Preparation of Li4Ti5O12 spherical particles for rechargeable lithium batteries

Spherical Li₄Ti₅O₁₂ particles were prepared via an emulsion-gel process. The preparation of spherical Li₄Ti₅O₁₂ such as the concentrations of the starting materials and heat treatment were optimized. The particle size distribution of the Li₄Ti₅O₁₂ prepared under optimized condition was very narrow, and the particle size was 0.45 μm. It was found that a short heat treatment in an infrared furnace was useful to crystallize amorphous LiTiO powders without aggregation of particles or morphology change. The obtained Li₄Ti₅O₁₂ had the spinel structure, and was phase pure. The prepared Li₄Ti₅O₁₂ exhibited a high discharge capacity of 160 mA h g⁻¹ at the potential of 1.5 V versus Li/Li⁺, and the charge–discharge cycle stability was excellent.     

Small-molecule vacuum processed melamine-C60, organic field-effect transistors

The transfer of benchtop knowledge into large scale industrial production processes represents a challenge in the field of organic electronics. Large scale industrial production of organic electronics is envisioned as roll to roll (R2R) processing which nowadays comprises usually solution-based large area printing steps. The search for a fast and reliable fabrication process able to accommodate the deposition of both insulator and semiconductor layers in a single step is still under way. Here we report on the fabrication of organic field effect transistors comprising only evaporable small molecules. Moreover, both the gate dielectric (melamine) and the semiconductor (C₆₀) are deposited in successive steps without breaking the vacuum in the evaporation chamber. The material characteristics of evaporated melamine thin films as well as their dielectric properties are investigated, suggesting the applicability of vacuum processed melamine for gate dielectric layer in OFETs. The transistor fabrication and its transfer and output characteristics are presented along with observations that lead to the fabrication of stable and virtually hysteresis-free transistors. The extremely low price of precursor materials and the ease of fabrication recommend the evaporation processes as alternative methods for a large scale, R2R production of organic field effect transistors.     

Synthesis and light emitting properties of fluorene–carbazole-based conjugated copolymers

A novel series of soluble conjugated copolymers comprised of 9,9′-bis(2-ethylhexylfluorene) and comonomer included carbazole moiety, 3,6-bis[1-{4-bromobenz(1-cyanovinylene)}]-9-(2-ethylhexyl)-carbazole (BCEC), were synthesized by nickel-catalyzed Yamamoto coupling reaction. The resulting copolymers exhibit good solubility in common organic solvents such as chloroform, chlorobenzene, etc. and good thermal stability. The copolymers are also easily cast in thin film on glass substrate. By means of the feed ratio, the electronic and optical properties of the polymers were tuned. The UV-Vis spectra of polymers exhibit absorption band at about 382 nm. These polymers showed photoluminescence (PL) maxima at 466 and 479 nm, respectively. The electroluminescence (EL) spectrum results were similar to the PL spectra. However, the EL spectra showed the possibility of the white light emission through the electroplex emission around 700 nm from the single polymer device. The EL spectra of the devices were little changed with the various current densities.     

Profiles of hydrogen molar fraction and temperature in ZrV1.9Fe0.1 alloy bed for hydrogen absorption

Profiles of hydrogen molar fraction and temperature in a long ZrV_1.9Fe_0.1 alloy particle bed with a small diameter were determined experimentally and analytically as a basic study of chemical heat pumps operated at higher temperature. Since the alloy bed absorbed hydrogen even at $\text{873}\text{K}$ and generated heat, the alloy was considered a suitable material for heat pump or hydrogen storage at higher temperature. Experimental profiles of both hydrogen molar fraction at the bed outlet and temperature inside the bed agreed with analytical solutions to heat and mass transfer equations. The analytical solutions were obtained under the conditions where constant-pattern approximation could be applied to the temperature and concentration profiles propagating in a bed with the same velocity. Properties relating with heat transfer such as a heat capacity, enthalpy change of hydrogen absorption and a heat-transfer coefficient between a wall and particles were correlated to two dimensionless parameters, α and β.     

Hydrogen production from sewage sludge solubilized in hot-compressed water using photocatalyst under light irradiation

Photocatalytic hydrogen production from a digested sewage sludge solubilized in hot-compressed water (573K) was investigated in order to develop a low-cost sacrifice agent for CdS-based photocatalysts from biomass. H₂ evolution occurred over a LaMnO₃/CdS composite photocatalyst under Xe lamp irradiation from water containing the solubilized sewage sludge and the amount of evolved H₂ reached more than $\text{30}\text{mmol}\text{/}\text{g}$-catalyst for a $\text{200}\text{h}$-reaction; on the other hand, no H₂ was formed in the absence of the solubilized sewage sludge. The H₂ evolution rate was comparable to that when typical Na₂S–Na₂SO₃ sacrifice agents were used, suggesting the applicability of a biomass-derived sacrifice agent for photocatalysis. Organic compounds, such as methanol and formic acid, contained in the solubilized sewage sludge are responsible for the H₂ evolution observed.     

Facile one-step synthesis of pellet-press-assisted saddle-curl-edge-like g-C3N4 nanosheets for improved visible-light photocatalytic activity

Graphitic carbon nitride (g-C₃N₄) has attracted increasing interest as a visible-light-active photocatalyst. In this study, saddle-curl-edge-like g-C₃N₄ nanosheets were prepared using a pellet presser (referred to as g-CN P nanosheets). Urea was used as the precursor for the preparation of g-C₃N₄. Thermal polymerization of urea in a pellet form significantly affected the properties of g-C₃N₄. Systematic investigations were performed, and the results for the modified g-C₃N₄ nanosheets are presented herein. These results were compared with those for pristine g-C₃N₄ to identify the factors that affected the fundamental properties. X-ray diffraction analysis and high-resolution transmission electron microscopy revealed a crystallinity improvement in the g-CN P nanosheets. Fourier-transform infrared spectroscopy provided clear information regarding the fundamental modes of g-C₃N₄, and X-ray photoelectron spectroscopy (XPS) peak-fitting investigations revealed the variations of C and N in detail. The light-harvesting property and separation efficiency of the photogenerated charge carriers were examined via optical absorption and photoluminescence studies. The valence band edge and conduction band edge potentials were calculated using XPS, and the results indicated a significant reduction in the bandgap for the g-CN P nanosheets. The Brunauer–Emmett–Teller surface area increased for the g-CN P nanosheets. The photocatalytic degradation performance of the g-CN P nanosheets was tested by applying a potential and using the classical dye Rhodamine B (RhB). The RhB dye solution was almost completely degraded within 28 min. The rate constant of the g-CN P nanosheets was increased by a factor of 3.8 compared with the pristine g-C₃N₄ nanosheets. The high crystallinity, enhanced light absorption, reduced bandgap, and increased surface area of the saddle-curl-edge-like morphology boosted the photocatalytic performance of the g-CN P nanosheets.     

Quaternary ammonium-functionalized poly(ether sulfone ketone) anion exchange membranes: The effect of block ratios

Anion exchange membranes based on quaternary ammonium-functionalized poly(ether sulfone ketone) block copolymers (QA-PESK) with various hydrophilic–hydrophobic oligomer block ratios (10:7, 10:18, and 10:26) were synthesized, and the block length effect on the membranes' physicochemical and electrical properties were systematically investigated. The QA-PESK-10-18 membrane, prepared using a hydrophilic and hydrophobic block ratio of 10:18, displayed well-balanced hydrophilic/hydrophobic phase separation, the highest conductivity of 23.19 mS cm⁻¹ at 20 °C and 57.84 mS cm⁻¹ at 80 °C, and the highest alkaline stability among the three block ratios tested, indicating that the membranes' properties were closely related to their morphologies, which were determined by the hydrophilic/hydrophobic ratio of the block copolymer. The H₂/O₂ single cell performance using the QA-PESK-10-18 revealed a maximum power density of 235 mW cm⁻².     

Mg/SiO2–Al2O3 supported nickel catalysts for the production of naphthenic hydrocarbon fuel by hydro-de-oxygenation of eugenol

Ni–Mg supported on both mesoporous Al₂O₃–SiO₂ (10) and γ-Al₂O₃ with Al₂O₃–SiO₂/Mg = 10 and γ-Al₂O₃/Mg = 10 ratio were prepared via wet impregnation method. The synthesized materials were characterized by XRD, N₂-sorption study, NH₃-TPD/H₂-TPR, FT-IR, DRS-UV and used in hydrodeoxygenation (HDO) of eugenol to produce hydrocarbons in a high pressure reactor. The reactant molecules could be facilitated to yield hydrocarbon fuel by active nickel active sites. The high oxygen removal efficiency of 75% was achieved with C9 hydrocarbon selectivity. Evaluation of catalytic properties such as high hydrogen consumption of 145 μmol/g (H₂-TPR) and enriched surface acidity of 2.35 mmol g⁻¹ (NH₃-TPD) was done. Ni/Mg-SA (10) exhibited the highest catalytic activity of 6.7 × 10⁻⁴ mol g⁻¹ s⁻¹ SRR and 10.27 s⁻¹ TOF respectively. The stability of catalysts was found to be 185 mg/g for Ni/Mg-SA (10) catalyst by TGA analysis. The structure-activity relationship was studied and the product distributions were also discussed in detail.