TY - JOUR
T1 - Interaction of oxygen and water with the (100) surface of pyrite
T2 - Mechanism of sulfur oxidation
AU - Sit, Patrick H.L.
AU - Cohen, Morrel H.
AU - Selloni, Annabella
PY - 2012/9/6
Y1 - 2012/9/6
N2 - We present a density-functional study of the adsorption and reactions of oxygen and water with the (100) surface of pyrite. We find that dissociative adsorption is energetically favorable for oxygen, forming ferryl-oxo, Fe 4+=O 2-, species. These transform easily to ferric-hydroxy, Fe 3+-OH -, in the presence of coadsorbed water, and the latter fully covers the surface under room conditions. A mechanism for surface oxidation is identified, which involves successive reactions with molecular oxygen and water, and leads to the complete oxidation of a surface sulfur to SO 4 2-. The crucial recurring process is the surface O 2- and OH - species acting as proton acceptors for incoming water molecules. Using a recently proposed method, we examine the oxidation state changes of the surface ions and the electron flow during the adsorption and oxidation processes. The oxidation mechanism is consistent with isotopic labeling experiments, suggesting that the oxygens in SO 4 2- from gas-phase oxidation are derived from water.
AB - We present a density-functional study of the adsorption and reactions of oxygen and water with the (100) surface of pyrite. We find that dissociative adsorption is energetically favorable for oxygen, forming ferryl-oxo, Fe 4+=O 2-, species. These transform easily to ferric-hydroxy, Fe 3+-OH -, in the presence of coadsorbed water, and the latter fully covers the surface under room conditions. A mechanism for surface oxidation is identified, which involves successive reactions with molecular oxygen and water, and leads to the complete oxidation of a surface sulfur to SO 4 2-. The crucial recurring process is the surface O 2- and OH - species acting as proton acceptors for incoming water molecules. Using a recently proposed method, we examine the oxidation state changes of the surface ions and the electron flow during the adsorption and oxidation processes. The oxidation mechanism is consistent with isotopic labeling experiments, suggesting that the oxygens in SO 4 2- from gas-phase oxidation are derived from water.
UR - http://www.scopus.com/inward/record.url?scp=84865963564&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84865963564&partnerID=8YFLogxK
U2 - 10.1021/jz300996c
DO - 10.1021/jz300996c
M3 - Article
C2 - 26292124
AN - SCOPUS:84865963564
SN - 1948-7185
VL - 3
SP - 2409
EP - 2414
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 17
ER -