Papers by Keyword: α-Fe₂O₃

Abstract: The rapid glucose detection is great significance in the food, biological and medical fields. In this paper, we show an unusual strategy for the synthesis of α-Fe₂O₃/g-C₃N₄ composite material with C-O-Fe bonds for applications in glucose detection. The structural composition and the existence of C-O-Fe bonds of α-Fe₂O₃/g-C₃N₄ were evaluated by XRD, FTIR, SEM, TEM and XPS. Due to the formation of C-O-Fe bonds, the BET surface area and electron transport ability of α-Fe₂O₃/g-C₃N₄ are improved. The electrochemical experiments revealed that the α-Fe₂O₃/g-C₃N₄ sensor exhibited a fast response time (< 5 s), a low detection limit (2.3 μM) and a wide linear range (0.1 mM - 5 mM). Furthermore, the powerful C-O-Fe binding energy provides a guarantee for the reasonable stability of the α-Fe₂O₃/g-C₃N₄ sensor. The presence of high concentrations of KCl, citric acid, ascorbic acid, dopamine and sucrose appeared to have no effects on the detection of glucose, indicating a high selectivity of this sensor.

Abstract: Synthesis and characterization of α-Fe₂O₃ nanoparticles were obtained from extraction of ilmenite iron sand with coprecipitation method and to obtain α-Fe₂O₃ nanoparticles, high energy milling (HEM) was used. Surface morphology and identification of the elements contained in the sample were analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). For phase analysis and crystal structure, X-ray diffractometer (XRD) was used. Moreover a vibrating magnetometer sample (VSM) was used to characterize its magnetic properties, while tunneling electron microscopy (TEM) was used for particle size characterization. Ilmenite-type iron sand has a diverse particle shape with a size of more than 100 μm with ilmenite (FeTiO₃) mineral content of about 64.7%. The results of extraction using coprecipitation method with sintering 750 °C, obtained hematite α-Fe₂O₃ material which has not been saturated to an external magnetic field of 1 tesla, the magnetic remanent value (Mr) is about 0.8 emu/g and the coercivity field value is Hc around 773 Oe. The average size of hematite α-Fe₂O₃ particles after being milled 50 hours is between 15-30 nm with a cube-like shape.

Abstract: The size effect of magnetic nanoparticles provides a various magnetic characteristic as a change of domain size. We report, synthesis of core-shell iron oxide and magnetic properties. Iron oxide particles were synthesized by co-precipitation method of iron (III) FeCl₃.6H₂O, iron (II) FeCl₂.4H₂O, in the mixture of with or without TEOS to investigated the physical properties. From XRD measurement, it was observed that all iron oxide particles with or without mixture of SiO₂ has a hematite phase of a-Fe₂O₃. From M-H loop measurement, it was observed that the iron oxide without SiO₂ has a ferromagnetic characteristic, while the iron oxide with SiO₂ showed a medium state as a contribution of superparamagnetic and ferromagnetic properties.

Abstract: In this paper, α–Fe₂O₃ photocatalyst with enhanced solar–driven photocatalytic activity was obtained from natural local groundwater sediment using a chemical solution method with subsequent calcination. The phase structures and crystallite size characterized by X–ray diffraction. The morphology and the particle size were investigated by scanning electron microscopy. The α–Fe₂O₃ was used as a catalyst to photodegrade MB under visible light illumination. The photocatalytic reaction rate constant of the α–Fe₂O₃ photocatalyst in the photocatalytic degradation of MB dye solution under LED light illumination with the presence of H₂O₂ was calculated to be 1.70×10^–2 min^–1. Moreover, the effect of H₂O₂ concentration on photocatalytic efficiency and the photocatalytic mechanism also were discussed.

Abstract: ELID ultra-precision grinding mirror surface can achieve nanometer precision. However, after the grinding wheel passivates the abrasive particles in electrolysis, it is easy to scratch the ultra-precision ELID grinding surface into the grinding process. In order to solve this problem, a non-abrasive grain α-Fe bonded grinding wheel is propose, which contains no abrasive particles. After electrolysis, oxide film is formed on the surface of the wheel. In ultra-precision ELID grinding, there is no abrasive particles involved, only the polishing effect of oxide film. There is no need to worry about the scratching of exfoliated abrasive particles that have been machined on ultra-precision ELID surfaces. Thus achieving extremely high surface accuracy.

Abstract: The formation mechanism of α-Fe2O3 on iron-bonded diamond wheel surface by ELID grinding is presented here. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used to analyze the compositions of the oxide films. X-ray diffraction analysis demonstrated the existence of the diffraction peak of α-Fe2O3, which was observed in ELID grinding iron-bonded diamond wheel surface. To illustrate the correctness of our theory, X-ray photoelectron spectroscopy analysis was also performed. Results reveal that the characteristic spectrum of oxide film on ELID wheel has coincidence with the standard spectrum of Fe_2p in α-Fe₂O₃. These results suggest the existence of α-Fe₂O₃ in oxide films on the grinding wheel surface. The potentiality that α-Fe₂O₃ can bring polishing effect to ELID grinding process has also been discussed. It helps understand how ELID grinding can achieve excellent surface finish for the workpiece.

Abstract: α-Fe₂O₃ thermoelectric thin films were electrodeposited onto copper substrates using chloride-based electrolytes by means of potentiostatic electrodeposition. The influence of several electrodeposition parameters on the surface morphology, elemental composition and electrical conductivity of the deposited films was studied and analyzed. The deposits formed porous, wire-like morphology, with the smallest width measured to be ~60 nm. The wires tend to aggregate to form clusters, in addition to multi-layered growth of the wires. Between the parameters studied, electrolyte concentration and deposition time parameters have higher influences on the electrical conductivity of the deposited films, with the increment up to two fold higher. Deposition potential parameter offered the lowest capability to improve on the electrical conductivity in addition to the non-uniform distribution of the measured electrical conductivities. The tunable electrical conductivity is favorable for improving the performance of α-Fe₂O₃ films for thermoelectric applications.

Abstract: This paper conducted a theoretical study on the generation and transformation mechanism of α-Fe₂O₃ in the oxide film and an experimental verification of the presence of it. Firstly, the electrochemical process of the generation and transformation of α-Fe₂O₃ in the oxide film was analyzed, followed by the measurement of the content of it in the oxide film using X-ray diffractometer.

Abstract: In this paper, α-Fe₂O₃ photocatalyst with high photocatalytic activity (IL-α-Fe₂O₃) was fabricated via hydrothermal routine using 1-ethyl-3- methylimidazolium dihydrophosphate ([EMIm]H₂PO₄). The specific surface area, structure, the photo-induced charge separation rate were characterized by Brunauer-Emmett-Teller (BET) measurements, X-ray diffraction (XRD), and surface photovoltage spectroscopy (SPS), respectively. The results show that adding ([EMIm]H₂PO₄ into the synthetic system alters the specific surface parameters and photo-induced charge separation rate. The photocatalytic activity for decolorization of methyl orange (MO) solution was investigated. The results show that the photocatalytic activity of IL-α-Fe₂O₃ is more than 2.5 times that of the reference α-Fe₂O₃ and the underlying mechanisms are discussed.

Abstract: In this paper, α-Fe₂O₃ nanocrystals have been synthesized, using FeCl₃, oleic acid, ethanol and NaOH as raw materials by a hydrothermal method at 180°C for 10h. The samples were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) for the information of crystal category, form and size. The results showed the materials are nanocubes and side-length about 20 nm. Moreover, the properties of α-Fe₂O₃ nanocrystals as anode materials for Li-ion batteries had been studied. The first-discharge capacity is 1280 mAh g^-1, which made this material maybe one of the candidates for the negative materials.