remove adsorbed oxygen from the platinum based catalysts in catalytic converters, ensuring that the catalysts do not become saturated with adsorbed oxygen. Direct catalytic decomposition of NOx to N2 and O2 in the presence of excess O2 would eliminate the need for reducing species in automobile engine exhaust streams, allowing these engines to be run more efficiently. We have been investigating the potential of ferroelectric supports to modify the behavior of supported layers to enable direct NOx decomposition. Our approach involves first principles density functional theory and surface science techniques. Using both approaches we have investigated the interactions of N, O, and NO with bare ferroelectric lead titanate surfaces and surfaces modified to expose catalytic layers, in particular Ru oxides. Theory indicates that the behavior of the PbTiO3 surface towards these species is sensitive to the polarization direction and termination of the ferroelectric and that stable RuO2-terminated surfaces can be created by manipulating the termination of the substrate. Experiments take advantage of plasma sources that allow the behavior of O and N atoms to be studied individually and expitaxial growth to manipulate the termination of the ferroelectric support. Favored reaction pathways are assessed using theory and temperature programmed desorption and related mass spectrometry methods.