两种表征金属有机双层膜络合和金属薄膜氧化反应动力学的方法

建立了两种新的薄膜反应动力学表征方法, 即透射光谱法和方块电阻法, 以克服传统动力学表征手段在薄膜体系氧化与络合反应过程中应用的局限性. 以透射光谱为表征手段, 得到了Ag/TCNQ(四氰基对醌二甲烷)金属有机双层薄膜的络合反应动力学曲线; 以方块电阻为表征手段, 得到了Cu薄膜的氧化反应动力学过程.     

超声合成Cu(INA)_2·4H_2O纳米晶及催化氧化苯乙烯

以硝酸铜和异烟酸(HINA)为原料,采用超声辐射法,合成了具有一维结构的Cu(INA)2·4H2O纳米晶。采用x射线衍射、透射电镜、红外光谱等技术对该纳米晶的结构和形貌进行了表征。结果表明,超声10 min即可获目标产物;在超声辐射的条件下,通过控制反应时间,能够调控该纳米晶尺寸和形貌。以双氧水为氧化剂,考察不同纳米晶对苯乙烯的催化氧化活性,结果显示反应温度为60℃、反应时间为12 h,n(H2O2)∶n(苯乙烯)∶n(催化剂)=1800∶300∶1时,氧化产物以苯甲醛和环氧苯乙烷为主,苯乙烯的最大转化率达到85.5%,转化数(TON)为252,苯环氧乙烷的选择性为69.1%。     

形貌可控γ-硫化锰纳米晶的制备及表征

在表面修饰剂聚乙烯吡咯烷酮(PVP)存在的条件下,使氯化锰和硫化钠发生反应,在76℃无水乙醇溶液中,制备出了亚稳态的-γMnS纳米晶.当反应的搅拌速度不同时,得到的产物分别呈球形和椭球形.采用X射线衍射(XRD)、透射电镜(TEM)、紫外吸收光谱分析(UV)、X射线光电子能谱(XPS)等手段对产物的形貌、结构和光学性质进行了表征,并据此推导了不同形貌纳米微粒的生长机理.     

TiO2纳米管阵列负载不同形貌Cu2O薄膜的制备及光电性能研究

本论文采用阳极氧化法在金属钛基底上制备高度有序的TiO2纳米管阵列薄膜,然后采用脉冲电流法在TiO2纳米管阵列上沉积Cu2O,从而制备出Cu2O-TiO2纳米管阵列异质结复合薄膜。借助X射线衍射仪(XRD),场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)等表征手段,详细探讨了Cu2O沉积过程中电解液的不同扰动方式(静止、磁力搅拌和超声搅拌)对复合薄膜物相和形貌的影响。实验结果表明电解液的扰动方式会影响Cu2O沉积过程中的离子扩散和微区化学环境,从而影响Cu2O的形貌。通过漫反射紫外-可见吸收光谱(UV-Vis)和光电流性能测试可知所制备的负载Cu2O型TiO2纳米管阵列薄膜具有显著的可见光响应效应。     

银纳米粒子的形貌可调控研究

在聚乙烯吡咯烷酮(PVP)保护下,以乙二醇(EG)为还原剂制备银纳米粒子.探讨了反应物浓度、反应温度对制备的纳米银粒子形貌的影响.采用X射线衍射(XRD)和透射电镜(TEM)来表征纳米银粒子的结构和形貌.结果表明,AgNO3和PVP的浓度,AgNO3和PVP的比例以及反应温度对纳米银粒子有较大影响,反应温度控制在140 ℃至160 ℃之间,易于控制纳米银粒子的形貌.     

纳米Cu(OH)2分解温度对CuO粒度的影响

以CuSO4.5H2O和NaOH为原料,采用沉淀法制备得到Cu(OH)2纤维,再进行Cu(OH)2的分解反应.考察了在不同实验条件下温度对Cu(OH)2热分解过程的影响.结果表明:在反应温度20℃,反应终点pH值为12,搅拌速度为1 200 r.min-1,NaOH溶液的滴加速度为50 mL.min-1的反应条件下,得到的样品为纳米Cu(OH)2纤维,其直径为10~30 nm、长度为1~6μm;在固相纳米Cu(OH)2热分解制备CuO过程中CuO粒径随温度的升高而增大,在温度不超过200℃时CuO的粒径约为20 nm左右;在液相中先沉淀后升温时,产物的形貌为球形,CuO粒径随温度的升高而增大,低于80℃可得到纳米级的CuO.     

纳米Cu2O的制备及其对高氯酸铵热分解的催化性能

 以Cu(NO3)2和NaOH为原料,以水合肼为还原剂,通过沉淀法在室温下制备了纳米Cu2O. 采用X射线衍射、透射电镜和X射线光电子能谱等手段对产物进行了表征,并用热分析法考察了不同形貌的纳米Cu2O对高氯酸铵热分解的催化作用. 结果表明,通过改变NaOH溶液的加入量可分别得到长针形和多边形的纳米Cu2O. 通过调节反应物浓度可以将纳米Cu2O粒径控制在19～68 nm. 不同形貌的纳米Cu2O均能强烈催化高氯酸铵的热分解,其中分散性良好的多边形纳米Cu2O的催化活性较高,添加2%的多边形纳米Cu2O可使高氯酸铵的高温分解温度降低103 ℃,分解放热量由590 J/g增至1350 J/g.     

三维分级结构氢氧化钴的合成

以硝酸钴为钴源,采用十六烷基三甲基溴化铵(CTAB)辅助,通过水热法合成了具有三维分级结构的β-Co(OH)2微球.采用粉末X射线衍射(XRD)、能谱元素分析(EDS)和扫描电镜(SEM)对产物进行表征.实验结果表明,产物β-Co(OH)2为由直径1～2μm和厚度约500nm的纳米板组装而成的微球.考察了CTAB的浓度、pH值和温度对产物形貌的影响.结果表明,CTAB的浓度和pH值对最终产物的形貌具有重要影响,而当水热温度在140～180℃区间内,反应温度对产物的形貌无影响.通过监控不同反应时间所获产物的形貌,初步探讨了三维结构的β-Co(OH)2的生长机制.     

纳米二氧化钒薄膜的制备及红外光学性能

采用双离子束溅射方法在Si3N4/SiO2/Si基底表面沉积氧化钒薄膜, 在氮气气氛下热处理获得二氧化钒薄膜. 利用X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱(XPS)研究了热处理温度对氧化钒薄膜晶体结构、表面形貌和组分的影响, 利用傅里叶变换红外光谱(FT-IR)对二氧化钒薄膜的红外透射性能进行了测试分析. 结果表明, 所制备的氧化钒薄膜以非晶态V2O5和四方金红石结构VO2为主, 经400 ℃、2 h热处理后获得了(011)择优取向的单斜金红石结构纳米VO2薄膜, 提高热处理温度至450 ℃, 纳米结构VO2薄膜的晶粒尺寸减小. FT-IR结果显示,纳米VO2薄膜透射率对比因子超过0.99, 高温关闭状态下透射率接近0. 小晶粒尺寸纳米VO2薄膜更适合在热光开关器件领域应用.     

Cu/SiO2纳米气凝胶的组成及催化氧化CO性能研究

以硝酸铜、 正硅酸乙酯和硝酸铈为原料, 利用溶胶-凝胶-超临界流体干燥技术制备了不同n(Cu)/n(Si)的用于CO催化氧化的Cu/SiO2系列气凝胶催化剂. 利用TEM、 XRD、 物理吸附、 微型反应器和气相色谱等对试样进行了表征. TEM观察结果显示, 试样中含有介孔的气凝胶结构, 5 nm左右的Cu粒子均匀地分布在SiO2的网络组织中. BET分析结果表明, 试样的比表面积均在140 m2/g以上. XRD分析结果显示, 添加铈前后, 试样的物相发生了从Cu 2+ →Cu+ →Cu的转变, 使试样的催化活性进一步提高. 试样的催化氧化CO活性表明, 组分中铜含量的不同及铜的不同物种直接影响试样的催化氧化CO的活性, 当组分中n(Cu)/n(Si)=2时, Cu/SiO2试样上CO完全氧化的温度降为210 ℃; 于400 ℃低温焙烧, 可使试样中有效活性组分全部转变成纳米晶CuO, 并进一步降低了CO完全转变成CO2的温度; 添加少量铈组分, 使试样催化氧化CO的tstart, t50及t90温度提前20 ℃以上, Cu/SiO2试样催化氧化CO动力学研究结果显示, 试样降低CO氧化温度的实质是降低了CO氧化的反应活化能.     

Thermal oxidative degradation of isotactic polypropylene catalyzed by copper and copper oxide interfaces

The oxidative degradation of isotactic polypropylene films coated on well-defined Cu(Cu₂O), CuO_0.67, and CuO films in a temperature range of 90–120°C in a quartz-spoon-gauge-reaction vessel was studied. This catalytic reaction has been compared with the oxidation of polypropylene without copper or oxide films. The reaction vessel contained, if needed, P₂O₅ and/or KOH as “getters” for H₂O and CO₂, these substances could be menitored continuously. Cu(Cu₂O) films were transformed during oxidation of the polymer to yellow CuO_0.67 below 100°C and above this temperature to black CuO in the presence of H₂O and CO₂, whereas in the absence of these compounds CuO was formed below 100°C and CuO_0.67 at 120°C. Characteristic autoxidation curves obtained in the absence of H₂O and CO₂ showed induction periods that were shorter for copper oxide-polymer interfaces than for glass-polymer interfaces (i.e., for uncatalyzed oxidation). Abnormalities were observed for Cu(Cu₂O)-polymer interfaces because of further oxidation of Cu during the reaction. The rates of oxygen consumption were faster for CuO_0.67-polymer and CuO-polymer than for the uncatalyzed reaction; the catalytic action of CuO_0.67 was somewhat larger than that of CuO. The important observation was made that the mechanism of oxidation is not the same in the absence and presence of reaction products; that is, H₂O and CO₂. This was confirmed by ion beam scattering experiments, which also revealed that an oxidation-reduction process takes place at Cu and their oxide interfaces. A mechanism for the catalytic oxidation process, based on the ease by which copper ions are released from the metal oxides at the interface, was formulated. These ions diffuse subsequently as actions of carboxylate anions into the bulk of the polymer. Arrhenius equations of oxygen consumption are given for all cases; the energy of activation calculated for the initiation of the uncatalyzed oxidation agrees with its literature value. The energy of activation for the initiation of the catalyzed reaction was a few kilocalories lower than that for the uncatalyzed reaction. Catalytic action is mainly operative for the initiation reaction at the interface and for the decomposition of hydroperoxides by copper ions. Preventing the delivery of copper ions to the polymer would be the most efficient way of inhibiting the catalysis.     

Preparation of Porous Titania Film by Modified Sol-Gel Method and its Application to Photocatalyst

Sol-Gel derived mesoporous titania films with controlled pore sizes were prepared by surfactant templating. The coating sol was obtained by hydrolysis of Ti(OC₄H₉)₄ in ethanol/HCl solution. The gel films, prepared by spin coating on glass substrate, were dried after immersion in surfactant solutions under an atmospheric pressure. The porous films of anatase with columnar and rectangular structure were obtained after annealing at 500°C. The annealed films are transparent and 80–140 nm in thickness. Refractive indices of the films with surfactant immersion were 10–20% lower than those of the films without immersion. The spacing between the columns or rectangular grains and the grain shape were found to depend on the surfactant species. The pohoto-catalytic activity of the films for the oxidation of NO _x was improved by the surfactant modification.     

Catalytic properties of aluminum/nickel-, copper-containing oxide film compositions

The possibility of the single-step formation of nickel- and copper-containing thin-film oxide systems on aluminum by plasma electrolytic oxidation was demonstrated. The resulting structures were found to be active in the reaction of CO oxidation to CO₂ in the temperature region 300–500°C. However, the resulting structures exhibited stable catalytic activity only in the simultaneous presence of nickel and copper compounds. The films were studied using X-ray diffraction, X-ray spectroscopic analysis, X-ray photoelectron spectroscopy, and electron microscopy. The resulting films exhibited an essentially inhomogeneous composition through the thickness. Electrolyte elements such as nickel, copper, sodium, and phosphorus were concentrated at the surface. Nickel occurred as Ni²⁺, and copper occurred as Cu⁺ and Cu²⁺. The surface contained carbon in detectable amounts.     

铁铜双金属催化剂选择性催化氧化氨为氮气

固定铜铁的总质量不变, 采用共浸渍法制备铜铁双金属催化剂. 为了更好地了解催化剂的性质, 分别用N₂吸附-脱附、H₂-程序升温还原(H₂-TPR)、NH₃-程序升温脱附(NH₃-TPD)、X射线衍射(XRD)和X射线光电子能谱(XPS)方法对制备的催化剂进行表征. 研究发现在100000 h^-1空速下, 铜铁双金属催化剂呈现出好的活性和氮气选择性. 在低温区, 随着铜含量的增加, 活性和氮气的选择性增加, 然而在高温区氮气的选择性直接和铁的含量相关. 其中催化剂Fe_0.25Cu_0.75/ZSM-5, 在350℃氨的转化率达到最高, 在300℃氮气的选择性上升到97%. Fe_0.75Cu_0.25/ZSM-5 在500 ℃有很高的氮气选择性甚至可以达到98%. 并且所有的催化剂均产生很少的N₂O副产物. 表征结果显示催化剂的酸量和铜物种的含量可以影响催化剂的活性, 并且高的还原能力和铁含量有助于高温氮气选择性的提高.     

氧化/还原预处理对Cu2O/AC催化甲醇氧化羰基化的影响

将醋酸铜热解制备的Cu₂O/AC(活性炭)催化剂,在氧化(O₂/N₂)和还原(H₂/N₂、CO/N₂)气氛下进行预处理。350 ℃下预处理4 h,氧化气氛中Cu₂O完全被氧化为CuO,还原气氛中Cu₂O被还原为单质铜。经CO/N₂预处理的催化剂表面Cu⁰分散性好,催化活性显著升高。在常压固定床微型反应装置上测试,在140 ℃的反应温度下,碳酸二甲酯的时空收率和选择性分别达到了261.9 mg/(g·h)和74.7%。反应后,还原气氛(H₂/N₂、CO/N₂)预处理的催化剂与Cu₂O/AC催化剂中铜物种价态组成趋于一致,催化活性亦趋于一致。关联反应前后催化剂表面铜物种的变化和催化活性的差异,可以认为Cu⁰具有较高的初始催化活性,Cu₂O活性和价态均较为稳定,CuO活性较低。     

Effect of temperature on the action spectra of pristine and Cu-grafted titania

The dependence of action spectra for pristine and Cu-grafted anatase TiO₂ on temperature for photocatalytic acetone vapor oxidation at 40, 100 and 140 °C is described. The results obtained demonstrate the thermal inhibition of activity under UV irradiation for pristine titania at 140 °C, while for TiO₂ grafted with copper species this inhibition is suppressed. Photonic efficiency of visible radiation energy utilization by Cu-grafted titania increases with temperature and exceeds the corresponding value for pure anatase in the investigated temperature range.     

硫化铜精矿物相分析及氧化机理研究

在海轮运输及样品的制备过程中,进口硫化铜精矿氧化的现象普遍存在,使得货物的重量和铜品位发生变化,但该种现象的机理研究不多。针对硫化铜精矿的物相进行分析,并对硫化铜精矿的氧化机理进行研究。首先,利用显微镜、扫描电子显微镜、X射线荧光光谱(XRF)、X射线衍射(XRD)等方法对两个硫化铜精矿进行物相分析,并对其中的主要元素和含铜主要物相进行定量化学分析。再次,利用热重分析(TGA)研究这两个硫化铜精矿发生氧化反应的温度,结果表明在400℃时铜精矿样品重量开始增加,在约650℃重量达到顶峰,随后重量开始下降。最后,分别在400、650和900℃对两个铜精矿样品进行灼烧,并利用XRF和XRD方法进行测定,从而研究铜精矿的氧化机理,结果表明在400℃时,出现了铁的氧化物和铜的硫氧化物,说明黄铜矿和黄铁矿开始氧化,但还没有完全氧化,在650℃时,化合物中的氧含量继续增加,硫含量逐步减少,在900℃时,铜和铁的化合物只剩氧化物,硫已全部被氧化。结果表明,硫化铜精矿中的铜、铁等元素在温度和时间的作用下逐步氧化,硫氧化物的产生为中间态,氧化物的产生为最终态。实验解释了进口硫化铜精矿氧化的原理,有助于贸易双方减少分歧,有助于海关技术中心更规范地制备样品,降低数据误差。     

Copper carboxylate formation in the thermal oxidative degradation of atactic polypropylene on copper oxide films

The thermal oxidation of atactic polypropylene on CuO_0.67 surfaces in air was studied using IR reflection-absorption spectroscopy. Degradative losses of primary, secondary, and tertiary alkyl hydrogens were observed. At 60 and 73°C, carboxylic acids are the primary degradation products, while at 85 and 100°C, copper carboxylate formation predominates and CuO_0.67 is decomposed. The distinct change in the oxidative mechanisms between 73 and 85°C apparently is related to an irreversible thermal transition in the atactic polypropylene films, which may favor carboxylate production by increasing the permeability of the films to oxygen and water vapor.     

Nitridation of Niobium Pentoxide Films in Ammonia by Rapid Thermal Processing

The feasibility of niobium oxynitride formation through nitridation of niobium pentoxide films in ammonia by rapid thermal processing (RTP) was investigated. Niobium films 200 and 500 nm thick were deposited by sputtering on Si(100) wafers covered by a 100 nm thick thermally grown SiO₂ layer. These as‐deposited films exhibited distinct texture effects. They were processed in three steps using an RTP system. The as‐deposited niobium films were first nitridated in an ammonia atmosphere at 1000 °C for 1 min and then oxidised in molecular oxygen at temperatures ranging from 400 to 600 °C. Those samples in which a single Nb₂O₅ phase was determined after oxidation were additionally nitridated in ammonia at 1000 °C for 1 min. Investigations show that surface roughness of the samples after oxidation of niobium films first nitridated in ammonia is lower than after direct oxidation of as‐deposited films in oxygen, although the niobium pentoxide phase formed after annealing was the same in both cases. We explain this result as being due to the large expansion of the niobium lattice during the direct oxidation of the niobium film in molecular oxygen and also to the high oxidation rate of the as‐deposited niobium film in oxygen. By incorporation of oxygen in the crystal lattice of niobium and rapid formation of niobium pentoxide, substantial intrinsic stress was built up in the film, frequently resulting in delamination of the film from the substrate. Nitrogen hinders the diffusion of oxygen in nitridated films, which leads to a decrease of the oxidation rate and thus slower formation of Nb₂O₅. Nitridation of the completely oxidised niobium films in ammonia leads to the formation of niobium oxynitride and niobium nitride phases.     

Enrichment,incorporation and oxidation of copper during anodising of aluminium–copper alloys

Porous anodic oxides generated on copper‐containing aluminium alloys are less regular than anodic oxides generated on pure aluminium. Specifically, a porous oxide morphology comprising layers of embryo pores, generated by a cyclic process of oxide film growth and oxygen evolution, is generally observed. In this work, the relation between the oxidation behaviour of copper during anodising and the specific porous oxide film morphology was investigated by electrochemical techniques, transmission electron microscopy and Rutherford backscattering spectroscopy (RBS). It was found that the anodising potential determines the oxidation behaviour of copper, and the latter determines the porous oxide morphology. At low voltage, relatively straight pores with continuous cell walls were obtained on Al? Cu alloys, but selective oxidation of aluminium atoms resulted in the occlusion of copper‐containing metallic nanoparticles in the anodic film. At higher potentials, copper oxidation promoted oxygen evolution within the barrier layer, and generation of a less regular film morphology. RBS, performed on Al? Cu alloy specimens, revealed a high volume fraction of copper atoms in the anodic films generated at low potentials and a reduced amount of copper atoms in the anodic oxide films generated at high potentials. Copyright © 2009 John Wiley & Sons, Ltd.