The Study On Properites Of Graphene/TiO₂ With Certain Active Facet

In this paper, First-principles calculations based on density functional theory（DFT） were used to explore the structure and properties of graphene hybridization with TiO₂ with a certain active facet. The theoretical layered structure model of graphene hybridization with a certain active facet was established. The ectronic properties such as band structure, density of states, work function, and blinding energy were obtained to investigate the photocatalytic performance and adsorotion activity. Additionally, TiO₂/graphene composites were prepared by a facile hydrothermal method, and the enhanced photocatalytic mechanism and the adsoption properties were evaluated. The details were as follows:1. First-principles calculations based on density functional theory（DFT） were used to explore the effect of graphene hybridization on the properties of anatase TiO₂ with a certain active facet. The electronic structure and properties of clean（101）,（100）,（110）,（010） and（001） surface were investigated, and the clean surface energy of different facet was obtained to explore the active facet of titanium dioxide, It indicated that the most stable facet was（101） facet, while（001） was the most active facet. In our work,（101） and（001） facets were chose to investigate the effect of graphene hybridization or combination on the anatase TiO₂. The electronic properties, such as band structure, density of states and the optical properties, were to illustrate the change of photoctalytic and adsorptive performance of TiO₂ with a certain facet, due to graphene hybridization. After combining with graphene, the band gap of TiO₂（101） reduced from 3.2eV to 0.948 eV, while the band gap of TiO₂（101） reduced from 3.2eV to 0.915 eV, The band gap decrease showed the electronic could jump from the valence band to the conduction band only absorbed a little energy which meaned a highiy transition for electrons, leading light in response to the widening scope of the photocatalyst. It also indicated there accured interactions between metal ions and TiO₂/G, which illiustrate that the adsorption of metal ion on the surface of TiO₂/G was thermodynamically stable.2. First-principles calculations were used to investigate the electronic properties of rutile TiO₂ with a certain active facet hybridized with graphene. The electronic structure and properties of clean（101）,（100）,（110） and（011） surface were investigated, and the clean surface energy of different facet was obtained to explore the active facet of titanium dioxide, It indicated that the most stable facet was（110） facet, while（100） was the most active facet. In our work,（110） and（100） facets were chose to investigate the effect of graphene hybridization or combination on the rutile TiO₂ with active facet. The electronic properties, such as band structure, density of states and the optical properties, were to illustrate the change of photoctalytic and adsorptive performance of rutile TiO₂ with a certain facet, due to graphene hybridization. After combining with graphene, the band gap of TiO₂（110） reduced from 3.0eV to 1.05 eV, while the band gap of TiO₂（100） reduced from 2.9eV to 0.91 eV, The band gap decrease showed the electronic could jump from the valence band to the conduction band only absorbed a little energy which meaned a highiy transition for electrons, leading light in response to the widening scope of the photocatalyst. It also indicated there acured interactions between metal ions and Ti O2/G, which illiustrate that the adsorption of metal ion on the surface of TiO₂/G was thermodynamically stable.3. The TiO₂/graphene nanocomposite materials（TiO₂/G） was synthesised by used the hydrothermal with the different quality of graphene, obtained by Hummers method. The samples were characterized by XRD, DRS, SEM, respectively. It indicated that the TiO₂/G exhibited good growth morphology and excellent photocatalytical and adsorptive performance.