期刊
APPLIED CATALYSIS B-ENVIRONMENTAL
卷 321, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apcatb.2022.122077
关键词
Atomic co -catalysts; Hematite; Intrinsic mechanism; Near -surface modulation; Soot oxidation
Atomically dispersed manganese sites were fabricated on well-defined alpha-Fe2O3 nanosheets through a ligand-assisted in-situ crystallization method. The Mn1Fe2O3-10 catalyst exhibited superior catalytic performance, with efficient soot purification through the NO2-assisted oxidation mechanism.
Herein, the atomically dispersed manganese (Mn) sites on well-defined alpha-Fe2O3 nanosheets (Mn1-Fe2O3) 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 [FeO6] octahedra with monodispersed Mn atoms, as well as the preservation of regularly exposed {001} surface. Under different NOx concentration (40, 500 and 2000 ppm), Mn1Fe2O3-10 catalyst presented the superior catalytic performance, whose T50 values are 455, 388 and 340 degrees C, respectively. By combining in-situ dynamic characterizations and DFT calculations, the surface [MnO5] and adjacent [FeO5] octahedra cooperatively boost two crucial steps: the dissociation of adsorbed O2 and the desorption of molecular NO2. The greater the amount of molecular NO2 produced, the higher the efficiency of soot purification via the NO2-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.
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