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Originally published in Science Express on 6 March 2008
Science 11 April 2008:
Vol. 320. no. 5873, pp. 218 - 222
DOI: 10.1126/science.1154833
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Reports

Linked Reactivity at Mineral-Water Interfaces Through Bulk Crystal Conduction

Svetlana V. Yanina and Kevin M. Rosso*

The semiconducting properties of a wide range of minerals are often ignored in the study of their interfacial geochemical behavior. We show that surface-specific charge density accumulation reactions combined with bulk charge carrier diffusivity create conditions under which interfacial electron transfer reactions at one surface couple with those at another via current flow through the crystal bulk. Specifically, we observed that a chemically induced surface potential gradient across hematite ({alpha}-Fe2O3) crystals is sufficiently high and the bulk electrical resistivity sufficiently low that dissolution of edge surfaces is linked to simultaneous growth of the crystallographically distinct (001) basal plane. The apparent importance of bulk crystal conduction is likely to be generalizable to a host of naturally abundant semiconducting minerals playing varied key roles in soils, sediments, and the atmosphere.

Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Post Office Box 999, MSIN K8-96, Richland, WA 99352, USA.

* To whom correspondence should be addressed. E-mail: kevin.rosso{at}pnl.gov

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Science. ISSN 0036-8075 (print), 1095-9203 (online)