Growth and Properties of Single-Crystalline γ-Fe₂O₃ Nanowires

Abstract

By carefully controlling the reacting conditions, including atmosphere, temperature, and time, we directly acquire the nanowires of γ-Fe 2 O 3 from the nanowires of R-Fe 2 O 3 in a reduced atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectrum, and transmission electronic microscope analyses demonstrate that the nanowires are single-crystalline γ-Fe 2 O 3 . The nanowires have a diameter ranging from 50 to 90 nm and their typical lengths are in the range of 10∼20 µm. The optical property of the nanowires is observed by photoluminescence spectrum. The magnetic behavior of it is investigated by a magnetic property measurement system. The blocking temperature is found to be about 200 K. In addition, the mechanism of the transformation from R-Fe 2 O 3 nanowires to γ-Fe 2 O 3 nanowires is preliminarily studied by ab initio approach. It is found that the role of H 2 is to change the Fe-O bonds in R-Fe 2 O 3 nanowires, and then R-Fe 2 O 3 is transformed into γ-Fe 2 O 3 .

Recyclable magnetic graphene oxide for rapid and efficient demulsification of crude oil-in-water emulsion

“…2(d)). In particular, the Fe2p 3/2 binding energy peak appears at 710.7 eV, which is close to the characteristic peak of the electronic structure of Fe 3+ in c-Fe 2 O 3 [27]. Based on the results of XRD and XPS, it can be concluded that the prepared magnetic ferrite was c-Fe 2 O 3 .…”

Activation of Ultrathin Films of Hematite for Photoelectrochemical Water Splitting via H2 Treatment

“…[21,41,[44][45][46] Of note is the identical onset of the Fe 2p 3/2 peaks for both samples A and B, which indicates an unlikely change in the crystal phase after H 2 treatment (i.e., no Fe 3 O 4 and no Fe 0 for- mation). We note that although the photoemission spectrum for maghemite (g-Fe 2 O 3 ) is practically indistinguishable from that of hematite, [41,46,47] and although there is one known example of conversion of hematite into maghemite by using H 2 at moderate temperatures, [48] maghemite is known to be photoelectrochemically inactive [49] and was not observed in the Raman spectra for either of the two samples (see Figure S9), nor in the PXRD patterns for thicker hematite films (see Figure S7). However, we cannot deny the possibility of formation of tetrahedral defect Fe 3 + sites following hydrogen treatment.…”

Tuning the Morphology of Metal Oxides for Catalytic Applications

“…228 234 Using such an approach, ␥ -Fe 2 O 3 nanorings, 159 dendritic particles, 235 and nanowires 236 were obtained from their ␣-type counterparts (Figure 10.18). In addition, slow oxidation of Fe films produced ␥ -Fe 2 O 3 nanofilms (∼50 nm in thickness).…”