Theoretical Study On The Photocatalytical Removal Of Hg~0 By Ti-based Graphene

Photocatalysis is one of the important manifestations of the interaction between light and matter,which refers to the complex process of photoreaction and catalytic reaction occurring between the materials and the surface adsorbate.The catalyst of photocatalytic is semiconductor mainly,among which,TiO₂ is used commonly.HoweVer,the energy gap of TiO₂ is so wide that the reaction can only be performed under UV,which result in a waste of energy.Nowadays the research is focused on the modification of TiO₂,so that a better photocatalytic efficiency under visible light can be realized.A great progress of the research on modification of TiO₂ has been made both in China and abroad,graphene as a assisted photocatalytis material has received much attention recently,but a few of studies on the physical mechanism.Therefore,this paper has studied deeply in the mechanism of the photocatalytic oxidation of gaseous mercury on titanium-based graphene materials based on density functional theory.Firstly,a crystal model of anatase TiO₂ is built to calculate the band structure and the density of electronic state by ab initio calculation based on the DFT.The most thermodynamic stable crystal face（101）of anatase TiO₂ was constructed based on the above model,and the effects of the band structure and density of electron states were investigated when N and Eu were doped on the crystal face respectively.Further reVeals the physical mechanism of the effect of the doping on the photocatalytic performance.Secondly,the graphene-doped anatase TiO₂ model was built by covering the 2D graphene material on the TiO₂（101）.The model was optimized with first-principles dynamics and first-principles,and the band structure and the density of electronic state of the optimized model were calculated to explain the physical mechanism for improving photocatalytic performance of Gr/TiO₂（101）;On the basis of the above model,research the effect of the doping of N and Eu on the Gr/ TiO₂（101）,and the result showed that the photocatalytic activity of the mixed composite material was best.Finally,to verify the accuracy of the calculation results above,anatase TiO₂ was prepared by hydrothermal reaction,and the preparation conditions were adjusted so that the main exposure surface of the material was（101）crystal face.The prepared materials were characterized by SEM,XRD,UV-Vis and BET.At the same time,the influence of different doping on the photocatalytic performance of mercury removal was explored by the surface response method.First,it further proved the correctness of the above calculation;the second,the optimum preparation condition of the material be determined.The results are compared to verify the correctness of the calculated results,and provide theoretical support for the modification of titanium-based materials.