External field-assisted solution synthesis and selectively catalytic properties of amorphous iron nanoplatelets
This work describes an easy and flexible approach for the synthesis of 2D nanostructures by external composite field-induced self-assembly. Amorphous iron nanoplatelets with a large aspect ratio were prepared by reducing a concentrated FeSO4 solution with NaBH4 without any templates or surfactants under a magnetic field and a shear field, and characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Based on the morphological dependence of the resultant iron nanostructures on the kinetic parameters such as reactant concentration, reaction temperature, external fields as well as reaction time, etc., a novel conceivable formation mechanism of the iron nanoplatelets was substantiated to be a self-assembly of concentrated iron nuclei induced by the synergistic effect of both a magnetic field and a shear field. Due to the amorphous nature and shape anisotropy, the as-synthesized iron nanoplatelets exhibit quite different magnetic properties with an enhanced coercivity of >220 Oe from isotropic iron nanoparticles. In the oxidation of cyclohexane with hydrogen peroxide as a 'green' oxidant, the as-obtained amorphous iron nanoplatelets show a conversion more than 84% and a complete selectivity for cyclohexanol and cyclohexanone due to the unique structure. Moreover, their catalytic performances are strongly influenced by their morphology, and the iron atoms located on the faces tend to catalyze the formation of cyclohexanol while those on the sides tend to catalyze the formation of cyclohexanone. The external composite field-induced solution synthesis reported here can be readily explored for fabricating other 2D magnetic nanoplatelets, and the resulting iron nanoplatelets are promising for a number of applications such as high efficient selective catalysis, energy, environment fields and so forth.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1047980
- Report Number(s):
- PNNL-SA-87854; JMACEP; KC0201050; TRN: US201216%%602
- Journal Information:
- Journal of Materials Chemistry, Vol. 22, Issue 9; ISSN 0959-9428
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANISOTROPY
ASPECT RATIO
ATOMS
CATALYSIS
CYCLOHEXANE
CYCLOHEXANOL
CYCLOHEXANONE
ELECTRON DIFFRACTION
FIELD EMISSION
HYDROGEN PEROXIDE
IRON
KINETICS
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MORPHOLOGY
NANOSTRUCTURES
NUCLEI
OXIDATION
SCANNING ELECTRON MICROSCOPY
SURFACTANTS
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY