Synergy of Single-Atom Fe₁ and Ce–O_v Sites on Mesoporous CeO₂–Al₂O₃ for Efficient Selective Catalytic Reduction of NO with CO

Nonprecious transition-metal oxides, especially Fe-, Cu-, Co-, and Mn-containing mixed oxides, have been regarded as promising alternatives for noble metal catalysts for the abatement of NO_x contamination. However, the identification of the real catalytically active sites for these mixed oxides remains unclear in most cases, which limits our in-depth understanding of the intrinsic mechanism. Here, we comprehensively investigated an iron–cerium–aluminum oxide (Fe₁/CeO₂–Al₂O₃) prepared with a co-precipitation method. Structural identification confirmed that Fe sites are atomically dispersed, bonding with four O atoms in the first coordination shell and with two Ce atoms in the second shell on average. Highly efficient removal of NO with 100% selectivity toward N₂ has been achieved over these sites at a temperature as low as 250 °C. In situ characterizations and computational studies revealed that the high activity and N₂ selectivity of Fe₁/CeO₂–Al₂O₃ can be attributed to the synergetic effect of the single-atomic Fe₁ site and surrounding Ce–O_v, which intensively promotes the adsorption of NO molecules and N₂O intermediates. Subsequently, Ce–O_v facilitates the N–O dissociation toward N₂ and then is regenerated with CO, forming CO₂ as a product. The present results provide valuable insights into the mechanism of transition-metal oxide catalysts for the NO–CO reaction and offer useful guidance for designing catalysts with high activity and selectivity.