Synthesis of morphological ZnO particles by a facile solution-based chemical method

In this study, a facile solution-based chemical method has been developed to produce ZnO particles in the presence of triethanolamine (TEA) and NaOH. In this novel method, TEA acted as complexing reagents, and NaOH contributed to the transformation of ZnO precursor (Zn–TEA complex) into ZnO particles. The core of this new strategy is to transform Zn–TEA complex into morphological ZnO particles directly by a facile solution method. The results from transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM) analysis revealed that the morphologies of the as-prepared ZnO samples evolved from slices to quasi-spheres by increasing the amount of TEA. X-ray diffraction (XRD), Raman and room-temperature photoluminescence (PL) tests showed that these ZnO samples had wurtzite structures. A reasonable mechanism for the transformation of Zn–TEA complex into morphological ZnO particles was supplied.     

Study of the effect of ligands on the fluorescence properties of terbium ternary complexes

Four ternary complexes of Tb(III) were synthesized by introducing the first ligand (L₁) (N-phenylanthranilic acid (N-HPA), α-furoic acid (FURA)) and the second ligand (L₂) (1,10-phenanthroline (Phen), 2,2′-dipyridyl (Bipy)), respectively. These complexes were characterized by elemental analysis, infrared spectra, XRD, UV spectra and fluorescence spectra. The effect of L₁ and L₂ on the fluorescence properties of terbium complexes was discussed. It showed that all the complexes exhibited ligand-sensitized green emission. The fluorescent intensity increased in the sequence of Tb(FURA)₃Bipy < Tb(N-PA)₃Phen < Tb(FURA)₃Phen < Tb(N-PA)₃Bipy. It indicated that L₁ affected fluorescence properties of the complexes differently when the corresponding L₂ altered. Meanwhile, the influence of L₂ on the luminescence properties of the complexes also depends on L₁. The results showed that L₁ and L₂ affected each other and worked together as a whole. The matching of L₁, L₂ and Tb³⁺ ion is very important to the luminescence properties of Tb(III) ternary complexes.     

Influence of the electric characteristics of II–VI semiconductor material on the electroluminescence of lanthanide complex

The organic-inorganic combined structural device (ITO/PVK:Eu/ZnS/Al) is fabricated based on layered optimization scheme. II–VI semiconductor material ZnS is acted as an electron function (transporting and acceleration) layer. The hot electrons which have been accelerated in the ZnS layer directly impact excitation europium ions through resonant energy transfer and then recombine with injected holes to form excitons in PVK or EuTTA₂(N-HPA)Phen. Europium (Eu) ions may also be excited by intramolecular energy transfer from ligands. There are two kinds of excitation mechanisms: impacted excitation and injected recombination for the combined structural device. The electroluminescence (EL) intensity of the combined structural device is strongly improved and reaches up to 381 cd/m² at 20 V compared with the pure organic structural device. It may be an effective method to improve the EL intensity of the lanthanide complex by using electric characteristics of inorganic semiconductor materials.     

Negative photoconductivity in low-dimensional materials

In recent years,low-dimensional materials have received extensive attention in the field of electronics and optoelectronics.Among them,photoelectric devices based on photoconductive effect in low-dimensional materials have a broad development space.In contrast to positive photoconductivity,negative photoconductivity(NPC)refers to a phenomenon that the conductivity decreases under illumination.It has novel application prospects in the field of optoelectronics,memory,and gas detection,etc.In this paper,we review reports about the NPC effect in low-dimensional materials and systematically summarize the mechanisms to form the NPC effect in existing low-dimensional materials.     

p-型层状氧化锌的热电性质研究

采用第一性原理和玻尔兹曼输运理论,我们系统的研究了p-型二层氧化锌的热电性质.基于对单层氧化锌的晶格优化,计算得到其无虚频的声子谱,证明了它的热力学稳定性.由此构建了热力学性质稳定的二层氧化锌.采用实空间有限差分法生成了二层氧化锌的二阶和三阶力常数,然后得到了其声子散射和晶格热导率,使用两种计算方法得到了其晶格热导率在室温下分别为κ_ι~(BTE)=2.65 W/m·K和κ_ι~(RTA)=2.38 W/m·K.并且得到了p-型二层氧化锌在300 K至900 K等差温度下的热电优值为0.052～0.601,证明通过调节温度可以获得较高的热电优值.     

A poly-dopamine based metal-organic framework coating of the type PDA-MIL-53(Fe) for ultrasound-assisted solid-phase microextraction of polychlorinated biphenyls prior to their determination by GC-MS

The authors describe an ultrasonic-assisted headspace method for solid phase micro-extraction (UA-HS-SPME) of 7 polychlorinated biphenyls (PCBs) with codes PCB28, PCB52, PCB101, PCB118, PCB138, PCB153 and PCB180. The coating is based on a poly-dopamine metal-organic framework [PDA-MIL-53(Fe)] on a stainless steel wire. The coating can be prepared and evenly deposited on the stainless fiber by dipping the PDA fiber into a solution of MIL-53(Fe). The assay is also environmentally friendly because water is used as the solvent. The effects of extraction time, addition of salts, pH value and power of ultrasonic power were optimized. The coating is found to possess a high selectivity and adsorption capacity for PCBs compared to commercial SPME fibers such as the divinylbenzene/carboxen/polydimethylsiloxane fibers. Following desorption, the PCBs were quantified by GC-MS. The detection limits are between 50 and 90 pg?g^?1 of PCBs in soil. The fibers can be easily prepared, and the batch-to-batch reproducibility (RDS) is <10% (for n = 6). The fibers are inexpensive, re-usable and can be easily manipulated, and particularly well suited for screening polychlorinated biphenyls in soil.

Open image in new window

Graphical abstract Schematic of the preparation of an extraction fiber using stainless steel wire as substrate, PDA as adhesive, and MIL-53(Fe) as the adsorbent. It was applied to the extraction of PCBs from soil. The fiber is durable and inexpensive.

     

DBSA-catalyzed hydrolysis of chain α-oxo ketene dithioacetals in water: Aqueous synthesis of β-ketothioesters

In this paper, we wish to report an environment friendly synthetic method for β-ketothioesters from a dodecylbenzenesulfonic acid (DBSA)-catalyzed hydrolysis reaction of chain α-oxo ketene dithioacetals in water. It was shown that the hydrolysis reaction of chain α-oxo ketene dithioacetals could efficiently occur in the presence of 7.5?mol% DBSA at 100?°C in water, affording the desired β-keto thioesters in excellent yields.     

量子点荧光印迹传感器的计算机模拟设计、制备及检测河水中4-硝基苯酚的应用

将量子点的荧光特性、表面分子印迹技术与计算机模拟技术相结合,分别以碲化镉、4-硝基苯酚、3-氨丙基三乙氧基硅烷和正硅酸四乙酯作为量子点、模板分子、功能单体和交联剂,制得具有荧光特性的分子印迹聚合物.对其结构、形貌、荧光性能和选择性进行了表征,结果表明,该聚合物对4-硝基苯酚具有良好的选择性和灵敏度,线性范围为1.0~80 nmol/m L,检出限为0.05 nmol/m L.将制备的量子点荧光印迹聚合物作为传感器,应用于河水中4-硝基苯酚的测定,加标回收率为98.6%~101.2%,相对标准偏差最高为1.37%.     

Fabrication of Electrospun PVDF Nanofibers with Higher Content of Polar β Phase and Smaller Diameter by Adding a Small Amount of Dioctadecyl Dimethyl Ammonium Chloride

In this work,the effect of dioctadecyl dimethyl ammonium chloride(DDAC,a kind of alkyl ammonium salt) on polar β phase content and the diameter of electrospun PVDF nanofibers was investigated for the first time.Our experimental results show that the diameter of the electrospun PVDF nanofiber could be largely reduced and the content of polar β phase also become dominant immediately by just adding a little amount of DDAC.When the mass fraction of DDAC reached 4%,the content of polar β phase increased by about 39.1% compared with PVDF nanofibers without DDAC.Besides,the crystallinity of PVDF nanofibers also increased with the addition of DDAC.Based on the results,the possible mechanism of cooperative effect between electrospinning and DDAC on fiber diameter and formation of β phase in PVDF was discussed.     

Characterisation and effect of polymer network deformation in reverse-mode polymer-stabilised cholesteric texture

In reverse-mode polymer-stabilised cholesteric texture (PSCT), the dynamic response is derived from local director reorientation governed by dielectric coupling effect/self-assembly and polymer network deformation. A double exponential rise/decay model is proposed to investigate the underlying physical mechanisms. Through simulation of the transient rise and decay processes, the polymer network deformation in PSCT can be quantitatively evaluated. Less deformation and faster restoration speed of the polymer network can suppress hysteresis. These results provide useful guidelines for future PSCT fabrication and performance optimisation.