A first principles study of CO2 adsorption on α-SiO2(001) surfaces.

In this work, using first principles calculations, an analysis of CO2 interaction with cleaved and reconstructed α-SiO2(001) surfaces was performed. We showed that CO2 could strongly interact with a cleaved surface forming CO3-like configurations. Here, the binding energy per CO2 molecule depends strongly on CO2 surface coverage and can reach -2.35 eV. Despite this, even with CO2 molecules, the cleaved surface has a substantially higher surface energy than that of the reoptimized "dense" surface. This observation is also consistent with molecular dynamics simulations. Because of this, for thermodynamically stable system, the interaction of CO2 molecules with a α-SiO2(001) surface should be treated as the physisorption of CO2 molecules on the reoptimized "dense" surface with the binding energy varying from -0.26 eV for single CO2 molecule adsorption to -0.32 eV per molecule for monolayer coverage.