Improving diffusion of water molecules in slits of titanium dioxide: Molecular dynamics simulation

Titanium dioxide(TiO₂)materials are expected to play an important role in helping to solve many serious environmental and pollution challenges, because of their excellent performance in the fields of photocatalysis, biomaterials, electrochemistry and industrial catalysis. Among all the applications of TiO₂ materials, there is a common process which is the contact of water molecules with TiO₂ materials. Thus, the surface structure of TiO₂, especially micro-structure of water molecules on TiO₂ surface, plays a key role in the applications. Moreover, since the TiO₂ material with larger surface area performs better, preparation of TiO₂ materials with nanoporous structures has become a research direction. Hence, the behavior of water molecules confined in the nanopores of TiO₂ is one of hot topics. Literature and our previous research showed that water molecules strongly adsorbed on the TiO₂ surface, and the strong adsorption hindered the mobility of water molecules in the TiO₂ pores. In this work we intended to improve the mobility of water molecules confined in TiO₂ pores by molecular dynamics studies, and to explain the reasons for the increase of mobility. These results could help experimental researchers to understand and reschedule their experiments. By adjusting a number of simulation parameters, we proposed that the more reliable method was covering the surface of TiO₂ with a carbon layer. This method could greatly improve the mobility of water molecules in the TiO₂ pores without altering the original experimental condition.