Hierarchical structural complexity in atomically precise nanocluster frameworks

The supramolecular chemistry of nanoclusters is a flourishing area of nano-research; however, the controllable assembly of cluster nano-building blocks in different arrays remains challenging. In this work, we report the hierarchical structural complexity of atomically precise nanoclusters in micrometric linear chains (1D array), grid networks (2D array) and superstructures (3D array). In the crystal lattice, the Ag₂₉(SSR)₁₂(PPh₃)₄ nanoclusters can be viewed as unassembled cluster dots (Ag₂₉–0D). In the presence of Cs⁺ cations, the Ag₂₉(SSR)₁₂ nano-building blocks are selectively assembled into distinct arrays with different oxygen-carrying solvent molecules―Cs@Ag₂₉(SSR)₁₂(DMF)_x as 1D linear chains (Ag₂₉–1D), Cs@Ag₂₉(SSR)₁₂(NMP)_x as 2D grid networks (Ag₂₉–2D), and Cs@Ag₂₉(SSR)₁₂(TMS)_x as 3D superstructures (Ag₂₉–3D). Such self-assemblies of these Ag₂₉(SSR)₁₂ units have not only been observed in their crystalline state, but also in their amorphous state. Due to the diverse surface structures and crystalline packing modes, these Ag₂₉-based assemblies manifest distinguishable optical absorptions and emissions in both solutions and crystallized films. Furthermore, the surface areas of the nanocluster crystals are evaluated, the maximum value of which occurs when the cluster nano-building blocks are assembled into 2D arrays (i.e. Ag₂₉–2D). Overall, this work presents an exciting example of the hierarchical assembly of atomically precise nanoclusters by simply controlling the adsorbed molecules on the cluster surface.     

Encapsulating metal organic framework into hollow mesoporous carbon sphere as efficient oxygen bifunctional electrocatalyst

Applying metal organic frameworks (MOFs) in electrochemical systems is a currently emerging field owing to the rich metal nodes and highly specific surface area of MOFs. However, the problems for MOFs that need to be solved urgently are poor electrical conductivity and low ion transport. Here we present a facile in situ growth method for the rational synthesis of MOFs@hollow mesoporous carbon spheres (HMCS) yolk–shell-structured hybrid material for the first time. The size of the encapsulated Zeolitic Imidazolate Framework-67 (ZIF-67) is well controlled to 100 nm due to the spatial confinement effect of HMCS, and the electrical conductivity of ZIF-67 is also increased significantly. The ZIF@HMCS-25% hybrid material obtained exhibits a highly efficient oxygen reduction reaction activity with 0.823 V (vs. reversible hydrogen electrode) half-wave potential and an even higher kinetic current density (J_K = 13.8 mA cm⁻²) than commercial Pt/C. ZIF@HMCS-25% also displays excellent oxygen evolution reaction performance and the overpotential of ZIF@HMCS-25% at 10 mA cm⁻² is 407 mV. In addition, ZIF@HMCS-25% is further employed as an air electrode for a rechargeable Zn–air battery, exhibiting a high power density (120.2 mW cm⁻² at 171.4 mA cm⁻²) and long-term charge/discharge stability (80 h at 5 mA cm⁻²). This MOFs@HMCS yolk–shell design provides a versatile method for the application of MOFs as electrocatalysts directly.     

CIGS薄膜太阳能电池的制备工艺和产业化前景

文章介绍了CIGS薄膜太阳能电池的结构及特性、吸收层的主要制备工艺、并简述了其产业化前景。     

现浇砼空心无梁楼盖GBF高强薄壁管安装方法

山东师范大学长清校区理科教学楼工程B1、B2区采用现浇空心无梁楼盖,采用GBF高强薄壁空心管成孔,施工过程中采用Φ14钢筋加工成定型限位插排,使空心管定位准确,安装快捷,同时利用8#钢丝对空心管进行固定,成功解决了混凝土浇筑过程中空心管的上浮问题,提高了工作效率.     

高被引科学家人才流动的计量分析

 对分子生物学与遗传学、物理学、化学、数学和计算机科学五个领域高被引科学家的人才流动现象进行了定量研究和分析。分别从机构层面和国家层面对不同领域高被引科学家的职业流动频次和流动频率进行了分析,结果显示出,大部分高被引科学家的机构流动频次在2-5之间,半数以上的高被引科学家有过国外工作经历。每经过6-7年高被引科学家更换一个工作单位;此外还进一步对分子生物学与遗传学领域高被引科学家的国际人才流动去向进行了观察和分析。