MoP nanosheets supported on biomass-derived carbon flake: One-step facile preparation and application as a novel high-active electrocatalyst toward hydrogen evolution reaction

Searching for Pt-free hydrogen evolution reaction (HER) electrocatalysts based on low-cost and eartha-bundant materials is a crucial task for hydrogen-based energy industry. In this work, we demonstrate the one-step facile preparation of MoP nanosheets supported on carbon flake via a solid-state reaction with the use of (NH4)(6)Mo7O24 center dot 4H(2)O, NaH2PO4 center dot 2H(2)O and a biomass, sodium alginate, as Mo, P and C sources, respectively. When used as a novel HER electrocatalyst, such composites are excellent in activity and durability in acidic electrolytes. Moreover, they are also active in neutral electrolytes. (C) 2014 Elsevier B.V. All rights reserved

Multifunctional Nd3+-sensitized upconversion nanomaterials for synchronous tumor diagnosis and treatment

Core-shell structured Nd3+-sensitized NaYF4:Yb/Nd/Er@NaYF4:Nd@mSiO(2) nanoparticles (NPs) were designed and synthesized. The NaYF4:Yb/Nd/Er@NaYF4:Nd core imparts the nanomaterials with luminescence properties for upconversion optical imaging under 808 nm laser irradiation, whereas the mesoporous SiO2 shell allows the nanomaterials to be loaded with anticancer drug doxorubicin (DOX). In vivo toxicity assessment has confirmed that the NPs have low systematic toxicity in healthy mice. In vivo antitumor activity shows that the nanocomposites exhibit greater antitumor efficacy than pure DOX. As a result, the composite nanomaterials can serve as nanotheranostic materials for synchronous upconversion luminescence imaging under 808 nm laser irradiation, and as anticancer drug delivery vehicles, so as to integrate the diagnosis and treatment of cancers in vivo

Cheap carbon black-based high-performance electrocatalysts for oxygen reduction reaction

A family of cheap carbon black based Fe-N-x/C electrocatalysts with superhigh-performance for oxygen reduction reaction (ORR) were synthesized. The one with Fe 10 wt% and N 1.57 wt% shows the best performance. The activity order of different active sites for ORR was revealed firstly: Fe-N-4/2-C > Fe-4-N-C > N-C >> Fe-4-C approximate to C

Self-assembly of an organic-inorganic hybrid nanoflower as an efficient biomimetic catalyst for self-activated tandem reactions

The BSA-Cu-3(PO4)(2)center dot 3H(2)O hybrid nanoflower was used as a biomimetic catalyst with excellent catalytic activity, durability and stability. When GOx was used as the protein component, this composite could realize self-activated cascade catalysis. Our nanoflower system could also be used to decompose organic pollutants with high efficiency

A hybrid linkage mode between T2,2 and T3 selenide clusters

A multi-level 3D selenide framework in an In3+-Ge4+ system was synthesized. The interconnection between super-supertetrahedral T2,2 and supertetrahedral T3 clusters via their terminal Se2- leads to a previously unknown hybrid T2,2-T3 linkage mode. The synthetic realization of this material represents another new level of complexity and demonstrates the versatility in the construction and property-engineering of cluster-based semiconducting materials

Conformations and dynamics of single flexible ring polymers in simple shear flow

The conformational, orientational and dynamical properties of single flexible ring polymers under simple shear flow are studied by a hybrid multiparticle collision dynamics simulation method. We found that contributing to the continuous stretching and constant alignment in the tank-treading motion, ring polymers undergo weaker deformation and orientation in the gradient direction, and show similar behaviors in the voracity direction compared with their linear analogues. We also present the mechanisms of both tumbling and tank-treading motions based on the time trajectories of relative deformation and orientation. Furthermore, the simulation results reveal that the special structures and unique dynamics of ring polymers in simple shear flow have an obvious influence on rheological properties, which are qualitatively different from the properties of linear polymers. (C) 2015 Elsevier Ltd. All rights reserved

Titanium dioxide encapsulated in nitrogen-doped carbon enhances the activity and durability of platinum catalyst for Methanol electro-oxidation reaction

The development of advanced catalyst supports is a promising route to obtain active and durable electrocatalysts for methanol electro-oxidation reaction. In the current work, nitrogen-doped carbon encapsulated titanium dioxide composite (TiO2@NCx) is constructed and serves as support material for the Pt catalyst. The TiO2@NCx support is fabricated by the procedure of an in-situ polymerization and subsequent pyrolysis. The synthesized Pt/TiO2@NCx catalysts show enhanced electrocatalytic performance towards methanol electro-oxidation compared with the commercial Pt/C catalyst. The enhancement can be ascribed to combinatory effect of N-doped carbon and TiO2, in which the tolerance to CO-poisoning and the intrinsic kinetics of methanol oxidation reaction are simultaneously improved by the bifunctional mechanism and the electronic effect. As a result, the as-developed TiO2@NCx composite is a promising catalyst support material for the application in fuel cell. (C) 2015 Elsevier B.V. All rights reserved

有机半导体薄膜中的载流子传输特性研究

在有机发光二极管中，载流子的注入和传输特性直接影响器件的性能，由于有机半导体分子结构及其薄膜形态的多样性和掺杂体系中分子-分子之间相互作用的不同行为，使有机半导体的传输特性变得更为复杂。因此，深入系统地研究有机半导体中载流子的传输行为，对建立传输特性与器件性能的关系，改进器件性能具有非常重要的意义。本论文以掺杂和非掺杂的有机电子传输材料以及共混材料体系为研究对象，用阻抗和电流-电压特性方法系统地研究了它们薄膜中载流子的传输特性。论文的具体工作内容如下： 1. 研究了不同厚度Alq3薄膜的电子传输特性。稳态电流-电压特性研究表明，Alq3薄膜的电子传输符合陷阱呈幂指数分布的空间电荷限制电流模型，总的陷阱密度约为8.6×1017 cm-3。导纳法测定的Alq3薄膜的电子迁移率（10-7 ~ 10-5 cm2V-1s-1）与薄膜厚度、电场强度相关。当薄膜厚度小于150 nm时，电子迁移率随电场增...In organic light emitting diodes, the carriers injection and transport properties directly affect the performance of the devices. In organic semiconductors, the charge transport characteristics become more complex because of the variety of molecular structures and film morphologies and the different behaviors of the interactions between molecules. Therefore, the systematical investigation on the charge transport characteristics in organic semiconductors is very important for establishing the relationship between the transport properties and device performance, and improving the performance of the devices. In this thesis, we have systematically investigated the carrier transport properties in doped and undoped organic electron-transport materials and blends by admittance spectroscopy techni..

过氧化物引发聚(3-羟基丁酸酯-co-4-羟基丁酸酯)交联及增容共混体系结构与性能的研究

来源于可再生资源的聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]和聚乳酸（PLA）作为生物基高分子材料这一大家族中的优秀代表，因其具有良好的生物降解性和生物相容性而成为具有巨大发展潜力的环境友好型高分子材料，越来越受到人们的重视。然而，作为脂肪族聚酯，P(3HB-co-4HB)和PLA自身存在以下缺陷：热稳定性差，结晶缓慢，尺寸稳定性差，熔体强度低，力学性能差等等，极大地限制了它们的广泛应用。 本论文针对P(3HB-co-4HB)和PLA的不足，提出了利用过氧化物引发交联的方法改变P(3HB-co-4HB)的分子链结构和凝聚态结构，旨在提高其熔体强度和改变其结晶行为；以及将此方法应用到P(3HB-co-4HB)和PLA共混体系，期望两组分间发生交联反应、增强两组分相容性、提高材料力学性能，开发出性能优良的生物可降解材料。由此发展出一种新的生物可降解脂肪族聚酯的改性...Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] and poly(L- lactide) (PLA) derived from renewable resources have received considerable attentions due to their good biocompatibility and biodegradability. However, as aliphatic polyesters, the inherent deficiencies of P(3HB-co-4HB) and PLA, such as the limited thermal stability, slow crystallization rate, limited dimensional stability, low melt strength, and poor mechanical properties, etc. have limited their wide applications. In the present dissertation, considering the disadvantages of P(3HB-co-4HB) and PLA, branched/crosslinked P(3HB-co-4HB) was prepared by peroxide to enhance the rheological properties and tailor the crystallization behavior through changing the structure of polymer chain firstly. Secondly, this method was i..

IR Spectral Study of Mesoscale Process during Urea Crystallization from Aqueous Solution

Unravelling the mesoscale process and the dynamic heterogeneous structures that appear nil the mesoscale in a crystallization system is important in designing and fabricating functional crystalline materials. Recent experimental observations show the existence of stable dusters and amorphous intermediates before the formation of a crystalline solid, which seems to contradict classical nucleation theory. Here we show by in situ infrared Spectroscopy and theoretical calculation that the liquid/solid phase transformation of urea proceeds through the agglomeration of primary clusters. The phase transformation pathway of urea in solution has been identified; in which urea molecules initially aggregate into one-dimensional (1D) molecular chains, and then these 1D molecular chains assemble to 2D plane-like and 3D net-like clusters. Crystalline urea with P-42(1)m symmetry can be formed when these 3D net-like clusters overcome a critical size. Both experimental and. calculated results demonstrate that the liquid/solid. phase transformation of urea in aqueous solution obeys the classical nucleation theory. Finally, a morphology diagram of urea is provided on the basis of relative chemical bonding energy density. This morphology diagram can be used to understand the multiple anisotropic geometries, for how urea crystals in an aqueous solution system can be laid out. Our results demonstrate the concept of identifying a particular mesoscale process in a urea crystallization system by both in situ vibration spectroscopy observations and chemical bonding calculations