Activation and dissociation of CO2 on the (001), (011), and (111) surfaces of mackinawite (FeS): A dispersion-corrected DFT study
Activation and dissociation of CO2 on the (001), (011), and (111) surfaces of mackinawite (FeS): A dispersion-corrected DFT study
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DOI：
10.1063/1.4929470
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发表时间：
2015-09-07
影响因子：
4.4
通讯作者：
de Leeuw, N. H.
中科院分区：
文献类型：
--
作者：
Dzade, N. Y.;Roldan, A.;de Leeuw, N. H.
硫化铁矿物，包括mackinawite（FeS），与生命起源理论有关，因为它们对二氧化碳（CO2）还原和转化为有机分子具有潜在的催化活性，这可能适用于液体燃料和商品化学品的生产。然而，对FeS表面上的CO2吸附、活化和解离的基本理解仍然不完整。在这里，我们使用了密度泛函理论计算，校正长程色散相互作用（DFT-D2），探索各种吸附网站和配置CO2的低指数mackinawite（001），（110）和（111）表面。我们发现，CO2分子的物理吸附弱的能量最稳定的（001）表面上，但吸附相对强烈的（011）和（111）FeS表面，优先在Fe位。CO2在（011）和（111）表面上的吸附显示出以从表面Fe物质到CO2分子的显著电荷转移为特征，这导致分子中的大的结构转变（即，形成带负电荷的弯曲的CO2-δ物质，通过振动频率分析证实具有较弱的C-O）。我们还分析了CO2在mackinawite（011）和（111）表面还原为CO和O的途径。CO2解离计算为相对于缔合吸附态略微吸热，在（011）和（111）表面上分别具有相对较大的1.25 eV和0.72 eV的活化能势垒。(C)2015 AIP Publishing LLC.
Iron sulfide minerals, including mackinawite (FeS), are relevant in origin of life theories, due to their potential catalytic activity towards the reduction and conversion of carbon dioxide (CO2) to organic molecules, which may be applicable to the production of liquid fuels and commodity chemicals. However, the fundamental understanding of CO2 adsorption, activation, and dissociation on FeS surfaces remains incomplete. Here, we have used density functional theory calculations, corrected for long-range dispersion interactions (DFT-D2), to explore various adsorption sites and configurations for CO2 on the low-index mackinawite (001), (110), and (111) surfaces. We found that the CO2 molecule physisorbs weakly on the energetically most stable (001) surface but adsorbs relatively strongly on the (011) and (111) FeS surfaces, preferentially at Fe sites. The adsorption of the CO2 on the (011) and (111) surfaces is shown to be characterized by significant charge transfer from surface Fe species to the CO2 molecule, which causes a large structural transformation in the molecule (i.e., forming a negatively charged bent CO2-delta species, with weaker C-O confirmed via vibrational frequency analyses). We have also analyzed the pathways for CO2 reduction to CO and O on the mackinawite (011) and (111) surfaces. CO2 dissociation is calculated to be slightly endothermic relative to the associatively adsorbed states, with relatively large activation energy barriers of 1.25 eV and 0.72 eV on the (011) and (111) surfaces, respectively. (C) 2015 AIP Publishing LLC.