TiCl_4和O_2在金红石型TiO_2(110)表面的吸附机理

基于密度泛函理论(DFT)中广义梯度近似(GGA)下的BLYP、PBE泛函,研究了TiCl_4、O_2在金红石型TiO_2(110)晶胞表面上不同位点的吸附,以及TiCl_4和O_2分子共吸附后在最稳定吸附构型上的解离过程。结果表明,O_2分子在TiO_2(110)晶胞表面上最稳定的吸附位点为氧空位,O_2分子吸附在氧空位后,其中一个O原子与Ti5c原子成键形成桥位氧(O_bri);另一个O原子形成O增原子(O_ada),吸附能为-11.58 kJ/mol,Mulliken电荷布居分析表明O_2分子向表面转移了0.12 eV电荷;TiCl_4分子在TiO_2(110)晶胞表面上最稳定的吸附位点为桥氧位,吸附能为-48.64 kJ/mol,Mulliken电荷布居分析表明TiCl_4分子向晶胞表面转移了0.26 eV电荷;TiCl_4与O_2在各自最佳的吸附位上吸附后,TiCl_4分子在O增原子(O_ada)的作用下按—TiCl_4→—TiCl_3→—TiCl_2→—TiCl的主要路径发生解离,在TiCl_4分子解离过程中,正反应方向上的活化能垒均小于逆反应方向上的活化能垒,说明TiCl_4分子的解离过程为放热反应。

The adsorption mechanisms of TiCl_4 and O_2 on the surface of rutile TiO_2(110)

In the paper,based on the BLYP and PBE functionalities of generalized gradient approximation (GGA) in density functional theory (DFT),the adsorption of TiCl 4 and O 2 molecules on the surface of rutile TiO 2 (110) and their dissociation process in the most stable adsorption configuration were studied. The results show that the most stable adsorption site of O 2 molecule on the surface of TiO 2 (110) cell was oxygen vacancy. After the O 2 molecule was adsorbed on the oxygen vacancy,one O atom formed a bridge with the Ti5c atom,and the other O atom was added at the same time. The adsorption energy was -11.58 kJ/mol. The Mulliken charge population analysis shows that the charge transfer of O 2 molecule to the surface was 0.12 eV. The most stable adsorption site on the unit cell was the bridge oxygen site with an adsorption energy of -48.64 kJ/mol. The Mulliken charge population analysis shows that the TiCl 4 molecule transfered 0.26 eV charge to the unit cell surface. TiCl 4 molecules were dissociated by the path of -TiCl 4→-TiCl 3→-TiCl 2→-TiCl under the action of O atom (O ada ) after TiCl 4 molecules were adsorbed on the adsorbed sites. In the TiCl 4 molecule dissociation process,the energy barriers in the positive reaction direction were less than those in the reverse reaction direction,indicating that the dissociation process of TiCl 4 molecules was exothermic.