CO2 adsorption on calcium oxide: An atomic-scale simulation study

We present a detailed study of CO2 adsorption on CaO, by means of atomic-scale simulations relying on Density Functional Theory. Combining ab initio thermodynamics of the CO2 gas phase and a thorough analysis of its interaction with the oxide, we build an orientation-sensitive adsorption model, which demonstrates that low coverage by the gas is expected in a wide range of working conditions, including the domain of stability of CaCO3 calcite. Investigation of the interactions between the adsorbed molecules reinforces this conclusion. Our work thus provides a strong hint that calcite nucleation should occur by a localised mechanism, discarding the possibility of collective surface transformation.