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 Fe 2 O 3 /CeO 2 catalysts for the selective catalytic reduction of NO with NH 3 (NH 3 –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, NH 3 –TPD and NO + O 2 –TPD. It is found that the CeO 2 nanorods and Fe 2 O 3 /CeO 2 nanorods predominately exposed {110} and {100} facets rather than the stable {111} facets on CeO 2 nanopolyhedra and Fe 2 O 3 /CeO 2 nanopolyhedra. The influence of the micromorphologies and surface properties of CeO 2 supports on the NO conversion and N 2 selectivity has been compared. The Fe 2 O 3 /CeO 2 nanorods achieve higher catalytic activity than the Fe 2 O 3 /CeO 2 nanopolyhedra for NH 3 –SCR of NO. The synergetic effect between CeO 2 supports and Fe 2 O 3 species has been demonstrated. The insight into molecular facet dependence by the DFT method clearly showed that the Fe 2 O 3 /CeO 2 {110} catalyst is more reactive to NO and NH 3 gases than the Fe 2 O 3 /CeO 2 {111} and naked CeO 2 {110}, which agree well with the experimental results. As a result, the outstanding catalytic performance of Fe 2 O 3 /CeO 2 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.