Mn-Doped Maghemite (γ-Fe₂O₃) from Metal-Organic Framework Accompanying Redox Reaction in a Bimetallic System: The Structural Phase Transitions and Catalytic Activity toward NOx Removal.

ABSTRACT: Mn-doped maghemite (γ-Fe₂O₃) particles were generated from a binary metal (Fe,Mn)-based metal-organic framework (MOF) via thermal decomposition under air. The X-ray photoelectron spectroscopy analysis revealed that the synthesis of Fe/Mn-MOF accompanied the reduction of the metal ions. The existence of Mn ions in this synthetic process leads to thermally stable maghemite particles under air. A temperature-induced structural phase transition from γ-Fe₂O₃ to α-Fe₂O₃ was observed through a mixed phase with another structure. Mn-doped γ-Fe₂O₃ and α-Fe₂O₃ exhibit superparamagnetic behavior. The sample annealed at 600 °C showed a mixed magnetic hysteresis loop indicating the existence of an intermediate structural phase between γ-Fe₂O₃ and α-Fe₂O₃ during the phase conversion from FeMn-MOF. The constructed Mn-doped iron oxides are active toward reducing nitric oxide with NH₃. The NO conversion is 97% over Mn-doped γ-Fe₂O₃ calcined at 320 °C.

SUBMITTER: Lee J 

PROVIDER: S-EPMC6641356 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature