Journal
APPLIED SURFACE SCIENCE
Volume 390, Issue -, Pages 412-421Publisher
ELSEVIER
DOI: 10.1016/j.apsusc.2016.08.095
Keywords
Iodine anions; Chalcopyrite; Surface adsorption; DFT calculations; XPS
Categories
Funding
- National Natural Science Foundation of China [11275147]
- Program for Changjiang Scholars and Innovative Research Team in University [IRT1280]
- Fundamental Research Funds for the Central Universities
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The adsorption of iodine anions (iodide and iodate) on the sulfur terminated (001) chalcopyrite surface has been systematically investigated combining first-principles calculations based on density functional theory (DFT) with X-ray photoelectron spectroscopy (XPS) measurements. Based on the total energy calculations and geometric optimization, the thermodynamically preferred site was copper atom for iodide adsorption and iron atom for iodate adsorption, respectively. In the case of Cu site mode, the iodate underwent a dissociative adsorption, where one I-O bond of iodate ion was broken and the dissociative oxygen atom adsorbed on the adjacent sulphur site. Projected density of states (PDOS) analysis further clarified the interaction mechanism between active sites of chalcopyrite surface and adsorbates. In addition, full-range XPS spectra qualitatively revealed the presence of iodine on chalcopyrite surface. High resolution XPS spectra of the I 3d peaks after adsorption verified the chemical environment of iodine. The binding energies of 618.8 eV and 623.5 eV for I 3d(5/2) peaks unveiled that the adsorption of iodide and iodate ions on copper-iron sulfide minerals was the result of formation of low solubility metal iodides precipitate. Also two I 3d peaks with low intensity around 618 eV and 630 eV might be related to the inorganic reduction of iodate to iodide by reducing S2- ion of chalcopyrite. (C) 2016 Elsevier B.V. All rights reserved.
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