纳米级金红石相二氧化钛晶胞数原子数和晶面原子数的计算与研究

以矿物晶体结构、晶体化学理论为基础，通过对纳米级金红石相二氧化钛颗粒的晶胞数、原子数及平行（001）面的表面原子数的计算，讨论了它们与纳米级金红石二氧化钛颗粒尺度大小的相关规律，并结合纳米微粒的特性对其进行了简要分析。     

锰氧化物的合成及在锂离子电池中的应用进展

能源是限制人类发展的重要因素,近年来随着新能源的发展,人们对于储能设备的要求也越来越高,其中,锂离子电池被认为是最具有发展前途的储能设备之一。目前,商用锂离子电池的负极材料以石墨为主,石墨虽然具有良好的导电性,但理论容量较低,已逐渐无法满足高能设备的大容量需求。过渡金属锰氧化物由于储量丰富、氧化形态多样、结构多元、理论比容量高、环境友好等特点,被认为是锂离子电池理想的替代负极材料之一。本文详细介绍了近年来4种锰氧化物（MnO、Mn₂O₃、Mn₃O₄和MnO₂）分别在纳米化和复合结构构筑两方面的材料设计及合成,总结比较了4种锰氧化物用作锂离子电池负极材料的性能,展望了锰氧化物在锂离子电池负极材料领域的发展前景和方向。     

超亲水毛细芯环路热管启动及热性能分析

为解决电子设备高热通量下的散热问题,采用H₂O₂氧化法对烧结毛细芯进行了超亲水改性,研究了毛细芯表面润湿性对吸液性能的影响。并将改性后的超亲水毛细芯应用到环路热管内,研究了倾斜角度及加热功率对超亲水毛细芯环路热管的换热特性的影响。实验结果表明：超亲水毛细芯的吸液速度增加,吸液时间较亲水毛细芯减小了3.52ms;与普通亲水毛细芯环路热管相比,在加热功率Q=200W时,超亲水毛细芯环路热管蒸发器中心温度降低了约6.0℃,在Q=20W时启动时间与温度分别降低了33s与2.5℃。同时发现超亲水毛细芯环路热管在正重力状态时的运行温度更低,热阻较小,最低热阻仅为0.084℃/W。     

Performance and characterization of supported metal catalysts for complete oxidation of formaldehyde at low temperatures

Activities of a series of metals (Pt, Pd, Rh, Cu, Mn) supported on TiO₂ were investigated for the catalytic oxidation of formaldehyde. Among them, Pt/TiO₂ was found to be the most promising catalyst. Nitrogen adsorption, hydrogen chemisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature programmed reduction (TPR) by H₂ were used to characterize the platinum catalysts. Using Ce_0.8Zr_0.2O₂, Ce_0.2Zr_0.8O₂, SiO₂ as supports instead of TiO₂, the activity sequence of 0.6 wt.% platinum with respect to the supports is TiO₂ > SiO₂ > Ce_0.8Zr_0.2O₂ > Ce_0.2Zr_0.8O₂, and this appears to be correlated with the dispersion of platinum on supports rather than the specific surface areas of the catalysts. Platinum loading on TiO₂ has a great effect on the catalytic activity, and 0.6 wt.% Pt/TiO₂ catalyst was observed to be the most active, which could be attributed to the well-dispersed platinum surface phase. The reduction temperature greatly affects the particle size and, consequently, the catalytic activity. The smaller particle size of platinum, due to its high dispersion on support, has a positive effect on catalytic performance. Increasing formaldehyde concentration and space velocity exhibits an inhibiting effect on the catalytic activity.     

Selective catalytic reduction of nitric oxide by propane over vanadia-titania aerogels

An investigation has been carried out of the effect of vanadia loading on the activity and selectivity ofV₂O₅TiO₂ aerogel catalysts, prepared by a two-step procedure, for the reduction of NO by propane. The structure of catalysts have been characterized by laser Raman spectroscopy and XRD measurements. At vanadia loading levels below ca. 4.4 wt%, the vanadia is present in the form of coordinated polymeric species, whereas crystallites of V₂O₅ are formed at higher vanadia contents. At this critical level of 4.4 wt% V₂O₅, the kinetic measurements showed also a maximum in the activity per mass of catalyst which very likely indicated that the coordinated polymeric surface species are more active than crystalline V₂O₅. The selectivity towards the formation of dinitrogen decreased as the loading increased, presumably because of the formation of larger polymeric species and V₂O₅ crystallites, below and above the critical loading level, respectively. For the reduction of NO by propane, titania supported vanadia aerogel catalysts are significantly more active, per mass of catalyst, and more selective towards N₂ formation than conventionalV₂O₅TiO₂ and V₂O₅Al₂O₃ aerogel catalysts, at vanadia loading levels below ca. 11 wt%.     

Carbon induced phase transformation in electrospun TiO2/multiwall carbon nanotube nanofibers

Nanofibers of titania and composite nanofibers of titania and multiwall carbon nanotubes were synthesized by electrospinning using a sol-gel process combined with activated carbon nanotubes. The relationships of treatment temperature, carbon nanotube content on the crystal phase, fiber morphology, and electric properties are reported. It is found that the rutile phase becomes more prominent at low heat treatment temperatures with an increase of carbon content in nanofibers, be it for higher amount of carbon due to reducing atmosphere or due to an increase in MWCNT. Atmospheric control and lower heat treatment temperatures enable crystalline nanocomposite fibers of anatase where the level of rutile is below the detection limit of XRD or Raman spectroscopy. This work provides a new path to fabricate electrospun TiO₂/MWCNT nanocomposite nanofibers with limited C-induced rutile phase.     

Preparation of hierarchical WO3 dendrites and their applications in NO2 sensing

Hierarchical WO₃ dendrites were synthesized via low-cost and environmental-friendly solvothermal strategy. Characterization results indicated that WO₃ dendrites were composed of several multi-directional dendritic nanosheets. To further understand the formation of WO₃ dendrites, time-dependent experiments were carried out and formation mechanism was investigated. Since such dendritic structures rarely occurred in the field of gas sensing, the synthesized WO₃ dendrites were subjected to detailed NO₂ sensing tests. Results demonstrated that WO₃ dendrites based sensors had low detection limit (200 ppb) and fast response and recovery (7 s, 12 s to 5 ppm NO₂). Moreover, the sensor was also highly sensitive, selective and stable at low optimal operating temperature of 140 °C.     

锰氧化物材料的制备及应用进展

锰作为一种常见的变价金属,其在催化反应中能够起到很好的催化作用。而且锰的氧化物作为最常用的过渡金属氧化物之一,因其较易调控出较大的比表面积、较强的吸附性能、较好的氧化还原能力以及较好的低温催化活性,已经成为了环境治理以及能源领域中的研究热点。介绍了MnO_x催化剂材料的合成、性质,以及在CO催化氧化、挥发性有机污染物的催化氧化、气体的吸附与分离以及电池的电极材料等应用方面一些最新的研究进展。     

纳米结构尖晶石型锂离子电池电极材料的研究进展

综述了近年来纳米结构尖晶石型锂离子电池电极材料（LiMn2O4、LiNi0.5Mn1.5O4和Li4Ti5O12）的研究进展,重点对纳米结构与电化学性能之间的关联性进行了总结和探讨,并对纳米结构电极材料的发展前景进行了展望。     

PAM辅助水热法制备形貌可控的ZnO纳米结构(英文)

采用PAM辅助水热法制备了形貌可控的ZnO纳米晶。X射线衍射分析表明,分别以水和丙三醇为溶剂制备的短棒和棒状的ZnO纳米晶是纤锌矿结构。场发射扫描电镜结果显示,短棒状ZnO的直径约200nm,长约1.5μm,而棒状ZnO的直径约100nm,长度约3μm。当ZnO形貌从短棒向棒状转变时,晶体纵横比从7.5转变成30。荧光光谱分析表明,位于400-450nm的紫峰强度随着形貌从短棒向棒状转变时增大,表明更细更长的ZnO一维纳米结构的缺陷越多;位于520-550nm的绿峰强度随着形貌从短棒向棒状转变时增大,表明更细更长的ZnO一维纳米结构的氧空位越多。并对不同溶剂对ZnO纳米晶形貌的影响机制及ZnO纳米晶在水热条件下的生长机理进行了探讨。