Interaction of Oxygen and Water with the (100) Surface of Pyrite: Mechanism of Sulfur Oxidation.
Interaction of Oxygen and Water with the (100) Surface of Pyrite: Mechanism of Sulfur Oxidation.
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DOI：
10.1021/jz300996c
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发表时间：
2012-08
期刊：
影响因子：
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通讯作者：
P. Sit;M. Cohen;A. Selloni
中科院分区：
文献类型：
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作者：
P. Sit;M. Cohen;A. Selloni
我们用密度泛函方法研究了氧和水在黄铁矿(100)表面的吸附和反应。我们发现，解离吸附有利于氧的生成，形成铁氧基、Fe(4+)、═O(2-)等物种。在共吸附水存在下，它们很容易转化为铁羟基，Fe(3+)-OH(-)，后者在室温下完全覆盖表面。确定了表面氧化的机理，包括与分子氧和水的连续反应，并导致表面硫完全氧化为SO4(2-)。关键的循环过程是表面O(2-)和OH(-)物种作为进入水分子的质子接受者。利用最近提出的一种方法，我们研究了表面离子在吸附和氧化过程中的氧化态变化和电子流动。其氧化机理与同位素示踪实验一致，表明SO4(2-)中的氧来源于水。
We present a density-functional study of the adsorption and reactions of oxygen and water with the (100) surface of pyrite. We find that dissociative adsorption is energetically favorable for oxygen, forming ferryl-oxo, Fe(4+)═O(2-), species. These transform easily to ferric-hydroxy, Fe(3+)-OH(-), in the presence of coadsorbed water, and the latter fully covers the surface under room conditions. A mechanism for surface oxidation is identified, which involves successive reactions with molecular oxygen and water, and leads to the complete oxidation of a surface sulfur to SO4(2-). The crucial recurring process is the surface O(2-) and OH(-) species acting as proton acceptors for incoming water molecules. Using a recently proposed method, we examine the oxidation state changes of the surface ions and the electron flow during the adsorption and oxidation processes. The oxidation mechanism is consistent with isotopic labeling experiments, suggesting that the oxygens in SO4(2-) from gas-phase oxidation are derived from water.