We then characterized the distribution of CO 2 at the air-water interface in terms of the density profiles along the z-axis (Figure ). We observe that the NNP force fields showed a greater density of CO 2 within the interfacial region compared to the SPC/E and two other classical water models (TIP4P and TIP5P) (Figure ). The respective PMFs associated with CO 2 adsorption within the interfacial region show significant difference in the well depth and the barriers associated with both the desoprtion of CO 2 from the interface and the transport of CO 2 to the aqueous phase (Figure ).