Investigation of the Facet-Dependent Catalytic Performance of Fe2O3/CeO2 for the Selective Catalytic Reduction of NO with NH3

The facet-dependent catalytic performance of Fe2O3/CeO2 catalysts for the selective catalytic reduction of NO with NH3 (NH3-SCR) has been investigated using combined experimental and density functional theory (DFT) methods. The structure and surface characteristics of the synthesized samples were characterized by XRD, XPS, TEM, ICP-AES, N-2 sorption isotherms, Raman spectra, photoluminescence spectra, H-2-TPR, NH3-TPD and NO + O-2-TPD. It is found that the CeO2 nanorods and Fe2O3/CeO2 nanorods predominately exposed {110} and {100} facets rather than the stable {111} facets on CeO2 nanopolyhedra and Fe2O3/CeO2 nanopolyhedra. The influence of the micromorphologies and surface properties of CeO2 supports on the NO conversion and N-2 selectivity has been compared. The Fe2O3/CeO2 nanorods achieve higher catalytic activity than the Fe2O3/CeO2 nanopolyhedra for NH3-SCR of NO. The synergetic effect between CeO2 supports and Fe2O3 species has been demonstrated. The insight into molecular facet dependence by the DFT method clearly showed that the Fe2O3/CeO2 {110} catalyst is more reactive to NO and NH3 gases than the Fe2O3/CeO2 {111} and naked CeO2 {110}, which agree well with the experimental results. As a result, the outstanding catalytic performance of Fe2O3/CeO2 nanorods is attributed to the adsorbed surface oxygen, oxygen defects and atomic concentration of Fe which are associated with their exposed {110} and {100} facets of nanorods.