Spatial distribution of adsorbed water layers at the TiO2 rutile and anatase interfaces

The spatial distribution functions of adsorbed water layers at hydrated rutile-(1 1 0) and anatase-(1 0 1) surfaces have been studied at 300 K, using equilibrium classical molecular dynamics. It was found that there is evidence of some hydrogen-bonding with water molecules outside the adsorbed layer for anatase-(1 0 1), but less for rutile-(1 1 0) – on average, about 1.6 per water molecule in anatase-(1 0 1), in contrast to 0.9 for rutile-(1 1 0). This is due to adsorbed water molecules being confined more firmly in the area between bridging oxygen atoms at the rutile-1 1 0 surface, while the more open-like nature of anatase-1 0 1 allows for greater contact with molecules outside the first layer.