基于2D卟啉金属有机框架纳米材料的高性能电化学传感

亚硝酸盐危害人类的身体健康。通过制备一种二维钴-卟啉金属有机框架纳米材料,构建了Co-卟啉/玻碳电极(Co-TCPP/GCE)无酶亚硝酸盐电化学传感器,建立了检测亚硝酸钠的电化学分析新方法。研究表明,该传感器亚硝酸根的最低检出限为0.617μmol/L,线性范围宽至1.0μmol/L～1.388 mmol/L,并展现出良好的重现性、稳定性和抗干扰能力,可应用于牛奶样品中亚硝酸盐含量的测定,建立了基于金属有机框架纳米材料检测牛奶中亚硝酸盐的新方法。     

一步电沉积制备多孔石墨烯/金纳米复合材料修饰电极测定芦丁

在玻碳电极(GCE)上覆盖一层多孔石墨烯/金纳米复合材料,制备了一种简单、低成本、高灵敏度的电化学传感器应用于芦丁的测定。考察了沉积圈数、缓冲液pH值对芦丁反应的影响。采用差分脉冲伏安法在优化条件下,芦丁浓度在1nmol/L～1μmol/L和1μmol/L～10μmol/L范围内与其氧化峰电流呈良好的线性关系,最低检出限为0.35nmol/L。     

自组装纳/微分级结构CoNi前驱体多孔微球对氢醌的选择性检测

开发了一种基于玻碳电极(GCE)表面修饰钴镍前驱体多孔微球(CoNiP/GCE)的电化学传感器,用于选择性测定氢醌。通过SEM、XRD和BET等多种手段对CoNi前驱体进行了表征。运用循环伏安法和示差脉冲伏安法研究氢醌在CoNiP/GCE表面的电化学性能。结果表明:CoNiP/GCE对氢醌有良好的电催化氧化性能。在0.5～5.0 mmol/L检测范围内,DPV峰电流与不同浓度氢醌展现了较好的线性关系,R~2=0.996 8,检测限为3.5μmol/L。此外,修饰电极能够在强干扰物质多巴胺的存在下实现对氢醌的特异性检测,检测范围是0.2～1.8 mmol/L,检测限为2.29μmol/L,R~2=0.992 8。CoNiP/GCE具有良好的选择性和抗干扰能力,适合进一步开发用于生物样品中氢醌检测的传感器。     

基于碳纳米管电化学传感器的构建与应用

采用电沉积法将钴沉积到多壁碳纳米管修饰(MWCNTs)的金电极表面上,采用扫描电镜对纳米复合材料的形貌进行了表征,发现Co/MWCNTs具有三维网络结构,且缠结致密,通过能谱仪分析此复合材料的主要化学成分是Co,C和O。使用此纳米复合材料构建了亚硝酸盐电化学传感器,考察了亚硝酸盐浓度、扫速对传感器的影响,使用安培法获得检测亚硝酸盐的线性范围是1.67μM～0.264 M,检出限为0.56μM(S/N=3)。该电化学传感器具有构建简单、稳定性高、成本低等优点。     

Au/UiO-66(Hf)纳米复合材料修饰电极电化学检测Cr（Ⅵ）的性能研究

采用溶剂热法和化学还原法制备出Au/UiO-66(Hf)纳米复合材料,再将该纳米复合材料修饰到玻碳电极上,运用线性扫描伏安法（LSV）实现了废水中Cr（Ⅵ）的有效检测。Au/UiO-66(Hf)/GCE传感器对质量浓度范围为100～1 000μg/L的Cr（Ⅵ）具有优异的线性响应,检测灵敏度为0.002 34μA·L/μg,最低检测限为18.76μg/L。同时,该传感器具有良好的稳定性与抗干扰性能,对实际电镀废水中Cr（Ⅵ）的检测回收率达105.03%。     

石墨烯修饰电极对吲哚丁酸的电分析应用研究

将电化学法制备的石墨烯与十二烷基苯磺酸钠在超纯水中超声1.5 h,实现对石墨烯的非共价改性。用所得的复合材料构建了一种石墨烯传感器，利用循环伏安法探究吲哚丁酸的电化学行为。在最优实验条件下，使用线性扫描伏安法对吲哚丁酸进行测定，线性浓度范围为0.5～100μmol/L,最低检测限为0.022μmol/L(S/N=3)。该传感器综合性能良好，将其应用在化肥中吲哚丁酸的测定，回收率为98.90%～101.03%。     

石墨烯/分子印迹聚合物的电化学传感器及其用于莱克多巴胺的检测

在石墨烯修饰的玻碳电极表面滴涂莱克多巴胺分子印迹聚合物,制备了莱克多巴胺分子印迹电化学传感器。优化了石墨烯浓度、分子印迹聚合物浓度、富集时间、p H值等对传感器的影响,优化后得到的最佳实验条件为:石墨烯浓度为0.3 mg/m L,莱克多巴胺分子印迹聚合物浓度为3.0 mg/m L,富集时间为5 min,磷酸盐缓冲溶液的p H值为7.0;在最佳条件下,石墨烯/分子印迹聚合物的电化学传感器对莱克多巴胺进行检测,其峰电流响应与莱克多巴胺的浓度在0.5~90.0μmol/L范围内具有良好的线性关系,检测限为0.16μmol/L(S/N=3)。石墨烯/分子印迹聚合物的电化学传感器成功应用于猪肉样品中莱克多巴胺含量的测定。     

基于金纳米粒子的适配体传感器比色检测牛奶中氨苄西林残留

本文构建一种基于金纳米粒子的比色适配体传感器,并利用紫外-可见分光光度计和智能手机实现了对牛奶中氨苄西林快速、灵敏的检测。在优化的实验条件下,两种信号输出方式(吸光度和RGB信号)的线性范围分别20 nmol/L～10μmol/L和50 nmol/L～10μmol/L,检测限分别为10 nmol/L和20 nmol/L。此外,该适配体传感器具有较好的选择性,并且在牛奶中的加标回收率为93.9%～104.3%。表明该比色适配体传感器具有很好的应用前景,尤其是RGB方法不需要采用精密仪器,就能实现现场快速检测抗生素残留。     

基于铁氰化镍/镍铝水滑石的非酶葡萄糖传感器的研究

利用镍铝水滑石(Ni Al-LDH)和铁氰化镍(Ni HCF)在碱性环境中对葡萄糖的协同电催化氧化作用,构筑了NiHCF/NiAl-LDH修饰的非酶葡萄糖传感器。利用电化学阻抗谱对传感器的组装过程进行了检测,用循环伏安法(CV)和计时电流法(I-t)对传感器的电化学行为进行了研究。此传感器对葡萄糖的检测在4.998×10~(-6)~1.623×10~(-4)mol/L范围内呈良好线性关系,相关系数为0.997,检测限为1.8177×10~(-7)mol/L。     

基于Cu-Mg-Al三元类水滑石修饰玻碳电极对食品中亚硝酸根的检测

制备了Cu-Mg-Al三元类水滑石修饰玻碳电极,研究了亚硝酸根在修饰电极上的电化学行为,Cu-Mg-Al三元类水滑石对亚硝酸根的电化学氧化具有明显的催化活性,评估了溶液pH值、扫描速率和施加电位对亚硝酸盐电流响应的影响,计算了电机有效表面积和NO2-在修饰电极表面的吸附容量,并初步探讨了催化机理,在优化的实验条件下,该修饰电极对NO2-的测定线性范围为0.1~10.42μmol/L,检测限为0.08μmol/L(S/N=3)。将该传感器用于食品中亚硝酸根离子的测定,结果满意。     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.