Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials?

The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy.     

Facile Synthesis and Tensile Behavior of TiO<Subscript>2</Subscript> One-Dimensional Nanostructures

High-yield synthesis of TiO₂ one-dimensional (1D) nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO₂ with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.     

我国利用高岭土、膨润土制备矿物纳米材料的研发现状与展望

文章介绍了多孔纳米粘土矿物、纳米高岭土、多孔状纳米煅烧高岭土、纳米级莫来石二氧化硅复合粉体、纳米级高纯莫来石、纳米蒙脱石、聚合物／纳米蒙脱石复合材料等矿物纳米材料方面的研发现状与进展、并分析非金属矿物高岭土、膨润土在纳米材料领域发展过程中的重要性、经济性与可操作性。指出了国家在相关政策上的鼓励与支持，是加速发展我国矿物纳米材料之重要前题。     

Hierarchical Self‐Organization of Nanomaterials into Two‐Dimensional Arrays Using Functional Polymer Scaffold

Fabrication of two and three‐dimensional nanostructures requires the development of new methodologies for the assembly of molecular/macromolecular objects on substrates in predetermined arrangements. Templated self‐assembly approach is a powerful strategy for the creation of materials from assembly of molecular components or nanoparticles. The present study describes the development of a facile, template directed self‐assembly of (metal/organic) nanomaterials into periodic micro‐ and nanostructures. The positioning and the organization of nanomaterials into spatially well‐defined arrays were achieved using an amphiphilic conjugated polymer‐aided, self‐organization process. Arrays of honeycomb patterns formed from conjugated C₁₂PPPOH film with homogenous distribution of metal/organic nanomaterials. Our approach offers a straightforward and inexpensive method of preparation for hybrid thin films without environmentally controlled chambers or sophisticated instruments as compared to multistep micro‐fabrication techniques.     

贵金属纳米材料及其产业化过程

对贵金属纳米材料的种类、用途、产业化方法和发展趋势等内容进行了综合评述。贵金属纳米材料包括贵金属单质和化合物纳米粉体材料、贵金属新型大分子纳米材料和贵金属膜材料等几大类，随着国家对黄金和白银专控政策的放开和纳米技术与传统的贵金属深加工产业的结合，贵金属纳米材料作为一类在工业生产中起着重要作用的新材料，具有良好的发展前景。非负载型贵金属纳米粉末常用化学还原法、光化学合成法、电化学沉积法以及热物理法等方法进行生产，负载型贵金属纳米粉体材料则一般采取化学法（浸渍法）、离子交换法和吸附法等）生产，这两类贵金属粉体材料是目前获得工业应用最多的贵金属纳米材料，贵金属纳米材料的产业化过程有其特殊性，其发展趋势可以概括为改造、隆本、集约化和多功能化。     

Photocatalytic degradation of dairy effluent using AgTiO2 nanostructures/polyurethane nanofiber membrane

Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver–titanium dioxide nanofibers (AgTiO₂ NFs) and silver–titanium dioxide nanoparticles (AgTiO₂ NPs) were individually incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth and continuous, with an average diameter of about 550 nm, and held their nanofibrous morphology even after more than 2 h of photocatalytic degradation of DE, due to the good stability of PU in the aqueous solutions, which indicates good imprisoning of the functional photocatalysts. The PU–AgTiO₂ NPs and PU–AgTiO₂ NFs were effective materials for degradation of DE, even after two successive cycles. PU–AgTiO₂ NPs and PU–AgTiO₂ NFs showed a maximum degradation of 75% and 95%, respectively after 2 h. The significant enhancement of degradation in the PU–Ag–TiO₂ NPs and PU–Ag–TiO₂ NFs is attributed to the photoactivity of Ag–TiO₂ material under visible light irradiation.