Visual detection of Al ions using conjugated copolymer-ATP supramolecular complex

A colorimetric Al³⁺ sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al³⁺ in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al³⁺ led to an evident visual color change. The lowest concentration of Al³⁺ for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al³⁺ in tap water. The proposed methodology showed selective and sensitive detection for Al³⁺ in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring.     

Effect of cooling rate on microstructure of friction-stir welded AA1100 aluminum alloy

In this work, the microstructural changes occurring during cooling of friction-stir welded aluminum alloy AA1100 were evaluated. To this end, friction-stir welding (FSW) was performed in a wide range of cooling rates of 20–62 K/s and the evolved microstructures were studied by using electron backscatter diffraction. Below 0.6 T_m (T_m being the melting point), the stir zone material was found to experience no significant changes during cooling. At higher FSW temperatures, however, notable changes occurred in the welded material, including grain growth, sharpening of texture, reduction of the fraction of high-angle boundaries and material softening.     

Micro-/Mesoporous conjugated polymer based on star-shaped triazine-functional triphenylamine framework as the performance-improved cathode of Li-organic battery

A novel organic conjugated polymer based on star-shaped triazine-functional triphenylamine framework poly[1,3,5-tris(4-diphenylamino-phenyl)triazine] (PTDAPTz) is designed and synthesized successfully by FeCl₃-catalysted chemical oxidative polymerization. The polymer PTDAPTz powder exhibits a compactly packed pleated skirt shape-like morphology with a high surface area (~930 m² g⁻¹) and a bimodal pore size distribution ranging from micropores (~0.55 nm) to small diameter mesopores (~2–6 nm). As explored as the cathode material, the obtained PTDAPTz presents the double charge–discharge process characteristics of both the free radical redox of triphenylamine unit and the bipolar redox of triazine unit in the polymer and a well-defined multistage charge/discharge voltage plateau (~3.8 V for p-doped and ~2.0 V for n-doped) during the charge–discharge process. Also, the PTDAPTz demonstrates an improved capacity (stabilized at 123 mA h g⁻¹ until 50th cycle) and the enhanced rate performance compared to polytriphenylamine (PTPAn). Specially, the discharge curve for the part of triphenylamine unit presents an obviously improved discharge plateau (~3.8 V for PTDAPTz compared to ~3.6 V for PTPAn) due to the electron-withdrawing effect of the triazine unit to triphenylamine. The elaborate structural design and created micro-/mesoporous morphology with the double charge–discharge process make PTDAPTz a potential candidate as the performance-improved cathode of Li-organic battery. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2574–2583     

Fervent Hype behind Magnesium Batteries: An Open Call to Synthetic Chemists—Electrolytes and Cathodes Needed

Magnesium metal is a superior anode which has double the volumetric capacity of lithium metal and has a negative reduction potential of −2.37 V vs. the standard hydrogen electrode. A major benefit of magnesium is the apparent lack of dendrite formation during charging which is one of the crucial concerns of using a lithium metal anode. In this Review, we highlight the foremost research in the development of electrolytes and cathodes and discuss some of the significant challenges which must be overcome in realizing a practical magnesium battery.     

Investigation of different liquid media and ablation times on pulsed laser ablation synthesis of aluminum nanoparticles

Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol, acetone, and ethylene glycol. Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) images, Particle size distribution diagram from Laser Particle Size Analyzer (LPSA), UV-visible absorption spectra, and weight changes of targets were used for the characterization and comparison of products. The experiments demonstrated that ablation efficiency in ethylene glycol is too low, in ethanol is higher, and in acetone is highest. Comparison between ethanol and acetone clarified that acetone medium leads to finer nanoparticles (mean diameter of 30 nm) with narrower size distribution (from 10 to 100 nm). However, thin carbon layer coats some of them, which was not observed in ethanol medium. It was also revealed that higher ablation time resulted in higher ablated mass, but lower ablation rate. Finer nanoparticles, moreover, were synthesized in higher ablation times.     

富锂层状正极材料Li2Mn1-xTixO3的合成及电化学性能

应用简单的高温固相烧结法合成了Ti掺杂改性的Li₂MnO₃材料。电子扫描显微镜、X射线衍射以及X射线光电子能谱分析表明Ti元素取代Mn离子掺入到Li₂MnO₃晶格中,且掺杂能有效地抑制一次颗粒的团聚。电化学阻抗和恒流充放电测试结果表明,在2.0~4.6 V的电压窗口下,掺杂改性的样品Li₂Mn_0.9Ti_0.03O₃的首圈放电比容量达到209 mAh·g^-1,库仑效率为99.5%,循环40圈后容量保持率为94%;当电流密度增大到400 mA·g^-1时,掺杂改性的样品仍然可以放出120 mAh·g^-1比容量,远高于同等电流密度下未掺杂的Li₂MnO₃原粉的比容量（52 mAh·g^-1）。Ti掺杂可有效地改善Li₂MnO₃的循环稳定性和倍率性能,有利于促进该材料的商业化应用。     

MoO42-取代对Nasicon型Li3Fe2(PO4)3正极材料电化学性能的影响

以MoO₄^2-部分取代Li₃Fe₂（PO₄）₃中的PO₄^3-,研究表明：加入的MoO₄^2-离子主要以固溶形式存在于Li₃Fe₂（PO₄）₃中,起到了显著改善其电化学性能的作用。其中,MoO₄^2-掺杂浓度为0.3的样品表现出最佳的电化学性能,其在0.5C倍率下的首次放电容量为113.7 mAh·g^-1,这一数值比未掺杂的提高了20.7%;经过60次循环充放电,容量保持率为94%。将放电倍率从0.5C逐步增大至5C,再降至初始的0.5C,并在每个倍率循环10次,这一材料的最终放电容量可达首次0.5C的95%。这些优异的性能应归因于MoO₄^2-掺杂使材料的氧化还原能力增强,氧化还原电对的电势差减小,电池内部的电荷转移电阻减小,以及Li⁺扩散系数增加。     

(Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ-Ce0.9Gd0.1O2-δ复合阴极的制备及电化学性质

采用EDTA-柠檬酸盐法制备了（Pr_0.9La_0.1）₂（Ni_0.74Cu_0.21Ga_0.05）O_4+δ（PLNCG）,并与Ce_0.9Gd_0.1O_2-δ（CGO）形成复合阴极PLNCG-CGO。XRD和SEM分析结果表明PLNCG与CGO在1 000℃具有较好的化学相容性。电化学阻抗测试结果表明PLNCG-30% CGO复合阴极在700℃的极化电阻为0.092 Ω·cm²;过电位为39.3 mV时,电流密度达到113.3 mA·cm^-2。氧分压分析表明电极反应的速率控制步骤为电荷转移过程。阳极支撑单电池（Ni-CGO/CGO/PLNCG-30% CGO）在700℃的最大输出功率密度达到569 mW·cm^-2,开路电压（OCV）为0.76 V。综上结果预示PLNCG-30% CGO复合阴极是一种有发展前景的电极材料。     

Porous V2O5-SnO2/CNTs composites as high performance cathode materials for lithium-ion batteries

Vanadium pentoxide (V₂O₅) exhibits high theoretical capacities when used as a cathode in lithium ion batteries (LIBs), but its application is limited by its structural instability as well as its low lithium and electronic conductivities. A porous composite of V₂O₅-SnO₂/carbon nanotubes (CNTs) was prepared by a hydrothermal method and followed by thermal treatment. The small particles of V₂O₅, their porous structure and the coexistence of SnO₂ and CNTs can all facilitate the diffusion rates of the electrons and lithium ions. Electrochemical impedance spectra indicated higher ionic and electric conductivities, as compared to commercial V₂O₅. The V₂O₅-SnO₂/CNTs composite gave a reversible discharge capacity of 198 mAh·g^?1 at the voltage range of 2.05–4.0 V, measured at a current rate of 200 mA·g^?1, while that of the commercial V₂O₅ was only 88 mAh·g^?1, demonstrating that the porous V₂O₅-SnO₂/CNTs composite is a promising candidate for high-performance lithium secondary batteries.     

Aromatization of Hantzsch 1,4-Dihydropyridines with Al(NO3)3·9H2O and/or Fe(NO3)3·9H2O in the Presence of Silica Sulfuric Acid Under Mild and Heterogeneous Conditions

A simple and convenient method for the aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is achieved via combination of aluminum or ferric nitrates and silica sulfuric acid as environmentally friendly and novel oxidizing media. This oxidation was carried out in dichloromethane under heterogeneous conditions with good to excellent yields.