The Study On Stucture And Properties Of TiO₂/WO₃/Graphene Composite Photocatalyst

In this paper, First-principles calculations based on density functional theory(DFT) were used to explore the electronic structure and properties, optical propertiesand photocatalytic mechanism of TiO2/graphene, WO3/graphene, TiO2/WO3nanocomposites. Additionally, the TiO2/WO3/graphene nanocomposites weresynthesized by ultrasonic hydrothermal method, which exhibited excellent adsorptivecapacity in removal of rhodamine-B in waste water. They can be summaried as thefollows:1. First-principles calculations based on DFT were used to study theinterfacial properties and its effect on visible light response for the hybridgraphene/anatase TiO2nanocomposites. After combined with graphene, the potentialfor the top of the valence band (VB) became more negative, leading to the decrease ofenergy gap. Electrons at VB can be directly excited from graphene (C2p) to thebottom of the conduction band (CB) of the anatase TiO2(Ti3d), which suppressed therecombination of photoexcited electron-hole pairs.2. The hybrid anatase TiO2(001)/graphene nanocomposites (TiO2(001)/G)was simulated and calculatd, and then the effect of graphene hybridization on energygap, interfacial charge transfer and visible light response was investigated in detail.The energy gap was reduced to0.47eV, leading to red shift in the absorption edge.And electrons in the upper of VB of TiO2were likely to be directly excited to grapheneunder visible light irradiation, which promoted the formation of well-separatedelectron-hole pairs.3. Based on the first principles method and structural model ofWO3/graphene nanocomposites, the effect of graphene hybridization on interfacialcharge transfer and visible light response were discussed. The enhancementmechanism of photocatalytic activity for WO3/graphene nanocomposites was analysed in detail.4. The layered structure model was used to study the geometry andelectronic properties of the (WO3)x/(TiO2)yheterostructures in this paper. The effect ofmolar ratio of WO3and TiO2on energy gap, oxidbillity, and charge carrier transportefficiency were calculated and analysised in detail.5. The ternary TiO2/WO3/graphene (TWG) nanocomposites were preparedby a salt-ultrasonic assisted hydrothermal method. The products were characterized byX-ray diffraction, scanning electron microscopy, transmission electron microscopy, etc.The TWG114(nT iO2: nWO3: ngraphene=1:1:4) exhibited interconnected3D porousnetwork with interconnected pores and excellent adsorptive capacity.