溶剂-凝胶法合成锂离子电池正极材料LiMn1/3Co1/3Ni1/3O2

使用溶剂-凝胶法合成了锂离子电池正极材料LiMn1/3Co1/3Ni1/3O2,考察了不同反应温度(850、900、950℃)对产品物性的影响。并通过扫描电镜、X-射线衍射研究材料的表观形貌和晶体结构,并进行了电化学性能测试。结果表明,合成的样品较为纯净,产品粒径小(0.5~1μm);900℃时合成的LiMn1/3Co1/3Ni1/3O2电化学性能的循环性及稳定性最好,50次循环后其放电比容量保持率为93.5%。

溶胶-凝胶法制备纳米二氧化硅

以正硅酸乙酯为原料,采用溶胶-凝胶法制备了纳米二氧化硅。通过控制原料配比、温度和催化剂等因素,分析其对成胶状态、成胶时间、产物粒径大小的影响,得到了制备纳米二氧化硅的优化工艺条件。

溶剂热辅助溶胶-凝胶法制备微纳米晶ZrSiO4陶瓷

采用溶剂热辅助溶胶-凝胶法,以氯氧化锆(ZrOCl2·8H2O)和正硅酸乙酯(TEOS)为原料,以乙醇溶液为溶剂介质,制备锆石(ZrSiO4)前驱体,将前驱体在1 400 ℃下煅烧6 h,即得微纳米晶ZrSiO4陶瓷(200~450 nm)。借助X射线衍射仪、扫描电子显微镜和密度测试仪对固化体进行分析测试,研究溶剂热温度和乙醇浓度对固化体的物相结构、微观形貌及致密性的影响规律。研究发现,溶剂热温度和乙醇浓度对固化体的合成及致密性具有较大的影响。在溶剂热温度为110 ℃及乙醇浓度为60%条件下,获得的微纳米晶ZrSiO4陶瓷具有较高密度(4.46 g/cm3)。

氧化钇掺杂块状SiO_2气凝胶的制备与表征

以正硅酸四乙酯（TEOS）为前驱体，YCl3．6H2O为掺杂剂，采用溶胶-凝胶法并结合CO2超临界干燥工艺得到了块状Y2O3-SiO2气凝胶，其中Y2O3掺杂含量控制在5wt％～30wt％范围内。利用扫描电镜（SEM）、透射电镜（TEM）、X射线衍射（XRD）、比表面积测定（BET）、X射线荧光分析（XRF）等测试手段对样品进行表征。结果表明：经过氧化钇掺杂后得到的Y2O3-SiO2气凝胶，不仅维持了SiO2气凝胶原有的空间网络结构，而且具有更高的热稳定性，经过900℃热处理2h后，10wt％Y2O3（0．447g的YCl3·6H2O）掺杂的Y2O3-SiO2气凝胶仍然处于无定形态，平均孔径约为21．3nm，比表面积高达643．8m2·g-1。

厘米级SiO_2气凝胶球体的制备及表征

以正硅酸乙酯(TEOS)为硅源,采用酸碱两步催化溶胶-凝胶法和CO_2超临界干燥技术成功制备出完整的厘米级SiO_2气凝胶球体。当配比条件为TEOS∶EtOH∶H_2O=1∶10∶4时制备的SiO_2气凝胶球体具有典型的纳米多孔网络结构。采用扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱仪(FT-IR)、孔径分布及比表面积测试仪(BET)、纳压痕技术对SiO_2气凝胶球体的表面形貌、内部结构、化学成分、比表面积、孔径分布及力学性能进行研究分析。研究表明:低温有利于制备出完整的厘米级SiO_2气凝胶球体。随着凝胶温度的增加,SiO_2气凝胶球体样品的收缩率逐渐增加,而孔隙率和比表面积逐渐减小。当凝胶温度为-5℃时,厘米级SiO_2气凝胶球体样品的平均孔径为24.8 nm,孔体积为4.9 m^3/g,比表面积高达1004.38 m^2/g,密度为0.104 g/cm^3,收缩率约为16.2%,孔隙率约为95.3%,弹性模量和硬度最大分别为8.79 MPa与5.24 MPa。

碳纳米管-二氧化钛纳米复合材料的制备、表征及其光催化性能

为了提高二氧化钛在可见光下的光催化活性,本文采用溶胶—凝胶溶剂热法制备不同负载量的碳纳米管—二氧化钛(CNTs-Ti O)纳米复合材料,采用扫描电子显微镜(SEM)2、透射电子显微镜(TEM)、X-射线衍射(XRD)等对该复合材料形貌和晶型的结构进行表征;对比CNTs-Ti O2和市售Ti O(P25)UV-vis2图谱,结果显示P25只能吸收单一的紫外光,而CNTs-Ti O2则在紫外和可见光下均有良好的光吸收性,并且随着CNTs含量的增加,CNTs-Ti O2对光的吸收性能越好;采用降解亚甲基蓝(MB)溶液研究CNTs-Ti O2的光催化活性,实验结果表明CNTs-Ti O2在可见光下具有良好的光催化性能。上述结果表明可以将CNTs-Ti O2纳米复合材料应用于降解工业废水污染物。

Effects of Ni doping contents on photocatalytic activity of B-BiVO_4 synthesized through sol-gel and impregnation two-step method

To enhance the photocatalytic activity of B-BiVO4,Ni-doped B?BiVO4photocatalyst(Ni-B-BiVO4)was synthesized through sol-gel and impregnation method.The photocatalysts were characterized by XPS,XRD,SEM,EDS,BET and UV-Vis DRS techniques.The results showed that single or double doping did not change the crystalline structure and morphology,but the particle size decreased with Ni doping.The band gap energy absorption edge of Ni-B-BiVO4shifted to a longer wavelength compared with undoped,B or Ni single doped BiVO4.More V4+and surface hydroxyl oxygen were observed in BiVO4after Ni-B co-doping.When the optimal mass fraction of Ni is0.30%,the degradation rate of MO in50min is95%for0.3Ni-B-BiVO4sample which also can effectively degrade methyl blue(MB),acid orange(AOII)II and rhodamine B(RhB).The enhanced photocatalytic activity is attributed to the synergistic effects of B and Ni doping.

A new solid acid SO_4^(2-)/TiO_2 catalyst modified with tin to synthesize 1,6-hexanediol diacrylate

A new solid acid catalyst,SO4^2-/TiO2 modified with tin,was prepared using a sol-gel method and its physicochemical properties were revealed by nitrogen adsorption-desorption,X-ray powder diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,infrared spectroscopy of adsorbed pyridine,temperature-programmed desorption of ammonia and thermal gravimetric analysis.The structure,acidity and thermal stability of the SO4^2-/TiO2-SnO2 catalyst were studied.Incorporating tin enlarged the specific surface area and decreased crystallite size of the SO4^2-/TiO2 catalyst.The total acid sites of the modified catalyst increased and Bronsted acid strength remarkably increased with increasing tin content.The decomposition temperature of sulfate radical in the modified catalyst was 100 ℃ greater and its mass loss was more than twice that of the SO4^2-/TiO2 catalyst.The SO4^2-/TiO2-SnO2 catalyst was designed to synthesize 1,6-hexanediol diacrylate by esterification of 1,6-hexanediol with crylic acid.The yield of 1,6-hexanediol diacrylate exceeded 87% under the optimal reaction conditions：crylic acid to 1,6-hexanediol molar ratio = 3.5,catalyst loading = 7%,reaction temperature = 130 ℃ and reaction time = 3 h.The modified catalyst exhibited excellent reusability and after 10 cycles the conversion of 1,6-hexanediol was above 81%.

Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalyst and Optimal Synthesis Conditions of the Support Prepared by Sol-gel Method

The support of catalyst for the direct synthesis of diphenyl carbonate （DPC） by heterogeneous catalytic reaction was prepared by the sol-gel method. Compared with activated charcoal, molecular sieve, porous ceramics, hopcalite, the support prepared by the sol-gel method has higher activity. The characterization of the support by X-ray diffraction （XRD） and transmission electron microscope （TEM） show that the mare crystal phase is Co2MnO4 and the average particle diameter is about 40 nm. The optimum conditions for synthesis of the support were determined by orthogonal experiments, which indicate that the proportion of Cu, Mn, and Co is the first important factor influencing the yield and selectivity of DPC. Temperature of calcination is the second one. The optimum conditions are： molar proportion of Cu, Mn, and Co being 1 ： 1 ： 1, temperature of calcination 700℃, drying at 100~C, temperature of water bath 85~C. The yield and selectivity of DPC in the process can reach 38% and 99% in the batch operation, respectively. The copper cobalt manganese mixed oxides chosen as the support contribute more to the high catalytic activity than the sol-gel method.

Selective catalytic reduction of NO with NH_3 over sol-gel-derived CuO-CeO_2-MnO_x/γ-Al_2O_3 catalysts

Granular CuO-CeO2-MnOx/γ-Al2O3 catalysts were synthesized by the sol-gel method. The performance of the CuO-CeO2-MnOx/γ-Al2O3 catalysts for the selective catalytic reduction (SCR) was studied in a fixed bed system. Preliminary tests were carried out to analyze the behavior of NH3 and NO over catalyst in the presence of oxygen. The optimum temperature range for SCR over the CuO-CeO2-MnOx/γ-Al2O3 catalysts is 300-400 ℃ . The catalysts maintain nearly 100% NO conversion at 350 ℃. The NH3 oxidation experiments show that both NO and N2O are produced gradually with the increase of temperature. The catalysts in this experiment have a stronger oxidation property on NH3, which improves the denitrification activity at low temperature. The over-oxidation of NH3 at high temperature is the main cause leading to a decrease in the NO conversion. The NH3 and NO desorption experiments show that NH3 and NO can be adsorbed on CuO-CeO2-MnOx/γ-Al2O3 granular catalysts. The transient response of NH3 and NO indicates that the SCR reaction proceeds in accordance with the Eley-Rideal mechanism. The adsorbed NO has little influence on the denitrification activity in SCR process.

Solvent-Triggered Self-Folding of Hydrogel Sheets

Intense investigations have been attracted to the development of materials which can recon-figure into 3D structures in response to external stimuli.Herein we report on the design and self-folding behaviors of hydrogels composed of poly(ethylene glycol)methyl ether methacry-late(OEGMA)and 2-(2-methoxyethoxy)ethyl methacrylate(MEO2MA).Upon immersion into a variety of solvents at room temperature,the resulting P(MEO2MA-co-OEGMA)hy-drogel sheets self-fold into 3D morphologies,and the observed transformation in shape is reversible.We further show that composition of the gel,gaseous environment,and prepara-tion procedure play important roles in the self-folding behavior of the resulting hydrogels.This work provides a facile approach for fabricating self-folding hydrogels.

Preparation and characterization of La_(1-x)Ce_xFe_(1-y-n)Co_yRu_nO_3 compounds

The mixed oxides La1 -xCexFe1-y-nCOyRunO3 were prepared by sol-gel method and used as catalysts for NO direct decomposition. The catalysts were characterized by DTA - TG, XRD, IR and BET. XRD analysis reveals that the samples are in a pure perovskite phase in 550 - 650 ℃, and catalyst structure keeps long else 20 decrease, and lattice parameters enhance when Ru is introduced. The characteristic peaks of samples are stronger during a temperature increase, and the particle size grows faster. IR analysis shows that the position and shape of adsorption peaks are almost the same among all samples, but with the Ru content increasing, 600 cm^-1 peak stretches to a high frequency and changes to disorder. The wave numbers move to low frequency when n = 0. 05, yet it doesn＇ t vary obviously when n 〉 0. 05. The BET surface area testifies that particle sizes of all catalysts increase with temperature increasing.

纳米氧化镍的合成研究

以硝酸镍为原料,加入柠檬酸、氨水、氢氧化钠和硫酸等添加物,通过溶剂-凝胶法以及固相法水热法合成纳米氧化镍。采用了X射线衍射仪(XRD)分析了产品结构,扫描电镜(SEM)分析了晶体形貌,粒度仪测量了纳米氧化镍的粒径。结果表明,随着温度的升高,颗粒结晶逐渐完善,产品粒径增大。固相法合成产物的粒径明显小于溶剂-凝胶法的产物。固相热分解法更加适合氧化镍粉末的制备。

Synthesis and electrochemical properties of highly dispersed Li_(4)Ti_(5)O_(12)nanocrystalline for lithium secondary batteries

A sol-gel method using lauric acid as surfactant was used to synthesize Li4Ti5O12 nanocrystals with an ultra-fine particle size distribution between 120 and 250 nm.In order to obtain the electrode materials with the best electrochemical performance,the content of lauric acid during Li4Ti5O12 synthesis was systematically studied.The physical and electrochemical properties of the synthesized samples were characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,laser particle size analysis,alternating current impedance（AC） and galvanostatic charge-discharge experiments.The highly dispersed Li4Ti5O12 nanocrystals obtained at 800 ℃ for 10 h can deliver a specific capacity of 163.3 mA-h/g at 1C rate without obvious capacity fade up to 50 cycles.The results suggest that well dispersed Li4Ti5O12 nanocrystals shorten the Li-ion diffusion length and enhance the electrochemical kinetics of the samples,which are very crucial to high rate capability.

Influence of pH value and chelating reagent on performance of Li_3V_2(PO_4)3/C cathode material

The Li3V2（PO4）3/C composite cathode material was synthesized via sol-gel method using three different chelating agents （citric acid, salicylic acid and polyacrylic acid） at pH value of 3 or 7. The crystal structure, morphology, specific surface area and electrochemical performance of the prepared samples were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and galvanostatic charge/discharge test. The results show that the effects of pH value on the performance of the prepared materials are greatly related to the chelating agents. With salicylic acid or polyacrylic acid as the chelating reagent, the structure, morphology and electrochemical performance of the samples are greatly influenced by the pH values. However, the structure of the materials with citric acid as the chelating agent does not change as pH value changes, and the materials own uniform particle size distribution and good electrochemical performance. It delivers an initial discharge capacity of 113.58 mA·h/g at 10C, remaining as high as 108.48 mA·h/g after 900 cycles, with a capacity retention of 95.51%.

BiFeO3负载钯金合金的制备及其光电催化效果的研究

以Bi(NO_3)_3.5H_2O和Fe(NO_3)_3.5H_2O作为原料,用溶剂-凝胶法制备铁酸铋纳米材料,并用NaBH_4作为还原剂将钯金合金负载在制备好的BiFeO_3纳米材料表面,运用X射线衍射仪,扫描电镜,场发射高分辨透射电镜,紫外-漫反射图谱和X射线光电子能谱等对材料进行表征,并探究了该材料在光催化、电催化和光电催化取出对硝基苯酚的效果。结果表明,负载了钯金合金的BiFeO_3光催化效果由着少量的增强,电芬顿催化降解效果十分显著,光电结合之后效果有了进一步的增强,在pH=3,200m A电流强度下4min将20mg/L的对硝基苯酚完全去除。表明负载了钯金合金的BiFeO_3是一种良好的电芬顿材料,且可用于光电结合进行催化降解。

Oxidative Coupling of Methane over Li/MgO： Catalyst and Nanocatalyst Performance

The Li/MgO catalyst and nanocatalyst were prepared by the incipient wetness impregnation and sol-gel method, respectively. The catalytic performance of the Li/MgO catalyst and nanocatalyst on oxidative coupling of methane was compared. The catalysts prepared in two ways were characterized by X-ray powder diffraction, Brunauer-Emmett-Teller surface and transmission electron microscope. The catalyst was tested at temperature of 973-1073 K with constant total pressure of 101 kPa. Experimental results showed that Li/MgO nanocatalyst in the oxidative coupling of methane would result in higher conversion of methane, higher selectivity, and higher yield of main products （ethane and ethylene） compared to ordinary catalyst. The results show the improved influence of nanoscale Li/MgO catalyst performance on oxidative coupling of methane.

Excellent Cracking Performance of Macroporous Amorphous Aluminosilicate Catalyst

Micrometer-scale macroporous aluminosilicate catalyst was prepared via the sol-gel process. Results of catalytic cracking of 1, 3, 5-triisopropylbenzene showed that the synthesized aluminosilicate catalyst exhibited much higher activity than traditional ZSM-5 zeolite under the same condition. It is worth mentioning that the polymer product selectivity of aluminosilicate was much lower than that of ZSM-5, which might be useful for implementing the catalytic cracking process. The unique structure of macroporous aluminosilicate with interconnected-macropores and continuous skeletons was believed to be responsible for its excellent catalytic activity and low polymer product selectivity. Detailed discussion on the reaction pathway was also conducted.

The impact of solvent and modifier on ZnO thin-film transistors fabricated by sol-gel process

Techniques for fabricating solution-processed zinc oxide(ZnO)-based thin-film transistors(TFTs)are feasible with solution using various routes.Here,ZnO TFTs were fabricated via sol-gel method using zinc acetate as the starting reagent with different modifiers and solvents.The ZnO thin-film semiconductors with well-controlled,preferential crystal orientation and densely packed ZnO crystals can be prepared with the optimized fabrication conditions,exhibiting excellent field-effect far exceeding those of hydrogenated amorphous silicon(a-Si:H).However,the field-effect characteristics of ZnO TFTs were different for different precursor systems which were constituted by zinc acetate,modifiers and solvents.The co-modification of acetoin and monoethanolamine for the precursor system exhibited higher extent of crystal orientation and field-effect.The maximum mobility of 7.65 cm2V-1s-1 and current on-to-off ratio of^105–106 have been obtained.

Green and efficient cycloaddition of CO2 toward epoxides over thiamine derivatives/GO aerogels under mild and solvent-free conditions

Thiamine derivatives that are cheap, readily available, non-toxic and green are used as heterogeneous catalyst for the generation of cyclic carbonates through cycloaddition of CO_2 to epoxides without the need of co-catalyst and solvent. The interaction between thiamine hydrochloride(VB_1-Cl) and substrates(CO_2 and propylene oxide) was proven by ultraviolet-visible spectroscopy and ~1H nuclear magnetic resonance analysis, and it is deduced that the synergistic action among multi-functional groups(hydroxyl, halide anion and amine) is a favorable factor for cycloaddition reaction. A series of VB_1/GO aerogels were facilely prepared through the addition of aqueous VB_1 derivatives to a suspension of GO in ethanol at room temperature. It was found that the aerogel generated through the interaction of VB_1-Cl with GO shows catalytic activity and stability higher than those of VB_1-Cl. It is because the electrostatic interaction between GO and VB_1-Cl enhances the nucleophilicity and leaving ability of anion. The effects of reaction temperature, catalyst loading, CO_2 pressure and reaction time on CO_2 cycloaddition to propylene oxide were thoroughly studied.