Journal ArticleDOI
Morphology and Electronic Structure of the Oxide Shell on the Surface of Iron Nanoparticles
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The results suggest that the coordination configuration in the oxide shell on Fe nanoparticles is defective as compared to that of their bulk counterparts.Abstract:
An iron (Fe) nanoparticle exposed to air at room temperature will be instantly covered by an oxide shell that is typically approximately 3 nm thick. The nature of this native oxide shell, in combination with the underlying Fe(0) core, determines the physical and chemical behavior of the core-shell nanoparticle. One of the challenges of characterizing core-shell nanoparticles is determining the structure of the oxide shell, that is, whether it is FeO, Fe(3)O(4), gamma-Fe(2)O(3), alpha-Fe(2)O(3), or something else. The results of prior characterization efforts, which have mostly used X-ray diffraction and spectroscopy, electron diffraction, and transmission electron microscopic imaging, have been framed in terms of one of the known Fe-oxide structures, although it is not necessarily true that the thin layer of Fe oxide is a known Fe oxide. In this Article, we probe the structure of the oxide shell on Fe nanoparticles using electron energy loss spectroscopy (EELS) at the oxygen (O) K-edge with a spatial resolution of several nanometers (i.e., less than that of an individual particle). We studied two types of representative particles: small particles that are fully oxidized (no Fe(0) core) and larger core-shell particles that possess an Fe core. We found that O K-edge spectra collected for the oxide shell in nanoparticles show distinct differences from those of known Fe oxides. Typically, the prepeak of the spectra collected on both the core-shell and the fully oxidized particles is weaker than that collected on standard Fe(3)O(4). Given the fact that the origin of this prepeak corresponds to the transition of the O 1s electron to the unoccupied state of O 2p hybridized with Fe 3d, a weak pre-edge peak indicates a combination of the following four factors: a higher degree of occupancy of the Fe 3d orbital; a longer Fe-O bond length; a decreased covalency of the Fe-O bond; and a measure of cation vacancies. These results suggest that the coordination configuration in the oxide shell on Fe nanoparticles is defective as compared to that of their bulk counterparts. Implications of these defective structural characteristics on the properties of core-shell structured iron nanoparticles are discussed.read more
Citations
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Journal ArticleDOI
Environmental Remediation and Application of Nanoscale Zero-Valent Iron and Its Composites for the Removal of Heavy Metal Ions: A Review
Yidong Zou,Xiangxue Wang,Xiangxue Wang,Ayub Khan,Pengyi Wang,Yunhai Liu,Ahmed Alsaedi,Tasawar Hayat,Tasawar Hayat,Xiangke Wang,Xiangke Wang,Xiangke Wang +11 more
TL;DR: Research shows that NZVI-based materials have satisfactory removal capacities for heavy metal ions and play an important role in the environmental pollution cleanup.
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Laminated magnetic graphene with enhanced electromagnetic wave absorption properties
TL;DR: In this paper, the authors reported a facile solvothermal route to synthesize laminated magnetic graphene and showed that there have significant changes in the electromagnetic properties of magnetic graphene when compared with pure graphene.
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Iron nanoparticles for environmental clean-up: recent developments and future outlook.
TL;DR: An up-to-date account of advancement in materials chemistry, reactivity with a wide spectrum of contaminants in addition to the well-documented chlorinated solvents, methods to enhance the colloidal stability and transport properties of nZVI in porous media, and the effects of n ZVI amendment on the biogeochemical environment are provided.
Journal ArticleDOI
Nanoscale zero-valent iron (nZVI): aspects of the core-shell structure and reactions with inorganic species in water.
TL;DR: The results presented herein highlight the multiple reactive pathways permissible with nZVI owing to its two functional constituents and grants the material with potentially new applications.
Journal ArticleDOI
Iron oxide shell mediated environmental remediation properties of nano zero-valent iron
TL;DR: In this article, the role of the oxide shell in the organic contaminant degradation efficiency and the molecular oxygen activation performance of nano zero-valent iron (nZVI) is discussed.
References
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Book
Interfaces in Crystalline Materials
TL;DR: The geometry of interfaces Dislocation for interfaces Models of interatomic forces at interfaces Models and experimental observations of structure Thermodynamics of interfaces Interface phases and phase transitions Segregation of solute atoms to interfaces Diffusion at interfaces Conservative motion of interfaces: interfaces as sources/sinks for diffusional fluxes.
Journal ArticleDOI
Synthesizing Nanoscale Iron Particles for Rapid and Complete Dechlorination of TCE and PCBs
Chuan-Bao Wang,Wei-xian Zhang +1 more
TL;DR: In this article, an efficient method of synthesizing nanoscale (1−100 nm) iron and palladized iron particles is presented, which is characterized by high surface area to volume ratios and high reactivities.
Journal ArticleDOI
Oxygen 1s x-ray-absorption edges of transition-metal oxides
F. M. F. de Groot,Marco Grioni,John C. Fuggle,Jacques Ghijsen,George A. Sawatzky,Harald Petersen +5 more
TL;DR: On a mesure les limites d'absorption des rayons X de l'oxygene 1s d'une serie d'oxydes de metaux de transition 3d dans les etats inoccupes du caractere metallique principal.
Journal ArticleDOI
Zero-Valent Iron Nanoparticles for Abatement of Environmental Pollutants: Materials and Engineering Aspects
TL;DR: Zero-valent iron nanoparticles (nZVI) are becoming an increasingly popular choice for treatment of hazardous and toxic wastes, and for remediation of contaminated sites as mentioned in this paper, and more than 20 projects have been completed or ongoing in North America, Europe, and Asia.