Activating well-defined α-Fe2O3 nanocatalysts by near-surface Mn atom functionality for auto-exhaust soot purification

Herein, the atomically dispersed manganese (Mn) sites on well-defined α-Fe 2 O 3 nanosheets (Mn 1 -Fe 2 O 3 ) were fabricated by a ligand-assisted in - situ crystallization method. Single-step surface engineering facilitates the in-situ replacement of Fe atoms in near-surface [FeO 6 ] octahedra with monodispersed Mn atoms, as well as the preservation of regularly exposed {001} surface. Under different NO x concentration (40, 500 and 2000 ppm), Mn 1 -Fe 2 O 3 -10 catalyst presented the superior catalytic performance, whose T 50 values are 455, 388 and 340 o C, respectively. By combining in-situ dynamic characterizations and DFT calculations, the surface [MnO 5 ] and adjacent [FeO 5 ] octahedra cooperatively boost two crucial steps: the dissociation of adsorbed O 2 and the desorption of molecular NO 2 . The greater the amount of molecular NO 2 produced, the higher the efficiency of soot purification via the NO 2 -assisted oxidation mechanism. Insights into the near-surface modulation and structure-activity relationship provide a promising strategy to improve the availability of surface-active sites in future heterogeneous catalysis. • Atomic Mn co-catalyst on well-defined α-Fe 2 O 3 nanosheets (Mn 1 -Fe 2 O 3 ) were fabricated. • Monodispersed Mn atoms achieve in-situ substitution of Fe atoms near {001} facet. • Mn 1 -Fe 2 O 3 -10 catalyst presented the highest catalytic efficiency for soot removal. • Surface Mn 5c and Fe 5c atoms boost the dissociation of O 2 and the desorption of NO 2 .