Facile Fabrication of Fe3O4@TiO2@C Yolk–Shell Spheres as Anode Material for Lithium Ion Batteries

Transition metal oxides have been actively exploited for application in lithium ion batteries due to their facile synthesis,high specific capacity,and environmental-friendly.In this paper,Fe3O4@TiO2@C yolk-shell(Y-S)spheres,used as anode material for lithium ion batteries,were successfully fabricated by Stober method.XRD patterns reveal that Fe3O4@TiO2@C Y-S spheres possess a good crystallinity.But the diffraction peaks’intensity of Fe3O4 crystals in the composites is much weaker than that of bare Fe3O4 spheres,indicating that the outer anatase TiO2@C layer can cover up the diffraction peaks of inner Fe3O4 spheres.The yolk-shell structure of Fe3O4@TiO2@C spheres is further characterized by TEM,HAADFSTEM,and EDS mapping.The yolk-shell structure is good for improving the cycling stability of the inner Fe3O4 spheres during lithium ions insertion-extraction processes.When tested at 200 mA/g,the Fe3O4@TiO2@C Y-S spheres can provide a stable discharge capacity of 450 mAh/g over 100 cycles,which is much better than that of bare Fe3O4 spheres and TiO2@C spheres.Furthermore,cyclic voltammetry curves show that the composites have a good cycling stability compared to bare Fe3O4 spheres.

Optimization of the operating conditions in a TiO_2/Fe_3O_4-SiO_2 photocatalytic reactor for the treatment of industrial wastewater containing Procion Red MX-5B

According to the design principle of the central composite experimental,the method of response surface analysis with three factors and three levels was adopted based on one factor test.A second-order quadratic equation for photocatalysis of Procion Red MX-5B was built.Response surface and contour were graphed with the decoloration rate of Procion Red MX-5B as the response value.Based on the analysis of the response surface plots and their corresponding contour plots,effects of pH value,irradiation time and catalyst loading were explored.By using this new method,the optimum decoloration condition was obtained as follows:pH value,1.3;irradiation time,49.9 min;catalyst loading,0.57 g/L.In the optimization,R-Squared and Adj R-Squared correlation coefficients for quadratic model were evaluated quite satisfactorily as 0.9310 and 0.8620,respectively.Under the optimum conditions established,the performance of 99.47% for color removal was experimentally reached.It was found that all factors considered have an important effect on the decolorization efficiency of Procion Red MX-5B.By the ANOVA analysis and model confirmation the optimal solution obtained using RSM was experimentally validated and credible with preferable instructional ability for experiments.

Fe_3O_4与SiO_2复合物合成及应用的实验设计

通过自组装技术设计了一个将纳米Fe3O4颗粒负载在Si O2载体上,制备Fe3O4-SiO2复合物的简单合成方法,并进行了对橙黄II污染物的降解分析。用空气氧化法制备了粒径20-30 nm的Fe3O4粉体。SEM及EDS分析表明：纳米Fe3O4颗粒能均匀分散在SiO2表面,复合物粒径约300-400 nm;随复合次数的增加,复合物表面的Fe含量逐渐递增。降解实验表明：制备的Fe3O4-SiO2复合物对橙黄Ⅱ的降解性高于纳米Fe3O4粉体的,且Fe3O4-SiO2复合物容易回收,具有较好的重复使用性。通过该实验可使学生掌握复合材料的合成方法及其在催化降解中应用,增强学生的科研意识及实践能力。

Facile Fabrication of Fe2O3/Nitrogen Deficient g-C3N4-x Composite Catalysts with Enhanced Photocatalytic Performances

The modification of graphitic carbon nitride can significantly improve the photocatalytic performance of graphitic carbon nitride(g-C3N4).Fe2O3/nitrogen-deficient g-C3N4-x composite catalysts were prepared with dicyandiamide as the precursor and Fe3+doped in this study.The composite catalysts were characterized by XRD,SEM,FT-IR,XPS and photocurrent measurements.Close interaction occurred between Fe2O3 and nitrogen deficient g-C3N4-x,more photogenerated electrons were created and effectively separated from the holes,resulting in a decrease of photocarrier recombination,and thus enhancing the photocurrent.Photocatalytic performance experiments showed that Fe2O3/nitrogen deficient g-C3N4-x could utilize lowenergy visible light more efficiently than pure g-C3N4,and the removal rate was 92%in 60 minutes.

Growth of High Magnetic a-Fe2O3 and Fe3O4 Nanowires via an Oxide Assisted Vapor-Solid Process

We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid process. Experimental results also indicate that previous immersion of the substrates in a solution of oxalic acid causes the grown nanowires to convert gradually into magnetite （Fe3O4） nanowires. Additionally, the saturated state of Fe3O4 nanowires is achieved as the oxalic acid concentration reaches 0.75 mol/L. The average diameter and length of nanowires expands with an increasing operation temperature and the growth density of nanowires accumulates with an increasing gas flux in the vapor-solid process. The growth mechanism of a-Fe2O3 and Fe3O4 nanowires is also discussed. The results demonstrate that the entire synthesis of nanowires can be completed within 2 h.

磁性纳米Fe3O4-SiO2载体的改性及其在脂肪酶固定化中的应用

将磁性纳米Fe3O4-SiO2载体去油和表面活化后,用硅烷偶联剂(KH-550)对载体表面进行氨基化改性,制备出氨基化改性的磁性纳米Fe3O4-SiO2载体。用X-射线衍射仪(XRD)、透射电镜(TEM)、傅里叶红外光谱仪(FT-IR)分别对载体进行表征,试验结果表明,用该种方法去油和活化不会使磁性纳米Fe3O4-SiO2载体内部的磁性纳米Fe3O4核晶型发生变化,且表面SiO2不会被溶解腐蚀,同时磁性纳米Fe3O4-SiO2载体表面能连接上氨基。将改性前、后的载体分别固定化脂肪酶应用于生物柴油酯化反应,试验结果表明改性前酯化率为26.78%,改性后酯化率为56.4%。将改性载体固定化脂肪酶重复10次应用于生物柴油酯化反应上, 10次平均酯化率达50.65%。该改性后的载体固定化脂肪酶牢固,不易脱落重复利用率高。

高盐度有机废水磁载催化剂降解工艺研究

以均匀沉淀法制备的Fe3O4磁粒为核心,以钛酸丁酯、正硅酸乙酯为原料,采用溶胶-凝胶法制备了磁载TiO2-SiO2-Fe3O4复合微粒,运用X射线衍射(XRD)、红外(IR)测试方法对所制得复合粒子进行表征,并以TiO2-SiO2-Fe3O4复合微粒为催化剂研究其高盐度有机废水催化降解的性能。结果表明,磁基体Fe3O4上包覆了一层SiO2和TiO2,制得磁载TiO2-SiO2-Fe3O4复合微粒。当有机废水pH=4.0,该催化剂的用量为3.0 g/L,空气体积流量为2 L/min,反应时间为1 h、温度为60℃时,COD的去除率为62.0%。