Thermal chemistry of H2S and H2O on the (100) plane of pyrite:: Unique reactivity of defect sites
Thermal chemistry of H2S and H2O on the (100) plane of pyrite:: Unique reactivity of defect sites
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DOI：
10.2138/am-1998-11-1213
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发表时间：
1998-11-01
影响因子：
3.1
通讯作者：
Schoonen, MAA
中科院分区：
文献类型：
--
作者：
Guevremont, JM;Strongin, DR;Schoonen, MAA
利用x射线光电子能谱（XPS）、程序升温解吸（TPD）和吸附氙（PAX）的光发射研究了在超高真空（UHV）清洗后的FeS2（100）的自然表面与H2O和H2S的相互作用。PAX对表面的短程阶数很敏感，可以研究缺陷对FeS2（100）表面反应性的影响。PAX结果表明，H2S和H2O与缺陷位点结合最强烈，我们提出的缺陷位点至少部分是硫阴离子空位。大多数H2O在200-300 K的温度区间内从这些位置解吸，而H2S在加热到500 K时解离成吸附的表面氢、S和SH。这种解离发生在缺陷位置，然后释放部分解离片段，被认为是表面氢，到黄铁矿表面的其他区域，被认为是化学测量的FeS2。加热到600 K时，含有解离碎片的S与缺硫位点进一步反应，形成类似于FeS2的新的表面位点。结果还表明，当加热到600 K时，表面氢溶解到黄铁矿体中。
The interaction of a natural face of FeS2 (100), cleaned in ultra-high vacuum (UHV), with H2O and H2S has been investigated with X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and the photoemission of adsorbed xenon (PAX). PAX is sensitive to the short-range order of the surface and allows the effects of defects on the surface reactivity of FeS2(100) to be studied. PAX results suggest that both H2S and H2O bind most strongly to defect sites that we propose are, at least in part, sulfur anion vacancy sites. Whereas the majority of H2O adsorbate desorbs from these sites in the temperature interval of 200-300 K, H2S dissociates upon heating to 500 K into adsorbed surface hydrogen, S, and SH. This dissociation occurs on defect sites that then release part of the dissociation fragment, which is thought to be surface hydrogen, onto other regions of the pyrite surface that are proposed to be stoichiometric FeS2. Heating to 600 K causes further reaction of S containing dissociation fragments with sulfur-deficient sites to form new surface sites that resemble FeS2. The results also suggest that surface hydrogen dissolves into the pyrite bulk upon heating to 600 K.