DFT-D2 Study of the Adsorption and Dissociation of Water on Clean and Oxygen-Covered {001} and {011} Surfaces of Mackinawite (FeS)
DFT-D2 Study of the Adsorption and Dissociation of Water on Clean and Oxygen-Covered {001} and {011} Surfaces of Mackinawite (FeS)
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DOI：
10.1021/acs.jpcc.6b06122
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发表时间：
2016-09-29
影响因子：
3.7
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.
我们提出了一个分散校正密度泛函理论研究氧和水的吸附和解离反应在{001}和{011}表面的mackinawitte （FeS）。本文介绍了在氧气和水的存在下mackinawite{001}和{011}表面氧化过程的初始步骤的化学图。结果表明，水与两表面的铁离子相互作用较弱，仅发生一定程度的氧化，而原子氧和分子氧相互作用较强；通过从FeS{011}表面阳离子中吸取大量电荷；从而使它们从Fe2+氧化为Fe3+形式氧化态。从计算的吸附能和活化能垒中我们发现，预吸附的氧可以很容易地激活O-H键，并促进H2O在FeS{011}上解离为铁羟基Fe3+- oh -，在FeS{001}上解离为零价硫羟基S-0-OH-。在预吸附O原子的作用下，FeS{001}上氢原子与H2O解离的活化能势垒从1.73 eV降低到1.19 eV，在FeS{011}上从0.83 eV降低到0.14 eV。这些发现提供了分子水平上对mackinawite氧化机制的认识，并且与实验结果一致，实验结果表明氧和水是mackinawite氧化过程和其可能通过灰长岩转化为黄铁矿的必要条件。
We present a dispersion-corrected density functional theory study of the adsorption and dissociation reactions of oxygen and water on the {001} and {011} surfaces of mackinawite (FeS). A chemical picture of the initial steps of the mackinawite {001} and {011} surfaces oxidation process in the presence of oxygen and water is presented in the present investigation. Our results show that, while water interacts weakly with the Fe ions On both surfaces and only oxidizes them to some extent, atomic and molecular oxygen interact strongly;with the FeS{011} surface cations by drawing significant charge from them; thereby oxidizing them from Fe2+ to Fe3+ formal oxidation state. We show from our calculated adsorption energies and activation energy barriers for the dissociation of H2O on the dean and oxygen-covered FeS surfaces, that preadsorbed oxygen could easily activate the O-H bond and facilitate the dissociation of H2O to ferric-hydroxy, Fe3+-OH- on FeS{011}, and to zerovalent sulfur-hydroxyl, S-0-OH- on FeS{001}. With the aid of preadsorbed O atom, the activation energy barrier for dissociating hydrogen atom from H2O decreases from 1.73 to 1.19 eV on the FeS{001}, and from 0.83 to 0.14 eV on the FeS{011}. These findings provide molecular level insight into the mechanisms of mackinawite oxidation, and are consistent with experimental results, which have shown that oxygen and water are necessary for the oxidation process of mackinawite and its possible transformation to pyrite via greigite.