金红石型TiO_2(110)表面吸附TiCl_4的微观机理

Microscopic Mechanism of Rutile Titanium Dioxide(110)Surface Adsorption TiCl_4 Molecule

采用密度泛函理论平面波赝势方法研究了TiCl_4分子在TiO_2(110)表面桥位氧上的吸附,对稳定吸附构型的吸附能、电荷密度、差分电荷密度、电子态密度、Mulliken电荷布居等进行计算和分析。研究结果表明,TiCl_4在完整晶胞表面不能吸附;在有氧空位的晶胞表面,TiCl_4以面心向下吸附最稳定,吸附过程为放热。当表面氧空位密度为12.5%、25%时,面心向下吸附方式的吸附能分别为-29.780 9kJ·mol^(-1)和-48.641 9kJ·mol^(-1),表明氧空位密度越高,吸附强度越强;带隙从1.304eV分别减小到0.074eV、0.015eV,能带结构的带隙宽度变窄,表明氧空位密度越高,带隙宽度越窄;TiCl_4分子向晶胞表面转移的电荷分别为0.2eV、0.26eV,说明随着表面氧空位密度增加,TiCl_4分子向晶胞表面转移的电荷量增加,表面对分子的氧化作用越强。

The paper studied the oxygen adsorption of the TiCl 4 molecules in TiO 2(110)on the surface of the bridge by using the density functional theory of plane wave turns potential method,based on which the stable adsorption configurations of adsorption energy,charge density and charge density difference,the density of electronic states,Mulliken charge,and Mulliken population were calculated and analyzed.The research revealed that the TiCl 4 could not be adsorbed in the surface of complete crystal cell while on the surface of the cell with oxygen vacancy,the adsorption of TiCl 4 molecules showed its high downward stability and the adsorption process is exothermic reaction.When the surface oxygen vacancy density were 12.5%and 25%,the surface adsorption energy downward could respectively be-29.780 9 kJ·mol-1 and-48.641 9 kJ·mol-1,which showed that the higher the density of oxygen vacancy was,the adsorption would be stronger.The band gap reduced from 1.304 eV to 0.074 eV and 0.015 eV respectively.In addition,the band gap changed narrow which indicated that the higher the density of oxygen vacancy was,the narrower the width of band gap would be.The charge that TiCl 4 molecules transferred to the cell surface was 0.2 eV and 0.26 eV.This results conveyed that with the increase of surface oxygen vacancy density,the charge that TiCl 4 molecules transferred to the cell surface increased,and the oxygen reaction of surface to molecules would be intenser.