高能量密度LiMn0.6Fe0.4PO4/C的制备及其电化学性能

以Mn(NO_3)_2、Fe(NO_3)_3·9H_2O、NH_4H_2PO_4、LiOH·H_2O为原材料,采用改进的溶胶凝胶法制备了具有高能量密度的Li Mn_(0.6)Fe_(0.4)PO_4/C材料。该方法通过金属和多种配体配位构筑的框架,把得到的一次纳米颗粒构筑为类球形的二次颗粒,即发挥了纳米材料优异的电化学性能,又提高了材料的压实密度,电池的能量密度可提升约30%。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、交流阻抗谱(EIS)、振实密度、粒度以及电化学测试等表征手段对材料的晶体结构、形貌和电化学性能进行了较系统的研究,结果表明此方法制备的LiMn_(0.6)Fe_(0.4)PO_4/C材料不仅具有较高的振实密度和电压平台,还具有优异的电化学性能:振实密度为1.3 g·cm~(-3),且在1C倍率下,放电中值电压为3.85 V,100次循环后,比容量仍有142.3 mAh·g~(-1),容量保持率为99.4%。     

基于超分子离子晶体的湿度传感构效关系研究

相对湿度是许多领域的关键参数,环境湿度与人们的生活密切相关,因此对湿度进行测量和控制是各个领域中值得关注的问题之一. 在前期的研究中,作者制备了一种新型的超分子离子材料（SIM）,它是由基于咪唑的双阳离子（如1,10-双（3-甲基咪唑-1-基）癸烷,C₁₀(mim)₂）和电活性二阴离子（如2,2'-连氮基-双（3-乙基苯并噻唑啉-6-磺酸）,ABTS）组成的,发现其对湿度具有敏感且快速的响应. 在此基础上,本文制备了6种不同碳链（C₄,C₆,C₈,C₁₀,C₁₂,C₁₄）的咪唑基化合物,发现其中3种（C₁₀,C₁₂,C₁₄）可与ABTS形成水稳定的SIM. 循环伏安法、计时电流法以及石英晶体微量天平表征了这些超分子离子材料的湿度传感性能,发现基于C12的SIM具有最佳的湿度传感性能. 同时,SEM结果显示随着碳链的增加,离子材料的厚度变薄并且形态变得不规则. 因此,作者认为疏水作用和材料比表面积均会影响湿度传感的灵敏度. 本研究为发展新的湿度响应的离子传感材料奠定了基础.     

利用升华物质2,4,6-三异丙基-1,3,5-三氧杂环己烷作模板剂制备聚苯胺包覆的中空硫电极材料

本文首次提出采用升华物质为模板,制备聚苯胺包覆的中空硫电极材料. 首先通过Na₂S₂O₃和稀HCl反应,在具有升华特性的ADD(2,4,6-三异丙基-1,3,5-三氧杂环己烷)微粒表面沉积一层S,然后在S的表面再沉积聚苯胺包覆层. 在经60 ^oC干燥12小时后,其中的ADD自然挥发,得到聚苯胺壳体包覆的中空硫复合物. SEM、TEM和TG分析表明,制得的聚苯胺包覆中空硫的粒径约为2 μm,硫含量为61.1%. 在500 mA·g^-1充放电电流下,首次放电比容量为776.2 mAh·g^-1,库仑效率为95.9%. 100次充放电循环后,放电比容量为524.7 mAh·g^-1. 由于聚苯胺包覆物的聚苯胺膜具有抑制聚硫锂向外的扩散作用,以及包覆物中的空间对放电时S的膨胀具有缓冲作用,聚苯胺包覆中空硫粉末的放电比容量和充放电稳定性均明显高于未包覆聚苯胺的中空硫和化学制备的硫. 这种制备导电聚合物包覆中空硫的新方法具有操作简单、成本低廉的优点,有进一步发展的前景.     

Sensitive Determination of Terbutaline Using a Platform Based on Nanoparticles of Europium Oxide and Carbon Nanotubes

This study presents a sensitive voltammetric determination of terbutaline (TER) on a platform based on carbon nanotubes (CNTs) and europium oxide nanoparticles (Eu₂O₃NPs) coated glassy carbon electrodes (GCEs). An ultrasonic bath was performed for the preparation of composite material. The material was characterized by energy dispersive X‐ray spectroscopy (EDX), X‐ray diffraction method (XRD) and scanning electron microscopy (SEM). The Eu₂O₃NPs/CNTs/GCE system was assessed for the oxidation of terbutaline (TER). A broad oxidation peak was appeared at 0.71 V using a bare GCE. However, the voltammetry of TER has been improved at a GCE coated with CNTs and a well‐defined anodic peak exhibited at 0.61 V. Furthermore, the nanoparticles of Eu₂O₃ and CNTs coated GCE has greatly improved the electrochemical behaviour of TER and a sharp peak was appeared at 0.59 V. Cyclic voltammetry at Eu₂O₃NPs/CNTs/GCE also reveals a high catalytic effect for the oxidation of TER with an oxidation peak that is distinctly enhanced compared to GCE and CNTs/GCE. Eu₂O₃ nanoparticles were utilized to enhance the surface area of GCE and then improve the sensitivity of the procedure. The response of TER was linear over a concentration range of 2.0×10^?8 M ?9.5×10^?6 M with an LOD of 3.7×10^?9 M. Square wave voltammetric analysis of tablets by Eu₂O₃NPs/CNTs/GCE yielded a recovery of 99.2 % with an RSD% of 3.2. The modified electrode (EuO₂NPs/CNTs/GCE) provides accuracy and precision to the analysis of samples.     

Synthesis and characterization of poly(N‐(2‐mercaptoethyl) acrylamide) microgel for biomedical applications

N‐(2‐mercaptoethyl) acrylamide (MEAM) monomer was synthesized by acrylation of cysteamine and was cross‐linked with ethylene glycol dimethacrylate (EGDMA) via dispersion polymerization forming poly(N‐(2‐mercaptoethyl) acrylamide) (p(MEAM)) microgel. Then, the prepared microgels were tested for potential biomedical use, eg, antioxidant capacity and blood compatibility, cytotoxicity, apoptotic, and necrotic cell death; drug delivery properties were determined. Antioxidant studies of p(MEAM) microgels revealed a super antioxidant capability with total phenol content and trolox equivalent antioxidant capacity as 6.05 ± 1.15 mg/L gallic acid equivalency and 40.96 ± 2.40 mM trolox/g, respectively. Moreover, the blood compatibility of p(MEAM) microgels on fresh blood was resulted in lower than 1.0% hemolysis ratios for all the studied concentration range, and the blood clotting index was determined as 60.66% at 2.0 mg/mL at microgel concentration. The biocompatibility studies employing WST‐1 test on L929 fibroblast cells and DLD‐1 colon cancer cells have shown that p(MEAM) microgel was biocompatible up to 200 μg/mL concentration with the cell viability values of 84.54% and 86.15% on L929 fibroblast and DLD‐1 colon cancer cells, respectively. Using Captopril was used as model drug to test p(MEAM) microgel as drug delivery device for in vitro release studies at different pHs. Release profile of Captopril was found linear up to 5 hours with the released amounts of 9.81, 12.24, and 13.78 mg g^‐1microgel at the pH 1.5, 7.4, and 9.0, respectively.     

There and Back Again—The Journey of LiNiO2 as a Cathode Active Material

This Review provides a comprehensive overview of LiNiO₂ (LNO), almost 30 years after its introduction as a cathode active material. We aim to highlight the physicochemical peculiarities that make LNO a complex material in every aspect. We specifically stress the effect of the Li off‐stoichiometry (Li_1?zNi_1+zO₂) on every property of LNO, especially the electrochemical ones. The key instability issues that plague the compound and the strategies that have been implemented so far to overcome them are discussed in detail. Finally, the open questions that remain to be addressed by the scientific community are summarized, and the research directions that seem the most promising to enable LNO to be fully exploited are elucidated.     

Finding Degradation Trigger Sites of Structural Materials for Airplanes Using X‐Ray Microscopy

Macroscopic properties of carbon fiber‐reinforced plastic (CFRP) and environmental barrier coating (EBC), widely used for airplanes, can be deteriorated by local cracks or degradation (“trigger sites”). We have tried to find these trigger sites using x‐ray microscopy (XM), which can provide the 2D or 3D images of the chemical states and microstructures. Crack initiation in CFRP was observed in a non‐destructive manner in multi‐scales (nm‐mm). 3D chemical‐state mapping of Yb in EBC was achieved with high resolution (<50 nm). In addition to XM, in‐situ observations at high temperatures were conducted for obtaining complementary information. X‐ray absorption spectroscopy (XAS) and x‐ray diffraction (XRD) analysis were performed simultaneously up to 1773 K. Dynamic XAS with short time‐resolution (<10 ns) was conducted to investigate changes in the local structure of metal. These approaches can help us identify degradation trigger sites in the materials.     

含巯基MTQ树脂的合成及对丙烯酸酯体系光固化性能的影响

以六甲基二硅氧烷、γ-巯丙基三乙氧基硅烷（KH-580）和正硅酸乙酯为原料,在酸性条件下通过水解共聚反应合成了含巯基MTQ树脂（SH-MTQ）。通过傅里叶红外光谱、核磁共振氢谱（¹HNMR）、凝胶渗透色谱和热重,对所合成的树脂进行了表征和分析。以1-羟基环己基苯基甲酮（184）为光引发剂,考察了含巯基MTQ树脂对三丙二醇二丙烯酸酯（TPGDA）光固化过程和材料性能的影响,发现含巯基MTQ树脂的加入使得TPGDA的光固化速率和双键转化率有所提高,并且固化膜硬度、热稳定性、透过率和接触角等材料性能也有所提高。     

不同重力下窄通道内薄材料表面的火焰传播

在常重力下模拟微重力燃烧对载人航天器的火灾安全具有重要意义.窄通道就是这样一种可以有效限制自然对流的模拟设施.但是,不同重力下火焰传播的相似性仍然是有待研究的问题.本文用实验和数值模拟的方法,比较了不同重力下有限空间内热薄材料表面的逆风传播火焰.不同重力下火焰形状和火焰传播速度的比较表明,1cm高的水平窄通道可以有效地限制自然对流,在常重力下用这种通道能够模拟微重力下相同几何尺寸的通道中的火焰传播.因此,在地面上首先利用水平窄通道,模拟相同环境中的微重力火焰传播,然后考虑通道尺寸变化对火焰传播的影响,有可能成为地面模拟其他尺寸的空间中的微重力燃烧的方法.