Ni(OH)2修饰的三聚氰胺泡沫用于可压缩超级电容器电极

通过化学镀和电化学镀的方法制备了一种Ni(OH)₂电化学活性材料修饰三聚氰胺泡沫(MF)可压缩骨架的超级电容器电极材料MF/Ni(OH)₂。MF/Ni(OH)₂可压缩电极材料表现出最佳的电容性能,例如循环稳定性(即使在40 mA/cm^-3的电流密度下经过2000次充放电循环后,可压缩电极仍能保持90.63%的初始电容)和可压缩稳定性(即使在压缩率为50%时,仍具有97.88%的电容保持率)。层状可压缩超级电容器由MF/Ni(OH)₂弹性材料作为阳极,镍/碳(Ni/C)为阴极以及实验室中常用的滤纸作隔膜材料组成。这种超级电容器装置在不同的压缩下表现出良好的电化学性能和优异的压缩稳定性。最后,使用可压缩的超级电容器来点亮LED灯,以展示其在柔性电子设备中的应用。这些优化的电化学和机械性能表明MF/Ni(OH)₂可作为可压缩超级电容器的应用中的候选电极。     

Oxygen-vacancy-enhanced Catalytic Activity of Au@Co3O4/CeO2 Yolk-shell Nanocomposite to Electrochemically Detect Hydrogen Peroxide

Biomimetic electrochemical sensors are very promising not only due to their lower expense and longer stability than conventional enzymatic ones, but they also often suffer from simultaneously achieving high sensitivity and good selectivity. Here we present a well-defined Au@Co₃O₄/CeO₂ yolk-shell nanostructure (YSN) that is first synthesized and exploited as highly efficient electrocatalysts for hydrogen peroxide (H₂O₂) detection. The introduced CeO₂ in Co₃O₄ matrix greatly facilitates the migration of lattice oxygen, which increases the concentration of surface oxygen vacancies (O_a), remarkably enhancing the adsorption ability of H₂O₂ and promoting the decomposition of H₂O₂ for faster electron transfer than pristine Au@Co₃O₄ core-shell nanostructure (CSN). The abundant O_a of Au@Co₃O₄/CeO₂ YSN is confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). The as-prepared biomimetic sensor delivers a wide dynamic range (5.0 nM to 5.4 μM), a low limit of detection (LOD) (2.74 nM), and a high sensitivity (35.67 μA μM⁻¹ cm⁻²), paving a new way to construct an ultrasensitive and selective enzyme-free biomimetic electrochemical sensor. Furthermore, the sensor is used to real-time monitor H₂O₂ released from human cervical cancer cells (HeLa) and human umbilical vein endothelial cells (HUVEC), demonstrating its great potential in practical applications.     

ABC三嵌段共聚物胶束从多间隔结构到多核结构转变的Monte Carlo模拟

采用Monte Carlo模拟方法研究了疏水-亲水-疏水(H-P-H)型ABC三嵌段共聚物在B嵌段的选择性溶剂中的自组装行为. 模拟结果表明, 通过调节A嵌段和C嵌段的疏水性和二者之间的不相容性, 体系中可以形成多种形貌各异的胶束. 根据胶束中疏水核结构的特点, 这些胶束大体上可以被分为多核型胶束和多间隔型胶束两种类型. 通过增强疏水嵌段的疏水性或降低A嵌段和C嵌段间的不相容性, H-P-H型ABC三嵌段共聚物胶束能够发生从多核型胶束向多间隔型胶束的转变. 进一步分析胶束中聚合物的链构象等微观结构信息发现, A嵌段和C嵌段间的排斥作用和疏水作用之间存在竞争关系, 而这种竞争关系是影响体系中形成多核型胶束还是多间隔型胶束的决定性因素.     

Ionic/electronic conductivity regulation of n-type polyoxadiazole lithium sulfonate conductive polymer binders for high-performance silicon microparticle anodes

Low-cost silicon microparticles(SiMP),as a substitute for nanostructured silicon,easily suffer from cracks and fractured during the electrochemical cycle.A novel n-type conductive polymer binder with excellent electronic and ionic conductivities as well as good adhesion,has been successfully designed and applied for high-performance SiMP anodes in lithium-ion batteries to address this problem.Its unique features are attributed to the stro ng electron-withdrawing oxadiazole ring structure with sulfonate polar groups.The combination of rigid and flexible components in the polymer ensures its good mechanical strength and ductility,which is beneficial to suppress the expansion and contraction of SiMP s during the charge/discharge process.By fine-tuning the monomer ratio,the conjugation and sulfonation degrees of the polymer can be precisely controlled to regulate its ionic and electronic conductivities,which has been systematically analyzed with the help of an electrochemical test method,filling in the gap on the conductivity measurement of the polymer in the doping state.The experimental results indicate that the cell with the developed n-type polymer binder and SiMP(~0.5 μm) anodes achieves much better cycling performance than traditional non-conductive binders.It has been considered that the initial capacity of the SiMP anode is controlled by the synergetic effect of ionic and electronic conductivity of the binder,and the capacity retention mainly depends on its electronic conductivity when the ionic conductivity is sufficient.It is worth noting that the fundamental research of this wo rk is also applicable to other battery systems using conductive polymers in order to achieve high energy density,broadening their practical applications.     

Enhanced conversion of α-cellulose to 5-HMF in aqueous biphasic system catalyzed by FeCl_3-CuCl_2

This study was to investigate the optimal additions of the cellulose decomposition reaction to obtain the most yield of 5-HMF and other furan derivatives in various biphasic systems with FeCl_3-CuCl_2 mixed catalysts,and explore its depolymerization kinetics.A series of controllable reactions have been performed under mild environmentally friendly atmosphere.The experiment results showed that49.13 wt% of 5-HMF was the maximum production along with 2.98 wt% other furan derivatives catalyzed by mixed Lewis acid FeCl_3-CuCl_2 under the two phases which included high concentration NaCl aqueous phase and n-butanol organic phase at 190℃ for 45 min.The conclusion suggested that two-phase systems benefited the yield of 5-HMF,furan derivatives via extracting the target products from reaction phase to organic phase to avoid rehydration of 5-HMF.The kinetic calculation revealed the conversion with mixed catalysts had lower reaction apparent activation energy(21.65 kJ/mol,190-230℃) and the reaction rate was faster than that with acid-based catalysts.Based on experiment exploration,the probable mechanism of cellulose decomposition with FeCl_3-CuCl_2 was proposed.     

An Electron Paramagnetic Resonance Study of the Orbital Ordering Compound MgTi<Subscript>2</Subscript>O<Subscript>4</Subscript>

We report the electron paramagnetic resonance (EPR) studies of MgTi₂O₄ in the 300–140 K range. Above the transition temperature T _t (~258 K), the EPR results indicate that MgTi₂O₄ is paramagnetic. The parameters of the EPR spectra show an anomalous change at T _t. The clear EPR lines can be observed in temperature between T _t and 220 K. Besides that the EPR intensity, g value, and EPR linewidth increase with decreasing temperature; in temperature range below 220 K, no clear EPR line can be detected. The EPR spectra results demonstrate that magnetic spin-singlet state and the orbital density wave of MgTi₂O₄ system are formed gradually with decreasing temperature at low temperature range.     

A Novel L‐Cysteine Electrochemical Sensor Using Sulfonated Graphene‐poly(3,4‐Ethylenedioxythiophene) Composite Film Decorated with Gold Nanoparticles

By exploiting the electrostatic interaction between positively charged 3,4‐ethylenedioxythiophene cation radicals and negatively charged sulfonated graphene (SG) sheets, we prepared a poly(3,4‐ethylenedioxythiophene)‐sulfonated graphene (SG‐PEDOT) composite film by a one‐step electrochemical process. The composite was further decorated with gold nanoparticles (AuNPs) and employed as an electrode material for the detection of L ‐cysteine (Cys). The SG‐PEDOT composite film is shown to provide a rough surface for the electrodeposition of AuNPs and to improve substrate accessibility and interaction with Cys. Moreover, the AuNPs‐decorated composite exhibits better electrocatalytic performance than that of a SG‐PEDOT composite only. Under optimum experimental conditions, the amperometric current of the sensor is linearly related to the concentration of Cys in the 0.1 to 382 µM range, and the detection limit is 0.02 µM (at S/N=3). The modified electrode displays favorable selectivity, good stability and high reproducibility. The method was successfully applied to the detection of Cys in spiked human urine.     

Peptide Dimethylation: Fragmentation Control via Distancing the Dimethylamino Group

Direct reductive methylation of peptides is a common method for quantitative proteomics. It is an active derivatization technique; with participation of the dimethylamino group, the derivatized peptides preferentially release intense a₁ ions. The advantageous generation of a₁ ions for quantitative proteomic profiling, however, is not desirable for targeted proteomic quantitation using multiple reaction monitoring mass spectrometry; this mass spectrometric method prefers the derivatizing group to stay with the intact peptide ions and multiple fragments as passive mass tags. This work investigated collisional fragmentation of peptides whose amine groups were derivatized with five linear ω-dimethylamino acids, from 2-(dimethylamino)-acetic acid to 6-(dimethylamino)-hexanoic acid. Tandem mass spectra of the derivatized tryptic peptides revealed different preferential breakdown pathways. Together with energy resolved mass spectrometry, it was found that shutting down the active participation of the terminal dimethylamino group in fragmentation of derivatized peptides is possible. However, it took a separation of five methylene groups between the terminal dimethylamino group and the amide formed upon peptide derivatization. For the first time, the gas-phase fragmentation of peptides derivatized with linear ω-dimethylamino acids of systematically increasing alkyl chain lengths is reported. Figure

?     

Metal‐Free Aminosulfonylation of Aryldiazonium Tetrafluoroborates with DABCO⋅(SO2)2 and Hydrazines

The coupling of aryldiazonium tetrafluoroborates, DABCO?(SO₂)₂, and hydrazines under metal‐free conditions leads to the formation of aryl N‐aminosulfonamides. The reaction proceeds smoothly at room temperature and shows broad functional‐group tolerance. A radical process is proposed for this transformation.     

铜树枝晶的水热合成以及结构表征和抗菌性能评价(英文)

在乙醇胺-水混合溶液中采用水热处理硫酸铜的方法制备了多结构的铜树枝晶;采用X射线粉末衍射仪、扫描电子显微镜、透射电子显微镜分析了所得样品的结构和形貌;采用牛津杯法评价了其对金黄葡萄球菌、枯草芽孢杆菌、大肠杆菌和绿脓杆菌的抗菌性能.结果表明,铜树枝晶由一个长的一级中心主干和许多高度对称分布在主干两侧的二级分支结构构成,且形貌均匀;反应温度、反应时间以及溶剂组成对铜树枝晶的形貌有很大影响.与此同时,铜树枝晶表现出选择性的抗菌行为,对金黄葡萄球菌、枯草芽孢杆菌和绿脓杆菌更有效.