Chen Manjiao, Hu Xinjun, Zhou Xinjun, Li Xiulan, Tian Jianping
School of Mechanical Engineering, Sichuan University of Science & Engineering, Zigong 643000, China.
Faculty of materials science and engineering, Kunming University of Science and Technology, Kunming 650093, China.
Phys Chem Chem Phys. 2023 Mar 22;25(12):8826-8835. doi: 10.1039/d3cp00039g.
The analysis of the surface chemical behavior of pyrite is highly crucial in the fields of environmental conservation, metal extraction, and flotation separation. In this paper, the mechanism of atomic reconstruction on the pyrite surface and the adsorption behavior of O on a reconstructed surface are calculated by density functional theory (DFT). Different reconstruction surfaces were constructed by deleting S and Fe atoms on the (100) surface of pyrite. In addition, the geometric configuration, formation energy, binding energy, cohesion energy, and surface electronic properties of the reconstruction surface were calculated. The adsorption energies and geometric configurations of O on different reconstructed surfaces were also determined. The results show that under Fe-poor conditions, the charge of Fe atoms increases, and S atoms form S on the reconstructed surface. The binding energy between the S and the substrate (ideal surface) is lower, which is similar to the S adsorption on the substrate surface with the Fe atom as the site. S has high cohesive energy and is resistant to being attacked by oxidants, which leads to structural collapse, and a low affinity for O. Under S-poor conditions, the -[Fe-S]- plane structure formed on the reconstructed surface. The -[Fe-S]- structure stably bonds to the substrate by an Fe-S bond, and exhibits strong binding energy. However, the -[Fe-S]- structure has low cohesive energy and exhibits thermodynamic instability. In contrast, O shows a strong affinity for the -[Fe-S]- structure, indicating that the deficiency of the S atom promotes the surface oxidation reaction. The mechanism of atomic reconstruction on the surface of pyrite is of utmost importance for understanding its surface chemical behavior.
黄铁矿表面化学行为的分析在环境保护、金属提取和浮选分离等领域至关重要。本文采用密度泛函理论（DFT）计算了黄铁矿表面原子重构的机理以及O在重构表面上的吸附行为。通过删除黄铁矿（100）表面的S和Fe原子构建了不同的重构表面。此外，还计算了重构表面的几何构型、形成能、结合能、内聚能和表面电子性质。同时确定了O在不同重构表面上的吸附能和几何构型。结果表明，在贫铁条件下，Fe原子的电荷增加，S原子在重构表面形成S。S与基底（理想表面）之间的结合能较低，这与以Fe原子为位点在基底表面吸附S的情况相似。S具有较高的内聚能，抗氧化剂攻击导致结构崩塌，且对O的亲和力较低。在贫硫条件下，重构表面形成-[Fe-S]-平面结构。-[Fe-S]-结构通过Fe-S键与基底稳定结合，并表现出较强的结合能。然而，-[Fe-S]-结构的内聚能较低，表现出热力学不稳定性。相比之下，O对-[Fe-S]-结构表现出较强的亲和力，表明S原子的缺乏促进了表面氧化反应。黄铁矿表面原子重构的机理对于理解其表面化学行为至关重要。
