Structure and Reactivity of the Hydrated Hematite (0001) Surface
T P. Trainor, Anne M. Chaka, P J. Eng, M Newville, G A. Waychunas, J G. Catalano, G E. Brown
Hematite (alpha-Fe2O3) is significantly more reactive to water and metal ions than its isostructure corundum (alpha-Al2O3u) under environmental conditions. However, the reason for this difference is not understood. Using crystal truncation rod diffraction and density functional theory (DFT), we show that the stable hydrated hematite (0001) surface consists of two domains one with Fe-rich regions terminated by singly coordinated hydroxyls, and one with oxygen-rich regions terminated by doubly and triply coordinated hydroxyls. The presence of singly coordinated hydroxyls on hydrated a-Fe2O3(0001) and their absence on hydrated alpha-Al2O3(0001) explain the higher reactivity of the former. DFT calculations indicate that water reacts with hematite both heterolytically and homolytically at a threshold water pressure orders of magnitude lower on a-Fe2O3(0001) than on alpha-Al2O3(0001).
ab initio, Crystal Truncation Rod diffraction, density functional theory, Fe2O3, Hematite, surface structure
, Chaka, A.
, Eng, P.
, Newville, M.
, Waychunas, G.
, Catalano, J.
and Brown, G.
Structure and Reactivity of the Hydrated Hematite (0001) Surface, Science
(Accessed May 16, 2022)