Interactions of Oxygen and Water Molecules with Pyrite Surface: A New Insight
Interactions of Oxygen and Water Molecules with Pyrite Surface: A New Insight
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氧和水分子与黄铁矿表面的相互作用：新的见解
DOI：
10.1021/acs.langmuir.7b04112
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发表时间：
2018
期刊：
影响因子：
3.9
通讯作者：
Chen Jianhua
中科院分区：
文献类型：
--
作者：
Li Yuqiong;Chen Jianhua
黄铁矿是自然界中最常见的硫化物，因其在酸性矿山排水、有用金属（铜、铅、锌、钼）硫化物矿物的浮选分离、光电和光伏应用、尘肺甚至生命起源等方面的作用而闻名。然而，黄铁矿的详细氧化行为仍不清楚且未被充分理解。本工作首次利用密度泛函理论模拟发现了黄铁矿（100）表面O2的新氧化途径；也就是说，在黄铁矿初始氧化态中，除了Fe位之外，S位也是可能的氧化位，可能发生更容易、更强的氧化。这是首次证实了其他研究者关于S位点直接氧化的猜想，这解释了同位素组成实验中黄铁矿氧化过程中少量O2永久掺入SO42中的情况（SO42中的O主要来自于水）。通过考虑 H2O 和 O2 的吸附顺序，我们在黄铁矿表面构建了各种 H2O-O2 共吸附模型。研究发现，在 O2 分子存在的情况下，H2O 分子会逐步解离。羟基自由基•OH是H2O解离过程中的活性氧物种。循环伏安测量证实了·OH 的存在。此外，H2O2也可能按照H2O-然后-O2顺序吸附在表面形成。
Pyrite is the most common sulfide in nature, and it is well-known for its roles in acid mine drainage, flotation separation of useful metal (Cu, Pb, Zn, and Mo) sulfide minerals, optoelectronic and photovoltaic application, pneumoconiosis, and even in the origin of life. However, the detailed oxidation behaviors of pyrite are still unclear and not well-understood. New oxidation pathways by O2on the pyrite (100) surface have been found in this work for the first time using density functional theory simulation; that is, besides Fe sites, S sites are also possible oxidation sites in the initial oxidation state of pyrite, where easier and stronger oxidation may occur. This is the first time to confirm the other researchers’ conjecture on the direct oxidation of S sites, which explains the isotopic composition experiments that a minor amount of O2is permanently incorporated into SO42–during pyrite oxidation (O in SO42–is mainly derived from water). We constructed various H2O–O2coadsorption models on the pyrite surface by considering the adsorption sequence of H2O and O2. It is found that the H2O molecule undergoes step-wise dissociation in the presence of the O2molecule. Hydroxyl radical •OH is the reactive oxygen species during H2O dissociation. Cyclic voltammetric measurements confirm the presence of •OH. In addition, H2O2may also be formed on the surface in terms of H2O-then-O2sequence adsorption.