科研之友
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摘要
The adsorption of O-2 on a sphalerite surface with vacancies and impurities is investigated through first-principle calculations based on density functional theory (DFT). The calculated results show that O-2 adsorption is unavailable on perfect sphalerite surfaces, while the presence of vacancies (e.g.. Zn-vacancy and S-vacancy) and impurity atoms (such as Fe, Mn, Cu and Cd) energetically favors the adsorption of O-2. The results show that the adsorption energy of O-2 on a S-vacancy surface is -408.25 kJ/mol, which is stronger than that of a Zn-vacancy surface at -218.55 kJ/mol. For a Zn-vacancy surface, the O 2p orbital interacts strongly with the S 3p orbital, and electrons transfer from the S atom to the O atom, which results in the oxidation of S. For the S-vacancy, the O 2p orbital interacts strongly with the Zn 3d orbital, and electrons transfer from the Zn atom to the O atom, which results in the oxidation of Zn. The adsorption energies of O-2 on the sphalerite surface with Fe, Mn, Cu and Cd impurities are -181.40 kJ/mol, -146.66 kJ/mol, -95.53 kJ/mol and -55.96 kJ/mol. respectively, which indicates that Fe-bearing sphalerite is easily oxidized, while Cd-bearing sphalerite is not easily oxidized. The oxygen molecule dissociates on Fe-, Mn- and Cd-bearing sphalerite surfaces, while oxygen does not dissociate on the Cu-bearing surface. The 3p orbital of S and the 3d orbital of Fe, Mn and Cu atoms donate electrons to the antibonding orbital pi(2p)* of the O atom, which enhances the bonding of oxygen with the sphalerite surface. However, the 4d orbital of the Cd atom donates fewer electrons, which weakens the bonding of oxygen with the surface.
- 出版日期2010-6-20
- 单位广西大学
