甲醇在FeS2(100)完整表面的吸附和分解

采用基于第一性原理的密度泛函理论结合周期平板模型方法, 研究了甲醇分子在FeS₂(100)完整表面的吸附与解离. 通过比较不同吸附位置的吸附能和构型参数发现: 表面Fe位为有利吸附位, 甲醇分子通过氧原子吸附在表面Fe位, 吸附后甲醇分子中的C―O键和O―H键都有伸长, 振动频率发生红移; 甲醇分子易于解离成甲氧基CH3O和H, 表面Fe位仍然是二者有利吸附位. 通过计算得出甲醇在FeS₂(100)表面解离吸附的可能机理: 甲醇分子首先发生O―H键的断裂, 生成甲氧基中间体, 继而甲氧基C―H键断裂, 得到最后产物HCHO和H₂.

Adsorption and Dissociation of Methanol on Perfect FeS2(100) Surface

First-principles calculations based on density functional theory (DFT) and the periodical slab model were used to study the adsorption and dissociation of methanol on the perfect FeS2(100) surface. The adsorption energy and the geometric parameters on the different adsorption sites showed that the Fe site was the most favorable adsorption site and O atoms were found to bind to Fe atoms. After adsorption, the C―O and O―H bonds of methanol were elongated and the vibrational stretch frequency was red shifted. The calculation results proved that methanol was prone to decomposition resulting in methoxy groups and hydrogen. We calculated the adsorption behavior of these methoxy groups and hydrogen on the FeS2(100) surface and found that the Fe sites were also the most favorable adsorption sites. A possible decomposition pathway was investigated using transition state searching methods: first the O―H bond of methanol was decomposed producing the intermediate methoxy group and subsequently the C―H bond of the methoxy group was broken resulting in final products of formaldehyde and hydrogen.