Elongational flow mixing for manufacturing of graphite nanoplatelet/polystyrene composites

Manufacturing strategy is of prime importance for the appropriate incorporation of filler into a polymeric matrix, and this in particular refers to nanofillers. Herein, direct‐graphite nanoplatelets are used as filler in polystyrene. The as‐received filler material contained microscopic size agglomerates formed by nanoscopic size graphite nanoplatelets. Refining of the microagglomerates (break‐up) and production of, desirably, single graphene layers (exfoliation) is the ultimate target for controlling production and thus properties of the present materials. Several processing methods including microcompounding, roll‐milling/calendering, Brabender mixing chamber, and solvent processing are used and compared with elongational flow mixing by a newly developed mixer. For the present system, sonication with surfactant assistance solvent processing yields both good micro deagglomeration and production of thin graphene nanostacks/layers. Also the elongational flow mixing efficiently refines the microagglomerates. Solvent processing and microcompounding are more efficient than the other processes in the production of exfoliated thin graphene stacks/layers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

富勒烯衍生物对有机薄膜电池开路电压的提高

有机太阳能电池凭借其制造成本低廉、质轻、可溶性加工等优势而不断引起科研工作者的关注。富勒烯是公认的聚合物太阳能电池最佳受体材料,针对其存在LUMO能级较低,不利于获得高开路电压的光伏器件的问题,对富勒烯类材料进行结构改性,提高其LUMO能级,从而达到提高开路电压(Voc)改善器件效率的目的.并就近年来报道的通过改善富勒烯衍生物受体材料结构来提高器件开路电压的方法在文中进行归纳,阐述聚合物太阳能电池性能与富勒烯衍生物受体材料结构之间的密切关系,为今后开发高效的聚合物太阳能电池受体材料提供参考。.     

球碳载体钕系催化丁二烯聚合的动力学参数

讨论了球碳载体钕系催化剂在不同陈化温度和陈化时间与催化丁二烯聚合活性的关系，同时测定了有关动力学参数，结果表明，同一陈化温度下，表观速率常数（ｋ）随聚合温度升高而增大，而同一聚合温度的ｋ值在０～７０℃陈化温度下先升后降，以３０℃为最佳，陈化温度不影响表观活化能，其值约为３５ｋｊ／ｍｏｌ；链增长速率常数和链转移速率常数均随聚合温度的升高而增大。     

Superconducting state in M3C60: Strong vs. weak coupling

The superconducting state in the doped fullerenes is due to strong coupling (e.g.,2.1 for Rb₃C₆₀) to low-frequency intramolecular modes _L 250 cm^–1 (^21/2). The analysis is based on an equation describingT _c for any strength of the coupling and on recent isotope effect and NMR data.     

Versatility of Carbon Enables All Carbon Based Perovskite Solar Cells to Achieve High Efficiency and High Stability

Carbon‐based perovskite solar cells (PVSCs) without hole transport materials are promising for their high stability and low cost, but the electron transporting layer (ETL) of TiO₂ is notorious for inflicting hysteresis and instability. In view of its electron accepting ability, C₆₀ is used to replace TiO₂ for the ETL, forming a so‐called all carbon based PVSC. With a device structure of fluorine‐doped tin oxide (FTO)/C₆₀/methylammonium lead iodide (MAPbI₃)/carbon, a power conversion efficiency (PCE) is attained up to 15.38% without hysteresis, much higher than that of the TiO₂ ones (12.06% with obvious hysteresis). The C₆₀ ETL is found to effectively improve electron extraction, suppress charge recombination, and reduce the sub‐bandgap states at the interface with MAPbI₃. Moreover, the all carbon based PVSCs are shown to resist moisture and ion migration, leading to a much higher operational stability under ambient, humid, and light‐soaking conditions. To make it an even more genuine all carbon based PVSC, it is further attempted to use graphene as the transparent conductive electrode, reaping a PCE of 13.93%. The high performance of all carbon based PVSCs stems from the bonding flexibility and electronic versatility of carbon, promising commercial developments on account of their favorable balance of cost, efficiency, and stability.     

Quadruple Junction Polymer Solar Cells with Four Complementary Absorber Layers

A monolithic two‐terminal solution‐processed quadruple junction polymer solar cell in an n–i–p (inverted) configuration with four complementary polymer:fullerene active bulk‐heterojunction layers is presented. The subcells possess different optical bandgaps ranging from 1.90 to 1.13 eV. Optical modeling using the transfer matrix formalism enables prediction of the fraction of absorbed photons from sunlight in each subcell and determine the optimal combination of layer thicknesses. The quadruple junction cell features an open‐circuit voltage of 2.45 V and has a power conversion efficiency of 7.6%, only slightly less than the modeled value of 8.2%. The external quantum efficiency spectrum, determined with appropriate light and voltage bias conditions, exhibits in general an excellent agreement with modeled spectrum. The device performance is presently limited by bimolecular recombination, which prevents using thick photoactive layers that could absorb light more efficiently.     

New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene–Cubane Reactions

As a new category of solids, crystalline materials constructed with amorphous building blocks expand the structure categorization of solids, for which designing such new structures and understanding the corresponding formation mechanisms are fundamentally important. Unlike previous reports, new amorphous carbon clusters constructed ordered carbon phases are found here by compressing C₈H₈/C₆₀ cocrystals, in which the highly energetic cubane (C₈H₈) exhibits unusual roles as to the structure formation and transformations under pressure. The significant role of C₈H₈ is to stabilize the boundary interactions of the highly compressed or collapsed C₆₀ clusters which preserves their long‐range ordered arrangement up to 45 GPa. With increasing time at high pressure, the gradual random bonding between C₈H₈ and carbon clusters, due to “energy release” of highly compressed cubane, leads to the loss of the ability of C₈H₈ to stabilize the carbon cluster arrangement. Thus a transition from short‐range disorder to long‐range disorder (amorphization) occurs in the formed material. The spontaneous bonding reconstruction most likely results in a 3D network in the material, which can create ring cracks on diamond anvils.     

Stabilization of IPR open-shell fullerenes C74 (D3h) and C76 (Td) in radical addition reactions

The analysis of previously experimentally obtained and characterized by X-ray perfluoralkyl derivatives C₇₄(D_3h)(CF₃)₁₂ and C₇₆(T_d)(CF₃)₁₂ have shown for the first time that the most feasible positions of addends are phenalenyl-radical substructures and/or hexagons with delocalized pi-bonds, that lead to stabilization of these molecules. The most probable addition positions of H^? and CF₃^? radicals to the «missing» fullerenes С₇₄ (D_3h) and С₇₆ (T_d) are revealed on the basis of developed approach of molecular modeling followed by DFT calculations. Radical addition reactions seem to be useful for stabilization of open-shell fullerenes.     

Detection of oxygen species generated of C70-Ag2Se heterojunction photocatalysts with excellent visible light driven photocatalytic performance

Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substance in natural water environment and can completely destroy various organic pollutants in wastewaters. In this study, a novel Ag₂Se-C₇₀ heterojunction photocatalysts were successfully prepared. Surface area and pore volumes of the Ag₂Se-C₇₀ samples showed decrease due to deposition of Ag₂Se. The generations of ROS were detected through the oxidation reaction from DPCI to DPCO. The photocurrent density and the PGO effect increase in the case with the modified C₇₀. The PGO effect of the C₇₀ modified with Ag₂Se composites is increased significantly due to the synergetic effect between the C₇₀ and the Ag₂Se nanoparticles.     

球碳钕系催化丁二烯-异戊二烯共聚物的红外光谱测定

红外光谱法（ＦＴ ＩＲ）测定了（Ｃ６０Ｘ）载体钕系催化剂引发不同丁二烯 异戊二烯摩尔比所得共聚物的组成变化规律,提出了球碳９７３ｃｍ－１吸收带可能与共聚物主链上双键与Ｃ６０分子骨架间存在π π相互作用有关的解释。