铈掺杂氧化锌(1000)晶面的SO_(2)吸附性能研究

Study on the adsorption properties of SO_(2) on the surface of cerium-doped zinc oxide(1000)

基于密度泛函理论,仿真建立了铈(Ce)掺杂氧化锌ZnO(1000)晶面的SO_(2)分子吸附模型,并计算了其吸附能、电荷转移量、吸附距离、电子态密度及脱附时间以探究吸附及脱附特性.计算得到Ce掺杂ZnO(1000)晶面的SO_(2)吸附结构有较大的吸附能(-1.66 eV),且在温度为398 K时,该体系具有符合实际传感检测过程的脱附时间(1.433×10^(3) s).结果表明Ce掺杂ZnO(1000)晶面对SO_(2)分子显示出优异的吸脱附性能.

As the insulating medium of gas insulated switchgear(GIS),sulfur hexafluoride(SF_(6))will decompose into a variety of gases after partial discharge,causing the decrease of its insulation performance.The decomposition of SF_(6) is not conducive to the stable operation of power system.Among them,SO_(2)is a kind of typical decomposition gas that has been attracted widely concerned.Therefore,the detection of SO_(2)gas is conducive to the effective evaluation of GIS insulation running state.As one of the most sensitive materials for detecting SO_(2)gas,the gas-sensing properties of ZnO are mainly affected by doping modification.In this paper,ZnO material doped with Ce element was selected to detect SO_(2)gas.Based on density functional theory(DFT)of the first principles,the intrinsic and Ce-doped ZnO(1000)plane were simulated and geometrical optimization was carried out.Then,different adsorption models of intrinsic and Ce-doped ZnO(1000)plane on SO_(2)molecules were established and optimized,and the adsorption energy,charge transfer amount,adsorption distance,electron density of state,deformation charge density and desorption time were calculated to explore the adsorption and desorption characteristics.The best adsorption model was selected based on the calculation results.In addition,the adsorption energy of SO_(2)on the Ce-doped ZnO(1000)plane is higher(-1.66 e V),which is about 3 times that of the intrinsic ZnO(1000)plane.Besides,according to the amount of charge transfer and the deformation charge density,it can be found that the charge transfer is more obviously in the doping adsorption model.Basing on the deformation charge density distribution,it can be observed that there is an obvious continuous area between the gas molecules and the Ce-doped ZnO(1000),indicating that a strong charge transfer has occurred between them.The density of states(DOS)of the doped adsorption system showed a more obvious change before and after the gas adsorption,and the band gap of the Fermi level accessory decreased,indicating the obvious change in conductivity of the system after adsorption.When the temperature is 398 K,the desorption time of the Ce-doped ZnO(1000)plane SO_(2)adsorption system is 1.433×10^(3) s,which is in line with the actual sensing process.The results show that the Ce-doped ZnO(1000)plane surface exhibited excellent adsorption-desorption properties for SO_(2)molecule.The results of this study show the application potential of Ce-doped ZnO materials in the field of gas sensing,and provide theoretical foundation for the detection of SO_(2)gas.At the same time,this study is a guide for the online monitor technology of GIS faults.