Uncovering the oxidation mechanism of sphalerite (ZnS) in the absence and presence of water: A first-principles investigation

Abstract

Herein, a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H₂O. The findings showed that single O₂ was preferred to be dissociated adsorption on sphalerite surface by generating S—O and Zn—O bonds, and the S atom on the surface was the most energy-supported site for O₂ adsorption, on which a≡Zn—O—S—O—Zn≡ structure will be formed. However, dissociated adsorption of single H₂O will not happen. It was preferred to be adsorbed on the top Zn atom on sphalerite surface in molecular form through Zn—O bond. Besides, sphalerite oxidation can occur as if O₂ was present regardless of the presence of H₂O, and when H₂O and O₂ coexisted, the formation of sulfur oxide (SO₂) needed a lower energy barrier and it was easier to form on sphalerite surface than that only O₂ existed. In the absence of H₂O, when SO₂ was generated, further oxidation of which would form neutral zinc sulfate. In the presence of H₂O, the formation of SO₂ on sphalerite surface was easier and the rate of further oxidation to form sulfate was also greater. Consequently, the occurrence of sphalerite oxidation was accelerated.

Keywords

First-principles / Oxidation / Sphalerite / H₂O / Lower energy barrier

Acknowledgement

This study was supported by the Postdoctoral Fellowship Program (Grade A) of China Postdoctoral Science Foundation (No. BX20240429), the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2024ZD1004007), the National Key R&D Program of China (Nos. 2022YFC2904502 and 2022YFC2904501), the National Natural Science Foundation of China (No. 52204298), the Major Science and Technology Projects in Yunnan Province (No. 202202AB080012), and the High Performance Computing Center of Central South University.

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