Preparation and Properties of Octadecahedral α-Fe2O3 Nanoparticles Enclosed by {104} and {112} Facets.

Octadecahedral α-Fe2O3 nanoparticles were hydrothermally synthesized in the presence of formamide. These octadecahedral α-Fe2O3 nanoparticles have a threefold axis and are enclosed by twelve dominant {112} facets and six {104} facets. In comparison with the {104} facets, the sterically less hindered {112} facets induced the selective adsorption of formamide more easily, which resulted in the gradual increase in the amount of {112} facets by decreasing the amount of {104} facets with increasing formamide. The coercivity ( Hc) of these octadecahedral particles increased successively as the aspect ratio ( c/ a) increased. The sensing capability of these particles toward H2O2 was investigated, and the response currents of the particles dominated by {112} facets showed a linear relationship with a concentration of H2O2 in the range from 40 μ M to 6.66 m M in different stages. [ABSTRACT FROM AUTHOR]