A simple model for the effect of hydration on the distribution of ferrous iron at reduced hematite (012) surfaces

Structural study of Fe(II) adsorption on hematite(11¯02)

“…Recent studies suggest there are at least three possible fates of the injected electron; (i) the electron is trapped in the near surface region, (ii) the electron migrates to bulk lattice, or (iii) the electron transport results in reduction of Fe(III) to Fe(II) at edge or defect sites, which is followed by release of Fe(II) from substrate to the solution. The first possibility is consistent with the energy optimizations conducted by Wang and Rustad (2006), where an electron is transferred between surface Fe(II) and structural Fe(III) resulting in a structure in which the reduced Fe(II) remains localized in the near surface region.…”

“…The electron transfer between adsorbed Fe(II) and underlying substrate is also shown for iron (hydr)oxide other than hematite (i.e., goethite and ferrihydrite) (Williams and Scherer, 2004;Silvester et al, 2005). Furthermore, previous theoretical studies suggest that there is a thermodynamic driving force for oxidation of the surface bound Fe(II) under aqueous conditions (Rosso et al, 2003;Kerisit and Rosso, 2006;Wang and Rustad, 2006). Thus, it is likely that the surface Fe(III) layer observed in the current study is a result of interfacial electron transfer between adsorbed Fe(II) and structural Fe(III).…”

Water structure at hematite–water interfaces

“…This study found the three surfaces considered here to be the three most stable surfaces. In later models, hydration was modeled with a single monolayer of water molecules (Parker et al, 1999;Jones et al, 2000;Lado-Touriñ o and Tsobnang, 2000;Wang and Rustad, 2006;de Leeuw and Cooper, 2007). The most advanced potential model simulations of hydrated hematite surfaces make use of molecular dynamics techniques and consist of mineral slabs or nanoparticles in contact with a hydration layer tens of Å ngstroms thick (Wasserman et al, 1997;Kerisit et al, 2005;Kerisit and Rosso, 2006;Spagnoli et al, 2006Spagnoli et al, , 2009.…”

Minerals and Aqueous Species of Iron and Manganese as Reactants and Products of Microbial Metal Respiration

“…These studies provide an unprecedented detailed view of the surfaces; surfaces of isostructural minerals corundum (a-Al 2 O 3 ) and hematite (a-Fe 2 O 3 ) have been shown to be similar but not identical (Catalano 2011). Furthermore, the electron transfer chains in redox reactions in iron oxides can be tracked to the minute detail in computational work (Wang and Rustad 2006).…”