基于山梨酸钾衍生多孔碳修饰电极用于橙皮素检测

以有机盐山梨酸钾(PS)作为模板,在氮气氛围下进行一步热解处理,制备出一种衍生的三维互连的多孔碳材料(PSIPC)。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、热重分析(TGA)及N₂吸附-脱附测试对该多孔碳材料进行表征。于不同热解温度下制备电极材料PSIPC-X(X=700、800、900℃),并采用滴涂法制备了山梨酸钾衍生多孔碳修饰电极(PSIPC-700/GCE、PSIPC-800/GCE及PSIPC-900/GCE),使用循环伏安法(CV)和差示脉冲伏安法(DPV)考察了橙皮素(HSP)在PSIPC-900/GCE上的电化学行为。结果表明,在最优条件下,HSP在该电极上的检测范围为0.05～15.0μmol/L,检出限为0.021μmol/L。该方法灵敏度高、检测范围广,可用于实际样品的检测。     

基于聚谷氨酸修饰玻碳电极的甲基对硫磷电化学传感器

制备了一种简单的聚谷氨酸修饰玻碳电极的用于检测甲基对硫磷的电化学传感器。 并应用循环伏安法研究了甲基对硫磷在该修饰电极上的氧化还原行为;甲基对硫磷的浓度检测采用差分脉冲伏安法,结果表明,甲基对硫磷在5.0×10-7～7.5×10-4 mol/L浓度范围与响应电流有良好的线性关系。 甲基对硫磷检测限（S/N=3）可达1.0×10-9 mol/L。 该法制备的传感器有望应用于实际样品中的甲基对硫磷的检测。     

碳和石墨烯对磷酸锰锂材料性能的影响

在采用溶剂热法制备磷酸锰锂的基础上,以蔗糖和石墨烯为碳源,制备了裂解碳和石墨烯含量不同的磷酸锰锂/碳/石墨烯复合材料,研究了裂解碳和石墨烯对材料性能的影响。采用扫描电镜（SEM）和透射电镜（TEM）对材料的形貌进行了表征。裂解碳包覆可以提高LiMnPO₄纳米片表面的电子导电性,对于材料性能的改善起到主要的作用;石墨烯可以提高纳米片之间的电子和离子导电性,改善材料的电化学性能。电化学测试表明,当裂解碳含量为4%、石墨烯含量为2%时,LiMnPO₄电极具有较好的电化学性能,在0.5C下的放电比容量为139.1 mAh·g^-1,循环100次后,容量保持率为93.6%。与添加单一碳和单一石墨烯的LiMnPO₄电极相比,该电极在0.5C下的放电比容量分别提高了35.0%和48.6%。     

Di‐ and Triphosphate Recognition and Sensing with Mono‐ and Dinuclear Fluorescent Zinc(II) Complexes: Clues for the Design of Selective Chemosensors for Anions in Aqueous Media

The synthesis of a new ligand (L1) containing two 1,4,7‐triazacyclononane ([9]aneN₃) moieties linked by a 4,5‐dimethylenacridine unit is reported. The binding and fluorescence sensing properties toward Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ of L1 and receptor L2, composed of two [9]aneN₃ macrocycles bridged by a 6,6′′‐dimethylen‐2,2′:6′,2′′‐terpyridine unit, have been studied by coupling potentiometric, UV/Vis absorption, and emission measurements in aqueous media. Both receptors can selectively detect Zn²⁺ thanks to fluorescence emission enhancement upon metal binding. The analysis of the binding and sensing properties of the Zn²⁺ complexes toward inorganic anions revealed that the dinuclear Zn²⁺ complex of L1 selectively binds and senses the triphosphate anion (TP), whereas the mononuclear Zn²⁺ complex of L2 displays selective recognition of diphosphate (DP). Binding of TP or DP induces emission quenching of the Zn²⁺ complexes with L1 and L2, respectively. These results are exploited to discuss the role played by pH, number of coordinated metal cations, and binding ability of the bridging units in metal and/or anion coordination and sensing.     

Electrochemical Behavior and Amperometric Detection of 4‐Chlorophenol on Nano‐Au Thin Films Modified Glassy Carbon Electrode

An amperometric sensor based on nano‐Au thin films was fabricated, by means of which a fast response to 4‐chlorophenol (4‐CP) can be achieved in the range of mM concentrations. The nanostructured Au thin film was prepared on glassy carbon electrodes by a template‐free, double‐potential step electrodeposition technique. Its structural feature can be controlled well by adjusting the deposition time. The amperometric detection of 4‐CP was performed at +0.85 V with a linear detection range from 0.2 to 4.8 mM and a detection limit of 0.11 mM (S/N=3). Besides, the effect of concentrations on the electrochemical behavior of 4‐CP on the Au thin film was investigated by linear sweep voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy.     

Electrochemical Sensor Based on Multi‐walled Carbon Nanotube/Gold Nanoparticle Modified Glassy Carbon Electrode for Detection of Estradiol in Environmental Samples

We report a rapid and simple method for sensing estradiol by electro‐oxidation on a multi‐walled carbon nanotube (MWCNT) and gold nanoparticle (AuNP) modified glassy carbon electrode (GCE). Compared with a bare GCE, AuNP/GCE and MWCNT/GCE, the composite modified GCE shows an enhanced response to estradiol in 0.1 M phosphate buffer solution. Experimental parameters, including pH and accumulation time for estradiol determination were optimised at AuNP/MWCNT/GCE. A pH of 7.0 was found to be optimum pH with an accumulation time of 5 minutes. Estradiol was determined by linear sweep voltammetry over a dynamic range up to 20 %mol L^?1 and the limit of detection was estimated to be 7.0×10^?8 mol L^?1. The sensor was successfully applied to estradiol determination in tap water and waste water.     

Fast‐response Electrochemical Detection of Trinitrotoluene at Sub‐ppb Levels on Nitrogenized Porous Carbon Spheres

We present sub‐ppt level detection of explosive trinitrotoluene by constructing a fast‐response electrochemical sensor using nitrogenized porous carbon spheres (NPCS). NPCS with nitrogen doping and amino functionalization accelerates charge transfer and trinitrotoluene accumulation. A high sensitivity of 60.2 μA cm^?2 ppb^?1 and a detection limit of 0.15 ppb are achieved on NPCS, among the best of recently reported trinitrotoluene electrochemical sensors. Moreover, response time of NPCS is greatly reduced by two times comparing with nitrogen‐free sample. NPCS also offers high selectivity, repeatability and stability, rendering new opportunities to fast detect trinitrotoluene for home security and environment protection.     

Impedimetric Enzyme‐Free Detection of Glucose via a Computation‐Designed Molecularly Imprinted Electrochemical Sensor Fabricated on Porous Ni Foam

Here we report a new molecularly imprinted electrochemical sensor (MIECS) for the impedimetric enzyme‐free analysis of glucose. A computational modeling strategy was first utilized to screen promising functional monomers for imprinting assembly, and simulation data suggested that methacrylic acid (MAA) exhibited a preferable capability to recognize the target molecule compared to other common monomers. Then the MIECS was prepared via introducing MAA‐based recognition sites onto a porous Ni foam with large surface. The fabricated sensor was subtly characterized by Raman spectroscopy, scanning electron microscopy, and cyclic voltammetry, and an impedimetric method was selected to detect the glucose target in a basic medium. Experimental results demonstrated that the proposed MIECS could selectively recognize glucose against coexisting species, with good linear responses of the charge transfer resistance upon the target concentration in the scope of 10∼55 mM. These results indicate its potential applications in the recognization and detection of glucose in complex matrices.     

Self‐Assembly of Water‐Soluble Platinum(II)‐Based Metallacalixarenes and Tuning Their Conformational Interconversion via Synergistic Effects between Solvents and Anions

The aqueous self‐assembly of the flexible ligand L bis(1H‐benz[d]imidazole‐1‐yl)methane and cis‐coordinated Pt^II precursors [(en)Pt²⁺, (tmeda)Pt²⁺, en=ethylenediamine, tmeda=N,N,N′,N′‐tetramethylethylenediamine)] led to the formation of the metallacalixarenes with full alternative conformations (e.g., two novel water‐soluble metallacalixarenes [M₂L₂]⁴⁺ and [M₃L₃]⁶⁺ with D₂ and D₃ symmetry, respectively). Their molecular structures were determined by single crystal X‐ray analyses in solid state. The two metallacalixarenes present different cavity sizes and the [M₃L₃]⁶⁺ cavity encapsulates one NO₃⁻. NOESY NMR revealed that the conformational interconversion between 1,3‐alternate conformer in methanol and cone conformer in DMSO was tuned via the synergistic effect between solvent and anion. Guest encapsulation is also discussed.     

A Superior Na3V2(PO4)3‐Based Nanocomposite Enhanced by Both N‐Doped Coating Carbon and Graphene as the Cathode for Sodium‐Ion Batteries

A superior Na₃V₂(PO₄)₃‐based nanocomposite (NVP/C/rGO) has been successfully developed by a facile carbothermal reduction method using one most‐common chelator, disodium ethylenediamintetraacetate [Na₂(C₁₀H₁₆N₂O₈)], as both sodium and nitrogen‐doped carbon sources for the first time. 2D‐reduced graphene oxide (rGO) nanosheets are also employed as highly conductive additives to facilitate the electrical conductivity and limit the growth of NVP nanoparticles. When used as the cathode material for sodium‐ion batteries, the NVP/C/rGO nanocomposite exhibits the highest discharge capacity, the best high‐rate capabilities and prolonged cycling life compared to the pristine NVP and single‐carbon‐modified NVP/C. Specifically, the 0.1 C discharge capacity delivered by the NVP/C/rGO is 116.8 mAh g^?1, which is obviously higher than 106 and 112.3 mAh g^?1 for the NVP/C and pristine NVP respectively; it can still deliver a specific capacity of about 80 mAh g^?1 even at a high rate up to 30 C; and its capacity decay is as low as 0.0355 % per cycle when cycled at 0.2 C. Furthermore, the electrochemical impedance spectroscopy was also implemented to compare the electrode kinetics of all three NVP‐based cathodes including the apparent Na diffusion coefficients and charge‐transfer resistances.     

An Electrochemical Sensor for the Detection of Cu2+ Based on Gold Nanoflowers‐modifed Electrode and DNAzyme Functionalized Au@MIL‐101 (Fe)

In this study, we developed an electrochemical sensor for sensitive detection of Cu²⁺ based on gold nanoflowers (AuNFs)‐modified electrode and DNAzyme functionalized Au@MIL‐101(Fe) (MIL: Materials of Institute Lavoisier). The AuNFs‐modified indium tin oxide modified conductive glass electrode(AuNFs/ITO) prepared via electrodeposition showed improved electronic transport properties and provided more active sites to adsorb large amounts of oligonucleotide substrate (DNA1) via thiol‐gold bonds. The stable Au@MIL‐101(Fe) could guarantee the sensitivity because of its intrinsic peroxidase mimic property, while the Cu²⁺‐dependent DNA‐cleaving DNAzyme linked to Au@MIL‐101(Fe) achieved the selectivity toward Cu²⁺. After the DNAzyme substrate strand (DNA2) was cleaved into two parts due to the presence of Cu²⁺, the oligonucleotide fragment linked to MIL‐101(Fe) was able to hybridize with DNA1 adsorbed onto the surface of AuNFs/ITO. Due to the peroxidase‐like catalytic activity of MIL‐101(Fe) and the affinity recognition property of DNAzyme toward Cu²⁺, the electrochemical biosensor showed a sensitive detection range from 0.001 to 100 μM, a detection limit of 0.457 nM and a high selectivity, demonstrating its potential for Cu²⁺ detection in real environmental samples.     

Electrospun Li3V2(PO4)3 Nanobelts: Synthesis and Electrochemical Properties as Cathode Materials of Lithium‐Ion Batteries

Novel Li₃V₂ (PO₄)₃ nanobelts, which was confirmed by the peaks of X‐ray diffraction, were prepared by a facile and environmentally friendly electrospinning method. A distinct nanobelt structure, with an average width of 2.5 µm and a thickness of 200 nm, is observed by scanning electron microscopy (SEM), while the specific surface area of 140.8 m²/g is estimated by a specific surface area analyzer. Moreover, the unique Li₃V₂(PO₄)₃ nanobelts exhibited a specific discharge capacity of 155.6 mAh/g at 0.2 C rate when they were used as cathode material in lithium‐ion batteries, on testing from 3.0 to 4.8 V. Remarkably, the batteries containing Li₃V₂(PO₄)₃ nanobelts displayed excellent cycling performance, with only a 0.02% fading rate per cycle after 50 cycles in the range 30–4.3 V. These outstanding electrochemical performances could be ascribed to the particular morphology, large surface area, homogeneous particle size distribution, and the one‐dimensional microstructure of Li₃V₂(PO₄)₃ nanobelts.     

Vibrational Spectra of Cluster Anions. 2. Vibrational Spectra of Compounds with the Cluster Anions [E4]4−: M4E4 (M = K,Rb, Cs; E = Ge,Sn) and β‐Na4Sn4

Vibrational spectra of the compounds M₄E₄ (M = K, Rb, Cs; E = Ge, Sn) and of β‐Na₄Sn₄ with the cluster anions [E₄]^4? were analysed based on the point group of isolated tetrahedranide units. The lower individual symmetry of the anions in the real structure being more patterned and complex primarily affects the spectra of the tetrahedro‐tetragermanides. ν₃(F₂) clearly splits both in Raman and IR and in the case of K₄Sn₄ only in IR. Rb₄Sn₄ and Cs₄Sn₄ exhibit very simple spectra with three bands in Raman and one band in IR. The breathing mode ν₁(A₁) for the quasi isolated [E₄]^4? cluster appears only in the Raman spectrum and is hardly influenced by the structural environment and by the nature of the alkali metal cations: ν₁(A₁) = 274 cm^?1 ([Ge₄]^4?) and 183‐187 cm^?1 ([Sn₄]^4?), respectively. The calculated valence force constants f_d(E–E) are: [Ge₄]^4? : f_d = 0.89 Ncm^?1 ( K ), 0.87 Ncm^?1 ( Rb ), 0.86 Ncm^?1 ( Cs ) and [Sn₄]^4? : 0.67 Ncm^?1 ( Na ), 0.66 Ncm^?1 ( K ), 0.67 Ncm^?1 ( Rb ), 0.68 Ncm^?1 ( Cs ). Both, the frequencies and the force constants fit well into the range previously reported.     

Determination of Cr(VI) with Selective Sensing of Cr(VI) Anions by a PVC‐Membrane Electrode Based on Quinaldine Red

A dichromate‐selective PVC‐membrane electrode based on Quinaldine Red (an acridinium derivative) is described. The electrode exhibits rapid (< 30 s) and linear response to the activity of Cr(VI) anions in the range of 5.2 × 10^?6 ?1.0 × 10^?1 M dichromate with the limit of detection 2.5 × 10^?6 Mof Cr₂O₇^2?. The sensor is used as an indicator electrode in potentiometric determination of Cr(VI) anions and is also suitable for end‐point indication in the titrations of proper metal ions with dichromate under laboratory conditions. The proposed electrode has been applied to the direct potentiometric determination of Cr(VI) anions in water samples with satisfactory results.     

Syntheses and Crystal Structures of Two New Open‐Framework Tin(II) Phosphates: Sn5O2(PO4)2 and Sn4O(PO4)2

Two new three‐dimensional neutral open‐framework tin(II) phosphates, Sn₅O₂(PO₄)₂ and Sn₄O(PO₄)₂, were synthesized under hydrothermal conditions with different ratio of tin(II) oxalate, phosphoric acid and 4,4′‐diaminodiphenylmethane. Their crystal structures have been solved by single‐crystal X‐ray diffraction methods. Sn₅O₂(PO₄)₂ crystallizes in the space group and contains six‐membered ring and twelve‐membered ring channels running parallel to the b axis. Sn₄O(PO₄)₂ crystallizes in the space group P2₁/n and contains intersecting eight‐membered ring channels. These two compounds have rare trigonal‐planar Sn₃O.     

基于纳米MnO2的免标记型DNA电化学生物传感器用于大肠杆菌的测定

以室温固相合成法制备纳米MnO2,通过壳聚糖（CHIT）的成膜效应将纳米MnO2固定在玻碳电极表面。DNA在MnO2/CHIT膜上的固定和杂交通过循环伏安和电化学交流阻抗进行表征。以电化学阻抗免标记法检测目标DNA,固定于电极表面的DNA探针与目标DNA杂交后使电极表面的电子传递电阻增大,以此作为检测信号可以高灵敏度地测定目标DNA。电化学阻抗谱检测大肠杆菌基因片段的线性范围为2.0&#215;10^-11 ～2.0&#215;10^-6mol/L,检出限为1.0&#215;10^-12mol/L。     

毛细管电泳-钴钛菁碳糊修饰电极电化学催化氧化测定羟胺和巯基类化合物

本文利用自制的毛细管电泳－电化学安培检测装置，以钴钛菁碳糊修饰电极为工作。电极，在中性磷酸体系缓冲溶液中，对四种羟胺和巯基类化合物的混合物进行了分离和测定，检测下限羟胺类化合物为５．０×１０－６ｍｏｌ／Ｌ巯基类化合物为１．０×１０－５ｍｏｌ／Ｌ。对实际尿样中的半胱氨酸进行检测，结果满意。