H2O在SrTiO3-(001)TiO2表面上吸附和解离的密度泛函理论研究

利用密度泛函理论研究了0.25单层(ML),0.5ML,0.75ML和1ML吸附率下H2O在SrTiO3-(001)TiO2表面上的吸附行为.比较了不同吸附率下分子吸附和解离吸附的稳定性,利用微动弹性带(nudged elastic band)方法计算了H2O的解离势垒.结果表明:在低吸附率(0.25ML和0.5ML)时,H2O表现为解离吸附;在0.75ML吸附率下,分子吸附和解离吸附同时存在;而在全吸附(吸附率为1ML)时,分子吸附更稳定.基于对H2O分子与表面之间以及H2O分子之间的电荷转移和相互作用的分析,讨论了吸附率对H2O吸附和解离的影响.

A density functional theory study on water adsorption on TiO2-terminated SrTiO3(001) surface

Water adsorptions on TiO2-terminated SrTiO3(001) surfaces at four kinds of coverages (0.25 monolayer(ML),0.5ML,0.75ML and 1ML) are investigatedby by using density functional theory calculations. Molecular and dissociative adsorptions of water are comparatively investigated. The nudged elastic band method is employed to calculate the dissociative energy barrier. The obtained results showed that dissociative adsorptions were energetically more favourable at low coverages (0.25ML and 0.5ML), whereas molecular adsorption was more favourable at high coverage (1ML), and particularly a special mixed adsorption was more favourable at 0.75ML. Based on these results, the influence of adsorption coverage on water dissociation is analyzed.