Enabling the Operation of Highly Compatible LiI-3-Hydroxypropionitrile Small-Molecule Solid-State Electrolytes in Lithium Metal Batteries via Stepped-Amorphization Strategy

Integrating the advantages of both inorganic ceramic and organic polymer solid-state electrolytes, small-molecule solid-state electrolytes represented by LiI-3-hydroxypropionitrile (LiI-HPN) inorganic–organic hybrid systems possess good interfacial compatibility and high modulus. However, their lack of intrinsic Li⁺ conduction ability hinders potential application in lithium metal batteries until now, despite containing LiI phase composition. Herein, inspired by evolution tendency of ionic conduction behaviors together with first-principles molecular dynamics simulations, we propose a stepped-amorphization strategy to break the Li⁺ conduction bottleneck of LiI-HPN. It involves three progressive steps of composition (LiI-content increasing), time (long-time standing), and temperature (high-temperature melting) regulations, to essentially construct a small-molecule-based composite solid-state electrolyte with intensified amorphous degree, which realizes efficient conversion from an I⁻ to Li⁺ conductor and improved conductivity. As a proof, the stepped-optimized LiI-HPN is successfully operated in lithium metal batteries cooperated with Li₄Ti₅O₁₂ cathode to deliver considerable compatibility and stability over 250 cycles. This work not only clarifies the ionic conduction mechanisms of LiI-HPN inorganic–organic hybrid systems, but also provides a reasonable strategy to broaden the application scenarios of highly compatible small-molecule solid-state electrolytes.     

A new approach to the synthesis of oligomers. Application to the synthesis of p-phenylene thioether wires

Oligothioethers 4-RC₆H₄(SC₆H₄-4)_nX (n = 1-3; X = Br, I; R = NO₂; X = Br; R = MeO. n = 1 and 2; X = I; R = MeO. n = 4; X = Br; R = NO₂) have been prepared through a process involving (i) palladium-catalyzed C-S coupling between 4-RC₆H₄(SC₆H₄-4)_n−1I and 4-BrC₆H₄SH to give 4-RC₆H₄(SC₆H₄-4)_nBr and (ii) copper-catalyzed replacement of Br by I.     

Nanocrystallization of anatase in amorphous TiO2

The kinetics of nanocrystallization in amorphous TiO₂ has been studied in non-isothermal conditions by DSC. It was found that this process could be well described by standard Johnson-Mehl-Avrami-Kolmogorov (JMA) model with kinetic exponent m≅1. The kinetic parameters were calculated by simultaneous analysis of experimental data taken at different heating rates. These parameters were used as a basis for prediction of crystallization kinetics in isothermal conditions. The agreement between the JMA model prediction and experimental data depends on the method of preparation of amorphous TiO₂.     

Solitonic waves in polyene dications and principles of charge carrier localization in π‐conjugated organic materials

The quantum‐chemical investigations by ab initio method (restricted Hartree–Fock/6‐31G**) have been performed for a series of unsubstituted, monosubstituted, and disubstituted neutral polyenes and their double charged cations. The waves of charge alternation (characterized by the difference in the electron densities at the nearest carbon atoms or Δq function) and bond length alternation (characterized by the lengths difference of the nearest carbon–carbon bonds or Δl function) are reported. Comparisons are made with the corresponding monocationic polymethine molecules. We found that ionization by two electrons results in formation of two solitonic waves of charge alternation, rather than superposition of two overlapping solitonic waves into one. These waves behave similar to two independent elastic particles, which do not penetrate into each other despite the special confinement by the length of chromophore π‐system. In monosubstituted polyene dication, Δq and Δl functions contain two waves each; however, only one wave is mobile and sensitive to a change of the chemical nature of the terminal group, whereas the second wave remains practically unchanged. The introduction of one oxymethyl or phenyl terminal groups leads to a relatively small shift of the mobile wave from the center to a direction of the terminal group. The effect of the amino or tropilium terminal groups is much more pronounced and leads to a shift of the mobile wave to the end of the molecule. In disubstituted polyene dication, both solitonic waves become mobile and shift symmetrically to both ends. The general principles of the charge localization described in this study may be used in molecular design and fine‐tuning of the charge transport properties in plastic photovoltaics and other organic semiconducting materials. © 2012 Wiley Periodicals, Inc.     

纳米Ni－B非晶态合金的催化性质研究

纳米Ｎｉ－Ｂ非晶态合金的催化性质研究杨军,崔黎丽,邓景发（复旦大学化学系,第二军医大学药学院,上海,２００４３３）关键词纳米材料,非晶态合金,催化性质纳米非晶材料融合了纳米晶与非晶材料的特性,既有很高的表面原子比,又呈高度几何无序状态。与普通非晶材料...     

Amorphous carbon nitride as an alternative electrode material in electroanalysis: Simultaneous determination of dopamine and ascorbic acid

Boron-doped diamond (BDD) films are excellent electrode materials, whose electrochemical activity for some analytes can be tuned by controlling their surface termination, most commonly either to predominantly hydrogen or oxygen. This tuning can be accomplished by e.g. suitable cathodic or anodic electrochemical pretreatments. Recently, it has been shown that amorphous carbon nitride (a-CN_x) films may present electrochemical characteristics similar to those of BDD, including the influence of surface termination on their electrochemical activity toward some analytes. In this work, we report for the first time a complete electroanalytical method using an a-CN_x electrode. Thus, an a-CN_x film deposited on a stainless steel foil by DC magnetron sputtering is proposed as an alternative electrode for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) in synthetic biological samples by square-wave voltammetry. The obtained results are compared with those attained using a BDD electrode. For both electrodes, a same anodic pretreatment in 0.1 mol L⁻¹ KOH was necessary to attain an adequate and equivalent separation of the DA and AA oxidation potential peaks of about 330 mV. The detection limits obtained for the simultaneous determination of these analytes using the a-CN_x electrode were 0.0656 μmol L⁻¹ for DA and 1.05 μmol L⁻¹ for AA, whereas with the BDD electrode these values were 0.283 μmol L⁻¹ and 0.968 μmol L⁻¹, respectively. Furthermore, the results obtained in the analysis of the analytes in synthetic biological samples were satisfactory, attesting the potential application of the a-CN_x electrode in electroanalysis.     

Analysis of silica fume produced by zircon desilication

Novel chemical methods have been developed to allow for the determination of the components of silica fume produced by zircon desilication. Hitherto, no methods have been described for the analysis of this material. The amorphous silica is first removed by treatment with sodium hydroxide. The residue from the hydroxide treatment may then be subjected to a suite of reagents to determine the zircon, the total zirconia, the monoclinic zirconia and the tetragonal zirconia content of the fume. The zircon content of the fume is determined by treatment of the hydroxide residue with concentrated hydrofluoric acid (HF). The total zirconia content of the fume is determined by digestion of the hydroxide residue with fuming sulphuric acid (oleum), while the relative amounts of monoclinic and tetragonal zirconia may be found by treatment of the hydroxide residue with 10%w/v HF, which attacks the less stable tetragonal phase. Both X-ray diffraction and particle size analysis were used to validate the steps in the analytical procedure. An explanation of the presence of tetragonal zirconia in the fume is proposed. A greater understanding of the composition of the fume led to the installation of a separator in the company's production line to remove the zircon. Australian Fused Materials (AFM) now produces a vastly superior grade of fume marketed under the code SF-98.     

Determination of Chlorinated Hydrocarbon Species in Aqueous Solution Using Teflon Coated ATR Waveguide/FTIR Spectroscopy

The potential of an optical sensor based on mid-infrared spectroscopy, utilising a zinc selenide (ZnSe) attenuated total reflectance (ATR) element coated with an amorphous Teflon polymer, to determine chlorinated hydrocarbon species (CHC) in an aqueous environment is examined. The polymer coating concentrates the analytes within the penetration depth of the Fourier transform infrared (FTIR) evanescent wave and excludes water from the region. Teflon AF (Amorphous Fluoropolymer) is a family of amorphous copolymers based on polytetrafluoroethylene (PTFE), and is commercially available in two polymeric grades. Teflon AF is highly amorphous in nature with a large 'void volume', exhibits excellent chemical resistance and low water absorption. Such properties identify it as an excellent candidate for enrichment coating on an ATR/FTIR sensor. The potential of both polymeric grades of Teflon AF as enrichment membranes for ATR/FTIR analysis of CHC species was examined and contrasted. A rapid, repeatable, reversible response was observed with both grades to a range of CHC species. Linear responses in the mg/L region, with detection limits in the low mg/L region were achieved with the system used.     

A hydrated amorphous iron oxide nanoparticle as active water oxidation catalyst

Developing efficient water oxidation catalysts (WOCs) with earth-abundant elements still remains a challenging task for artificial photosynthesis. Iron-based WOC is a promising candidate because it is economically cheap, little toxic and environmentally friendly. In this study, we found that the catalytic water oxidation activity on amorphous iron-based oxide/hydroxide (FeO_x) can be decreased by an order of magnitude after the dehydration process at room temperature. Thermogravimetric analysis, XRD and Raman results indicated that the dehydration process of FeO_x at room temperature causes the almost completely loss of water molecule with no bulk structural changes. Based on this finding, we prepared hydrated ultrasmall (ca. 2.2 nm) FeO_x nanoparticles of amorphous feature, which turns out to be extremely active as WOC with turnover frequency (TOF) up to 9.3 s^?1 in the photocatalytic Ru(bpy)₃²⁺-Na₂S₂O₈ system. Our findings suggest that future design of active iron-based oxides as WOCs requires the consideration of their hydration status.     

Photocatalytic Decomposition of 2，4-Dichlorophenoxyacetic Acid over Amorphous Titania Modified Pt（IV）under Visible Light

Amorphous microporous metal oxides of titanium（AMM-Ti）which can induce photocatalytic reactions under visible light irradiation was prepared by using Na2PtCl6 according to the sol-gel procedure affording high specific surface areas of 160-200 m2/g. The most active photocatalysts contained 3.0% P（t Ⅳ）. According to extended X-ray absorption fine structure（EXAFS）results,isolated PtCl4 molecules were homogeneously distributed in an almost exclusively amorphous matrix of titania. During the photocatalytic degradation of 2,4-dichlorophenoxyacetic acid（2,4-D）in aqueous solution containing a suspension of AMM-Ti,it was found that 2,4-dichlorophenol was the major intermediate. The initial rate of photo-degradation was studied as a function of the initial concentration of reactants by the linearised form of the Langmuir-Hinshelwood equation,by which rate constants k and equilibrium adsorption constants K were evaluated. The postulated charge separation mechanism at Pt （Ⅳ）/ AMM-Ti and photocatalytic degradation mechanism of 2,4-D were also proposed.