一种新型储氢材料——改性四氧化三铁的储氢性能研究

以金属Mo, Al, Cr, W可溶盐为添加物, 通过共沉淀法由FeCl₃和(NH₄)₂Fe(SO₄)₂•6H₂O的水溶液制备了单金属添加的Fe₃O₄改性储氢材料. 采用循环储氢性能评价方法, 研究了材料的储氢性能; 利用X射线粉末衍射、SEM扫描电镜和BET比表面积测试手段, 分析了材料储-放氢前后的微观结构. 结果表明: 添加了Mo金属的Fe₃O₄材料四次循环的放氢温度最低, 为310～314 ℃(放氢速率为300 μmol•min^－1•Fe-g^－1), 低于目前同类最好的储氢材料(50 ℃左右); 对材料的微观结构研究表明: 采用本文方法制备的金属添加的Fe₃O₄储氢材料其粒度大约在50～70 nm. 此外, 材料的催化活性主要与掺杂的金属类型和材料粒度的大小有关.     

Fe_2O_3-Modified Hydrogen Storage Alloys as Electrocatalyst for Borohydride Oxidation

The effects of hot alkaline treatment and Fe₂O₃ modification of hydrogen storage alloy on the electrocatalytic activity for oxidation of borohydride have been investigated using linear sweep voltammetry. The performance of borohydride electrochemical oxidation was significantly influenced by the hot alkaline treatment and Fe₂O₃ modification of the hydrogen storage alloy. The results showed that the current density of the Fe₂O₃‐modified hot alkaline‐treated hydrogen storage alloy electrode containing 5 wt% Fe₂O₃ reached 125 mA·cm^?2 in 0.10 mol·L^?1 NaBH₄ and 2 mol·L^?1 NaOH solution at ?0.55 V vs. saturated Ag/AgCl, KCl electrode.     

Non‐covalent Immobilization of Iron‐triazole (Fe(Htrz)3) Molecular Mediator in Mesoporous Silica Films for the Electrochemical Detection of Hydrogen Peroxide

Mesoporous silica thin films encapsulating a molecular iron‐triazole complex, Fe(Htrz)₃ (Htrz=1,2,4,‐1H‐triazole), have been generated by electrochemically assisted self‐assembly (EASA) on indium‐tin oxide (ITO) electrode. The obtained modified electrodes are characterized by well‐defined voltammetric signals corresponding to the Fe^II/III centers of the Fe(Htrz)₃ species immobilized into the films, indicating fast electron transfer processes and stable operational stability. This is due to the presence of a high density of redox probes in the material (1.6×10^?4 mol g^?1 Fe(Htrz)₃ in the mesoporous silica film) enabling efficient charge transport by electron hopping. The mesoporous films are uniformly deposited over the whole electrode surface and they are characterized by a thickness of 110 nm and a wormlike mesostructure directed by the template role played by Fe(Htrz)₃ species in the EASA process. These species are durably immobilized in the material (they are not removed by solvent extraction). The composite mesoporous material (denoted Fe(Htrz)₃@SiO₂) is then used for the electrocatalytic detection of hydrogen peroxide, which can be performed by amperometry at an applied potential of ?0.4 V versus Ag/AgCl and by flow injection analysis. The organic‐inorganic hybrid film electrode displays good sensitivity for H₂O₂ sensing over a dynamic range from 5 to 300 μM, with a detection limit estimated at 2 μM.     

Preparation and Characterization of Fe3O4/Ethiodized‐oil Magnetic Fluids Used in Arterial Embolization Hyperthermia

Fe₃O₄ nanoparticles (NPs) were prepared by the co‐precipitation of Fe³⁺ and Fe²⁺ with ammonium hydroxide, and were modified by four different surfactants. The modified Fe₃O₄ NPs were characterized by Fourier transform infrared spectroscopy, X‐ray powder diffraction, transmission electron microscopy and vibrating sample magnetometer. Then, the modified Fe₃O₄ NPs were dispersed in ethiodized‐oil by mechanical agitation and ultrasonic vibration to obtain stable Fe₃O₄/ethiodized‐oil magnetic fluids (MFs). The magnetic properties and rheological properties of the MFs were measured using a Gouy magnetic balance and a rotational rheometer, respectively. The saturation magnetization of the Fe₃O₄ modified by oleic acid was 52.1 emu/g. Furthermore, the result showed that the inductive heating effect of oleic acid stabilized Fe₃O₄/ethiodized‐oil MF was remarkable and it only took 650 s for the temperature rising from 25°C to 65°C. The specific absorption rate of the MF was 50.16 W/(g of Fe). It had a potential application in arterial embolization hyperthermia.     

铁粉为原料催化改性铁氧化物的储氢性能

以Fe粉为原料, 以金属Mo, Al和Ni可溶性盐作为添加剂, 通过浸渍法制备单金属添加和双金属添加的改性铁氧化物储氢材料Fe-Mo, Fe-Al, Fe-Mo-Ni和Fe-Mo-Al, 并研究了它们的储氢性能. 结果表明样品Fe-Mo改性效果最好: 如放氢温度由改性前的500 ℃降至改性后的290 ℃左右; 300 ℃时放氢速率最高, 由改性前的低于50 μmol•min^－1• Fe-g^－1到改性后的325 μmol•min^－1•Fe-g^－1 (10次平均); 4.53 wt%的平均实验储氢量与理论值4.8 wt%较接近; 储-放氢循环稳定性随着循环次数的增加呈逐渐增加的趋势. SEM微观结构和BET比表面积分析表明添加剂的种类对样品的改性作用更重要.     

The effect of calcination on morphology of phosphate coating and microstructure of sintered iron phosphated powder

Carbonyl iron powder was coated with phosphate layer using phosphating precipitation method. The phosphated powder was dried at 60 °C for 2 h in air and heat treated by calcination at 400 and 800 °C for 3 h in air. Cylindrical specimens density of ~6.5 g.cm^?3 based on iron phosphated powder calcined at 400 °C were sintered at 820, 900, 1110 °C in N₂ + 10%H₂ atmosphere and 1240 °C in vacuum for 30 min. The morphology and phase composition of the phosphate coating and sintered compacts were studied by scanning electron microscopy, atomic force microscopy (AFM) and X‐ray diffraction (XRD) analysis. Gelatinous morphology of dried phosphate coating (thickness of ~100 nm) containing nanoparticles of iron oxyhydroxides and hydrated iron phosphate was observed. From XRD, diffractogram indicated the presence of goethite α‐FeOOH, lepidocrocite γ‐FeOOH and ludlamite Fe₃(PO₄)₂.4H₂O. The calcined phosphate coating (thickness of ~ 400 nm) contained non‐homogeneous consistency of α‐Fe₂O₃ layer on iron particles, an inter‐layer of amorphous FePO₄ and Fe₃O₄ top layer. The transformation to crystalline FePO₄ structure occurred during calcination at 800 °C with the presence of α‐Fe₂O₃ forming a light top zone (rough morphology). The microstructure of compacts sintered in solid state at temperatures up to 900 °C has retained composite network character. A fundamental change in microstructure due to the liquid phase sintering occurred after sintering at temperatures of 1100 and 1240 °C. It was confirmed that the microstructure complex consists of spheroidized α‐Fe and α‐Fe₂O₃ phases surrounded by solidified liquid phase consisting various phosphate compounds. Copyright © 2013 John Wiley & Sons, Ltd.     

Time‐Resolved High and Low Temperature Phase Transitions of the Nanocrystalline Cubic Phase in the Y2O3‐ZrO2 and Fe2O3‐ZrO2 System

The nanocrystalline cubic Phase of zirconia was found to be thermally stabilized by the addition of 2.56 to 17.65 mol % Y₂O₃ (5.0 to 30.0 mol % Y, 95.0 to 70.0 mol % Zr cation content). The cubic phase of yttria stabilized zirconia was prepared by thermal decomposition of the hydroxides at 400°C for 1 hr. 2.56 mol % Y₂O₃‐ZrO₂ was stable up to 800°C in an argon atmosphere. The samples with 4.17 to 17.65 mol % Y₂O₃ were stable to 1200°C and higher. All samples at temperatures between 1450°C to 1700°C were cubic except the sample with 2.56 mol % Y₂O₃ which was tetragonal. The crystallite sizes observed for the cubic phase ranged from 50 to 150 Å at temperatures below 900°C and varied from 600 to 800 nm between 1450°C and 1700°C. Control of furnace atmosphere is the main factor for obtaining the cubic phase of Y‐SZ at higher temperature. Nanocrystalline cubic Fe‐SZ (Iron Stabilized Zirconia) with crystallite sizes from 70 to 137 Å was also prepared at 400°C. It transformed isothermally at temperatures above 800°C to the tetragonal Fe‐SZ and ultimately to the monoclinic phase at 900°C. The addition of up to 30 mol % Fe(III) thermally stabilized the cubic phase above 800°C in argon. Higher mol % resulted in a separation of Fe₂O₃. The nanocrystalline cubic Fe‐SZ containing a minimum 20 mol % Fe (III) was found to have the greatest thermal stability. The particle size was a primary factor in determining cubic or tetragonal formation. The oxidation state of Fe in zirconia remained Fe³⁺. Fe‐SZ lattice parameters and rate of particle growth were observed to decrease with higher iron content. The thermal stability of Fe‐SZ is comparable with that of Ca‐SZ, Mg‐SZ and Mn‐SZ prepared by this method.     

A Fe3O4‐Based Chemical Sensor for Cathodic Determination of Hydrogen Peroxide

A new cathodic scheme for hydrogen peroxide (H₂O₂) measurement by Fe₃O₄‐based chemical sensor was described. The unique characteristic of electrocatalytic property was firstly investigated by voltammetry. And then the amperometric response of H₂O₂ was measured at ?0.2 V (vs. Ag/AgCl) by Fe₃O₄ modified glassy carbon rotating disk electrode. The kinetic parameter was also calculated from Koutecky‐Levich plot, and the value was 6.4×10^?4 cm s^?1 in pH 3 citrate buffer. In order to benefit the possible biomedical applications, Fe₃O₄/chitosan modified electrode was also investigated in this experiment. There were several characteristic enhancements by the coated chitosan thin film for H₂O₂ sensor. The calibration curves were found to be linear up to 4.0 and 5.0 mM (r=0.999) in pH 3 and 7 with the detection limits of 7.6 and 7.4 μM L^?1 (S/N=3). The stability was evaluated by the results of half‐life time (t_50%) for 9 months at room temperature and 24 months at 4 °C.     

阴极催化剂Sm1.5Sr0.5MO4 (M＝Ni, Co, Fe)在低温常压下合成氨

利用溶胶—凝胶法制备了复合氧化物Sm1.5Sr0.5MO4 (M＝Ni, Co, Fe)(SSM),并利用XRD和SEM等对样品进行表征。用Nafion膜作电解质、以SSM作为阴极、Ni-SDC金属陶瓷为阳极、银-铂网做集流体组成单电池,在温度为25℃～100℃的低温常压下以干燥氮气和湿的氢气为原料进行电化学合成氨气测定,同时研究了影响氨合成的关键因素,确定了合适的工作温度,实验结果表明,最高氨产率可达到1.05×10-8mol·s-1·cm-2。     

A Core–Shell Fe/Fe2O3 Nanowire as a High‐Performance Anode Material for Lithium‐Ion Batteries

The preparation of novel one‐dimensional core–shell Fe/Fe₂O₃ nanowires as anodes for high‐performance lithium‐ion batteries (LIBs) is reported. The nanowires are prepared in a facile synthetic process in aqueous solution under ambient conditions with subsequent annealing treatment that could tune the capacity for lithium storage. When this hybrid is used as an anode material for LIBs, the outer Fe₂O₃ shell can act as an electrochemically active material to store and release lithium ions, whereas the highly conductive and inactive Fe core functions as nothing more than an efficient electrical conducting pathway and a remarkable buffer to tolerate volume changes of the electrode materials during the insertion and extraction of lithium ions. The core–shell Fe/Fe₂O₃ nanowire maintains an excellent reversible capacity of over 767 mA h g^?1 at 500 mA g^?1 after 200 cycles with a high average Coulombic efficiency of 98.6 %. Even at 2000 mA g^?1, a stable capacity as high as 538 mA h g^?1 could be obtained. The unique composition and nanostructure of this electrode material contribute to this enhanced electrochemical performance. Due to the ease of large‐scale fabrication and superior electrochemical performance, these hybrid nanowires are promising anode materials for the next generation of high‐performance LIBs.     

Sodium‐Ion Storage Properties of FeS–Reduced Graphene Oxide Composite Powder with a Crumpled Structure

The sodium‐ion storage properties of FeS–reduced graphene oxide (rGO) and Fe₃O₄‐rGO composite powders with crumpled structures have been studied. The Fe₃O₄‐rGO composite powder, prepared by one‐pot spray pyrolysis, could be transformed to an FeS‐rGO composite powder through a simple sulfidation treatment. The mean size of the Fe₃O₄ nanocrystals in the Fe₃O₄‐rGO composite powder was 4.4 nm. After sulfidation, FeS nanocrystals of size several hundred nanometers were confined within the crumpled structure of the rGO matrix. The initial discharge capacities of the FeS‐rGO and Fe₃O₄‐rGO composite powders were 740 and 442 mA h g^?1, and their initial charge capacities were 530 and 165 mA h g^?1, respectively. The discharge capacities of the FeS‐rGO and Fe₃O₄‐rGO composite powders at the 50th cycle were 547 and 150 mA h g^?1, respectively. The FeS‐rGO composite powder showed superior sodium‐ion storage performance compared to the Fe₃O₄‐rGO composite powder.     

Influence of mechanical activation time,annealing, and Fe/O ratio on Fe3O4/Fe composites formation from Fe2O3 and Fe powders mixture

Commercially, iron (α-Fe) and hematite (α-Fe₂O₃) powders were used for the synthesis of composite powders of Fe₂O₃/Fe type by mechanical milling. Several ratios of Fe₂O₃/Fe were chosen for the composite synthesis; the atomic percent of oxygen in the starting mixtures ranged from 21 to 46 %. The Fe₂O₃/Fe composite samples with various Fe/O ratios were milled for different milling times. The milled composite samples were subjected to the heat treatments in argon up to 900 °C. During the heat treatment at temperatures that do not exceed 550 °C, Fe₃O₄/Fe composite particles are formed by the reaction between the Fe₂O₃ and Fe. Further increase of the heat treatment up to 700 °C leads to the reaction of the Fe₃O₄/Fe composite component phases, resulting thus in the formation of FeO/Fe composite. The heat treatment up to 900 °C of the Fe₂O₃/Fe leads to the formation of a composite of FeO/Fe₃O₄/Fe independent of the milling time and Fe₂O₃/Fe ratios. The onset temperatures of the Fe₃O₄ and FeO formations decrease upon increasing the milling time. Another important aspect is that, in the case of the same milling time but with a large amount of iron into the composite powder the formations temperatures of Fe₃O₄ and FeO are also decreasing. The influence of the mechanical activation time, heat treatment temperature, and Fe/O ratio on the formation of the (Fe₃O₄, FeO)/Fe composite from Fe₂O₃+Fe precursor mixtures was studied by differential scanning calorimetry and X-ray diffraction techniques.     

Fe3O4@SiO2‐PANI‐Au Nanocomposite Prepared for Electrochemical Determination of Quercetin in Food Samples and Biological Fluids

A new electrochemical sensor based on Fe₃O₄@SiO₂‐PANI‐Au nanocomposite was fabricated for modification of glassy carbon electrode (Fe₃O₄@SiO₂‐PANI‐Au GCE). The Fe₃O₄@SiO₂‐PANI‐Au nanocomposite was characterized by TEM, FESEM‐EDS‐Mapping, XRD, and TGA methods. The Fe₃O₄@SiO₂‐PANI‐Au GC electrode exhibited an acceptable sensitivity, fast electrochemical response, and good selectivity for determination of quercetin. Under optimal conditions, the linear range for quercetin concentrations using this sensor was 1.0×10^?8 to 1.5×10^?5 mol L^?1, and the limit of detection was 3.8×10^?9 mol L^?1. The results illustrated that the offered sensor could be a possible alternative for the measurement of quercetin in food samples and biological fluids.     

Graphitized carbon and graphene modified Fe2O3/Li4Ti5O12 as anode material for lithium ion batteries

Graphitized carbon (GC) and graphene (GE) modified Fe₂O₃/Li₄Ti₅O₁₂ (LTO) composites have been synthesized via a solid‐state reaction, respectively. The structure, morphology and electrochemical performance of the materials have also been characterized with X‐ray diffraction (XRD), scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) system, X‐ray photoelectron spectrometer (XPS), Fourier transform infrared spectroscopy (FTIR) and electrochemical measurements. The discharge capacities of Fe₂O₃/LTO, GC/Fe₂O₃/LTO and GE/Fe₂O₃/LTO are 100.2 mAh g^?1, 207.5 mAh g^?1 and 238.9 mAh g^?1 after 100 cycles at the current density of 176 mA g^?1. The cyclic stability and rate capability are in the order of GE/Fe₂O₃/LTO > GC/Fe₂O₃/LTO > Fe₂O₃/LTO because of the synergistic effect between GC (GE) and Fe₂O₃/LTO. Copyright © 2016 John Wiley & Sons, Ltd.     

Research on WPU‐RGO/ATP‐Fe3O4/chitosan composites with excellent electrical and magnetic properties

First, attapulgite‐Fe₃O₄ magnetic filler (ATP‐Fe₃O₄) was prepared by using a chemical precipitation method. Subsequently, graphite oxide (GO) was prepared through Hummer method, and then reduced GO (RGO) was prepared through GO reduced by chitosan (CS). Finally, a series of WPU‐RGO/ATP‐Fe₃O₄/CS composites were prepared by introduced RGO/ATP‐Fe₃O₄/CS to waterborne polyurethane. The structure and properties were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis TGA, conductivity test, and tensile test. The experimental results indicated that thermal stability and tensile strength of nanocomposites were improved with the increase of the content of RGO/ATP‐Fe₃O₄/CS. Meanwhile, with the increase of the RGO/ATP‐Fe₃O₄/CS content, the electrical and magnetic properties of WPU‐RGO/ATP‐Fe₃O₄/CS composites were improved. When the content of RGO/ATP‐Fe₃O₄/CS was 8 wt%, the electrical conductivity and the saturation magnetic strength of WPU‐RGO/ATP‐Fe₃O₄/CS composites were 3.1 × 10^?7 S·cm^?1 and 1.38 emu/g, respectively. WPU‐RGO/ATP‐Fe₃O₄/CS composites have excellent electrical and magnetic properties.     

General Preparation of Heme Protein Functional Fe3O4@Au‐Nps Magnetic Nanocomposite for Sensitive Detection of Hydrogen Peroxide

Stable magnetic nanocomposite of gold nanoparticles (Au‐NPs) decorating Fe₃O₄ core was successfully synthesized by the linker of Boc‐L‐cysteine. Transmission electron microscope (TEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammograms (CV) were performed to characterize the as‐prepared Fe₃O₄@Au‐Nps. The results indicated that Au‐Nps dispersed homogeneously around Fe₃O₄ with the ratio of Au to Fe₃O₄ nanoparticles as 5–10/1 and the apparent electrochemical area as 0.121 cm². After self‐assembly of hemoglobin (Hb) on Fe₃O₄@Au‐Nps by electrostatic interaction, a hydrogen peroxide biosensor was developed. The Fe₃O₄@Au‐Nps/Hb modified GCE exhibited fast direct electron transfer between heme center and electrode surface with the heterogeneous electron transfer rate constant (Ks ) of 3.35 s⁻¹. Importantly, it showed excellent electrocatalytic activity towards hydrogen peroxide reduction with low detection limit of 0.133 μM (S /D =3) and high sensitivity of 0.163 μA μM⁻¹, respectively. At the concentration evaluated, the interfering species of glucose, dopamine, uric acid and ascorbic acid did not affect the determination of hydrogen peroxide. These results demonstrated that the introduction of Au‐Nps on Fe₃O₄ not only stabilized the immobilized enzyme but also provided large surface area, fast electron transfer and excellent biocompatibility. This facile nanoassembly protocol can be extended to immobilize various enzymes, proteins and biomolecules to develop robust biosensors.     

Comparison of Cadmium Cd2+ and Lead Pb2+ Binding by Fe2O3@SiO2‐EDTA Nanoparticles – Binding Stability and Kinetic Studies

This study describes the synthesis and characterization of ethylenediaminetetraacetic acid (EDTA) functionalized magnetic nanoparticles of 20 nm in size – Fe₃O₄@SiO₂‐EDTA – which were used as a novel magnetic adsorbent for Cd(II) and Pb(II) binding in aqueous medium. These nanoparticles were obtained in two‐stage synthesis: covering by tetraethyl orthosilicate and functionalization with EDTA derivatives. Nanoparticles were characterized using TEM, FT‐IR, and XPS methods. Metal ions were detected under optimized experimental conditions using Differential Pulse Anodic Stripping Voltammetry (DPASV) and Hanging Mercury Drop Electrode (HDME) techniques. We compared the ability of Fe₃O₄@SiO₂‐EDTA to bind cadmium and lead in concentration of 553.9 μg L^?1 and 647.5 μg L^?1, respectively. Obtained results show that the adsorption rate of cadmium binding was very high. The equilibrium for Fe₃O₄@SiO₂‐EDTA‐Cd(II) was reached within 19 min while for the Fe₃O₄@SiO₂‐EDTA‐Pb(II) was reached within 25 minutes. About 2 mg of nanoparticles was enough to bind 87.5 % Cd(II) and 54.1 % Pb(II) content. In the next step the binding capacity of Fe₃O₄@SiO₂‐EDTA nanoparticles was determined. Only 1.265 mg of Fe₃O₄@SiO₂‐EDTA was enough to bind 96.14 % cadmium ions while 5.080 mg of nanoparticles bound 40.83 % lead ions. This phenomenon proves that the studied nanoparticles bind Cd(II) much better than Pb(II). The cadmium ions binding capacity of Fe₃O₄@SiO₂‐EDTA nanoparticles decreased during storage in 0.5 M KCl solution. Two days of Fe₃O₄@SiO₂‐EDTA storage in KCl solution caused the 32 % increase in the amount of nanoparticles required to bind 60 % of cadmium while eight‐days storage caused further increase to 328 %. The performed experiment confirmed that the storage of nanoparticles in solution without any surfactants reduced their binding capacity. The best binding capacity was observed for the nanoparticles prepared directly before the electrochemical measurements.     

Nanocrystalline Manganese Iron Oxide as a Charge Storage Electrode

Phase pure nanocrystalline manganese iron oxide [(Mn_0.37Fe_0.63)₂O₃] was synthesized by combustion technique based on propellant chemistry principle employing citric acid as fuel. The synthesized powder was characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), BET, BJH analysis and electrochemical studies for possible application as a charge storage electrode. The average crystallite size was found to be 18.6 nm from XRD analysis. BET analysis yielded the surface area and specific pore volume of the powder to be 22.96 m² g^?1 and 0.0098 cm³ g^?1 respectively. The specific capacitance from cyclic voltammetric studies at scan rate 5 mV s^?1 was found to be about 30 F g^?1 cm^?2 while from charge discharge studies was found to be 27±1 F g^?1 cm^?2. In addition, the material showed appreciable stability during charge‐discharge cycling.     

Direct Electrochemistry of Horseradish Peroxidase Embedded in Nano－Fe304 Matrix on Paraffin Impregnated Graphite Electrode and Its Electrochemical Catalysis for H2O2

Fe3O4 particles coated with acrylic copolymer (ACP) of about 5--8 nm in diameter were synthesized and used for immobilization of horseradish peroxidase (HRP). Direct electrochemistry of HRP embedded in the nanosized Fe304 solid matrix modified paraffin impregnated graphite electrode (PIGE) was achieved,which is related to the heine Fe(Ⅲ)/Fe(Ⅱ) conversion of HRP. Cyclic voltammetry gave a pair of reproducible and welldefined redox peaks at about Ea of -0.295 V vs. SCE. The standard rate constant k, was determined as 2.7 s^-1. It demonstrated that the nano-Fe3O4 solid matrix offers a friendly platform to assemble the HRP protein molecules and enhance the electron transfer rate between the HRP and the electrode. UV-Vis absorption spectra and WrIR spectra studies revealed that the embedded HRP retained its native-like structure. The HRP/Fe3O4/PIGE showed a strong catalytic activity toward H2O2. The voltammetric response was a linear function of H2O2 concentration in the range of 10-140μmol/L with detection limit of 7.3 μmol/L (s/n = 3 ). The apparent Michaelis-Menten constant is calculated to be 0.42 mmol/L.     

Ammonia-treatment assisted fully encapsulation of Fe2O3 nanoparticles in mesoporous carbons as stable anodes for lithium ion batteries

To improve the initial coulombic efficiency and bulk density of ordered mesoporous carbons, active Fe₂O₃ nanoparticles were introduced into tubular mesopore channels of CMK-5 carbon, which possesses high specific surface area (>1700 m²·g^?1) and large pore volume (>1.8 cm³·g^?1). Fine Fe₂O₃ nanoparticles with sizes in the range of 5–7 nm were highly and homogenously encapsulated into CMK-5 matrix through ammonia-treatment and subsequent pyrolysis method. The Fe₂O₃ loading was carefully tailored and designed to warrant a high Fe₂O₃ content and adequate buffer space for improving the electrochemical performance. In particular, such Fe₂O₃ and mesoporous carbon composite with 47 wt% loading exhibits a considerably stable cycle performance (683 mAh·g^?1 after 100 cycles, 99% capacity retention against that of the second cycle) as well as good rate capability. The fabrication strategy can effectively solve the drawback of single material, and achieve a high-performance lithium electrode material.