The electronic properties and water desalination performance of a photocatalytic TiO2/MoS2 nanocomposites bilayer membrane: a molecular dynamic simulation.

Abstract

Due to the rapid depletion of water resources, more interest is paid for the efficient desalination process in recent years. MoS2 membrane aroused attention due to its high mechanical stability and electronic properties, which can sustain extra-large strains. In this study, the electronic properties and water desalination performance of TiO2/MoS2-hexagonal, and TiO2/MoS2-rhombohedral nanocomposites bilayer membranes were studied and simulated for the first time. The effect of TiO2 in the performance of MoS2 was observed in water desalination under the defined applied pressure ranging from 50 to 250MPa with a 6.4Å pore diameter. The membrane structure is created and optimized. The energy minimized for TiO2 from - 19,596.4282kcal/mol for the initial structure to - 19,605.1611kcal/mol for the final structure. For TiO2/MoS2-hexagonal, the energy minimized from - 4955.54271eV) to - 4955.62091eV and TiO2/MoS2-rhombohedral from - 6042.26925eV to - 6046.91835eV. A molecular dynamic (MD) simulation was performed using Material Studio 2019 to study the electronic properties under 0-1eV electric field using the CASTEP code. The results showed a better photocatalytic performance under the external electric field. The effect of external electric field significantly intensifies absorption in the visible range and achieved a high photocatalytic activity on TiO2/MoS2. TiO2, TiO2/MoS2-hexagonal and TiO2/MoS2-rhombohedral nanocomposites bilayer membranes are simulated and evaluated for the water desalination using ReaxFF software. Both MoS2 phases with TiO2 have achieved a high salt rejection up to 97% (P-value = 0.0036, R2 = 0.958), while TiO2/MoS2-rhombohedral achieved the highest permeability (6.0*10-8mmgcm-2s-1bar-1) (P-value = 0.000296, R2 = 0.972) under 250MPa applied pressure.