三维多级孔类石墨烯载三氧化二铁锂离子电池负极材料

采用简单的水解、热处理方法合成三氧化二铁（Fe₂O₃）负载在三维多级孔类石墨烯（3D HPG）上的复合材料. 3D HPG有效的导电网络有利于负载纳米Fe₂O₃,使其呈均匀分散状态,并有效增强纳米复合物的导电率,提高Fe₂O₃利用率,抑制纳米Fe₂O₃的团聚,从而制得稳定、高性能的锂离子电池负极材料. Fe₂O₃-3D HPG电极在50 mA·g^-1电流密度下首次放电容量达1745 mAh·g^-1,50周期放电容量保持于1095 mAh·g^-1.     

静电自组装方法合成的具有多孔三维网络结构的Fe_3O_4/石墨烯复合材料作为高性能锂离子电池负极材料(英文)

采用静电自组装方法,分两步合成Fe(OH)3/GO前驱体(GO:氧化石墨烯),再通过水热反应和600°C高纯氮气气氛下煅烧,获得了Fe3O4/石墨烯复合材料.通过X射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)、拉曼(Raman)光谱等多种分析,发现该复合材料具有三维多孔石墨烯网络结构.把合成的这种Fe3O4/石墨烯复合材料作为锂离子电池负极材料,电化学测试结果表明其具有优良的电化学性能:首次放电容量为1390 mAh·g-1,50次循环后容量为819 mAh·g-1.通过对比实验表明,三维石墨烯网络结构的形成对复合材料的电化学循环稳定性起着关键作用.     

分级多孔γ-Al2O3空心微球微波水热法制备及其对刚果红的快速吸附

以KAl(SO₄)₂和尿素为前驱体,通过微波水热法于180 ℃反应20 min,经600 ℃焙烧2 h制得分级多孔γ-Al₂O₃空心微球.所制备的样品被用于吸附典型有机染料刚果红(CR)溶液.结果表明,制备的γ-Al₂O₃空心微球直径为0.8-1.0 μm,厚度约为200 nm.此γ-Al₂O₃空心微球具有高的比表面积(243 m²·g^-1)和分级大孔-中孔结构,此结构非常有利于液相过程中的质量传递.微波水热法制备的γ-Al₂O₃空心微球比水热法制备的γ-Al₂O₃和商用的γ-Al₂O₃样品显示出更快和更强的吸附性能.此样品的吸附数据很好地符合假二级速率方程和Langmuir吸附理论模型.从Langmuir吸附理论模型计算得到微波水热法制备的γ-Al₂O₃空心微球的最大吸附量(q_max) 25 ℃时高达515.4 mg·g^-1.由于具有分等级结构、高比表面积、大的孔容和吸附能力,微波水热法制备的γ-Al₂O₃空心微球样品有望成为一种具有很好应用潜力的环境吸附剂.     

Metal-organic framework derived magnetic nanoporous carbon as an adsorbent for the magnetic solid-phase extraction of chlorophenols from mushroom sample

In this work, a metal-organic framework derived nanoporous carbon(MOF-5-C) was fabricated and modified with Fe_3O_4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon(Fe_3O_4@MOF-5-C) was then used for the magnetic solid-phase extraction of chlorophenols(CPs) from mushroom samples prior to high performance liquid chromatography–ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N_2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 m L, desorption solvent as 0.4 m L(0.2 mL×2)of alkaline methanol, and sample p H as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8–100.0 ng g~(-1)with the correlation coefficients between0.9923 and 0.9963. The limits of detection(S/N = 3) were in the range of 0.25–0.30 ng g~(-1), and the relative standard deviations were below 6.8%. The result showed that the Fe3O4@MOF-5-C has an excellent adsorption capacity for the analytes.     

Preparation and Properties of Magnetic-fluorescent Microporous Polymer Microspheres

Microporous microspheres can be used as functional nanomaterial carriers for their microporous structure and higher specific surface area. In this study, magnetic fluorescent polymer microspheres were prepared by incorporating Fe₃O₄ nanoparticles and CdSe/ZnS quantum dots(QDs) into hyper-crosslinked microporous polymer microspheres(HCMPs) via the in situ coprecipitation method and swelling-diffusion. The HCMPs predominantly have micropores, and their specific surface area is as high as 703.4 m²/g. The magnetic-fluorescent microspheres maintain the superparamagnetic behavior of Fe₃O₄, and the saturation magnetization reaches 38.6 A·m²/kg. Moreover, the composite microspheres exhibit an intense emission peak at 530 nm and achieve good fluorescence.     

碳海绵上电化学沉积Fe_2O_3纳米片及其增强电容性能

设计高性能的可压缩电极是实现可压缩电容器器件的关键,碳海绵(CS)具有理想的压缩形变,但却受制于有限的容量。本工作以CS为可压缩基底,通过恒电流沉积及低温热处理技术,在CS骨架上均匀沉积了α-Fe_2O_3纳米片。复合电极中Fe_2O_3的负载量随沉积时间的延长逐渐增加,且在沉积16 h后达到饱和。系统地考察了CS-Fe_2O_3复合电极在不同压力下的可压缩性能,并在三电极体系中,通过循环伏安、恒电流充放电等方法研究了CS-Fe_2O_3复合电极在3.0mol·L~(-1)KOH电解液中的电容性能。结果表明,当复合电极CS-Fe_2O_3压缩率减小时,电极的内阻增大,比电容相应减小。CSFe_2O_3-12电极在电流密度为1 A·g~(-1)时的最大比电容为294 F·g~(-1),且经过10000次恒电流充放电后,电容量仍然能保持初始值的81%,是一种潜在的电化学性能稳定的可压缩超级电容器电极材料。     

Magnetically separated and N,S co-doped mesoporous carbon microspheres for the removal of mercury ions

Magnetically separated and N, S co-doped mesoporous carbon microspheres (N/S-MCMs/Fe₃O₄) are fabricated by encapsulating SiO₂ nanoparticles within N, S-containing polymer microspheres which were prepared using resorcinol/formaldehyde as the carbon source and cysteine as the nitrogen and sulfur co-precursors, followed by the carbonization process, silica template removal, and the introduction of Fe₃O₄ into the carbon mesopores. N/S-MCMs/Fe₃O₄ exhibits an enhanced Hg²⁺ adsorption capacity of 74.5 mg/g, and the adsorbent can be conveniently and rapidly separated from wastewater using an externalmagnetic field. This study opens up new opportunities to synthesize welldeveloped, carbon-based materials as an adsorbent for potential applications in the removal of mercury ions from wastewater.     

A highly selective magnetic sensor with functionalized Fe/Fe3O4 nanoparticles for detection of Pb2+

A magnetic sensor for detection of Pb~(2+) has been developed based on Fe/Fe_3O_4 nanoparticles modified by3-(3,4-dihydroxyphenyl)propionic acid(DHCA). The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb~(2+) thus inducing the transformation of Fe/Fe_3O_4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time(T_2) of the surrounding water protons. Upon addition of the different concentrations of Pb~(2+) to an aq. solution of DHCA functionalized Fe/Fe_3O_4 nanoparticles(DHCA-Fe/Fe_3O_4 NPs)([Fe] = 90 mmol/L), the change of T_2 values display a good linear relationship with the concentration of Pb~(2+) from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb~(2+), DHCA-Fe/Fe_3O_4 NPs exhibited a high selectivity over other metal ions.     

纳米CoFe2O4/GNS负极制备及其电化学性能研究

采用溶剂热法一步合成纳米尺寸CoFe₂O₄/GNS复合材料（直径约为15 nm）,其颗粒尺寸均一,且均匀分散于石墨烯表面. 电化学测试结果表明,该复合物电极具有良好的循环和倍率性能,500 mA·g^-1电流密度下100周期循环比容量稳定在709 mAh·g^-1, 容量保持率高达95.8%;2 A·g^-1电流密度,其比容量仍高达482 mAh·g^-1.     

原位相分离合成V_2O_5/Fe_2V_4O_(13)纳米复合材料及其储钠性能

钠具有资源丰富、成本低廉等优势,因此钠离子电池被认为是未来替代锂离子电池的最佳候选者之一。然而,寻找合适的电极材料是当前制备高性能钠离子电池面临的难题之一。在众多候选材料中,钒酸盐材料通过引入阳离子增加钒的配位数,使得材料结构的稳定性得到提高,从而改善了钠离子电池的电化学性能。本文研究了一种原位相分离法合成V_2O_5/Fe_2V_4O_(13)纳米复合材料。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)等对电极材料形貌、组成和结构进行了表征。实验结果显示,V_2O_5/Fe_2V_4O_(13)纳米复合材料相对于V2O5纳米线材料,结构更加稳定,在0.1 A·g~(-1)电流密度下,初始放电容量由295.4 m Ah·g~(-1)提升到342 m Ah·g~(-1),循环100圈容量保持率由26.6%提高到65.8%,获得了更加优异的倍率性能(在1.0 A·g~(-1)电流密度下,容量由44 m Ah·g~(-1)提高到160 m Ah·g~(-1))。因此,V_2O_5/Fe_2V_4O_(13)纳米复合材料的研究为开拓新型高性能钠离子电池负极材料拓宽了思路。     

SO_4~(2-)功能化处理对Fe_2O_3催化剂上氨选择性催化还原NO_x性能的促进机理研究

采用沉淀法制备了Fe(OH)_3和Fe_2O_3。通过硫酸化处理得到SO_4~(2-)/Fe(OH)_3和SO_4~(2-)/Fe_2O_3两种催化剂,并将其应用于氨选择性催化还原NO_x(NH_3-SCR)反应,研究了SO_4~(2-)功能化处理对Fe_2O_3催化剂上NH_3-SCR脱硝性能的促进机理。结果表明,与纯的Fe_2O_3相比,硫酸化处理得到的催化剂上SCR活性得到显著提升;其中,SO_4~(2-)/Fe(OH)_3表现出更加优异的催化性能,在250-450℃时NO_x转化率高于80%,且具有优异的稳定性和抗H_2O+SO_2性能。XRD、Raman、TG、FT-IR、H_2-TPR、NH_3-TPD和in situ DRIFTS等表征结果显示,硫酸功能化处理能抑制Fe_2O_3的晶粒生长,同时SO_4~(2-)与Fe~(3+)结合形成硫酸盐复合物,提高了催化剂表面酸性位点的数量和酸强度,抑制了Fe_2O_3上的氨氧化反应,从而提高了其脱硝催化性能。     

尺寸可控的单分散四氧化三铁微球的省时制备

Monodisperse Fe₃O₄ microspheres with tunable diameters and high magnetic saturation were synthesized by a solvothermal reduction method. It was found that the morphology and structure of the Fe₃O₄ microspheres could be tuned by simply altering the amount of the reactants such as ferric chloride, sodium acetate, water, and the reaction time. The Fe₃O₄ microspheres obtained via this method possessed high purity, crystallinity, and a nearly spherical shape. Furthermore, they were monodispersed and no aggregation was found. Such monodisperse Fe₃O₄ microspheres had tunable diameters of 400-700 nm and the fabrication time was only 2-4 h. The products showed high magnetic saturation values, and their yields were typically more than 94%.     

理想与还原Fe2O3[001]表面上汞吸附协同催化CO分解作用

煤化学链燃烧必然释放汞,汞与载氧体表面相互作用,影响表界面的氧化还原反应。本文采用密度泛函理论计算,研究汞（Hg⁰）在理想表面（Fe₂O₃[001]）和一系列被还原表面（Fe₂O_2.75、Fe₂O_2.5、Fe₂O_2.25、Fe₂O_1.625、Fe₂O_0.875、Fe₂O_0.375和Fe）的吸附,以及Hg⁰对Fe₂O_1.625、Fe₂O_0.875、Fe₂O_0.375和Fe等表面催化CO分解反应的协同作用机理。Hg⁰物理吸附在理想Fe₂O₃[001]表面。随着Fe₂O₃[001]表面不断被还原,Hg⁰发生化学吸附。Hg⁰吸附降低了CO与Fe₂O₃、Fe₂O_2.75、Fe₂O_2.5和Fe₂O_2.25等表面之间的相互作用,抑制O传递氧化CO为CO₂的反应;载氧体进一步还原过程中,Hg⁰吸附促进了CO与Fe₂O_1.625、Fe₂O_0.875、Fe₂O_0.375及Fe等表面之间的相互作用,进而促进了表面对CO的催化分解反应,加速了载氧体表面的积碳,降低了化学链燃烧效率。因此,合理控制载氧体的还原程度既可以减弱Hg⁰的吸附,也可以抑制积碳的形成,这对化学链燃烧的操作优化至关重要。     

Preparation of few-layer reduced graphene oxide-wrapped mesoporous Li4Ti5O12 spheres and its application as an anode material for lithium-ion batteries

A three-dimensional few-layer reduced graphene oxide-wrapped mesoporous Li₄Ti₅O₁₂ (m-LTO@FLRGO) electrode is produced using a simple solution fabrication process. When tested as an anode for Liion batteries, the m-LTO@FL-RGO composite exhibits excellent rate capability and superior cycle life. The capacity of m-LTO@FL-RGO reaches 165.4 mA h g^-1 after 100 cycles between 1 and 2.5 V at a rate of 1 C. Even at a rate of 30 C, a high discharge capacity of 115.1 mA h g^-1 is still obtained, which is three times higher than the pristine mesoporous Li₄Ti₅O₁₂ (m-LTO). The graphene nanosheets are incorporated into the m-LTO microspheres homogenously, which provide a high conductive network for electron transportation.     

碳纳米管/五氧化二钒空心球的制备及其电化学性能研究

采用溶剂热法制备了碳纳米管穿插的分级结构五氧化二钒空心球（VOC_x）. 使用XRD、SEM、循环伏安曲线和充放电曲线研究了不同碳纳米管量对产物结构、形貌和电化学性能的影响. 结果表明,碳纳米管的加入明显改善了VOC的倍率特性. 碳纳米管含量为7.1%时,0.5 A·g^-1电流密度下,其比电容达到346 F·g^-1,8 A·g^-1电流密度时,其电容保持率可达75%. 与活性炭组装成混合电容器,在功率密度为700 W·kg^-1时,能量密度达12.6 Wh·kg^-1.     

Effective Removal of Tetracycline by Using Biochar Supported Fe3O4 as a UV-Fenton Catalyst

Novel Fe3O4-decorate hierarchical porous carbon skeleton derived from maize straw(Fe3O4@MSC)was synthesized by a facile co-precipitation process and a calcination process,which was developed as a UV assisted heterogeneous Fenton-like catalyst.The as-synthesized catalysts were characterized via X-ray powder diffraction(XRD), scanning electron microscope(SEM),transmission electron microscope(TEM),Brunauer-Emmet-Teller(BET)and vibrating sample magnetometer(VSM)at room temperature.The morphology and structure analysis revealed that the as-prepared Fe3O4@MSC retained the original pore morphology of the maize straw material.The non-uniform poly- hedral Fe3O4 grew on the whole surface of the MSC,which reduced the aggragation of Fe3O4 and provided more active sites to strengthen the UV-assisted Fenton-like reaction.As a result,the tetracycline(TC)degradation efficiency after 40 min reaction and total organic carbon(TOC)removal efficiency after 2 h reaction of Fe3O4@MSC catalyzing UV-Fenton system reached 99.2%and 72.1%,respectively,which were more substantial than those of Fe3O4@MSC/H2O2(31.5%and 2%),UV/H2O2 system(68%and 23.4%)and UV/Fe3O4/H2O2(80% and 37.5%).The electron spin resonance(ESR)results showed that the ·OH played an important role in the catalytic reaction.A possible degradation pathway of TC was proposed on the basis of the identified intermediates.Overall,the UV assisted heterogeneous Fenton-like process in Fe3O4@MSC improved the cycle of Fe^3+/Fe^2+ and activated the interfacial catalytic site,which eventually realized the enhancement of degradation and mineralization to tetracycline.     

Mo/Fe3O4(111)表面对燃煤烟气汞吸附的密度泛函研究

利用CASTEP软件包采用密度泛函理论计算研究了过渡金属Mo掺杂Fe_3O_4(111)Fe_(tet)表面对Hg~0、HgCl和HgCl_2的吸附特征,分析了Mo掺杂前后Fe_3O_4(111)Fe_(tet)表面上不同汞物种的吸附形态。结果表明,Mo掺杂Fe_3O_4(111)Fe_(tet)表面对HgCl和HgCl_2为化学吸附,而对Hg~0的吸附为物理吸附;与纯净表面相比,HgCl在Mo原子掺杂表面上的吸附能提高了40%-66%。HgCl_2在纯净Fe_3O_4(111)Fe_(tet)表面形成"M"形结构;而掺杂Mo原子后,由于Cl原子与Mo原子之间更强的相互作用,使得HgCl_2发生了完全解离,两个Cl原子分别与Mo原子和Fe原子成键吸附在表面,Hg脱附。相关研究结果可为脱除燃煤烟气中的汞提供一定的理论指导。     

锅炉结渣初始沉积层微观沉积机理研究

选取矾土Al₂O₃和赤铁矿Fe₂O₃,对这两种矿物做弹性常数的微观分析、对比,X射线衍射分析表明,煤灰与初始沉积层中的矿物种类相同,但两者中矾土Al₂O₃和赤铁矿Fe₂O₃的含量相差很大。采用第一性原理(first-principles)的超软赝势平面波方法,对Al₂O₃和Fe₂O₃的电子结构、弹性常数进行了计算。结果表明,从两种物质的结构角度分析,Al₂O₃晶体中Al³⁺、O^2-的堆积排列相对于Fe₂O₃中Fe³⁺、O^2-要稀疏,这是它们性质不同的结构原因;对于两晶体在<100>方向和切向上的化学键, Fe-O键比Al-O键更容易变形或者断裂,从而导致Fe₂O₃极易沉积在清洁水冷壁上;对Fe₂O₃,切向面对其沉积起了关键性的作用。     

Nanosized Pd assembled on superparamagnetic core–shell microspheres:Synthesis,characterization and recyclable catalytic properties for the Heck reaction

A series of magnetically recyclable Pd/Fe3O4@g-Al2O3 catalysts were synthesized using the superparamagnetic Fe3O4@g-Al2O3core–shell microspheres as the supporter and nano-Pd particles assembled on g-Al2O3 shell as the active catalytic component.The structure of the catalysts was characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),N2adsorption–desorption and vibrating sample magnetometer(VSM).The catalytic activity and the recyclability properties of the catalysts for the Heck coupling reaction with aryl bromides and the olefins were investigated.The results show that the microspheres of the magnetic Pd/Fe3O4@g-Al2O3 catalysts were about 400 nm and the nano-Pd particles assembled on g-Al2O3 shell were about 3–4 nm in size.The saturation magnetization(MS) of the magnetic catalysts was sufficiently high to allow magnetic separations.In the Heck coupling reactions,the magnetic Pd/Fe3O4@g-Al2O3 catalysts exhibited good catalytic activity and recyclability.With Pd/Fe3O4@g-Al2O3(0.021 mol%) catalyst,the bromobenzene conversion and product yield reached about 96.8% and 91.2%,respectively,at 120 8C and in 14 h.After being recycled for six times,the conversion of bromobenzene and the recovery of the catalyst were about80% and 90%,respectively.The nano-Pd particles were kept well dispersed in the used Pd/Fe3O4@g-Al2O3 catalysts.     

Pt/Au/Fe3O4的制备及其电化学性能

以制得的纳米Fe₃O₄颗粒作为载体,用还原法将还原出的Au与Pt分别负载到Fe₃O₄颗粒表面,制得纳米Pt/Au/Fe₃O₄复合材料。对Pt/Au/Fe₃O₄进行紫外可见光吸收光谱、透射电子显微镜、X射线衍射及光电子能谱等物理表征,结果表明,Au与Pt均匀地沉积到了Fe₃O₄纳米颗粒表面。对纳米Pt/Au/Fe₃O₄复合材料进行循环伏安扫描,当H₂PtCl₆的加入量达到8 mL时,Pt/Au/Fe₃O₄催化性能最佳;正扫电流峰i_p与扫描速率的平方根v^1/2线性相关,Pt/Au/Fe₃O₄催化氧化甲醇的过程受扩散控制;对催化剂进行201次循环伏安扫描,催化剂仍然能保持较好的催化性能且稳定性良好。因此,所合成催化剂Pt/Au/Fe₃O₄是一种具有良好化学稳定性的阳极催化剂材料。