A photocatalytic TiO₂/graphene bilayer membrane design for water desalination: a molecular dynamic simulation

The research about finding the effective membrane material is in progress; however, there are pros and cons for each material. Graphene membrane is a single layer of atoms in a two-dimensional hexagonal lattice which achieved high performance in water purification field. Addition of TiO₂ to the graphene membrane has been studied for the membrane modifications due to its high stability and photocatalytic performance. In this study, graphene/TiO₂ bilayer nanocomposite membrane has been simulated to enhance the mechanical and electronic properties of graphene membrane. Anatase TiO₂ (A-TiO₂), rutile TiO₂ (R-TiO₂), and their composite with graphene (G) have been simulated to evaluate the stability of the nanocomposite bilayers in water desalination for higher salt rejection percentage and water permeation. The membrane structure has been created and optimized using the geometry optimization task. The simulation of electronic and mechanical properties has been done by using Material Studio 2019. TiO₂ consisting rutile and anatase phases showed a band gap of 2.248 eV, which was reduced to 1.175 eV in combination with graphene. The bilayer composite of TiO₂ and graphene achieved higher membrane stability, and the salt rejection was 98% under applied pressure of 100 MPa. The graphene/TiO₂ bilayer nanocomposite membranes have been evaluated by simulation for water desalination process using molecular dynamics by ReaxFF software. In comparison with a graphene membrane, the results showed an increment in salt rejection and water permeability under different applied pressure.