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采用基于色散矫正密度泛函理论的第一性原理方法,研究石墨炔和石墨烯对TiO2光催化性能提高的机理.通过研究发现在石墨炔-TiO2(101)复合物中,石墨炔和TiO2(101)间相互作用较强,TiO2(101)表面上的O原子和其top位的C原子形成离域性强的C—O共价键.电子密度,电子差分密度和Mulliken电荷的计算结果显示,石墨炔复合TiO2(101)晶面更有利于电子在界面间的转移,并减低电子-空穴的复合率.通过对电子结构的分析发现,在石墨炔-TiO2(101)复合物的带隙中引入了多条杂质能级,而石墨烯-TiO2(101)复合物的带隙中没有杂质能级的出现.杂质能级能够为光激发时电子的跃迁提供辅助平台作用,有利于光催化性能的提高.同时石墨炔-TiO2(101)复合物的价带位置比石墨烯-TiO2(101)复合物更低,说明其氧化能力更强,有利于其光催化性能的提高.
The first-principle method based on the dispersion-corrected density functional theory (DFT) was used to study the mechanism of the increase of photocatalytic activity of TiO2 and graphene by graphite alkyne and graphene.It was found that in the graphene alkyne-TiO2 (101) 101), the O atom on the surface of TiO2 (101) forms a C-O covalent bond with the C atom on the top of it. The calculated results of electron density, electron density and Mulliken charge , The graphite alkyne composite TiO2 (101) crystal plane is more conducive to the transfer of electrons in the interface and reduces the electron-hole recombination rate.By analyzing the electronic structure, it is found that in the band of graphite alkyne-TiO2 (101) There are no impurity levels in the bandgap of the graphene-TiO 2 (101) complex.The impurity level can provide an auxiliary platform for the electron transition during photoexcitation, which is good for the light (101) complex is lower than that of graphene-TiO 2 (101) complex, indicating that its oxidation ability is stronger and its photocatalytic performance is better.