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A robust synthesis of gem-dialkyl acyclic diene monomers has been developed. This route is scalable, flexible, and biorenewable, allowing for the production of a wide range of diene monomers of different lengths and different gem-dialkyl substitutions starting from unsaturated esters derived from seed oils. The metathesis polymerization of these monomers and the hydrogenation of the resulting polyolefins lead to telechelic gem-dialkyl polyethylenes, which can be used as elastomers in the synthesis of polyurethanes and other block polymers.

The selective electrochemical reduction of CO2to CO in water by a Re(tBu-bpy)(CO)3Cl catalyst incorporated into multi-walled carbon nanotubes (MWCNT) was investigated. Current densities of ∼4 mA/cm2and selectivities (FECO) of 99% were achieved at −0.56 V vs RHE in CO2-saturated aqueous KHCO3solutions. The Re(tBu-bpy)(CO)3Cl catalyst has been widely studied as a homogeneous catalyst in organic solvents. Supporting Re(tBu-bpy)(CO)3Cl on MWCNTs increases current densities, decreases overpotential, retains selectivity for reduction of CO2to CO, and allows operation in water at pH = 7.3 compared to the molecular catalyst in acetonitrile solution. The Re/MWCNT electrocatalysts achieve TON > 5600 and TOF > 1.6 s–1. This electrocatalyst material is efficient, robust, simple to prepare, and scalable.

The catalytic properties of Re(ethynyl-bpy)(CO)3Cl and Re(vinyl-bpy)(CO)3Cl were studied and compared with those of the previously reported Re(tBu-bpy))CO)3Cl. As a molecular catalyst, Re(ethynyl-bpy)(CO)3Cl reduces CO2to CO with lower overpotential (η ≈ 0.525 V), higher selectivity for CO (FE 96%), and higher reaction rate (Icat/Ip= 27) compared to similar catalysts reported to date. The catalyst undergoes electropolymerization at the surface of a glassy carbon electrode in dry acetonitrile solution, creating a polymer film that is electroactive under a CO2atmosphere. In the presence of trifluoroethanol (TFE) (pKa35.4, MeCN) these films exhibit high efficiencies for CO (FECO97%). On the basis of preliminary studies, these electrodes show promise as heterogeneous electrocatalysts. Further optimization and understanding of deactivation pathways will be required to make these systems practical. The ethynyl functionalized Re(ethynyl-bpy)(CO)3Cl catalyst also can be attached to graphitic carbon electrodes through the “click” reaction. This represents the first example of attachment of a CO2reduction catalyst to an electrode surface by “click” chemistry.

The lithium–carbon monofluoride (Li-CFx) couple has the highest specific energy of any practical battery chemistry. However, the large polarization associated with the CFxelectrode (>1.5 V loss) limits it from achieving its full discharge energy, motivating the search for new CFxreaction mechanisms with reduced overpotential. Here, using a liquid fluoride (F)-ion conducting electrolyte at room temperature, we demonstrate for the first time the electrochemical defluorination of CFxcathodes, where metal fluorides form at a metal anode instead of the CFxcathode. F-ion primary cells were developed by pairing CFxcathodes with either lead (Pb) or tin (Sn) metal anodes, which achieved specific capacities of over 700 mAh g–1and over 400 mAh g–1, respectively. Solid-state 19F and 119Sn{19F} nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Raman, inductively coupled plasma (ICP), and X-ray fluorescence (XRF) measurements establish that upon discharge, the CFxcathode defluorinates while Pb forms PbF2and Sn forms both SnF4and SnF2. Technological development of F-ion metal-CFxcells based on this concept represents a promising avenue for realizing primary batteries with high specific energy.

Lithium-sulfur cells exhibit poor cycle life, due to the 'polysulfide shuttle' enabled by the dissolution of sulfur reduction products in organic electrolyte. Different strategies have been implemented to reduce the shuttle effects, including novel cathode designs to sequester polysulfides within the cathode, new electrolytes with reduced polysulfide solubility, and blocking layers to hinder polysulfide migration towards the anode. However, these are less successful in the case of high-energy Li/S cells with cathodes featuring substantial sulfur loadings, as proportionately greater polysulfide dissolution rapidly degrades performance. Additionally, the electrolyte/sulfur ratio is a limiting factor in high-energy cells, indicating that a minimum polysulfide solubility is required. Herein we describe the benefits of modified separators with the objective of blocking polysulfide migration. Specifically, we demonstrate improved discharge performance in laboratory Li/S cells with ceramic-coated separators, including single-sided and double-sided Al2O3-coated polyolefin material from commercial sources. We also developed a new AlF3 coating on a polyolefin separator that showed even greater improvements: higher initial specific capacity ([?]800 mAh/gS), coulombic efficiency (>96%), and cycle life (>100 cycles). Detailed analytical study via SEM and EDS of separators harvested from cycled cells indicated an approximately uniform sulfur distribution across the ceramic-coated separator. Finally, concentrated electrolytes, which reportedly minimize polysulfide diffusion and lithium dendrite growth, were tested and shown to yield high coulombic efficiency although with low sulfur utilization.

Exploration missions to the moons of the outer planets (such as Europa) pose unique challenges regarding the design of the spacecraft power source. Current aerospace qualified primary battery technologies cannot adequately meet the mass and volume requirements of proposed missions. Although they have not been used in prior deep space landed missions, lithium carbon-fluoride (Li/CFx) technologies were identified as a potentially viable option, both with and without blends of manganese dioxide (MnO2). To meet the performance requirements over the intended operating conditions of future NASA missions requires further development of this technology, in particular in the delivery of a high specific energy at moderate to low temperatures, and low discharge rates. A cell development effort was therefore pursued with an industrial battery cell manufacturer. Low (50 mA) and medium (250 mA) discharge rates were used to assess the performance of D-size cells under mission relevant conditions, between 0degC and [?]40degC. Select AA-size and C-size cells were also evaluated using similar rates scaled to the lower cell capacities. Developmental Li/CFx-MnO2 D-size cells designed for higher specific energy over these conditions were fabricated and tested, targeting operation between 0 and [?]40degC and a 50 mA constant discharge current, as the baseline operating condition.

Lithium-sulfur cells exhibit poor cycle life, due to the well-known 'polysulfide shuttle' enabled by the dissolution of the sulfur reduction products in organic electrolyte. Different strategies have been implemented to reduce the shuttle effects, with limited success, especially through use of low sulfur loadings (1-2 mg/cm2). Dense electrodes with high sulfur loadings are essential for high energy cells, however, such electrodes experience more serious polysulfide effects. In this paper, we describe the benefits of blending sulfur with a transition metal sulfide (here, TiS2 and MoS2) to form dense composite cathodes with enhanced conductivity. There is an improvement in both the initial capacity from sulfur utilization ([?]800 mAh/g based on sulfur content), the coulombic efficiency (>96%) and also in cycle life upon blending with the metal sulfide. High sulfur loadings (>12 mg/cm2 or [?]6 mAh/cm2 per side) were demonstrated to display high sulfur utilization in Li-S cells containing the metal sulfide blends either with or without coatings over the sulfur cathode. XRD studies were carried out to understand the redox behavior of the metal sulfide additive during charge/discharge cycling of the sulfur cathodes. DC polarization and Potentiometric Intermittent Titration Technique (PITT) measurements were made on sulfur cathodes with and without metal sulfide blends to determine the charge transfer and diffusional kinetics.

The effect of additives and electrolyte composition was investigated for Li||CFx and Li||CFx-MnO2 cells operated at low (ca. [?]40degC) temperature. Electrochemical impedance spectroscopy (EIS) and Tafel measurements indicated that the anode is far more resistive than the cathode at low temperatures. Adding a small amount of fluoroethylene carbonate (FEC) to a propylene carbonate (PC) + 1,2-dimethoxyethane (DME) + tetrahydrofuran (THF) ternary blend was found to have a beneficial effect on the anode of a cell when using 0.5 M LiClO4 as the electrolyte salt. Although the cathode impedance did increase with the addition of FEC, the overall cell impedance dropped dramatically, particularly at [?]40degC. Capacity at low temperature was not significantly improved with FEC addition, however, indicating that static (i.e. EIS) measurements may not be the best tool to understand the cell under dynamic (discharge) conditions. 15-crown-5 (as an additive) proved to have severe negative effects on specific capacity.

Nanostructured composite electrolyte films consisting of a cross-linked lyotropic liquid crystal (LLC) monomer, an organic carbonate liquid electrolyte (propylene carbonate, dimethylcarbonate, diethylcarbonate) and a Li salt (LiClO4, LiBF4, LiPF6) were systematically prepared and characterized at two electrolyte concentrations (0.245 and 1.0?m) and four liquid loading levels (5, 15, 30, 50 wt %). The LLC morphology of the films was investigated using polarized light microscopy and powder X-ray diffraction; their ionic conductivity was investigated using AC impedance measurements. Higher liquid electrolyte loadings and Li salt concentrations generally increased ionic conductivity, regardless of the liquid electrolyte or salt used. Some mixed-phase LLC morphologies displayed good ionic conductivity; however, as initially prepared, these formulations were at the limit of liquid uptake. In contrast, composites with a type II bicontinuous cubic (QII) LLC phase containing ordered, three-dimensional interconnected nanopores exhibited good conductivity using much less liquid electrolyte and a lower Li salt concentration, indicating that this structure is more amenable to ion transport than less ordered/uniform morphologies. When wetted with electrolyte solution and integrated into Li/fluorinated carbon coin cells, the QIIfilms were sufficiently strong to act as an ion-conductive separator and displayed stable open-circuit potentials. Many of the mixed-phase films gave shorted cells.

The cycle lives for cathodes of nanocrystalline iron trifluoride (FeF3) were measured in rechargeable lithium batteries at different depths of discharge. When the discharge was limited to less than one Li+ ion per FeF3, both the cycle life and energy efficiency were considerably greater than when converting FeF3 into Fe and LiF in deep discharge. An in situ X-ray diffractometry (XRD) study of the FeF3 cathode during its initial discharge to LiFeF3 showed a continuous change of the FeF3 diffraction pattern, indicating Li+ insertion into the rhombohedral FeF3 causing distortion of its lattice parameters. Electrochemical cycling is most reversible when this mechanism occurs in the absence of other changes in the crystal structure.

Nanoscale chemical patterning of different chemical species (amine, thiol, aldehyde, and biotin) in independent nanopatterns is achieved by the iterative application of thermochemical nanolithography (TCNL) to inscribe amine patterns followed by their chemical conversion to other functional groups. Due to the unique chemical stability of the patterns, the resultant substrates can be stored for weeks and subsequently be used for covalent and molecular‐recognition‐based attachment of nano‐objects using standard chemical protocols. In particular, the ability of this method to attach proteins and DNA to the chemical nanopatterns and to create co‐patterns of two distinctive bioactive proteins is demonstrated.

Here, a straightforward and general method for the rapid dendritic amplification of accessible surface functional groups on hydroxylated surfaces is described, with focus on its application to 3D biomineral surfaces. Reaction of hydroxyl‐bearing silica surfaces with an aminosilane, followed by alternating exposure to a dipentaerythritol‐derived polyacrylate solution and a polyamine solution, allows the rapid, layer‐by‐layer (LBL) build‐up of hyperbranched polyamine/polyacrylate thin films. Characterization of such LBL‐grown thin films by AFM, ellipsometry, XPS, and contact angle analyses reveals a stepwise and spatially homogeneous increase in film thickness with the number of applied layers. UV–Vis absorption analyses after fluorescein isothiocyanate labeling indicate that significant amine amplification is achieved after the deposition of only 2 layers with saturation achieved after 3–5 layers. Use of this thin‐film surface amplification technique for hydroxyl‐enrichment of biosilica templates facilitates the conformal surface sol–gel deposition of iron oxide that, upon controlled thermal treatment, is converted into a nanocrystalline (∼9.5 nm) magnetite (Fe3O4) coating. The specific adsorption of arsenic onto such magnetite‐coated frustules from flowing, arsenic‐bearing aqueous solutions is significantly higher than for commercial magnetite nanoparticles (≤50 nm in diameter).

Orange‐emitting phosphorescent copolymers containing iridium complexes and bis(carbazolyl)fluorene groups in their side chains are employed as the emissive layer in multilayer organic light‐emitting diodes (OLEDs). The efficiency of the OLED devices is optimized by varying characteristics of the copolymers: the molecular weight, the iridium loading level, and the nature and length of the linker between the side chains and the polymer backbone. A maximum efficiency of 4.9 ± 0.4%, 8.8 ± 0.7 cd A−1at 100 cd m−2is achieved with an optimized copolymer.

We have synthesised a series of new dinuclear metallocenes [{M(Cp*)(C5H4)}2X] (Cp*=η5‐pentamethylcyclopentadienyl; M=Fe, Co, X=CMe2, SiMe2, GeMe2; M=Fe, X=Si2Me4). For the neutral dicobalt complexes, magnetic susceptibility measurements reveal intramolecular antiferromagnetic interactions of −21 and −14 cm−1for SiMe2‐ and GeMe2‐bridged species, respectively, but negligible interaction for the CMe2‐bridged compound. In contrast, intervalence charge‐transfer (IVCT) data for the mixed‐valence monocations of both Fe and Co complexes show electronic coupling to decrease in the order CMe2>SiMe2>GeMe2. This suggests that electronic coupling is principally through‐space in contrast to results found from previous studies. The IVCT data also show much stronger coupling in the dicobalt species versus their diiron analogues.

The E-4,4′-bisdip-anisylaminostilbene cation is a class-III mixed-valence species with electronic coupling comparable to that in its biphenyl-bridged analogue, whereas its tolane-bridged analogue belongs to class II.

The effect of additives and electrolyte composition was investigated for Li‖CFxand Li‖CFx-MnO2cells operated at low (ca. −40°C) temperature. Electrochemical impedance spectroscopy (EIS) and Tafel measurements indicated that the anode is far more resistive than the cathode at low temperatures. Adding a small amount of fluoroethylene carbonate (FEC) to a propylene carbonate (PC) + 1,2-dimethoxyethane (DME) + tetrahydrofuran (THF) ternary blend was found to have a beneficial effect on the anode of a cell when using 0.5 M LiClO4as the electrolyte salt. Although the cathode impedance did increase with the addition of FEC, the overall cell impedance dropped dramatically, particularly at −40°C. Capacity at low temperature was not significantly improved with FEC addition, however, indicating that static (i.e. EIS) measurements may not be the best tool to understand the cell under dynamic (discharge) conditions. 15-crown-5 (as an additive) proved to have severe negative effects on specific capacity.

The bimetallic complex [V(Cp)]₂Pn, containing a V–V triple bond, has been synthesised; the vanadium centres adopt a syn-coordination and the complex exhibits a high-spin/low-spin equilibrium in both solution and the solid-state.

The bimetallic complex VCp2Pn, containing a V–V triple bond, has been synthesised; the vanadium centres adopt a syn-coordination and the complex exhibits a high-spinlow-spin equilibrium in both solution and the solid-state.

The cycle lives for cathodes of nanocrystalline iron trifluoride (FeF3) were measured in rechargeable lithium batteries at different depths of discharge. When the discharge was limited to less than one Li+ion per FeF3, both the cycle life and energy efficiency were considerably greater than when converting FeF3into Fe and LiF in deep discharge. An in situ X-ray diffractometry (XRD) study of the FeF3cathode during its initial discharge to LiFeF3showed a continuous change of the FeF3diffraction pattern, indicating Li+insertion into the rhombohedral FeF3causing distortion of its lattice parameters. Electrochemical cycling is most reversible when this mechanism occurs in the absence of other changes in the crystal structure.

On page 3696, Wang et al. report on the nanoscale chemical surface patterning of different chemical species (amine, thiol, aldehyde, and biotin) in independent nanopatterns by the iterative application of thermochemical nanolithography. Due to the unique chemical stability of the patterns, the resultant substrates can be stored for weeks and subsequently be used for the selective attachment of nanometer‐sized objects, such as proteins or DNA, using standard chemical protocols.

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