Nanomechanical properties of polyaniline and azo polyelectrolyte multilayer films

<正>Nanomechanical properties of multilayer films constructed of polyaniline(PANI) and azobeneze-containing polyelectrolytes(PNACN and PPAPE) were studied by using nanoindentation method.The multilayer films were prepared by the electrostatic layer-by-layer self-assembly through alternately dipping in the polymer solutions.The multilayer films deposited onto the glass slides after proper dry were used for the nanomechanical property testing.The nanomechanical measurement indicated that the PANI/PNACN and PANI/PPAPE multilayers possessed the mean elastic modulus of 5.42 GPa and 4.35 GPa,and hardness of 0.26 GPa and 0.18 GPa,respectively.The nanoscratch properties of the PANI/PNACN and PANI/PPAPE multilayer films were also measured.The critical loads of PANI/PNACN and PANI/PPAPE films were 103.52 mN and 100.59 mN.The degree of electrostatic cross-linking in the multilayers could be altered by exposing the films to aqueous solutions with different pH values.As a result,the modulus and hardness of the multilayer films were changed through the solvent treatment.Both modulus and hardness of the PANI/PNACN films obviously increased after dipping the multilayer films in solutions with pH in a range from 9 to 11.     

Self-assembled polyelectrolyte multilayer membranes with highly improved pervaporation separation of ethanol/water mixtures

Ethanol/water pervaporation through ultrathin polyelectrolyte multilayer membranes is described. The membranes were prepared by the layer-by-layer technique, i.e. by alternating sequential adsorption of cationic and anionic polyelectrolytes on a porous support. The separation capability was optimized by variation of the chemical structure of the polyelectrolytes, by variation of pH and ionic strength of the polyelectrolyte solutions used for membrane preparation and by annealing of the polyelectrolyte membranes. It was found that the separation is mainly affected by the charge density of the polyelectrolytes which is controlled by the chemical structure and the degree of ionisation of the polar groups. Selectivity for water was highest, if polyelectrolytes of high charge density such as polyethyleneimine (PEI), polyvinylamine (PVA) and polyvinylsulfate (PVS) were used and if the pH of the polyelectrolyte solutions was equal to the mean of the pK_a values of the corresponding cationic and anionic polyelectrolyte. Best results were obtained for PVA/PVS and PEI/PVS membranes which are characterized in detail with regard to their separation behavior.     

还原氧化石墨烯表面聚苯胺纳米阵列的制备及电化学电容性能

本文以阳极氧化铝(AAO)膜为模板,通过恒电位法在自组装还原氧化石墨烯(rGO)膜表面制备有序聚苯胺(PANI)纳米线阵列。通过拉曼光谱和场发射扫描电子显微镜分别对其结构和微观形貌进行了表征,并对PANI纳米线阵列的电化学电容性能进行了测试。结果表明,rGO膜表面可电沉积PANI,电沉积得到的PANI纳米线阵列具有比PANI薄膜材料更高的电容和比电容。     

Graphene from electrochemical exfoliation and its direct applications in enhanced energy storage devices

Graphite was electrochemically exfoliated in mixtures of room temperature ionic liquids and deionized water containing lithium salts to produce functionalized graphenes and such an electrochemical exfoliation technique can be directly used in making primary battery electrodes with significantly enhanced specific energy capacity.     

Architected porous metals in electrochemical energy storage

Porous metallic structures are regularly used in electrochemical energy storage (EES) devices as supports, current collectors, or active electrode materials. Bulk metal porosification, dealloying, welding, or chemical synthesis routes involving crystal growth or self-assembly, for example, can sometimes provide limited control of porous length scale, ordering, periodicity, reproducibility, porosity, and surface area. Additive manufacturing has shown the potential to revolutionize the fabrication of architected metals, allowing complex geometries not usually possible by traditional methods, by enabling complete design freedom of a porous metal based on the required physical or chemical property to be exploited. We discuss properties of porous metal structures in EES devices and provide some opinions on how architected metals may alleviate issues with electrochemically active porous metal current collectors, and provide opportunities for optimum design based on electrochemical characteristics required by batteries, supercapacitors or other electrochemical devices.     

Clay and DOPA containing polyelectrolyte multilayer film for imparting anticorrosion properties to galvanized steel

A facile and green approach is developed to impart remarkable protection against corrosion to galvanized steel. A protecting multilayer film is formed by alternating the deposition of a polycation bearing catechol groups, used as corrosion inhibitors, with clay that induces barrier properties. This coating does not affect the esthetical aspect of the surface and does not release any toxic molecules in the environment.     

Self-assembled oligo(phenylene ethynylene)s/graphene nanocomposite with improved electrochemical performances for dopamine determination

In this work, a novel 1,4-bis (4- aminophenylethynyl)benzene (OPE-NH₂, a symmetric linear conjugated oligo(phenylene ethynylene)s derive) and chemically-reduced graphene oxide (rGO) nanocomposite (OPE-NH₂/rGO) was synthesized by a simple self-assembly method. The OPE-NH₂/rGO nanocomposite was stable and water soluble. The formation of OPE-NH₂/rGO nanocomposite was ascribed to the π–π stacking interaction between the conjugated structure of OPE-NH₂ and rGO as well as the electrostatic force between the amino group of OPE-NH₂ and the carboxyl group on rGO, which was characterized by FT-IR, UV–vis spectra and fluorescence spectra. The OPE-NH₂/rGO nanocomposite exhibited significantly improved electrocatalytic activity to the oxidization of dopamine (DA) than that of rGO or OPE-NH₂. The electrochemical performances of OPE-NH₂/rGO were dependent on the OPE-NH₂ contents, and OPE-NH₂ content of 5 wt% exhibited the highest activity. Compared with that of rGO, the nanocomposite presented superior high sensitivity with detection limit of 5 nM, excellent selectivity, wide linear range (0.01–60 μM) and good stability on the determination of DA. The practical application of the developed OPE-NH₂/rGO nanocomposite modified electrode was successfully demonstrated for DA determination in human serum samples.     

石墨烯/还原氧化石墨烯/聚苯胺复合材料的制备及在超级电容器中的应用

本研究以低成本、易规模化的亲水性石墨烯/氧化石墨烯为前驱体,通过原位聚合的方法制备石墨烯/氧化石墨烯/聚苯胺复合材料,经过化学还原后制备得到石墨烯/还原氧化石墨烯/聚苯胺复合材料.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和傅里叶红外变化光谱仪(FT-IR)对制备的材料进行了结构和形貌的表征.运用循环伏安法...     

面向能源领域的石墨烯研究

化石能源枯竭以及地球环境污染已经成为并且在未来相当长一段时期内都将是人类面临的最严峻的危机之一.因此,寻找清洁的替代能源形式、有效的能量存储方式以及高效的能源利用途径是目前科学研究的热点.自从其高质量样品被制备和研究以来,石墨烯一直吸引着全世界科研工作者的兴趣;它的一系列独特的物理化学性质,为其在能源领域的应用提供了无限前景.本文对石墨烯在能源领域的最新研究进展以及其工业化应用作了简要综述,具体内容包括石墨烯材料在以下领域的应用：能源储存器件类,如超级电容器和锂离子电池;能源转化装置类,如燃料电池和太阳能电池.     

Directly drawing self-assembled, porous, and monolithic graphene fiber from chemical vapor deposition grown graphene film and its electrochemical properties

Integration of graphene into macroscopic architectures represents the first step toward creating a new class of graphene-based nanodevices. We report a novel yet simple approach to fabricate graphene fibers, a porous and monolithic macrostructure, from chemical vapor deposition grown graphene films. Graphene is first self-assembled from a 2D film to a 1D fiberlike structure in an organic solvent (e.g., ethanol, acetone) and then dried to give the porous and crumpled structure. The method developed here is scalable and controllable, delivering tunable morphology and pore structure by controlling the evaporation of solvents with suitable surface tension. The fibers are 20-50 μm thick, with a typical electrical conductivity of ～1000 S/m. The cyclic voltammetric studies show typical capacitive behavior for the porous graphene fibers with good rate stability and capacitance values ranging from 0.6 to 1.4 mF/cm(2). Decorated with only 1-3 wt % MnO(2), the graphene/MnO(2) composites exhibit remarkable enhancement of combined performance both with respect to discharge capacitance (up to 12.4 mF/cm(2)) and cycling stability. This special structure could facilitate chemical doping and electrochemical energy storage and find applications in catalyst supports, sensors, supercapacitors, Li ion batteries, etc.     

氧化石墨烯诱导的Ni-Co氢氧化物整体电极的制备及电储能特性

超级电容器作为一种新型储能装置,由于其能量密度、功率密度高和良好的循环稳定性,而在实际工业应用中(新能源汽车、航天航空业、电子通信系统、可穿戴设备等)显示出巨大的潜力.但目前面临的最大挑战是构造柔性、轻薄可变形的储能设备.在本项研究工作中,利用溶剂热法和真空抽滤法开发了一种碳基/层状金属氢氧化物的复合材料.设计将氧化石...     

MnO2/TiN heterogeneous nanostructure design for electrochemical energy storage

MnO(2)/TiN nanotubes are fabricated using facile deposition techniques to maximize the surface area of the electroactive material for use in electrochemical capacitors. Atomic layer deposition is used to deposit conformal nanotubes within an anodic aluminium oxide template. After template removal, the inner and outer surfaces of the TiN nanotubes are exposed for electrochemical deposition of manganese oxide. Electron microscopy shows that the MnO(2) is deposited on both the inside and outside of TiN nanotubes, forming the MnO(2)/TiN nanotubes. Cyclic voltammetry and galvanostatic charge-discharge curves are used to characterize the electrochemical properties of the MnO(2)/TiN nanotubes. Due to the close proximity of MnO(2) with the highly conductive TiN as well as the overall high surface area, the nanotubes show very high specific capacitance (662 F g(-1) reported at 45 A g(-1)) as a supercapacitor electrode material. The highly conductive and mechanically stable TiN greatly enhances the flow of electrons to the MnO(2) material, while the high aspect ratio nanostructure of TiN creates a large surface area for short diffusion paths for cations thus improving high power. Combining the favourable structural, electrical and energy properties of MnO(2) and TiN into one system allows for a promising electrode material for supercapacitors.     

Single-atom catalysts for electrochemical energy storage and conversion

The expedited consumption of fossil fuels has triggered broad interest in the fabrication of novel catalysts for electrochemical energy storage and conversion.E...     

Assembly and mechanical properties of phosphorus dendrimer/polyelectrolyte multilayer microcapsules

We report the preparation, characterization, and mechanical properties of polyelectrolyte/phosphorus dendrimer multilayer microcapsules. The shells of these microcapsules are composed either by alternating poly(styrenesulfonate) (PSS) and positively charged dendrimer G4(NH+Et2Cl-)96 or by alternating poly(allylamine hydrochloride) (PAH) and negatively charged dendrimer G4(CH-COO-Na+)96. The same multilayers were constructed on planar support to examine their layer-by-layer growth and to measure the multilayer thickness. Surface plasmon resonance spectroscopy (SPR) showed regular linear growth of the assembly upon each bilayer deposited. We probe the mechanical properties of these polyelectrolyte/dendrimer microcapsules by measuring force-deformation curves with the atomic force microscope (AFM). The experiment suggests that they are much softer than PSS/PAH microcapsules studied before. This softening is attributed to an enhanced permeability of the polyelectrolyte/dendrimer multilayer shells as compared with multilayers formed by linear polyelectrolytes. In contrast, Young's modulus of both dendrimer-based multilayers was found to be on the same order as that of PSS/PAH multilayers.     

Preparation of hexagonal nanoporous nickel hydroxide film and its application for electrochemical capacitor

Nanoporous nickel hydroxide film has been successfully electrodeposited on titanium substrate from nickel nitrate dissolved in the aqueous domains of the hexagonal lyotropic liquid crystalline phase of Brij 56. Low-angle X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM) studies show that the film has a regular nanostructure consisting of a hexagonal array of cylindrical pores with a repeat center-to-center spacing of about 7 nm. Preliminary electrochemical studies are carried out using cyclic voltammetry (CV) and chronopotentiometry technology. A maximum specific capacitance of 578 F g⁻¹ could be achieved for the nanoporous Ni(OH)₂ film electrode, suggesting its potential application in electrochemical capacitors.     

One-step electrochemical synthesis of MoS2/graphene composite for supercapacitor application

Journal of Solid State Electrochemistry - In this study, an MoS2/graphene composite is fabricated from bulk MoS2 and graphite rod via a facile electrochemical exfoliation method. The as-prepared...     

A review of transition metal chalcogenide/graphene nanocomposites for energy storage and conversion

Recent advances in the applications of transition metal chalcogenides/graphene (TMC/graphene) nanocomposites in future energy storage and conversion are reviewed. The synthesis processes and structures of TMC/graphene, workingpriciple of evergy energy device, and the electrochemical performances are summarized.     

Influence of temperature on the preparation of CoFe2O4 by the sol-gel method and its application in electrochemical energy storage

Journal of Solid State Electrochemistry - CoFe2O4 particles were successfully synthesized by a sol-gel proteic route in three different temperatures, and their structural and morphological...     

Layer-by-layer assembled multilayer of graphene/Prussian blue toward simultaneous electrochemical and SPR detection of H2O2

A new type of chemically converted graphene sheets, cationic polyelectrolyte-functionalized ionic liquid decorated graphene sheets (PFIL-GS) composite, was synthesized and characterized by Ultraviolet-visible (UV-vis) absorption, Fourier transform infrared, and Raman spectroscopy. It was found that the presence of PFIL enabled the formation of a very stable aqueous dispersion due to the electrostatic repulsion between PFIL modified graphene sheets. With respect to the excellent dispersibility of this material, we have fabricated a novel PFIL-GS/Prussian blue (PB) nanocomposite multilayer film via classic layer-by-layer (LBL) assembly. The assembly process was confirmed by UV-vis spectroscopy and surface plasmon resonance (SPR) spectroscopy, which showed linear responses to the numbers of the deposited PFIL-GS/PB bilayers. Moreover, the as-prepared composite films were used to detect hydrogen peroxide (H₂O₂) by electrochemical surface plasmon resonance (EC-SPR) spectroscopy. This real time EC-SPR technique can provide simultaneous monitoring of both optical SPR signal and electrochemical current responses upon injecting H₂O₂ into the reaction cell. The experimental results revealed that both the electrochemical and SPR signal exhibited splendid linear relationship to the concentration of the injected H₂O₂, and the detection limit could be up to 1 μM.