三维花状铜基复合物及其低温煅烧衍生物用于高效析氧反应

采用一种简单易行的方法来制备铜基电化学催化剂,该催化剂用于析氧反应。利用沸石咪唑酯骨架-67(ZIF-67)为前驱体,通过铜离子刻蚀合成新型铜基复合物(命名为Cu-NF)。它具有特殊的三维花状形貌和中孔结构,其形貌受铜离子与ZIF-67的质量比的影响。随后,Cu-NF经过低温煅烧处理,得到了不同温度下的衍生物,而煅烧过程并未改变其原始形貌。煅烧温度决定了活性物种的组成及含量,并增强了材料的多孔性。其中,300 ℃煅烧得到的产物Cu-NF-300具有最好的析氧反应性能：在 1.0 mol·L^-1 KOH 溶液中,过电位低达 347 mV,塔菲尔斜率为 93 mV·dec^-1。该材料电化学性能的提高归因于其三维结构以及低温煅烧所带来的活化作用。     

淀粉改性SiO2载体的预处理温度 对其负载的铜基催化剂甲醇转化性能的影响

以淀粉为改性剂制备了淀粉改性的SiO₂载体(SSi),经不同温度(T)焙烧处理后再负载活性铜组分(10%,质量分数),获得一系列铜基催化剂(Cu/SSi-T);采用TG、FT-IR、XRD、H₂-TPR、SEM和氮气吸附等技术对载体和催化剂进行了表征,并考察了其对甲醇低温转化反应催化性能。结果显示,淀粉的存在可以减缓载体表面硅羟基的脱除速度;载体表面硅羟基有利于铜物种的分散,从而提高催化剂的活性。不同预处理温度能调变载体表面硅羟基浓度、比表面积和孔结构,并对催化剂上铜物种的晶粒大小及其催化性能有显著的影响。     

Structural and optical properties of CdO nanowires synthesized from Cd(OH)2 precursors by calcination

CdO nanowires were produced by calcination process using Cd(OH)₂nanowires as precursors. The Cd(OH)₂ nanowires were synthesized via arc discharge method submerged in de‐ionized water. Transmission electron microscopy (TEM) analysis of the as‐synthesized Cd(OH)₂ nanowires revealed that nanowire morphology was abundant form with the diameters range from 5 to 40 nm. In addition to the nanowire morphology, Cd(OH)₂ nanospheres and hexagonal shaped nanoparticles were also displayed. The Cd(OH)₂ nanostructures were used as precursors to produce CdO nanowires and calcinated in air at 400 °C for four hours. After calcination, the structural, morphological and optical properties of the as‐synthesized CdO nanowires were characterized by means of TEM, selected area electron diffraction (SAED), X‐ray diffraction (XRD) and UV‐vis spectroscopy. The XRD and SAED techniques showed that the as‐synthesized Cd(OH)₂ nanostructures could be transformed into CdO nanostructures after the calcination process. TEM results revealed that the as‐synthesized CdO nanowires were 5–30 nm in diameter and shorter than corresponding Cd(OH)₂ nanowires. In addition, the diameters of the spherical or irregular CdO nanoparticles ranged from 20 nm to 50 nm. UV‐vis spectroscopy analysis was showed that the direct gap of the CdO nanowires were found to be 2.60 eV which is slightly higher than the earlier reported values of the bulk CdO for direct band gaps (2.3 eV) due to quantum size effect. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

若干物理处理方法对稀土荧光粉Y2O3:Eu3+发光性能的影响

采用物理法对商品化稀土荧光粉Y2O3：Eu^3＋进行改性，考察了真空干燥温度、焙烧温度对其发光性能的影响。SEM和TEM观测结果表明，经过200℃真空干燥后，随着焙烧温度的增加，荧光粉的分散性得到改善，且以纳米颗粒为主（5～85nm）。XRD测量结果表明，随着焙烧温度的增加，Y203：Eu^3＋的结晶度逐渐增加。发射光谱测试结果表明，真空干燥温度为200℃，焙烧温度为1200℃时得到的样品的发光性能较好。     

阴离子柱撑磁性镍铝水滑石的制备及表征

将磁性基质与镍铝类水滑石组装制备磁性镍铝水滑石。研究了磁性基质含量、焙烧温度对水滑石磁学性能及结构的影响。并采用SEM、XRD、FT-IR、DSC-TG及VSM(vibrating sample magnetometer)等测试技术对制备的水滑石的结构和磁学性能进行了表征。结果表明,磁性基质的引入赋予镍铝类水滑石以超顺磁性,磁性基质含量对样品的磁性能起决定性作用,磁性镍铝水滑石的比饱和磁化强度随磁性基质含量的增加而增加;XRD分析结果表明,磁性基质的引入没有改变水滑石的典型层状结构且随着磁性基质含量的增多,磁性镍铝水滑石的特征衍射峰的衍射强度有所降低,n(Ni2 )/n(Fe2 )达到20时,XRD谱图中开始出现Fe3O4晶相的衍射峰;前驱体经1073K焙烧后出现尖晶石晶相;DSC-TG分析结果表明,磁性基质的引入没有改变水滑石2个阶段吸热的特征,这与XRD的检测结果一致。     

不同温度焙烧的Au-Pd/SiO2催化剂上甲醇选择性氧化制备甲酸甲酯

以溶胶固定法制备了Au-Pd/SiO₂催化剂,考察了催化剂焙烧温度对甲醇选择氧化制甲酸甲酯反应性能的影响。在200~500℃,400℃焙烧的Au-Pd/SiO₂具有最好的低温催化性能,在室温下就有活性,反应温度为100℃时甲醇转化率为25.3%,甲酸甲酯的选择性为100%。采用BET、XRD、UV-vis DRS、XPS、TEM和DRIFTS技术对催化剂进行表征,结果表明,催化剂中活性组分Au和Pd的高分散性,合适的Au和Pd粒径,Au-Pd合金的形成以及Au和Pd之间的强相互作用力,有利于甲醇氧化为甲酸甲酯反应的进行。初步推测出了甲醇在Au-Pd/SiO₂上氧化为甲酸甲酯的反应机理,甲醇在Au-Pd/SiO₂催化剂上是通过甲氧基中间体得到甲酸甲酯的。     

焙烧温度对CuO/Fe2O3/ZrO2甲醇水蒸气重整制氢催化剂性能的影响

采用XRD、TPR和EXAFS等手段，考察了焙烧温度对CuO/Fe2O3/ZrO2物化性能和甲醇水蒸气重整制氢活性及其选择性的影响。结果表明，催化剂中氧化铜的晶粒随着焙烧温度的提高而增大，铜的配位环境发生变化。在焙烧温度623K－723K范围内，对甲醇水蒸气重整反应的甲醇转化率和氢选择性影响较小，其结构参数变化值较小。当焙烧温度提高到923K时，催化剂的活性因ZrO2晶化和铜组分的聚焦而显著降低。结果铁的加入使ZrO2的相变温度向后推移，并且有效地阻止了CuO颗粒的聚集。     

Optimization of electrospun TiO2 nanofibers photoanode film for dye‐sensitized solar cells through interfacial pre‐treatment,controllable calcination,and surface post‐treatment

Dye‐sensitized solar cells (DSSCs) are generally viewed as next generation photovoltaic devices. Electrospun TiO₂ nanofibers (NFs) film can be used to construct photoanode for DSSCs. A systematic strategy to optimize such a novel photoanode material of DSSCs was elaborated in this paper. A main drawback of NFs photoanode is the poor adhesion of ceramic NFs film to its conductive glass substrate. This problem can be well solved by sandwiching a transition layer between the overlaid NFs film and the underlaid glass substrate through an interfacial spin‐coating pre‐treatment. After electrospinning, a controllable calcination is also indispensable for obtaining an ideal nanofibrous mat with good morphology and adhesion. The choice of calcination parameters including temperature, holding time, and heating rate was discussed in detail. In addition, a surface TiCl₄ post‐treatment can further improve adhesion as well as strength for the NFs photoanode film. And the performance of the resulting DSSCs will benefit from the TiCl₄ post‐treatment. Copyright © 2013 John Wiley & Sons, Ltd.     

纳米Au/TS-1催化剂的制备及用于甲醇羰基化体系

采用负压沉积沉淀法、等体积浸渍法、负压等体积浸渍法等方法制备了纳米Au/TS-1催化剂,研究了深床焙烧和等离子体焙烧,以及焙烧温度和焙烧气氛对催化剂中纳米金粒子大小和催化性能的影响,并采用ICP、TEM、XRD、UV-vis、XPS对催化剂金粒子进行了物化性能表征,采用甲醇羰基化制乙酸甲酯反应表征催化性能.结果表明,不同制备方法、不同焙烧方法、不同焙烧温度和焙烧气氛对负载型纳米Au/TS-1沸石分子筛催化剂中金粒子的大小、形貌、物化性质和催化性能有明显影响.其中,3种制备方法中,氢气气氛下焙烧均比空气和氮气气氛下焙烧得到的催化剂的金粒子尺寸更小,分散更均匀,约为5~10 nm.与其它方法相比,负压沉积沉淀法可制得分散更均匀的金粒子,Au/TS-1沸石催化剂中的金粒子尺寸更小,平均粒径为1~5 nm.催化性能评价结果显示,3种方法制备出的负载型金催化剂用于催化甲醇羰基化制乙酸甲酯反应体系中,甲醇的转化率分别为85%、75%、60%,乙酸甲酯选择性可高达68%,反应温度200℃为最好.