Dissertation > Mathematical sciences and chemical > Physics > Solid State Physics > Surface physics

Density Functional Theory Study of Dimethyl Ether Adsorption on the Low-Index Pt Surface

Author LiuHui
Tutor YinGePing
School Harbin Institute of Technology
Course Chemical Engineering and Technology
Keywords Dimethyl ether Pt surface Adsorption DFT
CLC O485
Type Master's thesis
Year 2008
Downloads 58
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In this paper, the present state and progress of researchs on the elctro-catalysis of DME, namely, Dimethyl ether, and the adsorption of organic small moleculars on the surface of solid catalyst were reviewed and the importance of quantum chemistry study about the process of electro-catalysis were pointed out. Fether more, some of the quantum chemistry theory and methods involved in these paper were introduced. The impact of surface Pt atoms arrangement and electric field on the adsorption geometry structure, adsorption intensity and stability of DME molecular had been studied.The structure optimization of free DME molecular and Pt(100), Pt(110), Pt(111) surface was done for the more stable low energy sutrctures. And the surface relaxation was used only for the surface model. The results show that the distance of C-O and C-H bond are 0.14nm and 0.11nm. The surface reconstruction of Pt suface has happened and the top layer Pt atoms move up a little.The study of adsorption behavior of gaseous DME molecular on the different sites of Pt surface shows that the molecular orientation changes by the adsorption sites. The distance between C-O-C plane and the surface increase in the order:Top<Bri<Hcp. Furthermore, the bonds of DME alongate and the maximum of adsorption energy and total charge-transfer decrease in the order: Pt(110)>Pt(100)>Pt(111)。It means the adsorption DME on the Pt(110) surface is strongest and that structure is the most stable.As one of the most important factor of the electro-catalysis, electric field was used for study of DME adsorption. The results show that it has little influence on the Top site adsorption structure.But on the other sites, the existence of electric field changes the alongation of bonds which means the enhance of DME activation), and the structure tile a little. C-H bond which is closer to the surface helps the cleavage of C-H. And the electric field increases the adsorption energy and charge transfer of the adsorption system.

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