A density functional theory study on the modifications of graphene nanosheets with selected metals

M.Sc. (Chemistry)Abstract: The modifications of graphene nanosheets with a metal oxide is a state of the art subject that has received large amounts of interest over the past decade. In the current work density functional theory studies are conducted to better understand and provide more insight into the experimentally determined results of these systems. Our calculations were done using the DFT + U approach to mimic the experimental results and avoid the known underestimation achieved by standard DFT. The generalized gradient approximation of Perdew-Burke-Ernzerhof functional as implemented in Cambridge Serial Total Energy Package within the Material Studio 2016 software package was used to treat the exchange-correlation effects. The electron-ion interaction was described using the ultrasoft pseudopotentials. A systematic study of electronic and optical properties of titanium dioxide under visible light was simulated using first principles calculations. The findings support the application of TiO2 in photo energy generation after graphene modifications. A theoretical band gap of 3.15 eV complimented the experimentally obtained band gap of 3.2 eV. Finally, our results revealed that upon protonation there was charge generation and this has the potential for application in photo energy generation. Studies of graphene as a support and transport material in photocatalysis, which is used to store generated charge carriers, are also reported. A model of graphene was generated and the morphological, electronic, phonon properties electrostatic potentials, as well as ballistic transport properties of the materials,.