Molecular Dynamics Study of Water Adsorption on TiO₂ Nanoparticles

This study uses molecular dynamics simulations performed in a parallel computing environment to investigate the adsorption of water molecules on the surface of anatase and rutile nanoparticles ranging from 2.5 to 4 nm at room temperature and at hydrothermal conditions. Phase enhancement occurs when these nanoparticles are immersed in water and the coverage per unit area of the nanoparticles increases with increase in size. The residence time of water molecules at the nanoparticle surface is ∼5−6 times longer at room temperature than that under hydrothermal conditions. Examining the oxygen and hydrogen atom distribution from the nanoparticle surfaces, it is found that there are two hydration layers around all the nanoparticles under consideration at all conditions. In the first hydration layer, water molecules have two different simultaneously existing orientational preferences depending on their local environment.