In situ synthesis of hematite nanoparticles using a low-temperature microemulsion method
Graphical Abstract
A novel microemulsion method is described for the in situ synthesis of α-Fe2O3 nanoparticles with ferrihydrite as a precursor and trace Fe (II) as a catalyst which does not require any calcination step. The nanoparticles were characterized by X-ray diffractometer (XRD) and transmission electron microscopy (TEM). It was found that the size of α-Fe2O3 nanoparticles was influenced by ω (ω = nH2O / nCTAB) and weight ratio of CTAB to n-octane.
Introduction
Hematite (α-Fe2O3), which is the most stable iron oxide under ambient conditions, has attracted an increasing interest in the fields of nanoscience and nanotechnology because of its potential applications in pigments [1], gas sensors [2], field effect transistor [3], photoelectrolysis reactors [4], [5], contrast reagents/drug delivery [6], magnetic storages [7], photoanode for possible photo-electrochemical cell [8], catalysts [9], and so on. It is well known that the morphology and size of α-Fe2O3 have a great impact on their chemical and physical properties [10]. In order to control particle sizes and obtain narrow distributed and monodispersed nanoparticles, various strategies have been employed [11]. Microemulsions have been widely used since they can provide controllable “micro-reactors” (surfactant-covered water pools) that limit particle growth and agglomeration and render particle sizes in the nm scale [12]. As a result, the particles obtained in microemulsion systems are generally very fine and monodispersed. For example, Bumajdad's group has achieved successfully α-Fe2O3 nanoparticles by a microemulsion method [13]. However, microemulsion method usually involves synthesizing a precursor gel of iron, followed by further high-temperature calcinations to form the oxide with crystallinity.
In this paper, a low-temperature microemulsion method has been employed to synthesize directly α-Fe2O3 nanoparticles with trace Fe (II) as a catalyst. This procedure is different from the reported methods of microemulsion in literatures without any requirement of calcination step at high temperature (e.g., 400 °C) [13]. Moreover, the novel method could maintain a great many of advantages, such as simple equipment, homogeneous grain size distribution, lower agglomeration etc.
Section snippets
Experimental
Analytical grade reagents (hexadecyl trimethyl ammonium bromide, n-octane, n-butanol, ferric chloride hexahydrate FeCl3·6H2O and sodium hydroxide NaOH) and distilled water were used in all experiments.
Hexadecyl trimethyl ammonium bromide, n-butanol and n-octane were used as surfactant, cosurfactant and oil phase, respectively. The surfactant, cosurfactant and oil phase with the weight ratio 1:0.8:2.83 were mixed and then a certain volume of mixture solution of FeCl2 and FeCl3 was added. The
The catalysis of Fe (II) on the transformation of ferrihydrite in microemulsion
Ferrihydrite prepared in microemulsion system at pH 7 was heated and refluxed for 10 h or 4.5 h in the absence or presence of trace amounts of Fe (II) ions. XRD patterns of the samples are shown in Fig. 1. It can be seen in Fig. 1 that ferrihydrite has transformed into α-Fe2O3 in the presence of trace amounts of Fe (II) ions (Fig. 1b), while no detectable change is found when ferrihydrite is heated and refluxed for 10 h in the absence of trace amounts of Fe(II) ions(Fig. 1a). All the peaks in
Conclusion
Nanosized hematite particles can be directly synthesized by a simple microemulsion method without any requirement of calcination step at high temperature. The size of hematite particles can be controlled by regulating ω value or the weight ratio of surfactant to n-octane. The particle size increases with the increase of ω value, and increasing the weight ratio of surfactant to n-octane is beneficial to prepare smaller α-Fe2O3 nanoparticles.
Acknowledgments
This work was supported by a grant from the Natural Science Foundation of Hebei Province (E2006000167).
References (22)
- et al.
Impact of structural features on pigment properties of α-Fe2O3 haematite
J. Solid State Chem.
(2008) - et al.
Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications
Biomaterials
(2005) - et al.
Synthesis and magnetic properties of the γ-Fe2O3/poly-(methyl methacrylate)-core/shell nanoparticles
Solid State Sci.
(2004) - et al.
Kinetic modeling of the oxidation of CO on Fe2O3 catalyst in excess of O2
J. Catal.
(2008) - et al.
Generation of metal oxide nanoparticles in optimized microemulsions
J. Colloid Interface Sci.
(2007) - et al.
The formation of hematite from ferrihydrite using Fe(II) as a catalyst
J. Mol. Catal. A: Chem.
(2005) - et al.
Physical and photo-electrochemical characterizations of α-Fe2O3. Application for hydrogen production
Int. J. Hydrogen Energy
(2009) - et al.
Synthesis of nanosilver colloidal particles in water/oil microemulsion
Colloids Surf., A
(2007) - et al.
Synthesis of CeF3 nanoparticles from water-in-oil microemulsions
Powder Technol.
(2000) - et al.
Synthesis of CuS nanocrystal in cationic gemini surfactant W/O microemulsion
Mater. Des.
(2010)
Synthesis of silver nanoparticles — effects of concerned parameters in water/oil microemulsion
Mater. Sci. Eng. B
Cited by (49)
Synthesis and effect on the surface morphology & magnetic properties of ferrimagnetic nanoparticles by different wet chemical synthesis methods
2022, Powder TechnologyCitation Excerpt :As a result, researchers concentrate on synthesizing FMNPs utilizing various synthesis approaches to regulate their size, shape, and morphology with tunable features. The several synthesis routes for FMNP synthesis includes (Table 2) chemical co-precipitation [25], sol-gel [26], hydrothermal [27], sonochemical methods [28], thermal decomposition [29], microemulsion [30], electrochemical deposition [31], laser pyrolysis [32], solvothermal methods [33], thermal pyrolysis [34], chemical vapor deposition [35], microwave-assisted method [36], and aerosol pyrolysis [37]. Table 1 enlists the benefits and drawbacks of various approaches, with the pros being stated first.
Physicochemical study of the sustainable preparation of nano-Fe<inf>2</inf>O<inf>3</inf> from ferrous sulfate with coke
2020, Journal of Cleaner ProductionCitation Excerpt :Based on the valence state of Fe, the preparations of α-Fe2O3 can be divided into two types. One is the oxidation from Fe(II) to Fe(III) with oxidants and precipitants (Liu et al., 2005), which includes chemical precipitation (Sivakumar et al., 2014) and solid-state reaction (Li et al., 2014); the other is the direct preparation of α-Fe2O3 from Fe (III) under various experimental conditions (Han et al., 2011), which includes the hydrothermal method (Xu et al., 2015), sol-gel method (Kopanja et al., 2016), and pyrolytic process (Chen et al.,2010). The characteristics of the methods are shown in Table 1.
Optical and dielectric properties of anodic iron oxide films
2020, Applied Surface ScienceGreen synthesis of inorganic nanoparticles using microemulsion methods
2020, Green Sustainable Process for Chemical and Environmental Engineering and Science: Green Inorganic SynthesisGamma irradiation and microemulsion assisted synthesis of monodisperse flower-like platinum-gold nanoparticles/reduced graphene oxide nanocomposites for ultrasensitive detection of carcinoembryonic antigen
2019, Sensors and Actuators, B: ChemicalCitation Excerpt :The water droplets provide a sufficient micro environment during the preparation of monodispersed metal nanoparticles and the formation size of mentioned nanoparticles are adjusted by the size of the water droplets in the microemulsion. The central advantages of adding microemulsions during the preparation process contrasted with other methods are the regulation of the size and morphology of the nanoparticles and the prevention of agglomeration of the nanoparticles. [33–36]. Hence, we designed the microemulsion assisted gamma irradiation to prepare rGO-PtAu nanocomposites in which flower-like PtAu NPs were supported on the surface of rGO.