Size Of Fe2O3 Particles Research Articles

The effects of raw materials particle sizes on the solid-state reaction progress, morphology and magnetic properties of M-type strontium hexaferrites

In this work, the effects of SrCO3 and Fe2O3 particle size on the reaction process, morphology and magnetic properties of M-type strontium hexaferrites (SrM) have been further studied. Pure strontium hexaferrite magnetic sample based on SrCO3 and Fe2O3 molar ratio of 1:6 has been successfully prepared at 1150 °C. The results indicated that Fe2O3 particle size was the main factor of affecting the formation of SrM, a pure SrM phase magnetic sample was able to obtain at lower calcination temperatures by using fine Fe2O3 powder as raw material, and at the same calcination temperature, a sample using fine Fe2O3 powder as raw material was able to obtain pure SrM phase magnetic sample with shorter holding time. When the mean particle size of Fe2O3 was below 60 nm, a pure SrM phase magnetic sample was able to form at 1150 °C at a molar ratio of 1:6 of SrCO3 and Fe2O3. In this case, the magnetic parameters of the sample with the optimum magnetic parameters were saturation magnetization MS = 77.8 emu/g and coercive force HC = 4122 Oe. And the solid-state reaction process of the corresponding samples was slightly faster when the mean particle size ratio of Fe2O3 and SrCO3 was between 0.35 and 0.36. Assuming that a SrCO3 particle is surrounded by Fe2O3 particles, it can be inferred that the corresponding molar ratio of Fe and Sr of the nearest raw material particles is between 3.6 and 3.8.

Monitoring of the Fe2O3 Particle Size Distribution by Intensity in the Context of Digital Company

This research studies monitoring of Fe2O3 iron particle size produced in industrial companies on the premises of a hot rolling mill. The analysis used the distribution curve method - particle size distribution by intensity. This method determined which particles occur most often in the sample, what is the average particle size, smallest and largest particles. Digitization of individual procedures and monitoring of technological processes provides data that can be worked with at a given time.The obtained data represent a source of information for their further processing in the field of maintenance prediction.

Magnetic-Induced Swing Adsorption over Iron Oxide/13X: Effects of Particle Size and Oxide Phase on Sorbent Regeneration in Ethylene/Ethane Separation

Magnetic induction has emerged as a viable method for regeneration of sorbents during separation processes. In this work, we investigated the efficacy of magnetic sorbents comprising iron oxide and zeolite 13X in ethylene/ethane separation via a magnetic induction process. The electromagnetic properties of the sorbents were tuned by varying the iron oxide (Fe2O3) particle size (30 nm, 100 nm, 5 μm) and iron oxide phase structure (FeO, Fe2O3, Fe3O4) at 20 wt % loading. The effects of these parameters on adsorption capacity, selectivity, and desorption rates were systematically investigated. The microporosity and surface area of magnetic sorbents were reduced by increasing the particle size of Fe2O3 from 30 nm to 5 μm. The results indicated that regardless of iron oxide particle size or phase structure, the C2H4/C2H6 selectivity ranges between 2.44 and 2.65 for all the magnetic sorbents. The specific heat absorption rate (SAR) was increased by ∼60% upon increasing the magnetic field intensity from 21.4 to 31.4 mT when the particle size increased from 30 nm to 5 μm. Fe3O4 was found to outperform the other phases by exhibiting 91.3 and 93.3% higher SAR than Fe2O3 and FeO at 31.4 mT, respectively, owing to its unique lattice structure with dual ion states (Fe2+ and Fe3+). Fe3O4/13X exhibited an ethylene desorption rate of 0.41 mmol/g·min at 21.4 mT, which was 58.5% faster than that under conventional thermal heating. Additionally, the sorbent was found to be highly durable, maintaining its adsorption and desorption capabilities over five consecutive cycles in the magnetic induction swing adsorption (MISA) process, conducted at 25 °C and 1 bar during adsorption and at 31.4 mT during desorption. These results indicate the potential of Fe3O4/13X as an effective magnetic sorbent in the MISA process. This study builds on our previous proof-of-concept work on the potential of magnetic sorbents as stimuli-responsive materials for light olefin/paraffin separation.

Magnetic-Field Assisted Gas Desorption from Fe2O3/Zeolite 13X Sorbent Monoliths for Biogas Upgrading

Magnetic induction has emerged as an attractive method for regenerating adsorbents during separation processes. In this work, we investigated the applicability of magnetic composite sorbents comprising Fe2O3 and zeolite 13X in biogas upgrading via a magnetic induction process. The sorbent materials with 10, 15, and 20 wt % Fe2O3 content were formulated into monolithic contactors via additive manufacturing and their physiochemical and magnetic properties were assessed accordingly. The effects of Fe2O3 particle size, magnetic field intensity, and monolith composition and configuration on CO2 and CH4 desorption rates as well as heating and cooling rates were systematically investigated. Our results indicated that 5 μm-size Fe2O3 with a loading of 20 wt % in the composite is the best performing material exhibiting heating, cooling, and desorption rates of 6.56 °C/min, 3.84 °C/min, and 0.25 mmol CO2/g min, respectively. It was also found that the layer-by-layer printing approach outperforms the homogenously mixed method in formulating magnetic monoliths by exhibiting heating, cooling, and desorption rates of 7.78 °C/min, 4.89 °C/min, and 0.376 mmol CO2/g min, respectively. Lastly, the advantage of induction heating over traditional heating in quickly regenerating the adsorbent was demonstrated. This work highlights the suitability of the induction heating method in upgrading biogas as a renewable source of energy.

Nano-Fe/SiO2 catalysts prepared by facile colloidal deposition: Enhanced durability in Fischer-Tropsch synthesis

Nano-iron catalysts exhibit good performances in the Fischer–Tropsch synthesis to lower olefins (FTO), however, there is still a lack of simple methods for their preparation. In this work, we introduced a facile colloidal deposition (CD) method to fabricate silica-supported Fe2O3 nanoparticles using a colloidal solution readily prepared from ferric hydroxide. With increasing the Fe loading from 16.3 % to 31.6 %, the Fe2O3 particle size increased from 1.3 to 6.1 nm. The catalytic performances in FTO were tested at a H2/CO molar ratio of 1. At a Fe loading of 30.4 %, the catalyst having a particle size of 4.7 nm showed the highest lower olefin selectivity and the lowest CO2 selectivity, outperforming analogs prepared by impregnation method. Furthermore, this catalyst showed good stability in a 200-hour durability test, while the impregnated analogue quickly deactivated due to serious coking. Presumably, the effective contact areas between the nanoparticles and the generated carbon sheets are geometrically small, which results in weak van der Waals forces between them, preventing the former from being heavily covered by the latter. Besides, from the point of view of the carbide decomposition mechanism of coking, due to the relatively low volume to surface area ratios of the intermediate carbide nanoparticles, the surface concentrations of carbon atoms released from them are low, which delays the coke formation. This study may provide a simple method to fabricate supported nano-iron catalysts, and cast some light on understanding catalyst durability in FTO.

The impact of nanometric Fe2O3 on the magnetic, electronic, and photocatalytic behavior of TiO2@Fe2O3 heterostructures

The synthesis method we used enables the homogeneous deposition of both relatively large and small Fe2O3 nanoparticles on the surface of TiO2. SAED analysis shows that TiO2 NCs crystallize in anatase form and Fe2O3 as hematite in all cases. The formation of a TiO2@Fe2O3 heterostructure leads to an increase in photocatalytic activity (in the presence of H2O2) compared to pure titanium and iron oxides. Mössbauer spectra confirm the existence of the hematite structure of Fe2O3 and, together with XPS, the presence of Fe3+ only. Fe2O3 nanoparticles on the surface of TiO2 nanocrystals are in the paramagnetic/superparamagnetic state. Magnetization curves under ZFC and FC conditions also indicate the effect of the size of Fe2O3 particles on the magnetic properties of TiO2@Fe2O3 nanostructures. The magnetic properties of the TiO2@Fe2O3 heterostructure exhibit sensitivity to the size of nanometric Fe2O3 grains. The energies of optical transitions in nanometric Fe2O3 reveal the occurrence of a quantum-size effect. The heterostructures forms a complex structure; on the one hand, at the TiO2 acceptor level associated with the incorporation of Fe3+ into the structure of TiO2 anatase there is present on the other hand, the microstructure differentiation responsible for the occurrence of three optical transitions in Fe2O3.

Enhancing the synergism of Fe3O4 and Fe5C2 to improve the process of CO2 hydrogenation to olefines

CO2 hydrogenation to olefines is a feasible carbon capture and utilization (CCU) route. The process includes sequential reactions of reverse water gas shift (RWGS) reaction and Fischer-Tropsch synthesis (FTS) reaction. The acceleration of FTS is crucial to improve the olefines yield. A microemulsion anti-solvent extraction (MAE) method was proposed to prepare Fe-based catalyst on the support of Al2O3. Ethanol solution of Fe(NO3)3 was encapsulated in microdroplets, and then loaded on Al2O3 by the extraction of ethanol from the microdroplets to isooctane phase. The average size of micro droplets was 7.5 nm. After calcination, the particle size of Fe2O3 was 6 nm. After carburization with CO, the interface formed between Fe3O4 and Fe5C2 was restricted in a narrow space with a mean size of 12 nm. Through TEM-Mapping, XRD, XPS and TPC characterization, the distribution uniformity of Fe and the neighboring degree of Fe3O4 and Fe5C2 on the as-prepared catalyst MAE-Fe1K1 was improved effectively. An enhanced synergistic effect between Fe3O4 and Fe5C2 was obtained. The catalytic performance evaluation results showed that yield of C2-C4 olefins reached 0.063 mmol·gFe−1·s−1 after 12 h of reaction. It exhibited better catalytic performance than most catalysts reported in the literatures. The results showed that the proposed microemulsion anti-solvent extraction strategy is an effective method to prepare Fe-based catalyst for CO2-FTO reaction with an excellent catalytic performance.

Chemical looping reforming of toluene via Fe2O3@SBA-15 based on controlling reaction microenvironments

Macromolecular volatiles are one of the important components of biomass pyrolysis products. Chemical looping reforming can efficiently convert macromolecular components into hydrogen-rich syngas. Oxygen carriers with good partial oxidation performance and excellent recycling performance are the key factor. In this work, the embeddedness strategy was proposed to regulate the micro-reaction environment of oxygen carriers and thus improve the recycling and partial oxidation performance. The characteristics of toluene chemical looping reforming via Fe2O3 embedded in SBA-15 (Fe2O3@SBA-15) were studied in fixed-bed reactor. The performances of Fe2O3 and Fe2O3@SBA-15 were compared. The effect of pure Fe2O3 particle size, Fe2O3 loading amount, and reaction temperature were investigated. Thermodynamic analysis results showed that the reaction could proceed spontaneously when the temperature was higher than 600℃. The experimental results showed that chemical looping reforming process could be divided into two stages, including partial oxidation and catalytic cracking. The main product in the first stage was syngas, while the main product in the latter stage was H2 and coke. The Fe2O3 particle size decreased from 5um to 30 nm, and the CO selectivity increased from 25.87% to 33.15%. This indicated that the nanocrystallization of Fe2O3 would improve the partial oxidation performance. Compared with pure Fe2O3, the CO selectivity of Fe2O3@SBA-15 rose from 25.9% to 96.2%. The utilization rate of lattice oxygen and the conversion rate of toluene increased significantly. At 900℃, toluene was nearly completely converted, and the utilization rate of lattice oxygen reached 92.7%. The toluene conversion increased with the elevation of Fe2O3 loading, and the CO selectivity always remained above 87.9%. With the elevation of reaction temperature from 700℃-900℃, toluene conversion increased from 30.5% to 95.6%, while CO selectivity decreased slightly. More importantly, the stability test results showed that after 10 cycles, toluene conversion rate only dropped by 1.9%, and the average concentration of gas products remained stable. The above results showed that the embeddedness of Fe2O3 in SBA-15 could effectively improve CO selectivity, enhance the transmission and release of lattice oxygen, and elevate the catalytic performance and cycle stability of oxygen carriers.

Protrudent electron transfer channels on kaolinite modified iron oxide QDs/N vacancy graphitic carbon nitride driving superior catalytic oxidation

Optimizing electron transfer channels and sufficiently exposing active sites to trigger an efficient Fenton-like reaction are vital for manipulating catalytic properties of water treatment. Herein, Fe2O3 quantum dots were prepared and integrated with composites of g-C3N4 and kaolinite with nitrogen (N) vacancies (FONGK-10) for bisphenol A (BPA) removal in a peroxymonosulfate (PMS)/visible light (Vis) system. X-ray absorption near-edge structures and extended X-ray absorption fine structures demonstrated interface’s combined properties. In particular, the tight interfacial contact and introduction of N vacancies resulted in the formation of effective electron channels, which caused more effective separation of electron–hole pairs and an extended response time of 1.5 × 10−4 s. Furthermore, the introduction of kaolinite reduced the Fe2O3 particle size and accelerated PMS consumption. The k value in FONGK-10/PMS/Vis system was 4.5 times that of the FONGK-10/PMS and 27.5 times that of the FONGK-10/Vis system, and the synergetic system exhibited superior consecutive catalytic performance in a fluidized-bed catalytic unit, degrading ~100% of BPA in 200 min. The exposed electron channels significantly maintained the Fe(III)/Fe(II) stable dynamic cycle, thereby enhancing the activation of PMS and photocatalysis performance.

α-Fe2O3 conversion anodes with improved Na-Storage properties by Sb addition

We evaluated the Na-storage properties of Fe2O3/Sb composite electrodes prepared using α-Fe2O3 with different particle sizes and Sb, and investigated the effect of Sb addition on their charge−discharge cycling performances as Na-ion battery anodes. With reducing the Fe2O3 particle size, the initial reversible capacity of the Fe2O3 electrode was increased, whereas the capacity decay became more pronounced. The 10 wt% addition of Sb could significantly improve the rapid capacity decay which was observed for the electrode of Fe2O3 with the smallest particle size. These results suggest that Sb improved the conductions of electron and Na ions in the electrode. The overpotential of desodiation reactions of Fe2O3 was obviously suppressed by the Sb addition. This result indicates that Sb maintained the electron percolation network between the sodiated Fe2O3 particles to improve the reversibility of Fe2O3 conversion reaction. Consequently, we could demonstrate that Sb has a remarkable effect of drawing out the potential anode performance of abundant and inexpensive Fe2O3.

Synthesis of Fe2O3 nanomaterials for a rechargeable battery anode

Iron electrode plays an important role in iron-air batteries. Mastering the fabrication technology of this electrode material is a key step in improving capacity, cycling efficiency, and lowering the cost of commercial batteries. The sol-gel method is known to be simple and easy to implement for producing nanomaterials. In this study, α-Fe2O3 nanoparticles with various shapes were synthesised by the sol-gel method for iron-air battery anodes. Electrochemical characteristic measurements performed on Fe2O3/AB electrodes using synthesised Fe2O3nanomaterials showed that the size and morphology of iron particles strongly affect their cycleability. Optimisation of the fabrication process to obtain the suitable Fe2O3 particle size and shape for the best electrochemical properties was performed. Additionally, the effect of the K2S additive in electrolyte solution on the electrochemical properties of the Fe2O3/AB electrode was also studied.

Hydrothermal Preparation of Fe2O3 Nanoparticles for Fe-Air Battery Anodes

Fe2O3 nanoparticles were synthesized from iron nitrate [Fe(NO3)3·9H2O] by hydrothermal method for Fe-air battery anodes. The crystal structure and morphology of the obtained Fe2O3 powder were studied by x-ray diffraction and scanning electron microscopy. Fe2O3/acetylene black (AB) composite electrodes were fabricated by mixing the synthesized Fe2O3 nanoparticles with AB carbon and were then subjected to electrochemical measurements. Results indicated that the duration of hydrothermal treatment significantly influences the morphology and size of synthesized Fe2O3. The morphology and particle size of Fe2O3 also affect the electrochemical properties of Fe2O3/AB composite electrodes, viz., smaller particles provide greater capacity than larger ones. The resistance of electrodes gradually increases during cycling, thereby causing a decrease in the capacity of Fe2O3/AB electrodes.

Experimental and kinetics study on SO3 catalytic formation by Fe2O3 in oxy-combustion

Sulfur trioxide (SO3) is corrosive and environmentally harmful. Under oxy-combustion mode, the formation of SO3 is aggravated due to flue gas recirculation, and should be more concerned than that under traditional air-combustion mode. In this paper, the catalytic formation of SO3 by iron oxide (Fe2O3) under oxy-combustion mode was experimentally studied in a fixed-bed reactor, and effects of temperature (300–900 °C), atmosphere, catalyst particle size, SO2, O2, and H2O concentrations were discussed. Results show that Fe2O3 promotes SO3 formation, and the yield of SO3 reaches a maximum at 700 °C under both air- and oxy-combustion modes. Increasing O2 concentration in a range of 5–20% promotes the catalytic formation of SO3, whose effect is restricted at a higher O2 concentration. Both increases of SO2 concentration in a range of 500–3000 ppm and steam concentration in a range of 0–20% decrease the SO3 yield. A significant effect of Fe2O3 particle size on SO3 catalytic formation is observed. When the particle size decreases from 50-75 μm to 10–25 μm, the inflection temperature shifts from 700 °C to 600 °C, while the maximum SO3 yield increases by 33%. Kinetics analysis results show that in this case, the catalytic conversion from SO2 to SO3 by Fe2O3 has an apparent activation energy Ea of 18.9 kJ/mol and a pre-exponential factor A of 5.2 × 10−5. At 700 °C and with Fe2O3 particle size of 50–75 μm, the global reaction orders of SO2 and O2 for SO3 formation are 0.71 and 0.13, respectively.

Rapid synthesis of Cr-doped γ-Fe2O3/reduced graphene oxide nanocomposites as high performance anode materials for lithium ion batteries

Cr-doped γ-Fe2O3/reduced graphene oxide (rGO) nanocomposites are successfully synthesized through a rapid and environmentally friendly microwave method in just 10 min. Under the microwave heating, graphene oxide (GO) is reduced to rGO with ferrous ion (Fe2+) served as the reductant, and Cr-doped γ-Fe2O3 nanoparticles are synthesized in the meantime. It is found that Cr doping can not only affect the phase of Fe2O3, but also has an effect on the morphology, the electrical conductivity and the electrochemical properties. As anode material for lithium ion batteries, the 4.0 at% Cr-doped γ-Fe2O3/rGO nanocomposites exhibit the highest reversible capacity of 1060 mAh g−1 after 100 cycles (66.9% of the initial capacity) at a current density of 100 mA g−1. Furthermore, when assembled as a full cell against commercial cathode including LiCoO2 and LiNi1/3Mn1/3Co1/3O2, the battery shows promising cycling performance. The superior electrochemical performance could be attributed to the uniform nanostructure and the synergistic effect between Fe2O3 and rGO as well as the doping of chromium, which can reduce the size of Fe2O3 particles and improve the electrical conductivity.

Comparative Studies of Mesoporous Fe2O3/Al2O3 and Fe2O3/SiO2 Fabricated by Temperature-Regulated Chemical Vapour Deposition as Catalysts for Acetaldehyde Oxidation

Temperature-regulated chemical vapour desorption was used for deposition of Fe2O3 nanoparticles on the surface of mesoporous Al2O3 and SiO2. The entire internal structure of mesoporous substrates, with a mean particle diameter of several hundred micrometres, was coated by Fe2O3 nanoparticles < 2–3 nm in lateral size. Although Fe2O3/Al2O3 had a smaller mean Fe2O3 particle size with superior dispersion of Fe2O3 nanoparticles, Fe2O3/SiO2 showed a higher CO2 evolution rate than Fe2O3/Al2O3. In combination with the results of acetaldehyde adsorption and desorption experiments, we suggest that acetaldehyde interacts more strongly with Al2O3 than SiO2. This can reduce the collision frequency of acetaldehyde with catalytically active Fe2O3 nanoparticles deposited on Al2O3, thereby reducing the total oxidation rate of acetaldehyde. We demonstrate that temperature regulated-chemical vapour deposition is a promising method for preparation of mesoporous substrate-based catalysts for efficient oxidation of volatile organic compounds with different mesoporous materials. Moreover, we show that interaction between supporting material surfaces and reactant molecules is a critical factor for determining activity in heterogeneous catalysis.

Two synthesis approaches of Fe-containing intercalated montmorillonites: Differences as acid catalysts for the synthesis of 1,5-benzodeazepine from 1,2-phenylenediamine and acetone

Two approaches were considered for the preparation of Fe-containing composites based on montmorillonite and comparison of their structural, physicochemical and catalytic properties. The first approach (Si,Fex-Mt materials) was based on the intercalation of Cheto montmorillonite (Mt) by 3-aminopropyltriethoxysilane (APTES) and FeCl3 via the sol-gel polymerization technique. Fe/Si atomic ratios were 6:94, 18:82 and 30:70. Then Si,Fex-Mt materials were calcined in air at 400 or 500°C for the APTES removal. The second approach (Al13−xFex-Mt materials, x=1 and 2) was based on the pillaring method using Keggin type mixed Al13−xFex-polycation (x=1, 2) and montmorillonite from Cheto, Arizona, USA (Mt) as starting material. The intercalated Al13−xFex-Mt materials were calcined at 400 or 500°C. The physicochemical characterization pointed out the effectiveness of the incorporation of Fe and Si into the interlayer space of the clay mineral. The fixation of small amounts of Fe (1.9wt%) increased the basal space from 9.57 to 13.89Å, but the further fixation of Fe content slightly decreased the basal space. The specific surface area increased from 80 up to 171m2/g. The oligomeric state of Fe2O3 particles depended on its content; the larger Fe content, the larger particle size of Fe2O3. Catalytic properties of Si,Fex-Mt and Al13−xFex-Mt materials were studied in the cyclocondensation of 1,2-phenylenediamine with acetone to 1,5-benzodiazepine. The yield of 1,5-benzodiazepine was found to rise with increasing of the Fe content in Si,Fex-Mt. Catalytic performance of Si,Fex-Mt was lower in comparison with Al13−xFex-Mt, that is in agreement with the amount of Lewis acid sites.

CO2 hydrogenation to hydrocarbons over alumina-supported iron catalyst: Effect of support pore size

The effect of support pore size of FeK/Al2O3 catalysts on the catalytic performance in CO2 hydrogenation reaction was investigated. A total of 8 iron-based catalysts supported on alumina with different pore size were prepared by incipient wetness impregnation where the amount of Fe and K were fixed at 15 and 10wt%, respectively. N2 adsorption/desorption, XRD, TPR and PZC were used to characterize the supports and catalysts. The results show that the support pore size impacts the size of Fe2O3 particles formed in the catalyst; increasing pore size of Al2O3 supports led to increased size of Fe2O3 particles formed in the pores. Catalyst pore sizes of 7–10nm and the corresponding Fe2O3 particle sizes of 5–8nm were the most active for CO2 hydrogenation to hydrocarbons. Outside this range, larger pore size further decrease the iron dispersion and reduce the number of active sites; smaller pore size is not favorable on account of the too small Fe2O3 particle sizes and lower reducibility of the small particle.

Radio frequency shielding behaviour of silane treated Fe2O3/E-glass fibre reinforced epoxy hybrid composite

In this work, radio frequency shielding behaviour of polymer (epoxy) matrixes composed of E-glass fibres and Fe2O3 fillers have been studied. The principal aim of this project is to prepare suitable shielding material for RFID application. When RFID unit is pasted on a metal plate without shielding material, the sensing distance is reduced, resulting in a less than useful RFID system. To improve RF shielding of epoxy, fibres and fillers were utilized. Magnetic behaviour of epoxy polymer composites was measured by hysteresis graphs (B-H) followed by radio frequency identifier setup. Fe2O3 particles of sizes 800, 200 and 100 nm and E-glass fibre woven mat of 600 g/m2 were used to make composites. Particle sizes of 800 nm and 200 nm were prepared by high-energy ball milling, whereas particles of 100 nm were prepared by sol–gel method. To enhance better dispersion of particles within the epoxy matrix, a surface modification process was carried out on fillers by an amino functional coupling agent called 3-Aminopropyltrimethoxysilane (APTMS). Crystalline and functional groups of siliconized Fe2O3 particles were characterized by XRD and FTIR spectroscopy analysis. Variable quantity of E-glass fibre (25, 35, and 45 vol%) was laid down along with 0.5 and 1.0 vol% of 800, 200, and 100 nm size Fe2O3 particles into the matrix, to fabricate the hybrid composites. Scanning electron microscopy and transmission electron microscopy images reveal the shape and size of Fe2O3 particles for different milling times and particle dispersion in the epoxy matrix. The maximum improved sensing distance of 45.2, 39.4 and 43.5 % was observed for low-, high-, and ultra-high radio frequency identifier setup along with shielding composite consist of epoxy, 1 vol% 200 nm Fe2O3 particles and 45 vol% of E-glass fibre.

Electrochemical properties of Fe2O3 microparticles and their application in Fe/air battery anodes

To identify an adequate material for Fe/air battery anodes, we used pure α-Fe2O3 with 1–10 μm grain size as active material to for comparison with commercial materials. Highly relative homogeneous micro α-Fe2O3 with mainly rhombohedral-like shape was prepared by a controlled synthesis method. The effect of morphology, shape, and particle size of Fe2O3 on the electrochemical behavior of Fe2O3/AB electrode was investigated using X-ray diffraction, scanning electron microscopy coupled with X-ray energy-dispersive spectroscopy, transmission electron microscopy, cyclic voltammetry, and galvanostatic cycling performance. Results showed that the prepared α-Fe2O3 provided shaper redox peaks and deposition peaks that were separate from hydrogen evolution. In the initial cycles, both commercial Fe2O3 nanoparticles and prepared α-Fe2O3 microparticles yielded similar discharge capacities but the prolonged cycling of the prepared microparticles provided higher capacities.

A stable and high-capacity anode for lithium-ion battery: Fe2O3 wrapped by few layered graphene

Fe2O3 wrapped by few layered graphene nanosheets composites (Fe2O3-FLG) have been synthesized via a facile and massive one-step P-milling method, which is effective in reducing the particle size of Fe2O3 and exfoliating the graphite into FLG. The composite shows good electrochemical performance due to the tight wrapping of FLG nanosheets, which is beneficial to electric conductivity and integrity of the electrode. The sample treated under 20 h retains a reversible capacity of 758 mAh g−1 at 200 mA g−1 after 300 cycles, which equals to 88% of its theoretic capacity. With the superior electrochemical performance, Fe2O3-FLG composites prepared via the P-milling method could be promising as anode materials for high performance lithium-ion batteries.