Mechanism of the Effect of Fe Doping on the CuO (111) Surface on the Reactivity and Water/Sulfur Resistance Performance of CuFe Layered Double Oxide Catalysts for Selective Catalytic Reduction of NO with C3H6: A DFT + U Study

Previous experimental research revealed the beneficial synergistic effect of Cu and Fe in CuFe-LDOs catalysts for C₃H₆–SCR. However, the intensive understanding of the reaction mechanism on the microscopic level remains limited. In this study, the configuration of Fe-doped CuO (111) surface was optimized, and the adsorption energy, charge distribution, projected density of states, transition state, and reaction pathway were calculated based on the density functional theory method. Results showed that doping with Fe significantly strengthened the adsorption of NO, O₂, and C₃H₆ molecules on the catalyst surface and boosted the electronic interactions. The excellent water-sulfur resistance of Fe atoms significantly minimized the negative effects of H₂O/SO₂ on catalyst activity. The Cu–Fe synergistic effect reduced the energy barrier for NO oxidation from 1.08 to 0.56 eV and facilitated the formation of more stable nitrates. Meanwhile, the introduction of Fe raised the energy barrier for *H₂O dehydrogenation from 0.07 to 0.46 eV, thus preserving more active sites. Furthermore, *OH adsorption on the Fe-CuO (111) surface was unstable, rendering the negative effect of H₂O on the catalyst reversible. Comparing the reaction pathways of dynamic adsorption revealed that the C₃H₆–SCR reaction proceeded more easily when NO and O₂ were saturated before C₃H₆ was adsorbed. The results of this study support the experimental findings and offer microscopic insights into Cu–Fe synergy in C₃H₆–SCR, aiding future improvements of these catalysts.