WO_3(001)表面活性氧物种的理论研究

采用第一性原理结合周期性平板模型的方法,对O_2在完整和缺陷WO_3(001)表面的吸附行为进行了研究.结果表明:WO_3(001)完整表面上吸附态的O_2不易成为表面氧化反应的活性氧物种,当吸附质与表面作用时,将优先与表面晶格氧(O_t)成键,进而形成表面缺陷态,体系呈现金属性,电导率增大.比较O_2在缺陷表面上各吸附构型的吸附能发现,O_2的吸附倾向于发生在缺陷位置(W_v)上,且表现为氧气分子中的两个氧原子均与缺陷位W_v作用,形成新的活性氧物种(O_2~-);吸附后表面被氧化,电导率降低.

A Theoretical Study on the Active Oxygen Species of WO3(001) Surface

The adsorption behaviors of O2 on the perfect and defective WO3(001) were systematically investigated by a first-principles method combined with the periodic slab model. The calculation results indicate that the oxygen molecule adsorbed on the perfect WO3(001) surface could not be the active oxygen species for the surface redox reaction. When the adsorbate molecule react with the clean surface, it preferentially bonded with the lattice oxygen atom (Ot), in the meanwhile the surface defect state was formed accompanied with the improvement of surface conductivity. According to the adsorption energy, the O2 adsorption tended to occur at the defect site (Wv) for the defective WO3(001) surface. Both oxygen atoms of the O2 molecule reacted with Wv and a new oxygen species O2- was formed. After O2 adsorbing, the defective surface was re-oxidized and the surface conductivity reduced.