Influence of water, dihydrogen and dioxygen on the stability of the Cr2O3 surface: A first-principles investigation

In this theoretical work, the stability of α-Cr2O3 surfaces in various oxidizing and reducing environments has been investigated. The electronic structure calculations, the magnetic properties of the bulk and surfaces have been explored within the DFT+U framework. Investigating a large number of possible terminations we show that the oxidation promotes the formation of a chromyl surface in agreement with the existing literature. We show that the hydrogenation of bare chromia surface is not thermodynamically favored, however, adding hydrogen to the chromyl surface leads to a very stable hydroxide termination. Regarding water adsorption, we discuss the differences between the experiment results published in (M. A. Henderson, S. A. Chambers, Surf. Sci. 449 (2000) 135) leading to a fully hydrated surface and those published in (V. Maurice, S. Cadot, P. Marcus, Surf. Sci. 471 (2001) 43) leading to a fully hydroxylated surface. Finally we present a new hydrated surface (fully hydroxylated surface) noted [-Cr2-(OH)3], which is consistent with experimental observations.