MgO has a typical rocksalt structure and possesses a high melting point and high ionic character. Although the stoichiometry and crystallinity are nearly constant, the morphology can vary in terms of shape, particle size, and surface structure. The MgO(100) facet is unambiguously the most stable because of its low surface energy, and it is therefore normally a product after cleavage, and it is the sole surface generated by current wet chemical methods. Numerous studies have demonstrated that the shape and size of crystalline MgO is highly influential on the adsorption properties and the configuration of the surface species formed during chemical adsorption. For example, SO 2 is found to bind in a monodentate fashion at the edge/corner sites of the aerogel nanocrystal but prefers bidentate adsorption on flat (microcrystalline) surfaces. [1,2] This selectivity is also found for acetylene in theoretical ab initio calculations and solid-state NMR experimental studies in which no stable dissociation products on the flat (100)-like surface could be obtained theoretically or experimentally. [3] Furthermore, nanostructured MgO has been reported to be extremely effective for the destructive adsorption of numerous environmental toxins and several chemical warfare agents (VX, sarin, mustard gas). [4][5][6] However, the (111) surface consists of alternating polar monolayers of oxygen anions and magnesium cations and thus, a strong electrostatic field perpendicular to the (111) surface is created. [7] Such a surface has provided a prototype for the study of surface structure and surface reactions, and has attracted a great geal of attention from both experimental and theoretical studies. [8,9] These studies indicate the importance of size and shape control in MgO synthesis for its applications: it is not only the surface
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