α-Fe2O3 Nanoplates Research Articles

Deciphering the facet-dependent scavenging potential of α-Fe2O3 nanocrystals for U(VI) and Eu(III) from aqueous phase

The utilization of biocompatible and inexpensive adsorbents for the effective scavenging of U(VI) and Eu(III) from wastewater is still an open challenge in nuclear waste management. Herein, three kinds of α-Fe2O3 nanocrystals with different morphologies, i.e., α-Fe2O3 nanospheres (HNSs), nanoplates (HNPs) and nanorods (HNRs), which were exposed (102), (001), and (110) facet, respectively, was used to scavenge U(VI) and Eu(III) from aqueous solutions via an adsorption procedure. Various techniques of N2 adsorption–desorption, FT-IR, XRD, XPS, TEM, SEM and EDS were applied to characterize these adsorbents before or after adsorption. The results indicated that the adsorption capacity of U(VI) and Eu(III) was in the order of HNPs (001) > HNRs (110) > HNSs (102), namely, α-Fe2O3 nanoplates was proved to be a good adsorbents, with removal capacity of 221 mg/g and 131 mg/g for U(VI) and Eu(III) scavenged on HNPs, respectively. The kinetics of U(VI) and Eu(III) scavenging agreed with the pseudo second order kinetic model, suggesting that chemical interaction is mainly responsible for U(VI) and Eu(III) scavenging on these materials. Furthermore, the Freundlich model fit the best for adsorption isotherms of U(VI) and Eu(III). The present study demonstrated that these α-Fe2O3 nanocrystals are promising materials in nuclear waste management.

Synthesis and characterization of α-Fe2O3 nanoplates/aluminum fumarate metal-organic framework nanosheets as a nanocarrier for anticancer drug

α-Fe2O3 nanoplates/Aluminum Fumarate metal-organic framework (α-Fe2O3/AlFu) nanocarriers were successfully synthesized through a facile hydrothermal method and used as a drug delivery system (DDS). 5-Fluorouracil (5-Fu) as an anticancer drug was incorporated into the nanocarriers through plunging in the drug solution (5-Fu/α-Fe2O3/AlFu). The developed nanocarriers, including AlFu, α-Fe2O3/AlFu, and 5-Fu/α-Fe2O3/AlFu, were well-characterized which confirmed their successful synthesis. The electron microscopy images indicated that the flower shape of AlFu MOF with an average diameter of 500 nm was decorated with the α-Fe2O3 nanoplates. The flower of AlFu was formed by some nanosheets with a diameter of 20 nm. The average diameter of the nanoplates of α-Fe2O3 was about 200 nm. The α-Fe2O3 nanoplates fell apart from the AlFu flower and were located on the nanosheets of AlFu. The nanocarriers with high surface areas were found to be proper support for loading the 5-Fu drug. The vibrating sample magnetometer (VSM) results revealed that 5-Fu/α-Fe2O3/AlFu nanocarriers retained superparamagnetic properties when embedded with α-Fe2O3 nanoplates. Results represent the better loading efficiency of the α-Fe2O3/AlFu nanocarriers (65 %) compared to its components. To demonstrate the efficiency of 5-Fu/α-Fe2O3/AlFu as novel nanocarriers for controlled release of 5-Fu, in-vitro drug delivery tests were carried out in a simulated normal (pH = 7.4 and T = 37.4 °C) and tumor (pH = 5 and T = 42 °C) tissues’ environment. It was shown that low drug release (59.8 %) occurred at neutral pH and that more than 88.8 % of the loaded drug was released at the condition of cancer cells. Temperature and pH stimulate 5-Fu release from nanocarriers. Under cancer cells conditions, the release kinetic follows the Weibull distribution model, while in normal cells conditions, the Korsmeyer-Peppas model is used. Notably, the MTT test established that the α-Fe2O3/AlFu nanocarriers have no toxicity against BT-20 breast cancer cells.

Influence of α-Fe2O3, CuO and GO 2D nano-fillers on the structure, physical properties and antifungal activity of Na-CMC–PAAm blend

The present work aims to improve the uses of the carboxymethyl cellulose–polyacrylamide (Na-CMC–PAAm) blend for energy storage, optoelectronic applications, biological control, and plant disease management. Nano-sized materials (α-Fe2O3 nanoplates (NP), CuO NP, and GO nanosheets (NS), were synthesized and incorporated into the blend. The phase purity and morphologies of the used fillers were studied by XRD and HR-TEM. The interactions and complexation between the nano-fillers and the blend chains were investigated using XRD and FTIR spectra. The chemical composition and surface morphology of the nanocomposites were studied using EDS and FE-SEM analysis. UV-vis-NIR spectra revealed that the blend shows about 95% transmittance, reduced by 10–30% after doping. The absorption and refractive indices, as well as the optical gaps of the blend, were greatly affected by the doping. The dielectric constant and loss depend on the type of filler and the applied frequency. The maximum ac conductivity of the blend at 303 K and 4.0 MHz is 21.5 × 10–4 S/m and increased to 23.5 × 10–4 S/m after doping with CuO NP. The thermal stability, activation energy, stress–strain curves, and tensile strength are dependent on the filler type. All nanocomposite solutions except the blend exhibited a wide range of antifungal properties against pre- and post-harvest phytopathogenic fungi. Aspergillus niger among the examined fungi showed high sensitivity to the tested nanocomposite solutions. Furthermore, the CuO/blend nanocomposite had the highest antifungal activity against all tested fungi. Based on that, we suggest the use of CuO/blend and GO/blend nanocomposites to control and combat pre- and post-harvest fungal plant diseases.

Excellent organic dye adsorption capacity and recyclability of hydrothermally synthesized α-Fe2O3 nanoplates and nanorices

α-Fe2O3 and Fe3O4 nanoplates and nanorices were synthesized by hydrothermal reaction and used for organic pollutant adsorption and removal studies. The effect of size and morphology of α-Fe2O3 and Fe3O4 nanoplates and nanorices on the dye adsorption efficiency were investigated systematically. The adsorption studies showed a good selectivity and high adsorption capacity (~93%) of the α-Fe2O3 nanoplates towards congo red (C.R.) dye, due to the formation of hydrogen bonding between amine group (─ NH2) of C.R. and surface carboxylate group (─ COOH), and adsorbed ─ OH groups of α-Fe2O3 nanoplates. The α-Fe2O3 nanoplates also showed excellent recyclability with negligible loss of the adsorption capacity, owing to their stable morphology and crystal structure. The excellent C.R. adsorption capacity of the α-Fe2O3 nanoplates was further confirmed by conducting experiments with a solution containing a mixture of dyes. Our findings indicate that the synthesized α-Fe2O3 nanoplates have a great potential in removing industrial waste, such as C.R. from polluted water.

Z-Scheme 2D/2D α-Fe2O3/g-C3N4 heterojunction for photocatalytic oxidation of nitric oxide

Heterojunctions have attracted considerable attention for efficiently utilizing solar energy and improving conversion efficiency during pollutant degradation. Herein, carbon nitride and hematite (α-Fe2O3) are used to prepare a Z-scheme 2D/2D α-Fe2O3/g-C3N4 heterojunction using an impregnation-hydrothermal method. The unique 2D/2D structure has a high interfacial area and widely-dispersed active sites. The energy band structure of the Z-scheme heterojunction leads to broad visible-light absorption and promotes charge transfer. Optimizing the content of the α-Fe2O3 precursor in composite leads to a maximum efficiency of 60.8% for the removal of 600 ppb of NO, which is approximately 1.78 times that of g-C3N4 (34.2%). The photocatalytic performance is greatly promoted because of the formation of the heterojunction and the strong interfacial action between g-C3N4 nanosheets and α-Fe2O3 nanoplates. Cycling experiments verify that the α-Fe2O3/g-C3N4 heterojunction has good stability and reusability. The α-Fe2O3/g-C3N4 heterojunction therefore has great potential in sustainable and efficient pollutant degradation.

Magnetic field induced uniaxial alignment of the lyotropic liquid-crystalline PMMA-grafted Fe3O4 nanoplates with controllable interparticle interaction.

Magnetite (Fe3O4) nanoplates with a hexagonal platelet shape were synthesized by two steps: hydrothermal synthesis of iron(iii) oxide (α-Fe2O3) nanoplates followed by wet chemical reduction of the α-Fe2O3 nanoplates. Then, poly(methyl methacrylate) (PMMA) chains were grafted onto the surface of the hexagonal Fe3O4 nanoplates (F) via surface-initiated atom transfer radical polymerization (SI-ATRP), which ensures dispersion stability in organic solvents and ionic liquids. After mixing with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim+][NTf2−]), a representative ionic liquid, the resulting PMMA-modified F were found to show good lyotropic liquid-crystalline (LC) behaviour in [Emim+][NTf2−] and to exhibit a fast response to the application of an external magnetic field. Ultrasmall-angle synchrotron X-ray scattering (USAXS) measurements verified that the PMMA chain length, the weight ratio of the ionic liquid and the external magnetic field could significantly influence the interparticle distance (ID) of the PMMA-modified F in [Emim+][NTf2−]. In particular, the lyotropic LC phase could be assigned as a nematic phase with a columnar alignment. In addition, the PMMA-modified F maintained a uniaxially aligned nematic columnar structure along the magnetic field direction. Our study also determined the mechanism for the special alignment of the PMMA-modified F under an external magnetic field by analysing the growth axis, the easy magnetic axes, and the interparticle distance of F. The results suggested that the special alignment of the PMMA-modified F was affected by the interparticle interaction caused by the PMMA long chains on F under the magnetic field. Furthermore, the present study revealed that PMMA-modified F exhibited a new magnetic field responsive behaviour that led not only to the formation of a uniaxial alignment structure but also to control of ID with the help of the PMMA soft corona under the application of a magnetic field. These features could prove to be a promising advance towards novel applications of magnetic nanoparticles (NPs), such as functional magnetic fluids, rewritable magnetic switching devices, and smart magneto-electrochemical nanosensors.

Activating Hematite Nanoplates via Partial Reduction for Electrocatalytic Oxygen Reduction Reaction

For redox-active hematite (α-Fe2O3) materials, the adverse electroconductivity deeply obstructs the electrocatalytic activity. Herein, a series of iron oxides including α-Fe2O3 nanoplates, α-Fe2O3/Fe3O4 composites, and Fe3O4 material was prepared via a controllable reduction treatment on α-Fe2O3 precursor. When these iron oxides were characterized as electrocatalysts for oxygen reduction reaction (ORR), it was found that α-Fe2O3 nanoplates could be effectively activated via the reduction treatment. In particular, as the combined merits of composition optimization and electroconductivity improvement, the as-reduced composite consisting of α-Fe2O3 (49.6%) and Fe3O4 (50.4%) achieved the best activity of reaching the current density of 4.90 mA cm–2 at the potential of 0.4 V versus reversible hydrogen electrode (RHE) accompanied by a Tafel slope of 76 mV dec–1 and a high selectivity for four-electron pathway, surpassing single-phase α-Fe2O3 and Fe3O4, as well as other congeneric iron oxide composites. This hig...

One-Step Solvothermal Formation of Pt Nanoparticles Decorated Pt2+-Doped α-Fe2O3 Nanoplates with Enhanced Photocatalytic O2 Evolution

The photooxidation of water into O2 has been identified as the barrier of water-splitting, and light-driven water oxidation catalysts have been intensively explored to develop highly active water splitting materials. Despite the fascinating advantages for photocatalytic water oxidation, such as abundance in nature, inexpensiveness, low toxicity, thermo/photostability, and suitable electronic band structures, hematite α-Fe2O3 is a poor photocatalyst for water oxidation due to its short exciton lifetime and hole diffusion length, weak carrier mobility, and shallow sunlight penetration depth. In this work, we have synthesized Pt nanoparticles decorated Pt2+-doped α-Fe2O3 nanoplates (Pt/Pt-Fe2O3 NPs) by a one-step solvothermal route which exhibit the enhanced photoactivity and photostability for water oxidation. The introduction of the Pt into the α-Fe2O3 by the means of elemental doping and nanoparticle decoration accounts for the enhanced performance. The doping of Pt2+ into α-Fe2O3 improves the isolation e...

Hydrothermal synthesis of graphene-encapsulated 2D circular nanoplates of α-Fe2O3 towards enhanced electrochemical performance for supercapacitor

Transition metal oxides especially Fe2O3 has been widely considered as a potential electrode material for current commercial supercapacitors. However, the low electronic conductivity limits the obtained specific capacitance and cycle stability of supercapacitor devices. In the present work, 2D nano-circular-like α-Fe2O3 coupled reduced graphene oxide (rGO) composites have been synthesized for the first time via a simple, inexpensive hydrothermal process. Moreover, circular α-Fe2O3 nanoplates are well-dispersed on rGO layers, which can offer abundant active sites and effectively buffer the reunion of α-Fe2O3 nanocomposites during the electrochemical reactions. At an optimal ratio of 10 wt% GO, the as-prepared sample exhibits electrochemical performance with excellent specific capacitance of 621.3 F g−1 at 5 mV−1 and 533 F g−1 at 1 A g−1, which is better than that of pure α-Fe2O3. Most attractively, the specific capacitance is highly retained about 77% after 14000 cycles, revealing superior cycle ability.

α-Fe2O3 nanoplates with superior electrochemical performance for lithium-ion batteries

On account of the high theoretical capacity, high corrosion resistance, environmental benignity, abundant availability and low cost, the research on α-Fe2O3 has been gradually fastened on as promising anodes materials toward lithium-ion batteries (LIBs). A high-performance anode for LIBs based on α-Fe2O3 nanoplates have been selectively prepared. The α-Fe2O3 nanoplates can be synthesized with iron ion-based ionic liquid as iron source and template. The α-Fe2O3 nanoplates as the anode of LIBs can display high capacity of around 1950 mAh g−1 at 0.5 A g−1 which have exceeded the theoretical capacity of α-Fe2O3. On account of unique nanoplate structures and gum arabic as binder, the α-Fe2O3 nanoplates also exhibit high rate capability and excellent cycling performance.

Decoration of α-Fe₂O₃ on Graphene for Photocatalytic and Supercapacitive Properties.

The α-Fe2O3/graphene composites were obtained by solvothermal method, graphene oxide (GO) nanosheets were served as supporting materials for anchoring the α-Fe2O3, GO was reduced during this process. The morphology and structure of composites were characterized by X-ray powder diffraction, Scanning electron microscope and Transmission electron microscopy. Compared with the bare α-Fe2O3 nanoplates, the morphology of α-Fe2O3 decorated in graphene partly changed from nanoplates to truncate octahedral. Because of the synergistic effect of graphene and α-Fe2O3, the α-Fe2O3/graphene composites exhibited improved photocatalytic performance, significantly better than that of the bare α-Fe2O3 nanoplates. The specific capacitance of α-Fe2O3/graphene was about 2.9 times as high as that of the α-Fe2O3 nanoplates at a current density of 0.5 A/g. The α-Fe2O3/graphene composites also showed magnetic properties, which indicated the composites can be used in various fields.

Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity

Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase α-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10–20nm thickness, 80–100nm landscape dimensions (aspect ratio ∼5) and 3–4nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core–shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity HC=2340Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles’ for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications.

Self-assembling Ni(OH)2/α-Fe2O3 composites for pseudocapacitors with excellent electrochemical performance

Novel two-dimensional (2D) nanostructured Ni(OH)2 nanosheet/α-Fe2O3 nanoplate composites (NFCs) were successfully synthesized by a simple two-step solvothermal method where the proportion of α-Fe2O3 nanoplates was found to be controllable. These composites achieved excellent performance in aqueous electrolyte due to the synergistic effect between Ni(OH)2 nanosheets and α-Fe2O3 nanoplates, such as high specific capacitance and long-term cycle stability. The obtained NFC8 possessed a maximum mass specific capacitance of 1745.33F g−1 at a current density of 2 A g−1, and with 84.28% retention after 3000 cycles galvanostatic charge/discharge at a high current density of 20 A g−1. The above results show that these novel 2D nanostructured Ni(OH)2/α-Fe2O3 composites are promising electrode materials for pseudocapacitors.

Manganese-doped hematite nanoplates with enhanced and non-enzymatic electrochemical sensing performance

ABSTRACTMn-doped α-Fe2O3 (α-Fe2-xMnxO3) nanoplates were synthesized by facile hydrolysis method. The structure and morphology of the samples were characterized by various techniques. The nanoplates were used to modify glassy carbon electrode (GCE), which was used to detect uric acid by cyclic voltammetry and chronoamperometry. Compared with bare and α-Fe2O3/GCE, α-Fe2-xMnxO3/GCE showed higher oxidation peak current, with a shift in oxidation potential. Improvement in electrochemical detecting performance is mainly attributed to manganese addition. α-Fe1.6Mn0.4O3/GCE exhibits an excellent activity, good sensitivity, stability, repeatability and reproducibility.

A controlled solvethermal approach to synthesize nanocrystalline iron oxide for congo red adsorptive removal from aqueous solutions

Nanocrystalline Fe3O4 xerogel with tunable sizes and α-Fe2O3 nanoplates have been successfully synthesized through a facile sol–gel method combined solvothermal process under alcohol solvents or water medium without any surfactants. The influence of organic solvent type on the structural properties of Fe3O4 xerogel is discussed. The hydroxyl groups and polarity of alcohols make a crucial role in tuning the size of the Fe3O4 xerogels. Herein, larger specific surface area was obtained in Fe3O4 xerogel (93.6 m2 g−1) and α-Fe2O3 nanoplates (26.9 m2 g−1) compared with common iron oxides. The adsorption performances of Fe3O4 xerogel and α-Fe2O3 nanoplates are examined as adsorbents in congo red (CR) removal and the adsorption experiments were performed based on various parameters, such as initial CR concentrations, solution pH, and contact time. The Langmuir, Freundlich isotherm models were employed to discuss the adsorption behavior. The results indicated that the equilibrium data were perfectly represented by the Langmuir isotherm. The maximum adsorption capacity reached 244.50 and 251.89 mg g−1. Pseudo-first-order and pseudo-second-order models were employed to analyze the kinetics data and the adsorption behavior can be better described by pseudo-second-order model. Furthermore, adsorbents of Fe3O4 xerogel possess excellent recycle ability which can be effectively and rapidly extracted from water through its magnetic property. These Fe3O4 xerogel and α-Fe2O3 nanocrystals have the potential to be promising low-cost and efficient candidates for future water treatment.

One-step solvothermal synthesis of quasi-hexagonal Fe2O3 nanoplates/graphene composite as high performance electrode material for supercapacitor

This article describes a facile one-pot solvothermal method to prepare Fe2O3/graphene composite as high performance electrode material for supercapacitor. The morphology and structure of the samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra and nitrogen isothermal adsorption-desorption. The results reveal that the efficient loading of quasi-hexagonal α-Fe2O3 nanoplates and the reduction of graphene oxide were simultaneously realized. The electrochemical measurement demonstrates that Fe2O3/rGO composite shows a specific capacitance as high as 1083Fg−1 at a discharge current density of 2Ag−1. Even at the current density of 10Ag−1, the specific capacitance is still as high as 517Fg−1. After 1000 cycles, the capacity retention is still maintained at 75%. The electrochemical performances of the composites are superior to the pure samples owing to the synergistic effect of Fe2O3 and rGO.

Hollow α-Fe2O3core–shell colloidosomes: facile one-pot synthesis and high lithium anodic performances

Colloidosomes are three dimensional superstructures composed of building blocks with various morphologies and would have great application potentials in many fields. However, complicated synthesis procedures have restricted their extensive applications. In this work, we reported a facile one-pot synthesis approach to fabricate hollow core–shell α-Fe2O3 colloidosomes via a solvothermal method. The colloidosomes have an average diameter of 3 μm and both the core and the shell of the α-Fe2O3 colloidosomes are assembled by α-Fe2O3 nanoplates, which are composed of α-Fe2O3 nanoparticles. When evaluated as a lithium-ion battery anode, these core–shell α-Fe2O3 colloidosomes exhibited high reversible discharge and charge capacities and stable cyclability.

One-pot synthesis of α-Fe2O3 nanoplates-reduced graphene oxide composites for supercapacitor application

In the present work, two-dimensional α-Fe2O3/rGO nanocomposites were fabricated by one-pot solvothermal approach. Structural and morphological studies showed that the as-prepared α-Fe2O3/rGO nanocomposites were actually composed of α-Fe2O3 nanoplates encapsulated in rGO nanosheets to form two-dimensional nanostructure. As an electrode material for supercapacitor, the specific capacitances of α-Fe2O3/rGO nanocomposites was 903Fg−1 at the current density of 1Ag−1, which is superior to that of bare α-Fe2O3 nanoplates. The α-Fe2O3/rGO nanocomposites with high electrical conductivity and nanostructure allows for effective ion and charge transport in the whole electrode. The results enable the α-Fe2O3/rGO nanocomposites to be promising materials for high performance energy-storage systems.

Hematite nanoplates: Controllable synthesis, gas sensing, photocatalytic and magnetic properties

Uniform hematite (α-Fe2O3) nanoplates exposing {001} plane as basal planes have been prepared by a facile solvothermal method under the assistance of sodium acetate. The morphological evolution of the nanoplates was studied by adjusting the reaction parameters including the solvent and the amount of sodium acetate. The results indicated that both the adequate nucleation/growth rate and selective adsorption of alcohol molecules and acetate anions contribute to the formation of the plate-like morphology. In addition, the size of the nanoplates can be adjusted from ca. 180nm to 740nm by changing the reaction parameters. Three nanoplate samples with different size were selected to investigate the gas sensing performance, photocatalytic and magnetic properties. As gas sensing materials, all the α-Fe2O3 nanoplates exhibited high gas sensitivity and stability toward n-butanol. When applied as photocatalyst, the α-Fe2O3 nanoplates show high photodegradation efficiency towards RhB. Both the gas sensing performance and the photocatalytic property of the products exhibit obvious size-dependent effect. Magnetic measurements reveal that the plate-like α-Fe2O3 particles possess good room temperature magnetic properties.

Effects of morphology and exposed facets of α-Fe2O3 nanocrystals on photocatalytic water oxidation

The catalytic activity of α-Fe2O3 nanocubes, nanoplates, nanoflakes and nanoparticles for visible light-driven water oxidation is strongly morphology-dependent; α-Fe2O3 nanocubes with exposed {012} facets exhibit far higher activity than nanosheets with exposed {001} facets.