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Doped motifs offer an intriguing structural pathway toward improving conductivity for battery applications. Specifically, Ca-doped, three-dimensional "flower-like" Li4-xCaxTi5O12 ("x" = 0, 0.1, 0.15, and 0.2) micrometer-scale spheres have been successfully prepared for the first time using a simple and reproducible hydrothermal reaction followed by a short calcination process. The products were experimentally characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge testing. Calcium dopant ions were shown to be uniformly distributed within the LTO structure without altering the underlying "flower-like" morphology. The largest lattice expansion and the highest Ti3+ ratios were noted with XRD and XPS, respectively, whereas increased charge transfer conductivity and decreased Li+-ion diffusion coefficients were displayed in EIS for the Li4-xCaxTi5O12 ("x" = 0.2) sample. The "x" = 0.2 sample yielded a higher rate capability, an excellent reversibility, and a superior cycling stability, delivering 151 and 143 mAh/g under discharge rates of 20C and 40C at cycles 60 and 70, respectively. In addition, a high cycling stability was demonstrated with a capacity retention of 92% after 300 cycles at a very high discharge rate of 20C. In addition, first-principles calculations based on density functional theory (DFT) were conducted with the goal of further elucidating and understanding the nature of the doping mechanism in this study. The DFT calculations not only determined the structure of the Ca-doped Li4Ti5O12, which was found to be in accordance with the experimentally measured XPD pattern, but also yielded valuable insights into the doping-induced effect on both the atomic and electronic structures of Li4Ti5O12. [ABSTRACT FROM AUTHOR]

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. Here, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm2 photocurrents at the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films. [ABSTRACT FROM AUTHOR]

Excellent durable antifogging film, which is composed of hollow microspheres and ZnO nanorods, is fabricated via combining airless spray and crystal growth methods. Because the thermal insulation effect of hollow microspheres strengthens the superhydrophobicity of the micro- and nanostructure composite film at lower temperatures, durable antifogging is realized successfully. When the film is placed in a low-temperature, high-humidity environment, supercooled tiny water droplets cannot spread on it and can easily coalesce and jump off from the surface, exhibiting the robust superhydrophobic and antifogging performance for a significantly long time. This investigation provides insight into designing structured thermal insulation surface materials to realize antifogging that can be applied into microdevices used in cold, high-humidity environments. [ABSTRACT FROM AUTHOR]

The limitation for the biomedical application of porous organic polymers (POPs) is the big size and poor dispersibility in aqueous media. Herein, a nanoscale metal-organic framework (MOF)@POP composite, named UNM, has been synthesized by epitaxial growth of the photoactive porphyrin-POPs (H2P-POP) on the outer surface of amine containing UiO-66 (UiO-AM). After the growth of POPs, the crystallization, pore structure, and size distribution of UNM are retained well. The formed UNM possesses a small size of less than 200 nm and could be internalized by cancer cells. Such light-activated UNM exhibits efficient ability to generate ¹O2 under various experimental conditions, which can be further applied for PDT efficacy. The present work demonstrates the great potential of nanoscale porous polymers in biomedical fields and cancer treatment. [ABSTRACT FROM AUTHOR]

Ta3N5nanostructuresare widely explored as anodesfor photoelectrochemical (PEC) water splitting. Although the materialshows excellent semiconductive properties for this purpose, the keychallenge is its severe photocorrosion when used in typical aqueousenvironments. In the present work we introduce a NiFe layered doublehydroxide (LDH) cocatalyst that dramatically reduces photocorrosioneffects. To fabricate the Ta3N5electrode, weuse through-template anodization of Ta and obtain oxide nanorod arraysthat then are converted to Ta3N5by high temperaturenitridation. After modification with our cocatalyst system, we obtainedsolar photocurrents of 6.3 mA cm–2at 1.23 VRHEin 1 M KOH, and an electrode maintains about 80% of theinitial activity for extended irradiation times. [ABSTRACT FROM AUTHOR]

A series of swallow-shaped tetrathiafulvalene (TTF)-based liquid crystal (LC) molecules (a-6TTFn, where 6 represents the number of carbon atoms in the two tails of a-6TTFnand nis the even number of carbon atoms in the alkyl chains attached to the side of the asymmetric TTF mesogen, n= 6−12) was designed and synthesized. One of this series of swallow-shaped asymmetric TTF molecules (abbreviated as a-6TTF12) having 12 carbon atoms in the alkyl chains attached to the side of the asymmetric TTF mesogen served as an example in this study. Major phase transitions and their origins in a-6TTF12 were studied with combined techniques of differential scanning calorimetry (DSC), one-dimensional (1D) wide-angle X-ray diffraction (WAXD) and solid-state carbon-13 (13C) nuclear magnetic resonance (NMR) experiments. a-6TTF12 formed a highly ordered liquid crystalline (ΦLC) phase at higher temperatures and a crystalline (ΦCr) phase at lower temperatures. On the basis of the experimental results, it was found that the highly organized columns in the ΦLCphase partially lost their long-range positional order compared with the ΦCrphase at lower temperatures due to the distinct molecular packing of alkyl chains during the transition from ΦLC↔ ΦCr. Furthermore, it was realized that there are two main driving forces in the formation of the ordered columnar phases. One was the π−π interaction among the TTF-based mesogens, and the other was the nanophase separation between the rigid TTF-based mesogens and the flexible alkyl chains. The structure, molecular packing symmetry, and morphology of a-6TTF12 in different phases were identified using 2D WAXD together with selected area electron diffraction (SAED) from transmission electron microscopy (TEM). Bright-field TEM images of polyethylene-decorated films of a-6TTF12 allow us to confirm its molecular self-organization which was first identified by SAED as well as by 2D WAXD from oriented films. Morphological observations utilizing cross-polarized optical microscopy (POM) on the micrometer length scale validated the phase transitions and molecular orientation in the macroscopically oriented film. [ABSTRACT FROM AUTHOR]

We present an efficient way to calculate the phase diagram of the quaternary Li−Fe−P−O 2system using ab initio methods. The ground-state energies of all known compounds in the Li−Fe−P−O 2system were calculated using the generalized gradient approximation (GGA) approximation to density functional theory (DFT) and the DFT+U extension to it. Considering only the entropy of gaseous phases, the phase diagram was constructed as a function of oxidation conditions, with the oxygen chemical potential, μ O 2, capturing both temperature and oxygen partial pressure dependence. A modified Ellingham diagram was also developed by incorporating the experimental entropy data of gaseous phases. The phase diagram shows LiFePO 4to be stable over a wide range of oxidation environments, being the first Fe 2+-containing phase to appear upon reduction at μ O 2= −11.52 eV and the last of the Fe-containing phosphates to be reduced at μ O 2= −16.74 eV. Lower μ O 2represents more reducing conditions, which generally correspond to higher temperatures and/or lower oxygen partial pressures and/or the presence of reducing agents. The predicted phase relations and reduction conditions compare well to experimental findings on stoichiometric and Li-off-stoichiometric LiFePO 4. For Li-deficient stoichiometries, the formation of iron phosphate phases (Fe 7(PO 4) 6and Fe 2P 2O 7) commonly observed under moderately reducing conditions during LiFePO 4synthesis and the formation of iron phosphides (Fe 2P) under highly reducing conditions are consistent with the predictions from our phase diagram. Our diagrams also predict the formation of Li 3PO 4and iron oxides for Li-excess stoichiometries under all but the most reducing conditions, again in agreement with experimental observations. For stoichiometric LiFePO 4, the phase diagram gives the correct oxidation products of Li 3Fe 2(PO 4) 3and Fe 2O 3. The predicted carbothermal reduction temperatures for LiFePO 4from the Ellingham diagram are also within the range observed in experiments (800–900 °C). The diagrams developed provide a better understanding of phase relations within the Li−Fe−P−O 2system and serve as a guide for future experimental efforts in materials processing, in particular, for the optimization of synthesis routes for LiFePO 4. [ABSTRACT FROM AUTHOR]

A new series of mixed-framework compounds in the chalcohalide family has been synthesized using the conventional solid-state reactions. These include CdSb 2Se 3Br 21and its isoelectronic indium derivatives InSb 2S 4X (X = Cl 2and Br 3) and InM 2Se 4Br (M = Sb 4and Bi 5). Single crystals were grown from direct interaction of stoichiometric mixtures of respective elemental and binary compounds. The parent compound cadmium antimony selenobromide, CdSb 2Se 3Br 2, was synthesized by heating the stoichiometric mixture of CdBr 2and Sb and Se at 450 °C followed by slow cooling. Single-crystal structure analysis was carried out by employing X-ray diffraction methods, showing that this compound crystallizes in the monoclinic crystal system ( C2/ m, No. 12) with a= 20.998(4) Å, b= 4.0260(8) Å, c= 12.149(2) Å, β = 119.00(3)°, and V= 898.3(3) Å 3. The framework exhibits mixed CdBr 2and Sb 2Se 3sublattices, respectively, adopting the (110) and (100) NaCl-type structures. The former consists of dual octahedral chains of Cd-centered [CdBr 5Se] units sharing cisBr edges, and the chains propagate along the baxis via sharing transBr edges of the octahedra. The Sb 2Se 3sublattice is made of three edge-shared [SbSe 5] square-pyramidal units, features commonly seen in antimony and Sb-containing selenides. The apex selenium atoms of the aforementioned [CdBr 5Se] unit are corner-shared with [SbSe 5] sublattices to form a composite slab along the (−101) plane. The lone-pair electrons of Sb 3+cations point into the space between the stacked slabs. The indium derivatives 2– 5were synthesized by substituting the trivalent In 3+for divalent Cd 2+cations, along with a stoichiometric amount of charge-compensating halide anions. These four new In derivatives are isostructural with 1and can be formulated as (InSX)(Sb 2S 3) (X = Cl and Br), and (InSeBr)(M 2Se 3) (M = Sb and Bi) with respect to the composite lattices of CdBr 2and Sb 2Se 3. The UV–vis reflectance spectroscopy and band structure calculations confirm that these compounds are semiconductors with steep band gap absorption edges around 1.1–1.8 eV. In light of the observed blue shift in the absorption edge with respect to the dimensionally reduced post-transition-metal chalcogenide M 2Q 3sublattices, we claim quantum confinement effect of the optical band gap, which is the first example among inorganic mixed-anion compounds reported thus far. [ABSTRACT FROM AUTHOR]