镍、铅、LB膜对n-Si光电极的修饰

本文研究了金属(镍、铅)与Langmuir-Blodgett膜对n-Si电极光电化学行为的影响, 观察到镍与铅能增强该电极的能量转换效率与稳定性。测定和讨论了八种有机物得的LB膜对n-Si/Ni电极的修饰作用, 最佳的长链香豆素LB膜使其效率倍增。还研究了具有MIS器件结构的Si/LB/Al电极的光电化学行为, 发现它具有良好的光电效应。     

电活性分子L-B膜修饰CdSe薄膜电极的光电化学研究

用电活性分子——硬脂酸二茂铁酯L-B膜修饰了薄膜CdSe电极,在单色光650nm光照下用循环伏安法研究修饰的薄膜电极的光电化学性能。研究结果指出经多层L-B膜修饰后,薄膜CdSe电极的,I-V性能和光稳定性都有明显改善。用界面能级关系讨论了硬脂酸二茂铁酯L-B膜在光照的CdSe薄膜/Fe(CN)₆^4-溶液界面起传递电荷的中介作用,加速了界面的电荷转移。     

硬脂酸二茂铁酯L-B膜修饰SnO2电极的阻抗研究

测定了二茂铁衍生物——硬脂酸二茂铁酯L-B膜修饰SnO₂电极在Fe(CN)₆^3-/4-溶液中的阻抗性能,用单纯形法求出了等效电路中的元件参数值,计算了电极反应速度常数K_s。从分析SnO₂电极修饰不同层的硬脂酸二茂铁酯L-B膜的界面阻抗和电极反应的动力学性能,表明与在固相中研究的硬脂酸二茂铁酯L-B膜的阻抗性能明显不同,在Fe(CN)₆^3-/4-溶液中表现了电活性分子修饰电极的界面阻抗行为,进一步证实了修饰在SnO₂电极上的硬脂酸二茂铁酯L-B膜在Fe(CN)₆^3-/4-的氧化还原电极反应过程中,起电荷传递的中介作用。     

二茂铁衍生物L—B膜修饰SnO2电极的性能

用外层单电子快速转移的氧化还原剂二茂铁及其衍生物修饰电极,在电极/溶液界面作为电子传递的中介物,可使电极上进行的慢反应得到加速、起中介催化作用。目前研究较多的是共价键合和高分子膜的修饰,其他方式的修饰报道不多。用能实现分子有序化排列的L-B膜技术进行氧化还原电活性分子的修饰电极还未见报道。我们用L-B膜技术在SnO_2电极上修饰了二茂铁的衍生物-硬脂酸二茂铁酯(FcOCOC_(17)H_(35))双亲化合物,曾研究了修饰膜的电化学可逆行为和稳定性。本文研究硬脂酸二茂铁酯L-B膜修饰的SnO_2电极     

Pd纳米粒子敏化的纳米单层TiO_2-Ru(Ⅱ)螯合物修饰电极对单磷酸鸟苷的电催化氧化行为

利用LB膜技术可控制备了纳米单层的二氧化钛-有机钌螯合物杂化膜,并研究了上述无机-有机杂化膜修饰电极在Pd纳米粒子敏化后对单磷酸鸟苷(GMP)的电催化氧化行为.实验结果表明:(1)纳米单层TiO2/[Ru(phen)2(dC18bpy)]2+(简称为TiO2-Ru)杂化膜的平均厚度为(3.2±0.5)nm;(2)在光照条件下TiO2-Ru杂化膜能有效催化还原[Pd(NH3)4]2+形成粒径位于20～200nm之间的Pd纳米粒子;(3)纳米单层TiO2-Ru/Pd杂化膜能高效催化氧化具有供电子能力的单磷酸鸟苷(GMP),与纳米单层TiO2-Ru杂化膜修饰的ITO电极(ITO/TiO2-Ru)相比,当工作电压为1200mV时,ITO/TiO2-Ru/Pd电极在含有1×10-3molL-1GMP的磷酸盐缓冲液中,单位面积的催化氧化电流提高了约36倍;(4)Pd纳米粒子的引入消除了金属钌螯合物中配体对电子传递的阻碍作用,改变了电子传递途径,从而有效减少了电子空穴对的复合,提高了杂化膜修饰电极(ITO/TiO2-Ru/Pd)的电子传递效率.     

有机钌螯合物/TiO_2杂化膜修饰电极上Pt纳米团簇的光电流增强效应

利用LB膜技术可控制备了纳米单层和多层的二氧化钛-有机钌螯合物杂化膜,并研究了上述无机-有机杂化膜修饰电极在Pt纳米团簇敏化后的光电流增强效应.实验结果表明:(1)纳米单层TiO2/[Ru(phen)2(dC18bpy)]2+(简称为TiO2-Ru)杂化膜的平均厚度为(3.6±0.5)nm;(2)在光照条件下TiO2-Ru杂化膜能有效催化还原[Pt(NH3)6]4+形成粒径位于20～160nm之间的Pt纳米团簇;(3)Pt纳米团簇的引入消除了金属钌螯合物中配体对电子传递的阻碍作用,改变了电子传递途径,从而有效减少了电子空穴对的复合,提高了Pt纳米团簇敏化的n层杂化膜修饰电极(ITO/(TiO2-Ru)n/Pt)在支持电解质中的光电流.与纳米单层TiO2-Ru杂化膜修饰的ITO电极(ITO/TiO2-Ru)相比,当工作电压为900mV时,ITO/TiO2-Ru/Pt在0.1mol·L-1的NaClO4电解质溶液中和光照(λ360nm)条件下,单位面积的光电流提高了约5倍;(4)ITO/(TiO2-Ru)n/Pt电极光电流的大小与杂化膜的层数密切相关,当TiO2-Ru杂化膜的层数从一层、二层增加到四层时,光电流呈现先升高后下降行为,这表明ITO/(TiO2-Ru)n/Pt电极的电子传递过程直接通过非电活性的二氧化钛纳米单层进行.     

二茂铁衍生物LB膜修饰Pt电极的循环伏安法性能

本文研究了单取代二茂铁酯和双取代亚麻酸二茂铁酯LB膜修饰Pt电极的循环伏安法性能,用修饰电极的循环伏安模型对实验结果进行拟合,计算了在转移压力分别为20,30,40mN·m^-^1下LB膜修饰Pt电极的覆盖度,并分析和讨论了不同转移压力下修饰的二茂铁LB膜的电荷转移中介作用     

二茂铁衍生物LB膜修饰Pt电极的循环伏安法性能

本文研究了单取代二茂铁酯和双取代亚麻酸二茂铁酯LB膜修饰Pt电极的循环伏安法性能,用修饰电极的循环伏安模型对实验结果进行拟合,计算了在转移压力分别为20,30,40mN·m^-^1下LB膜修饰Pt电极的覆盖度,并分析和讨论了不同转移压力下修饰的二茂铁LB膜的电荷转移中介作用     

硬脂酸二茂铁酯L-B膜的电化学性能研究

本文研究二茂铁衍生物——硬脂酸二茂铁酯(FcOCOC₁₇H₃₅)L-B膜技术修饰SnO₂电极的循环伏安性能.实验结果用电极表面吸附(修饰)分子的表面活度理论进行计算机拟合和此较,实验数据与理论符合较好.进一步求得修饰分子的标准电极电势和修饰量。结果表明硬脂酸二茂铁酯L-B膜电化学性能稳定,可逆性较好,可以作为快速电荷转移的修饰电极材料。     

聚3-氯噻吩修饰CdSe纳米棒复合膜电极光电化学性能研究

采用水热法制备了具有闪锌矿和纤维锌矿结构的CdSe纳米棒. 纳米棒直径约为100 nm, 长度约为300 nm. 当外加电极电势为-0.6 V 时, 经聚3-氯噻吩[Poly(3-chlorothiophene), P3CT]修饰的CdSe纳米棒具有最大光电流, 并且CdSe/P3CT复合膜电极最高光电转换效率(IPCE)为13.5%, 低于CdSe纳米棒膜电极17.7%的最高IPCE. CdSe/P3CT复合膜电极中存在p-n异质结, p-n异质结的存在使得CdSe/P3CT复合膜电极在长波区(>410 nm)的IPCE整体高于CdSe纳米棒薄膜电极的IPCE.     

聚马来酸偶氮萘己单酯LB膜对n—Si（100）的光敏化作用

合成了聚马来酸{6-[4-(1-偶氮)-萘氧]己基}单酯功能化合物,并在不同基底(CaF_2,n-Si(100))上沉积其LB膜,利用UV-Vis和IR光谱对膜性质和结构进行了表征.对膜修饰表面的硅片表面光电压谱测试发现,它对单晶硅具有很强的敏化作用.对界面电子过程也进行了初步讨论.     

荧光素衍生物LB膜对TiO2电极的光敏化作用

合成了三种荧光素长碳链衍生物，通过LB技术将它们组装成单分子薄膜，修饰在用溶胶-凝胶法制备的TiO2透明电极上，研究了这些LB膜的结构和特性及它对TiO2的光增感作用．并对其光敏化机理作了阐述．     

四硫富瓦烯衍生物/硬脂酸LB膜的表征

研究了四（苄硫基）四硫富瓦烯／硬脂酸（TBT－TTF／SA）（1：1）LB膜、二（亚乙二硫基）四硫富瓦烯／硬脂酸（BEDT－TTF／SA）（1：1）LB膜和四（十六烷硫基）四硫富瓦烯／硬脂酸（THT－TTF／SA）（1：1）LB膜的结构．从X射线衍射结果得到了LB膜的层间距离．X射线衍射图显示了TBT－TTF／SALB膜和BEDT－TTF／SALB膜的层间结构由硬脂酸控制．从偏振红外结果计算出硬脂酸和四硫富瓦烯衍生物在LB膜中的取向角．根据分子取向角确定了LB膜的层间结构．用分子长度和分子取向角得到的层间距离与从X射线衍射得到的层间距离相吻合．     

Photoconductive properties of organic-inorganic hybrid films of layered perovskite-type niobate

A hybrid film of layered niobate and an organic amphiphile was prepared by the Langmuir-Blodgett (LB) method. Trimethylammonium-exchanged perovskite-type niobates ((CH(3))(3)NHSr(2)Nb(3)O(10)) were exfoliative to form an aqueous suspension. A monolayer of octadecylamine was produced on such an aqueous dispersion as a template for a hybrid film. A hybrid film was transferred as a Y-type LB film onto a hydrophilic glass plate or an ITO substrate. The structure of a deposited film was investigated with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and atomic force microscopy (AFM) measurements, indicating a layer-by-layer structure with a single or double sheet of niobate as an inorganic composite. From the cyclic voltammogram on an ITO electrode modified with the Y-type 10 layered film, the lower edge of the conduction band of a niobate layer was determined to be - 0.6 V (vs Ag/AgCl). ac impedance and dc measurements were carried out on 1, 5, and 10-layered LB films (2 mm (electrode spacing) x 8 mm (width)) with aluminum electrodes. The freshly deposited samples behaved as an insulator under the illumination of 280 nm light (2.04 x 10(16) quanta s(-1)). Photoconductivities appeared, however, when they were preirradiated with a 150 W Xe lamp (ca. 2 x 10(18) quanta s(-1)) for 0.5-8.5 h. The process was denoted as photomodification. From the FT-IR and XRD results, it was deduced that the photomodification of LB films caused the decomposition of organic templates (octadecylammonium) accompanied by the collapse of layer-by-layer structures. dc analyses on the 5- and 10-layered films after photomodification also showed that they behaved as a photosemiconductor under UV light illumination.     

Microstructure and Ion Exchange in Stearic Acid Langmuir-Blodgett Films Studied by Fourier Transform Infrared-Attenuated Total Reflection Spectroscopy

Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectra have been recorded of 11-layer Langmuir-Blodgett (LB) films of stearic acid deposited at various surface pressures (0.1, 15, and 35 mN/m), and the molecular orientation angles were evaluated quantitatively, which supplied insight into the molecular order with the alkyl chains tightly packed like crystal in the LB films deposited at the zero and higher surface pressures. These experimental results indicate that, in the Langmuir film as the precursor of LB films, stearic acid molecules self-aggregate to form two-dimensional crystalline domains already even at the zero surface pressure, which results in the inhomogeneity of monolayer. The analysis of dependence of nu(C=O) intensity on the surface pressure, surface density, and subphase temperature leads to the conclusion that the defects in LB films originate from the Langmuir film and be conserved upon deposition. Annealing below 50 degrees C and cooling could improve the monolayer homogeneity, and thus a defect-free or low-defect LB films can be deposited. Furthermore, ion exchange conducted in the LB films, on the other hand, confirms the existence of structure defects in LB films of stearic acid. The polar plane microstructure, lateral transport along the polar planes and the coordination types of stearic acid/cation system may be the rate-limiting process. The results have implication on the possible uses of stearic acid LB films as ion-exchange materials or sensors. Copyright 2001 Academic Press.     

PREPARATION AND PROPERTIES OF TETRA (p-VINYLPHENOXY) METALLOPHTHALOCYANINES

This paper describes the preparation and Langmuir-Blodgett (LB) monomolecular film formation of H_2, Cu, Ni, Co, and Zn phthaloeyanine compounds with p-vinyiphenoxy peripheral substituent on each benzo ring at either 2- or 3- position [i.e., tetra (p-vinylphenoxy) substituted isomer mixture]. These phthalocyanine derivatives form stable LB films at the film pressures greater than 10 dynes/cm. The surface pressure-area isotherms indicate that the phthalocyanine units are densely packed with a eofacial orientation. Schottky cells of [Indium-Tin Oxide/LB film/Al] were prepared and their electronic properties were examined. Much better rectifying properties, diode parameter, break-down potential and mechanical strength were notified by the post-polymerization of LB-layers. On exposing the polymerized films to tetrahydrofuran vapor, the absorption maxima of Q-band shift bathochromically by about 100 nm, being sensitive to diode laser light.     

Photoelectrical properties of Langmuir–Blodgett films of poly(methyl phenylsilane)s

Langmuir–Blodgett (LB) films were prepared from poly(methylphenylsilane) bearing electron acceptor π-conjugated substituents. The small limiting area (0.078 nm²) per one repeating unit of polysilane (PSi) in monomolecular film and the large thickness of the film (6 nm) suggest that the polymer chains are not fully spread on water surface. The electrical and photoelectrical properties of Al/LB film/Au sandwich cells containing various numbers of the polysilane layers were studied. Holes were transported from the Al electrode through the LB film to the Au electrode when the light was absorbed by the polysilane. The highest photovoltaic effect occurred in the first monolayer of polysilane at the Al contact. The cell resistivity and the photovoltage were decreased by parallel conductance of defects in the films consisting of small numbers of PSi layers.     

十六烷基三辛基铵静电吸附氯金酸的Langmiur-Blodgett膜及其修饰聚氯乙烯液膜金离子选择性电极的研究

首次尝试用Langmiur-Blodgett(LB)技术修饰PVC液膜离子选择性电极,在PVC液膜表面上制得十六烷基三辛基铵-氯金酸LB膜,明显改善了PVC液膜金离子选择性电极的某些工作性能。电极线性响应范围为1×10~(-2)～1×10~(-7)mol/L,对常见的9种阳离子和4种阴离子的干扰能力明显的增强,响应速度也有所提高。若能改进挂膜方式,可望进一步改善有关性能。