Effect of Surface Structure of α-Fe2O3 on the Selective Catalytic Reduction of NO by NH3

alpha-Fe2O3 samples with nanocube and nanorod morphologies were synthesized by a simple hydrothermal route. The samples were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), temperature- programmed reduction by H-2 (H-2-TPR), and temperature-programmed desorption of NO (NO-TPD), and tested for the selective catalytic reduction with NH3 (NH3-SCR) of NO at moderate temperatures. The alpha-Fe2O3 nanocubes possessed predominantly exposed {012} faces with low surface energy, while the nanorods also had some high energy {110} faces exposed. The catalytic activities of the alpha-Fe2O3 samples were predominantly governed by their surface structures. The nanorods showed much higher activity than the nanocubes under identical conditions, consistent with the better redox properties of the nanorods as confirmed by H-2-TPR and NO-TPD measurements. Therefore, alpha-Fe2O3 nanorods with exposed high energy faces have much higher activity for NH3-SCR than nanocubes with exposed low energy faces under identical reaction conditions.