Surface-mediated redox reactions involving Fe-bearing oxides play a central role in various environmental processes. Given the ubiquity of goethite in the environment and a number of open questions concerning the mechanisms of redox reactions at this mineral surface, it is important to understand goethite redox reactivity at the atomistic level. We employ density-functional-theory calculations combined with ab initio molecular dynamics simulations and a small-polaron migration approach to examine aqueous Fe(II) adsorption to and electron exchange with Fe(III) at goethite surfaces.  Thermodynamically favorable pathways for Fe(II)-Fe(III) interfacial electron exchange are predicted and discussed in terms of local structure and energetics. The obtained results provide important mechanistic veracity for proposed redox recrystallization of goethite by the bulk electrical conduction mechanism.

Fe(II) adsorption and electron exchange with Fe(III) at FeOOH (Goethite) surfaces

247th National Meeting (2014)

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