钯/石墨烯/离子液体纳米复合物的过氧化氢电化学传感器

将一定比例的石墨烯(GN)与离子液体(IL)1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)超声混匀GN-IL,并滴涂在玻碳电极(GC)上,然后通过电沉积法在此电极上沉积钯纳米颗粒制得Pb/GN-IL/GC修饰电极。采用循环伏安法和计时电流法研究了该传感器对H2O2的电催化还原行为。结果表明,与IR修饰电极和石墨烯修饰电极相比,该电极对H2O2具有更好的电催化活性。此传感器对过氧化氢检测的线性范围为4.0×10-6~4.3×10-4mol/L,检出限为2.1×10-6mol/L。     

[Co(Ⅱ)(H2O)6](C4H4O4)·2C6H12N4·4H2O修饰电极电化学催化谷胱苷肽研究

利用气相沉积法研制了基于TiO2凝胶固定化[Co(H2O)6](C4H4O4).2C6H12N4.4H2O(CoL)修饰电极。研究了该修饰电极对谷胱苷肽(GSH)的催化活性,发现在pH 7.5,0.1 mol/L NaAc-HAc的缓冲溶液中,CoL对电氧化GSH浓度之间有较好的线性关系.线性范围为2×10-6~1×10-4mol/L,检测下限为8×10-7mol/L,相对标准偏差为2.0%(cGSH=5×10-6mol/L,n=6)。应用该法测定生物样品中谷胱苷肽的含量并与紫外分光光度法进行对照,结果一致。     

金纳米粒子修饰电极对过氧化氢的电催化性能

构建了一种基于金纳米粒子修饰电极的过氧化氢(H2O2)传感器。采用循环伏安法研究了修饰电极在H2O2溶液中的电化学行为。实验结果表明,在p H=6.8的PBS缓冲溶液中,该修饰电极对H2O2具有明显的催化还原作用。在优化实验条件下,采用计时电流法检测了H2O2的线性范围为2.5×10-5~1.6×10-3 mol/L,检测下限为1.0×10-6 mol/L。此传感器具有较高的灵敏度、较好的重现性、稳定性及抗干扰能力。     

石墨烯修饰玻碳电极同时测定邻苯二酚和对苯二酚

将自制的氧化石墨烯以滴涂法修饰在玻碳电极表面,通过电化学还原方法制备得到石墨烯修饰电极。考察了电化学还原条件、修饰量以及底液等对修饰电极的影响。修饰电极对对苯二酚和邻苯二酚的电化学氧化还原表现出很高的电催化能力和分离能力。在0.1 mol/L磷酸盐缓冲溶液(pH7.0)作为支持电解质,利用循环伏安法和微分脉冲伏安法,石墨烯修饰电极可同时检测邻苯二酚和对苯二酚,二者的微分脉冲伏安响应与浓度在8.0×10-6～1.2×10-4mol/L和3.0×10-6～1.0×10-4mol/L范围呈良好的线性关系,检出限分别为1.2×10-6mol/L及3.7×10-7mol/L(3倍噪音法)。     

多壁碳纳米管/磷钼酸修饰电极对抗坏血酸的电催化作用

制备了GC/MWNTs/PMo12O340-修饰电极,研究了其在硫酸溶液中的电化学行为,采用循环伏安法研究了修饰电极对抗坏血酸的电催化特性。结果表明,该修饰电极在硫酸溶液中的电化学行为是表面控制过程。抗坏血酸的浓度在3×10-3～1×10-2mol/L范围内,催化电流与抗坏血酸的浓度呈现良好的线性关系,该修饰电极具有较好的稳定性。     

碳纳米管/氧化亚铜修饰电极检测间苯三酚

采用恒电位法在玻碳电极表面沉积线度100~200 nm、具有八面体结构的氧化亚铜,再将多壁碳纳米管(MWCNTs)修饰到其表面,制备MWCNTs/Cu2O/GC修饰电极。在pH=5.8的Na Ac-HAc缓冲液体系中,该电极对间苯三酚表现出良好的电催化活性。优化了实验条件,建立了间苯三酚的高灵敏检测方法。在2.5×10-9~6.5×10-6mol/L浓度范围内,其氧化电流与浓度呈线性关系。检测限为8.3×10-10mol·L-1。对模拟水样进行测定,回收率97.0%~103.5%。     

纳米氧化铜/石墨烯修饰电极的制备及对H_2O_2的检测

采用电化学方法在玻碳电极上修饰石墨烯及纳米氧化铜,制备了纳米氧化铜/石墨烯修饰电极(nanoCuO/ERGO/GCE)。研究了纳米氧化铜/石墨烯修饰电极的电化学性质。该修饰电极在氢氧化钠溶液中,低电位下(0.08V)可催化氧化过氧化氢。在2.3×10-5~3.0×10-3mol/L和3.0×10-3~8.3×10-3mol/L浓度范围内,过氧化氢的响应电流与浓度呈良好的线性关系,线性相关系数分别为0.9943和0.9972,检测限为6.96×10-6mol/L(三倍噪音法)。     

复合电沉积制备镍-石墨烯电极及其电催化析氢性能研究

以紫铜为基体,电沉积制备了镍还原氧化石墨烯(Ni-RGO)复合电极,研究了石墨烯质量浓度、电流密度、pH、温度和时间对Ni RGO复合电极的电催化析氢性能。得到最佳配方和工艺条件为:Ni(NH2SO3)2·4H2O 350 g/L,NiCl2·6H2O 10 g/L,C6H8O7·H2O 5 g/L,H3BO320 g/L,十二烷基苯磺酸钠0.12 g/L,RGO 0.16 g/L,pH 3.5,温度40°C,电流密度5 A/dm^2,时间10 min。该条件下所得Ni-RGO复合电极的电催化析氢性能最佳。     

一步法电沉积制备纳米金/碳纳米管修饰电极及对邻苯二酚电催化性能研究

以羧基化碳纳米管(CNT-COOH)溶液作为支持电解质,采用多电位阶跃电沉积方法将CNTs和纳米金同步直接沉积到玻碳电极表面,制备了对邻苯二酚(CAT)具有很高的电催化氧化作用的纳米金-碳纳米管修饰电极(Au/CNTs/GCE),其催化效果强于单独的金纳米粒子或碳纳米管修饰电极。通过优化沉积时间、pH和扫速对修饰电极的影响,并考察了在最佳条件下CAT在Au/CNTs/GCE修饰电极上的电化学行为,发现CAT在该修饰电极上发生可逆的氧化还原反应,响应电流与浓度在4.0×10-6～8.0×10-5mol/L和1.0×10-4～1.0×10-3mol/L范围内呈线性关系,相关系数分别为0.9996和0.9985,检出限为4.5×10-7mol/L(S/N)。     

亚硝酸盐在石墨烯/壳聚糖修饰电极上的电化学行为及测定

本实验采用滴涂法制备了石墨烯(GR)-壳聚糖(CS)修饰的玻碳电极(GCE)。用循环伏安法和时间电流曲线研究了NO_2~-在石墨烯-壳聚糖修饰的玻碳电极上的电化学行为。结果表明,此修饰电极对NO_2~-有较好的电催化活性,在最佳实验条件下,NO_2~-在该修饰电极上的线性范围为0.16~3200μmol/L,检出限(S/N=3)为0.16μmol/L。石墨烯-壳聚糖修饰的玻碳电极具有很好的稳定性、重现性和灵敏度。此电极用于实际水样的NO_2~-的含量测定,回收率为97.2%~102.6%,结果令人满意。     

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.     

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.     

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.     

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.