【作者】 李丽；

【导师】 田燕妮；

【作者基本信息】 山西大学 ， 无机化学， 2012， 硕士

【摘要】 六硼化镧LaB6是一种高导电率,高熔点和具有化学稳定性的无机化合物,由于其卓越的物理和化学性质,在现代技术中主要被用于阴极发射材料,而在1968年它被用作一种电化学工作电极用于定量分析测定Eu(III)。本研究工作的第一部分主要阐述了改用石蜡作粘合剂来制备LaB6电极的方法,同时使用循环伏安法(CV)对该电极的性能做了初步的评估。通过LaB6与石蜡的各种不同比例的试验,获知使用LaB6与石蜡比例为5：1时制作的LaB6电极在0.2mo1·L-1pH5.5的HAc-NaAc缓冲液中对Eu3+的检测可以达到较高的灵敏度和较宽的检测范围。实验证明使用石蜡作粘合剂制备的电极比前人制备的LaB6电极不仅制备方法简单,而且电极具有较高的选择性和灵敏度。研究工作的第二部分围绕电化学修饰电极展开,主要讨论了采用各种修饰剂：聚四氟乙烯阳离子交换膜Nafion、纳米金粒子GNP、聚二烯丙基二甲基氯化铵PDDA、双十二烷基二甲基溴化铵DDAB、多壁碳纳米管MWNTs以及十二烷基磺酸钠SDS,对LaB6电极的修饰及其对Eu3+的电化学响应,同时与石墨电极作对比,旨在找到一种合适的修饰剂使得修饰后的LaB6电极对Eu3+的检测效果优于石墨电极。通过实验发现使用SDS/MWNTs修饰后的LaB6电极对Eu3+具有良好的检测效果,最后对该电极的性能进行了讨论,计算了电子转移系数(α)和电子转移速率常数(k_s),该修饰电极具有良好的线性范围,在40μmol·L-1～1.7mmo1·L-1浓度范围内是其检测信号的最佳范围。研究工作的第三部分是基于纳米磁性Y-Fe2O3对过氧化氢的电催化特性和LaB6电极的高导电性而制成可用于灵敏检测过氧化氢的新式传感器。该电极具有制备方法简单,价格低廉,灵敏度高,线性范围宽等优点。使用循环伏安法和计时电流法,在磷酸缓冲液PBS(pH7.0,0.1mol·L-1)中,得到该传感器对过氧化氢的检测下限为6.34x10-8mol·L-1,线性范围为2.0x10-7～6.0x10-4mol·L--1灵敏度为2.01x107μAM-1cm-2，工作曲线的相关系数为0.9997。该传感器对无机盐离子和生物大分子具有良好的抗干扰性,可用作检测H202的一种新的选择。更多还原

【Abstract】 Lanthanum hexaboride (LaB6) is an extremely hard inorganic compound, with high conductivity, high melting point and chemical stability. It is widely used in modern technology as an excellent thermionic electron emission source because of its preeminent physical and chemical properties. In1968, it was first used as the electrochemical working electrode for determination of Eu3+. The first part of this paper is about the preparation of the LaB6electrode using the paraffin as a binder. The performance of the electrode was initially assessed by cyclic voltammetry (CV). Taking into account the tightness of adhesion, and the electrochemical current response, many different quality ratios of these two substances were tried, and the results showed that the quality ratio of5:1(LaB6:paraffin) was best for the electrode response signal. The electrode exhibited a high sensitivity, good linear range for the determination of the Eu3+with the0.2mol-L-1pH5.5HAc-NaAc solution as the buffer. The experimental results showed that the LaB6electrode using paraffin as a binder is not only easy to preparation but also with higher selectivity and sensitivity than previous work.The second part of the research work is about the electrochemical modified electrode. We intended to find a good modified LaB6electrode which had a better electrochemical response than pyrolytic graphite electrode. By using many different modifiers such as Nafio、GNP、PDDA、DDAB、 MWNTs and SDS, we found that SDS/MWNTs/LaB6electrode showed a good CV response to Eu3+. The performance of the modified electrode was initially assessed by CV, the charge-transfer coefficient (a) and the electron-transfer rate constant (ks) were discussed. The modified LaB6electrode exhibited a good linear dependence on the concentration of Eu3+from40μmol·L-1tol.7mmol·L-1.A novel hydrogen peroxide (H2O2) sensor based on LaB6electrode was reported in the third part. By using the catalysis of the y-Fe2O3nanoparticles, we fabricated y-Fe2O3-LaB6sensor for the determination of hydrogen peroxide. The performance of the sensor was initially assessed by CV and amperometric i-t curve methods. In phosphate buffer (pH7.0,0.1mol·L-1), the y-Fe2O3-LaB6sensor exhibited a good linear dependence (R=0.9997) on the concentration of H2O2from2.0x10-7mol·L-1to6.0x10-4mol·L-1, a high sensitivity of2.01x107μAM-1cm-2and a detection limit of6.34x10-8mol·L-1. Furthermore, the sensor was also good resistant towards typical inorganic salts and some biomolecules. Our developed electrochemical sensor provides an attractive alternative choice for the determination of H2O2.更多还原