WO3（001）表面活性氧物种的理论研究

Theoretical study on the active oxygen species of WO3（001） surface

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.

The adsorption behaviors of O 2 on the perfect and defective WO 3(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 WO 3(001)surface could not be the active oxygen species for the surface redox reaction.When the adsorbate molecule reacts with the clean surface,it preferentially bonds with the lattice oxygen atom(O t),in the meanwhile the surface defect state is formed accompanied with the improvement of surface conductivity.According to the adsorption energy,the O 2 adsorption tends to occur at the defect site(W v)for the defective WO 3(001)surface.Both oxygen atoms of the O 2 molecule reacts with W v and a new oxygen species O 2-is formed.After O 2 adsorbing,the defective surface is re-oxidized and the surface conductivity reduces.