(134a) Structure Sensitivity of Dimethyl Ether Electro-Oxidation

Dimethyl Ether (DME) is an attractive chemical for both on-board hydrogen generation as well as a fuel in direct electro-oxidation in fuel cells.^{[1, 2]}  Experimental studies of the electro-oxidation have demonstrated significant structure sensitivity on Pt – specifically when comparing the (111) and (100) facets.^[3]   Using periodic, self-consistent density functional theory calculations, we evaluate the thermodynamics of dimethyl ether (DME) electro-oxidation on a number of model (100) and (111) facets of elemental fcc metals, including Au, Ag, Cu, Pt, Pd, Ni, Ir, Rh. We also evaluate the thermochemistry of the elementary steps on Pt(211) and Rh(211) to investigate the role of steps and undercoordinated sites towards this chemistry.  Using our DFT results, we predict the most-probable reaction mechanism and the energy efficiency and catalytic activity of each of these model surfaces.  Furthermore, by comparing results on the different facets, we attempt to elucidate the origins of the experimentally observed structure sensitivity of DME electro-oxidation.

 [1] Semelsberger, T. A.; Borup, R. L.; Greene, H. L., Journal of Power Sources 2006, 156, 497.

 [2] Kerangueven, G.; Coutanceau, C.; Sibert, E.; Leger, J. M.; Lamy, C., Journal of Power Sources 2006, 157, 318.

 [3] Lu, L.; Yin, G.; Tong, Y.; Zhang, Y.; Gao, Y.; Osawa, M.; Ye, S., Journal of Electroanalytical Chemistry 2010, 642, 82.