AVS 61st International Symposium & Exhibition
    Advanced Surface Engineering Monday Sessions
       Session SE+PS+TF-MoA

Paper SE+PS+TF-MoA10
Designing a Precious Metal-Free Catalyst for Purification of Automotive Exhausts: NO Reduction and CO Oxidation on CuO(110) Surface

Monday, November 10, 2014, 5:00 pm, Room 302

Session: Pulsed Plasmas in Surface Engineering
Presenter: Mamoru Sakaue, Osaka University, Japan
Authors: H. Kasai, Osaka University, Japan
J. Moreno, Osaka University, Japan
A.A. Padama, Osaka University, Japan
C. Matsuda, Daihatsu Motor Co., Ltd, Japan
K. Naito, Daihatsu Motor Co., Ltd, Japan
M. Uenishi, Daihatsu Motor Co., Ltd, Japan
H. Tanaka, Daihatsu Motor Co., Ltd, Japan
Y. Nishihata, Japan Atomic Energy Agency, Japan
M. Sakaue, Osaka University, Japan
Correspondent: Click to Email
Nitrogen oxide (NOx) and carbon monoxide (CO) are known by-products of fossil fuel combustion, which greatly contribute to atmospheric pollution. Thus, understanding the conversion process of NOx and CO into less hazardous gases is of utmost importance. It is well known that precious metals (such as Rh, Pd and Pt) work well to reduce these pollutant gases, but their high cost is a road block to a more prevalent use. Therefore, a more readily available and inexpensive material with comparable, if not better, catalytic performance is needed. Our group has investigated the role of surfaces as a foundation to realizing designer materials, in this case for exhaust purification [1]. In particular, we have previously studied the dissociation of nitric oxide (NO) on Cu2O(111) surface [2-4]. In this work, we look at the possibility of using a CuO catalyst for NO reduction and CO oxidation. Using density functional theory, we first investigated the dissociation process of NO on CuO(110) surface [5]. We found that NO is molecularly adsorbed perpendicular to the surface on the active hollow site between the surface Cu-atoms with an N-end configuration. An energy barrier of 1.1 eV was obtained for NO dissociation. The dissociated state was found to be most stable when the coadsorbed N and O atoms are on adjacent hollow sites. In comparison with the Rh(111) surface, the CuO(110) provides lower activation barrier for NO dissociation and lower adsorption energies for coadsorbed N and O atoms. To further investigate the oxidation of CO after the NO dissocation process, CO was adsorbed on the CuO(110) surface with coadsorbed N and O atoms. In this case, CO was molecularly adsorbed on top of a surface Cu atom while attracting the adsorbed O atom. An energy barrier of 0.9 eV was obtained for the CO oxidation process. This barrier was lower than the case of CO oxidation on Rh(111) surface with adsorbed oxygen atoms. The resulting CO2 molecule was stably adsorbed with its center on top of a surface Cu atom. The results obtained in this study are in agreement with our experimental findings. In conclusion, we believe that CuO is a very promising catalyst for the purification of automotive exhausts.