Theoretical investigation on the adsorption configuration and (•)OH-initiated photocatalytic degradation mechanism of typical atmospheric VOCs styrene onto (TiO2)n clusters.
Theoretical investigation on the adsorption configuration and (•)OH-initiated photocatalytic degradation mechanism of typical atmospheric VOCs styrene onto (TiO2)n clusters.
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(TiO2)(n)簇对典型大气VOCs苯乙烯的吸附构型和(OH)-O-中心点引发光催化降解机理的理论研究
DOI：
10.1038/srep15059
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发表时间：
2015-10-12
影响因子：
4.6
通讯作者：
An T
中科院分区：
文献类型：
--
作者：
Wang H;Ji Y;Chen J;Li G;An T
本研究用密度泛函理论研究了不同的(TiO2n)n簇对苯乙烯的吸附机理和羟基自由基(·OH)引发的光催化降解机理。苯乙烯是一种典型的大气挥发性有机化合物(VOC)，通过其具有很强的化学吸附能力的乙烯基团，很容易被吸附在(TiO2n)n团簇上。这表明(TiO2n)n团簇(小于1 nm)能够有效地吸附和捕获苯乙烯。吸附的苯乙烯很容易被·OH攻击，形成一系列的乙烯基羟基加合物。相反，苯基-OH-加合物和H-抽提产物在该体系中很难形成。用正则变分过渡态理论进行的动力学计算表明，温度对光催化降解过程中的速率常数影响不大。二氧化钛的存在不会改变苯乙烯的降解机理，但可以加快其光催化降解速率，且随着二氧化钛团簇尺寸的增大，光催化降解速率增加，因此，二氧化钛纳米团簇催化剂应该具有有效降解苯乙烯的光催化能力。这一理论研究从分子水平上揭示了二氧化钛催化剂的催化作用和苯系大气污染物的光催化降解机理。
In this study, the adsorption mechanism and hydroxyl radical (•OH)-initiated photocatalytic degradation mechanism of styrene onto different (TiO2)n clusters were investigated using density functional theory. Styrene, a typical model atmospheric volatile organic compound (VOC), was found to be readily adsorbed onto (TiO2)n clusters through its vinyl group with strong chemisorption. This suggests that (TiO2)n clusters (sub 1 nm) are able to effectively adsorb and trap styrene. Adsorbed styrene is then easily attacked by •OH to form a series of vinyl-OH-adducts. Conversely, phenyl-OH-adducts and H-abstraction products are very difficult to form in this system. Kinetics calculations using canonical variational transition state theory show that temperature has little effect on the rate constants during photocatalytic degradation process. The presence of TiO2 does not change the degradation mechanism of styrene, but can accelerate its photocatalyic degradation rate, and the rate will increase as TiO2 cluster size increases; as such, the TiO2 nano-clusters catalyst should have the photocatalytic ability to effectively degrade styrene. This theory-based study offers insights into the catalytic effect of TiO2 catalyst and the photocatalytic degradation mechanism of benzene series air pollutants at the molecular level.