铜钴硫化物材料的制备及其电化学性能研究

本文以三水合硝酸铜、六水合硝酸钴分别作为铜源和钴源,通过水热法和离子交换法成功合成了铜钴氧化物和铜钴硫化物。SEM结果显示铜钴硫化物和铜钴硫化物都具有纳米花状结构。其中,铜钴硫化物的纳米薄片更薄,大约为40~50 nm,团聚现象更低。用恒电流法测得在1.0 A/g的放电电流密度下,其比容可达572 F/g。在2.0 A/g的放电电流密度下循环3000次,其容量保持率可达77%。     

一种具有花状形貌的纳米氢氧化钴材料及制备方法

一种具有花状形貌的纳米氢氧化钴材料及其制备方法,该材料通过自组装的方法合成。室温下油水两相体系中,利用金属钴与碱反应,在软模板的参与下,利用软模板的导向作用和包裹作用制备得到。该方法操作简单,容易控制。     

稀土掺杂花状钨酸钙纳米晶溶剂 热法合成及其发光性能

以水-乙二胺二元溶剂热法及热处理合成了四方晶系稀土掺杂花状钨酸钙纳米晶。考察了混合溶剂比例、煅烧温度及掺杂稀土离子等条件对钨酸钙发光性能的影响,并分析了其形成机理。利用X射线衍射（XRD）、扫描电镜（SEM）、傅里叶变换红外光谱（FT-IR）和光致发光（PL）光谱等对钨酸钙结构、形貌及其性能进行了表征。结果表明：在水与乙二胺体积比为1∶2、反应温度为160 ℃、反应时间为24 h条件下合成前驱物,前驱物经800 ℃煅烧得到四方晶系稀土掺杂花状钨酸钙纳米晶;掺杂不同稀土离子得到在紫外光激发下发出不同颜色光的钨酸钙基荧光粉。     

花状ZnO的水热合成与表征

以金属锌为原料,引入偶联表面活性剂作为晶体生长控制剂,在温和的水热条件(150℃)下一步合成了花状纳米结构的ZnO.使用XRD,TEM,SEM,SAED等测试手段,对产物的化学组成和形貌特征进行了分析和表征.结果表明,花状ZnO纳米结构由ZnO纳米棒组成,该ZnO纳米棒为六方晶系且表现为单晶性质.ZnO纳米棒纯度高、粒径较小、长直、光滑而且大多一端聚集而另一端向四周放射性分布,呈较完美的花状结构.初步探讨了ZnO单晶纳米棒和花状ZnO纳米结构的形成机理.分析表明,ZnO纳米棒及其花状结构的形成与偶联表面括性剂特殊的性质及分子结构有关.     

采用聚乙二醇200作溶剂合成花状Ni和NiS纳米结构

以聚乙二醇（PEG）200作溶剂，合成了花状Ni和NiS纳米结构。用X射线衍射仪（XRD）和扫描电子显微镜（SEM）对产物进行了表征。实验结果表明：产物形貌均为由交织的纳米片组成的花状Ni和NiS结构，其中纳米片的厚度分别为约10nm和20nm。对溶剂和有机表面活性剂对NiS纳米结构形貌的影响也进行了研究。实验结果表明PEG200在合成花状Ni和NiS纳米结构起着关键性作用。     

水热法制备Zn-Mg-Al花状水滑石

采用水热法,以尿素为沉淀剂,Zn(NO3)2、Mg(NO3)2和Al(NO3)3为原料,在120℃下连续反应10 h后制备了Zn-Mg-Al水滑石纳米片以及由纳米片组装成的花状结构水滑石。利用XRD、FTIR、TG-DTA、ICP和SEM分别对产物的尺寸、结构和形貌进行了分析。结果表明,合成的水滑石具有均一的花状形貌,花状晶体直径约8μm左右,构成花状结构的纳米片厚度约为100 nm,花状水滑石晶体具有良好的"记忆效应"。初步阐释了花状水滑石的可能形成机理。     

水热合成三维花状薄水铝石及其形成机理

在水溶液体系中,利用十六烷基三甲基溴化铵(CTAB)作为模板剂,水热合成了由纳米薄片自组装成的三维花状薄水铝石。采用XRD,SEM和TEM对其物相结构和形貌进行了分析,研究了反应温度和反应时间对产物形貌的影响。研究结果表明:在反应温度为160℃和反应时间为24h时,得到形貌规则统一、分散均匀的花状薄水铝石。该花状结构是由厚50nm的纳米薄片自组装而成,直径550～800nm,在其形成过程中,模板剂CTAB起到关键作用,并推断了纳米薄片自组装花状结构的形成机理。     

稀土Sm掺杂棒花状ZnO的制备及其光催化性能研究

由硝酸锌、硝酸钐、十二烷基硫酸钠制备Sm掺杂棒花状纳米氧化锌,考察制备温度、分散剂浓度、Sm掺杂等因素对氧化锌形貌和光催化性能的影响,采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、能量色散X射线谱(EDS)、X射线光电子能谱(XPS)进行表征。结果表明,制备温度、分散剂浓度、Sm掺杂量等对棒花状纳米氧化锌的形貌和光催化性能有显著的影响。在60℃下,分散剂浓度为28 mmol/L、Sm掺杂量为5%时,所制备的棒花状纳米氧化锌的形貌规整且光催化性能最好。     

一种磷酸锌纳米结构材料的简易合成

在环境条件下,无表面活性剂或模板存在,通过简单的湿化学法,合成了3D花状磷酸锌[Zn3(PO4)24H2O]纳米结构。采用扫描电子显微镜、透射电子显微镜、X-射线衍射仪和红外分光光度计等对样品进行表征显示,3D花状磷酸锌是由平均厚度为35~40 nm的二维纳米薄片自组装而成,聚集在一起的具有分层结构的花瓣,形成了开放的3D花朵。水浴陈化温度和反应体系的pH值是合成完美的3D花状磷酸锌的关键因素。这种简易的合成方法,为磷酸锌纳米结构的生产提供了重要的实验依据。     

稀土Sm掺杂棒花状ZnO的制备及其光催化性能研究

由硝酸锌、硝酸钐、十二烷基硫酸钠制备Sm掺杂棒花状纳米氧化锌,考察制备温度、分散剂浓度、Sm掺杂等因素对氧化锌形貌和光催化性能的影响,采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、能量色散X射线谱(EDS)、X射线光电子能谱(XPS)进行表征。结果表明,制备温度、分散剂浓度、Sm掺杂量等对棒花状纳米氧化锌的形貌和光催化性能有显著的影响。在60℃下,分散剂浓度为28 mmol/L、Sm掺杂量为5%时,所制备的棒花状纳米氧化锌的形貌规整且光催化性能最好。     

CO oxidation in the presence of hydrogen on Au/TiO2 catalyst: an FTIR–MS study

A new and simple method for obtaining highly dispersed Co/ZrO₂ catalyst is described. The presence of ethylenediamine during the preparation of Co/ZrO₂ was studied and compared with a reference catalyst conventionally prepared. Addition of an aqueous solution of ethylenediamine to a cobalt nitrate solution had a dramatic effect on the catalytic performance of the catalyst as compared with a reference catalyst. This promotional effect was explained in terms of higher cobalt dispersion in the catalysts using ethylenediamine. The reason why ethylenediamine improves dispersion of the cobalt species was explained in terms of the size of the stable complex ions which could be formed in situ during impregnation. The best catalytic results were also explained in terms of Co-support interaction since new cobalt species were reducible at lower temperatures.     

Conductance behavior of some tris(ethylenediamine)cobalt(III) complexes and their ion association in some dipolar aprotic solvents

The conductance behavior of dilute solutions of tris(ethylenediamine)cobalt(III) perchlorate in acetonitrile(AN), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and propylene carbonate (PC) was studied at 25°C. From the conductivities of these solutions the limiting molar conductivity of the tris(ethylenediamine)cobalt(III) ion and the ion association constant of the ion pair formed between the tris(ethylenediamine)cobalt(III) and the perchlorate ion have been determined. The Walden products of the tris(ethylenediamine)cobalt(III) ion in these solvents were found to be approximately constant. It was concluded from the ion association constants obtained that the degree of ion association was determined by not only the dielectric constant but also the basicity of these solvents. The ion association constants of tris(ethylenediamine)cobalt(III) ion with some anions which were determined from the conductivities of the dilute DMF and DMSO solutions at 25°C were found to increase to a great extent with the decrease in crystallographic radii of anions. The tendency could not be explained by the usual electrostatic theory. The conductance behaviour is discussed from the view point of the solvent effects which influence the ion-ion interaction.     

Additional effects of cobalt precursor and zirconia support modifications for the design of efficient VOC oxidation catalysts

The influence of the ZrO₂ support modification by Y₂O₃ and the presence of ethylenediamine (“en”) during the preparation of Co/ZrO₂ were studied and compared with a reference catalyst conventionally prepared by impregnation of ZrO₂ with an aqueous solution of Co(NO₃)₂. The effect of the en/Co molar ratio (x = 1–3) was studied. Activation of cobalt species was followed by differential thermal and thermogravimetric analyses (DTA/TG) analyses and by specific surface area measurements which evidence the complete cobalt precursor decomposition at 450 °C, whatever the support composition and the en/Co molar ratio. The addition of an aqueous solution of ethylenediamine to a cobalt nitrate solution led to a strong increase in the catalytic activity of the activated solids for the toluene deep oxidation as compared to the reference catalyst. The best catalytic results were explained in terms of cobalt oxides dispersion (X-ray diffraction (XRD)) and also in terms of Co-support interaction (H₂-temperature-programmed reduction (TPR)). The generated cobalt species were reducible at much lower temperatures and were more active in the toluene total oxidation. Finally, an efficient catalyst was produced combining the modifications of the support by yttrium oxide and of the precursor (use of ethylenediamine).     

Modified Co3O4/ZrO2 catalysts for VOC emissions abatement

The catalytic activity study of cobalt oxides dispersed on different supports evidenced first the highest performances of zirconia based catalysts in the reaction of toluene oxidation. The influence of the presence of ethylenediamine (en) during the preparation of Co/ZrO₂ and the ZrO₂ support modification by Y₂O₃ were then studied and compared with reference catalyst prepared conventionally by impregnation of ZrO₂ with an aqueous solution of Co(NO₃)₂. Addition of an aqueous solution of ethylenediamine to a cobalt nitrate solution led to a strong increase on the catalytic activity of the activated solids in the toluene deep oxidation as compared with the reference catalyst. The best catalytic results were explained in terms of cobalt oxides dispersion but also in terms of Co–support interaction. The generated cobalt species were reducible at much lower temperatures and then were more active in the toluene total oxidation. Finally an efficient catalyst for VOC oxidation was produced combining the modifications of ZrO₂ by yttrium and of the precursor.     

NO与乙二胺合钴离子气液反应动力学研究

用乙二胺合钴水溶液实现NO的液相催化氧化,乙二胺合钴离子作氧化催化剂,废气中残存的氧气作氧化剂,使NO的氧化和吸收同时进行。采用搅拌反应器分别在有氧和无氧时,对NO与乙二胺合钴离子气液反应动力学进行研究,结果表明当乙二胺合钴浓度大于0.02mol/L时,过程为气膜控制。氧的存在有利于NO的吸收,其分压越大,越有利于NO的氧化和脱除。气体中有氧存在时,最佳NO脱除温度为50℃,并推得吸收反应动力学方程。     

Characterization,activity and selectivity of ethylenediamine modified Co/SiO<Subscript>2</Subscript> FT catalyst prepared by sol-gel method

Co/SiO₂ catalysts were prepared by sol-gel method with varied en (ethylenediamine)/Co molar ratios under the same pH. Their physical-chemical properties were compared with those prepared with similar en/Co molar ratios at natural pH or without adding ethylenediamine. Regardless of pH, the catalysts prepared using ethylenediamine possessed high microporosity, which led to a better selectivity to C_5–18 hydrocarbons, versus the catalyst possessing higher mesoporosity which showed slightly higher C₁₈₊ selectivity. As enough positions in the coordination sphere were blocked by ethanediamine ligands, the formation of cobalt silicate disfavored for (en/Co=2) catalysts, which resulted in the higher activity in FT reaction. Whereas the catalysts prepared with lower or higher en/Co molar ratio both showed lower activity due to the formation of [(SiO)Co(en)(EtOH)₃] species or the electronic adsorption of cobalt complexes in the negatively charged silica surface, respectively. However, for the catalyst without using ethylenediamine, the lowest activity and the highest CH₄ selectivity obtained due to its much lower reducibility. This work was presented at the 7 ^th China-Korea Workshop on Clean Energy Technology held at Taiyuan, Shanxi, China, June 26–28, 2008.     

Effect of fuel type on structural and physicochemical properties of solution combustion synthesized CoCr2O4 ceramic pigment nanoparticles

Due to importance and wide applications, CoCr₂O₄ ceramic pigment nanoparticles were synthesized via low-temperature solution combustion route by different fuels including ethylenediamine/oxalic acid, ethylenediamine/citric acid, oxalic acid/citric acid and ethylenediamine/oxalic acid/citric acid. Physicochemical properties of the synthesized samples were determined by different techniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX) and color/optical properties were evaluated based on CIELAB system by spectrophotometer. Moreover, thermodynamic considerations of combustion reactions for CoCr₂O₄ nanopigments formation in terms of calculated adiabatic flame temperature and enthalpy of combustion reaction were studied. The Comparison of results and data showed that cobalt chromite pigment nanoparticles synthesized by using ethylenediamine/citric acid and ethylenediamine/oxalic acid/citric acid fuels exhibited higher purity, smaller crystallite size and lower degree agglomeration.     

Preparation,characterization, and catalytic activity of polymer supported ethylenediamine and glycine cobalt complexes

Polymer-supported ethylenediamine cobalt chloride and glycine cobalt chloride have been prepared with 2, 5, and 10% divinylbenzene (DVB) styrene copolymer macroporous beads by sequential attachment of the bifunctional ligand followed by treatment of metal salt with the functionalized polymer beads. Physicochemical properties like moisture content, bulk density, swelling, and thermal stability of the supported catalysts have been studied. Probable structures have been proposed based on spectroscopic data obtained from electronic, infrared, far-infrared, and in some cases ESCA. Catalytic activity have been tested for hydrogenation of 1-octene and decomposition of hydrogen peroxide as model reactions.     

Electrolytic preparation of an isomer pair of cobalt (III) mixed complexes

The electrolytic preparation of some coordination compounds of cobalt (III), such as the amino-, sulphato- and acetato-complexes, had already been described [1–5]: the presence of the ligand in the electrolysed solution stabilizes the + 3 oxidation state of cobalt, which is generated anodically. All the cobalt (III) complexes prepared up to date by electrochemical methods contain various numbers of the same ligand group, without having regard to the coordinated water molecules. In this note we deal with the electrolytic preparation of two mixed complexes of cobalt (III),cis- andtrans-[Co en₂ (OCOCH₃)₂]ClO₄, where en=ethylenediamine.Work carrid out with the aid of C.N.R. (Consiglio Nazionale delle Ricerche).     

Polymer-metal complexes,based on poly(itaconic acid ester) derivatives,as catalysts for the decomposition of hydrogen peroxide

Poly(methyl itaconates) and poly(heptyl itaconates), modified with ethylene diamine (EN) and tetraethylene pentamine (TETRAEN) side chains, were complexed with cobalt and copper ions, and their efficiencies as catalysts for the decomposition of hydrogen peroxide were assessed. All the polymer complexes studied were found to be active catalysts, but it was observed that the polymers with TETRAEN side chain, when complexed with CoCl₂ and CuCl₂ were less efficient than polymers with EN side chains which were complexed with trans-dichlorobis(ethylenediamine) cobalt(III) chloride, trans-[Co(EN)₂Cl₂]Cl. One feature of interest was that when the alkyl side chain of the poly itaconate was heptyl the rate of decomposition of hydrogen peroxide was faster than when the alkyl group was methyl.