Adsorption of methanol and methoxy on the α-Cr2O3(0001) surface

We present density functional theory calculations of methanol and methoxy adsorption at the Cr-terminated α-Cr2O3(0001) surface. We report on the equilibrium geometries of the adsorbed methanol and methoxy molecules, analyse the bonding to the surface, and discuss the dissociation energetics of methanol into methoxy on the surface. We found that methanol adsorbs with its O atom situated above a threefold coordinated hollow site in the surface O layer at a distance of 2.12 Å from the nearest-neighbour Cr atom, and with a calculated adsorption energy of 0.82 eV. For the methoxy molecule we found the optimum adsorption geometry to be with the methoxy O on top of a Cr atom and with the CO-axis tilted away from the surface normal by ∼55◦. Methoxy is strongly bound to the surface with an estimated adsorption energy of 3.3 eV. (Some figures in this article are in colour only in the electronic version)