Pt表面形貌对乙二醇分解机理的影响

A DFT Analysis on Ethylene Glycol Decomposition Mechanism on Pt(111) Surface

运用广义梯度近似(GGA)的密度泛函理论(DFT)结合平板模型,研究了乙二醇在不同形貌的Pt(111)表面(包括Pt(111),Pt(111)-step,Pt(111)-double-step)的分解反应机理。结果表明,乙二醇及其分解中间体的吸附热与不同形貌表面配位数有关,配位数越低,吸附能力越强。乙二醇的脱氢反应机理也与表面形貌有关。在Pt(111)和Pt(111)-step上,先是O—H键断裂,形成HOCH2CH2O中间体,然后是C—H键断裂,形成HOCH2CHO中间体;而在Pt(111)-doublestep上先是O—H键断裂,形成HOCH2CH2O中间体,之后仍是O—H键断裂,形成OCH2CH2O中间体。

The DFT-GGA method combined with the slab model was applied to study the ethylene glycol decomposition on Pt（111）model catalysts such as Pt（111）,Pt（111）-step[i.e.,removed one row of top layer from Pt（111）]and Pt（111）-double-step[that is,remove two rows of top layer and one row of second layer from Pt（111）].The calculation results show that the adsorption energy of ethylene glycol and other decomposition species depends on the coordination number of surface atom,and the low coordination number relates to the high adsorption energy.Moreover,it was found that the reaction mechanism of ethylene glycol decomposition depends on the surface morphology：On both Pt（111）and Pt（111）-step,the ethylene glycol decomposition proceeds via the initial O—H bond scission,forming HOCH2CH2O intermediate,and following C—H bond cleavage,forming HOCH2CHO;While on the Pt（111）-double-step surface,the reaction mechanism involves the initial O-H bond scission,forming HOCH2CH2O,and following second O—H bond cleavage,forming OCH2CH2O intermediate.