Synergy of Single-Atom Fe1 and Ce–Ov 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 NOx 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–Ov, which intensively promotes the adsorption of NO molecules and N2O intermediates. Subsequently, Ce–Ov 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.