Naslov
Electrostatic potentials and charge distributions at structurally defined hematite/electrolyte interfaces

Autori
Chatman, Shawn ; Zarzicki, Pjotr ; Preočanin, Tajana ; Rosso, Kevin

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Geochimica et Chosmochimica acta, Goldschmidt 2010 / - : Elsevier, 2010, A163-A163

Skup
Goldschmidt 2010

Mjesto i datum
Knoxville (TN), Sjedinjene Američke Države, 13.06.2010. - 18.06.2010

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Surface potential; hematite; electrostatic potential; surface charging

Sažetak
The chemical behavior of mineral interfaces with aqueous solution is an important factor in soil evolution, microbemineral interaction, atmospheric chemistry, and waste remediation. Traditionally, aqueous mineral reactivity has been studied using colloidal mineral suspensions or isolated crystallographically well-defined surfaces. These approaches either average the contribution of all crystallographic faces or focus on one distinct crystal/solution interface. Consequently, with regard to semiconducting minerals, analysis of macroscopic kinetic phenomena has ignored the existence of spatially remote but coupled interfacial electron transfer reactions. Low-to-wide band gap iron oxides, such as hematite, are a major constituent in many natural soils. In wet environs the dissolution/crystallization of iron oxides is intimately linked with the presence of aqueous Fe2+ ions. Characterizing the complete electron transfer processes involved during interfacial Fe2+/Fe3+ redox reactions is key to understanding the role of iron oxides in water bearing enviroments. Building on previous work [1], here we report measurements and molecular simulations of the electrostatic potential profile across crystallographically defined ((-Fe2O3) hematite-electrolyte interfaces. We use a combination of open circuit potential, cyclic voltammetry and impedence measurements to assess the potential distribution as a function of pH, electrolyte type, and equilibration time. In particular, we focus on the structural origins of surface-specific differences in rest potentials, flat-band potentials, depletion zones widths, and charging behavior for (001), (012), (110), (113), (125), (211) and (214) faces. By directly comparing the results from a variety of crystal faces we attempt to elucidate morphology-dependent average system behavior. Ultimately this line of investigation is expected to enable insight into the interaction between solid-state electron transport and surface/solution redox Fe3+-Fe2+ transformations in the iron oxide system.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA