Surface structure and energetics of oxygen and CO adsorption on α-Mo 2C(0 0 0 1)

Abstract

Adsorption of oxygen and CO on Mo- and C-terminated α-Mo 2C(0 0 0 1) has been investigated at the density functional level of theory. On the Mo-terminated surface, the most stable adsorption configuration ( 1) has atomic oxygen capping the threefold Mo hollow position over a second layer carbon atom ( V C, C vacancy site). On the C-terminated surface, the most stable adsorption configuration ( 8) has atomic oxygen capping the threefold Mo hollow site over a first layer carbon atom ( H C, C hollow site). For CO adsorption, the most stable configuration ( 17) has CO capping structure over carbon vacancy ( V C) on the Mo-terminated surface, but atop of the surface carbon with the formation of ketenylidene (C C O) species on the C-terminated surface ( 21). Analysis of density of states reveals the metallic character of the clean and oxygen doped surfaces and the activation of the surfaces by oxygen adsorption.