Au修饰薄膜CdSe电极的界面动力学行为的研究

研究了Au修饰的薄膜CdSe电极在多硫溶液中的瞬态光电流行为,测量了界面异相电荷转移,表面电荷复合及光腐蚀反应速度常数K_F,K_R及K_c。结合了光电子能谱(XPS)及扫描电镜(SEM)表面分析,对三种不同Au量修饰的薄膜CdSe电极进行界面动力学行为的分析。     

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。     

CdSe敏化TiO2纳米晶多孔膜电极的制备及其光电性能研究

研究了CdSe敏化TiO2纳米晶多孔薄膜电极的制备及其表征,采用涂敷法将溶胶-凝胶法制备的TiO2胶体制备成纳米晶多孔薄膜,采用化学沉积法制备的CdSe对其进行了敏化处理.敏化后增加了对可见光的吸收作用和光生载流子的输运速度,减少了CdSe上光生载流子的复合,改善了电极内光生电荷的传递特性,获得了较大的稳态光电流.这种薄膜电极改进后可用于制作敏化太阳能电池的光阳极.     

电化学交流阻抗在量子点敏化太阳电池中的应用

研究量子点敏化太阳电池(QDSSCs)电极界面电荷转移,抑制电极界面电荷复合,促进电荷的正向流动成为提高QDSSCs效率急需解决的问题。特别是寻找一种能有效研究光阳极/电解液界面的电荷转移和复合以及对电极催化活性的表征方法。电化学交流阻抗(EIS)是一种常用的研究电极界面阻抗和电容的分析方法。利用EIS可以对QDSSCs光阳极/电解液界面电荷转移,对电极催化活性进行有效的评价。     

不同基材上Co掺杂CdSe薄膜电极的制备及光电催化性能

采用脉冲电流沉积法制备了负载于氧化锡铟(ITO)导电玻璃、不锈钢板、镍板和铜板等不同基材上的Co掺杂CdSe薄膜电极,利用紫外可见漫反射和交流阻抗实验测试了Co掺杂CdSe薄膜电极的性能,并以对硝基苯酚降解来评价该薄膜的光电催化性能.结果表明:基材的种类对Co掺杂CdSe薄膜电极的性能影响较大,其催化降解对硝基苯酚的活...     

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SnO_2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SnO_2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SnO_2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。     

薄膜CdSe及CdSexTe1—x电极的光电子能谱研究

用X射线光电子能谱(XPS)研究了不同含氧气氛中烧结的薄膜CdSe及Cdse_xTe_(1-x)电极表面,以及薄膜与Ti底基之间的界面。研究中发现,二种薄膜电极的表面形成了CdO,SeO_2及TeO_2氧化物,与薄膜接触的Ti底基表面上形成了TiO_2。用俄歇电子能谱(AES)对在电极表面及Ti表面所生成的氧化层分别进行了深度分析。结果表明,各种氧化物形成的程度有很大的不同,氧化层厚度也存在差异。对影响薄膜电极的光电性能的因素进行了讨论。     

控电位法制备CdSe纳米线阵列及其性能研究

以SeO2为硒源,以阳极氧化铝为模板,采用电化学方法对SeO2在碱性电解液中的还原过程进行了分析,确定了控电位制备CdSe纳米线的沉积电位和镀液组成,并分析了其沉积机理。在此基础上,以阳极氧化铝为模板,通过控电位法成功获得CdSe纳米线阵列。采用扫描电子显微镜、透射电子显微镜和X-射线衍射对所制备的材料进行了形貌和结构表征。扫描电镜形貌分析表明,CdSe纳米线阵列高度有序、直径均一;直径约100 nm,与模板孔径一致。X-射线衍射测试表明,所制得的CdSe纳米线为立方晶型。光电性能测试表明,CdSe纳米线阵列电极的开路电位差值为324.8 mV,高于CdSe薄膜(125.5 mV);光催化降解罗丹明B测试表明,5 h后,CdSe纳米线的降解率达94.29%,强于CdSe薄膜(52.03%)。     

钒钛酸-聚苯胺薄膜电极的制备及电化学性能

以苯胺和自制钒钛酸为原料,ITO导电玻璃为基底,利用一步法和两步法分别制备了钒钛酸-聚苯胺薄膜修饰电极,系统地研究了该复合薄膜的成膜机理和电化学行为。实验结果表明,一步法比两步法制备过程简单,且钒钛酸能逐层固定在聚苯胺薄膜里。该修饰电极不仅保持了钒钛酸的电化学活性和电催化性能,并具有良好的稳定性。两种方法制备的薄膜修饰电极对酸性水溶液中的碘酸钾均具有显著的的电催化还原作用。     

载有微量贵金属的n-TiO_2电极的光电化学研究

利用在富氧和乏氧溶液中光照下与不光照下测得的极化曲线,研究了载有铂和银的TiO_2电极的光电化学行为及反应机理。在富氧溶液中,光照载有贵金属的TiO_2电极时,贵金属上发生氧的还原反应,其速度与光照与否无关;而在未被贵金属覆盖的电极表面上进行水或其它组份的光氧化;二者组成一对共轭反应,相当于短路的光电化学电池。共轭反应速度一般由氧的还原反应速度控制。增加贵金属的载量能使共轭反应速度增大,外电路中通过的电流等于这一对反应所引起的电流的代数和。根据对极化曲线的分析和界面阻抗的测量结果,可以确定载在TiO_2表面上的铂、银与基底之间的接触基本上是欧姆型的。光照下贵金属中的电子具有与半导体整体相同的费米能级。在含载有贵金属的TiO_2粉末的悬浮液中实现了CN~-和二乙胺的光氧化,其速度随贵金属载量变化的规律可用上述反应机理加以解释。     

cdSe_xTe_(1-x)薄膜电极光溶解性能的研究

用循环伏安法对半导体Cdse_xTe_(1-x)薄膜电池的光溶解性能进行了研究。在1mol/L KCl溶液中测量光溶解产物的阴极还原特性,考察了在多硫化钠,多硫化钾及铁氰化钾溶液中的光腐蚀行为。用此方法还研究了薄膜电极表面的光刻蚀过程和pH的影响,并用X射线光电子能谱分析光刻进行不同时间后,电极表面发生的变化。     

Enhanced photoelectrochemistry and interactions in cadmium selenide-functionalized multiwalled carbon nanotube composite films

Cadmium selenide-functionalized multiwalled carbon nanotube (CdSe-f-MWCNT) composite films have been synthesized by the percolation of a f-MWCNT dispersion through the macropores of electrodeposited CdSe thin films during electrophoretic deposition. Evidence for efficient charge transfer from CdSe to f-MWCNTs was obtained by photoluminescence quenching and proof for strong interactions was provided by X-ray photoelectron spectroscopy analyses, which revealed a significant decrease in the reduced Se²⁻ content and evolution of new signals due to oxidized Se, and high resolution transmission electron microscopy and atomic force microscopy images of CdSe decorated f-MWCNTs in the composite film. Sputter depth profiling of the composite confirmed a homogeneous mixing of nanoparticulate CdSe and f-MWCNTs. A quasi solid-state photoelectrochemical cell fabricated by coupling the composite film with an ionic liquid based gel polymer electrolyte containing the I₃/I⁻ redox pair not only showed larger photocurrents, photovoltage and incident photon to current conversion efficiency as compared to the analogous CdSe cell but also showed a remarkably enhanced stability to photoerosion. The ability of f-MWCNTs to mediate fast charge transfer and retard charge recombination rate in the composite was also evident from electrochemical impedance spectroscopy (EIS) results. Cell degradation upon exposure was also reflected in the altered EIS parameters such as increased charge transfer resistance and the reduced ease of charge transport through the composite.     

拉氏变换阻抗分析测量CdSe薄膜电极的表面态

在光电化学光能转换的研究中,由于多种因素在半导体/溶液界面形成了各种性质和作用不同的表面态,在界面的电荷和能量转移中起着重要作用,对光电转换性能产生较大的影响。对于多晶半导体——作为具有实用前景和目前深受重视的光电转换材料,由于存在较多的晶格缺陷和晶粒界面,在表面形成了浓度较高的表面态,这些表面态可作为光生电子空穴的复合中心,是造成多晶材料光电转换效率低于单晶材料的主要原因。因此测量和研究半导体/溶液界面的表面态能量分布,性质及作用对研究光电转换过程的机理,特别是对改善多晶半导体的性能都具有直接的重要意义。     

Electrochemical solar cells with polypyrrole-coated CdSe sintered electrodes

A thin layer of polypyrrole was formed on sintered CdSe electrodes. The photoelectrochemical properties of bare CdSe and P-Py/CdSe electrodes were studied in electrolyte with the redox couple [K₃Fe(CN)₆]. The results were explained by assuming that a p-n junction is formed on CdSe electrodes with polypyrrole working as a p-type semiconductor.     

影响染料敏化二氧化钛纳米晶太阳能电池的因素

介绍了染料敏化二氧化钛纳米晶太阳能电池的结构及工作原理,对影响染料敏化太阳能电池性能的因素,如纳米二氧化钛膜的制备、表面修饰、耦合及掺杂或复合,敏化染料与电极表面的吸附、吸收光谱与太阳光谱的匹配、染料的设计合成,以及电解质的研究进展进行了综述。指出染料和电解质的性能是今后发展中的主要制约因素,纳米多孔膜的制备、染料的光电化学反应机理和染料的设计合成、双敏化、固态空穴传输材料替代液体电解质以及纳晶多孔电极与染料间能量传递及电子转移的微观本质等领域是今后的主要研究方向。     

Characterization of N,N′-dimethyl-3,4,9,10- perylenetetracarboxylic acid diimide and phthalocyaninatozinc(ii) in electrochemical photovoltaic cells

As a direct comparison to all-solid state photovoltaic cells, photoelectrochemical cells consisting of n-type N,N-dimethyl-3,4,9,10-perylenetetracarboxylic acid diimide (MePTCDI) and p-type phthalocyaninatozinc(ii) (PcZn) thin film electrodes vapour-deposited onto ITO have been investigated in aqueous ferri/ferrocyanide, p-benzoquinone/hydroquinone or I3–/I– electrolytes. The ferri/ferrocyanide cell has been studied in more detail, and the results are discussed with regard to the HOMO-, LUMO- and Fermi-energies of the materials used. A setup of the electrodes in a tandem cell could increase the efficiency of the cell due to improved light harvesting. Saturation of the photocurrent with increasing ferri/ferrocyanide electrolyte concentration at single PcZn or MePTCDI electrodes is discussed using a model of reactant adsorption prior to the charge transfer step. In addition, a decrease observed for the open-circuit voltage of the entire cell with increasing ferri/ferrocyanide concentration leads to an optimum concentration of 10–3 moldm–3.     

Charge transport properties of poly(N-vinylimidazole) containing [Os(N)6]2+/3+ moieties

The rate of charge transport of electrodes modified with osmium containing poly(N-vinylimidazole) has been examined as a function of the nature of the contacting electrolyte solution and of temperature. Heterogeneous electron transfer from the electrode into the polymer film has also been investigated. The charge transport parameters show that the nature of the electrolyte anion and its concentration have a large impact on the polymer morphology. In sulfuric acid the films appear significantly swollen, hydrated, and porous, while in perchlorate-containing solutions they are rather compact. Activation energies for the rate-determining step of charge transport show that, depending on the electrolyte, segmental chain motion or ion movement represents the rate-limiting process.     

Diffuse layer effects on the current in galvanic cells containing supporting electrolyte

We study the effect of an inert supporting electrolyte on the steady-state ionic current through galvanic cells by solving the full Poisson-Nernst-Planck transport equation coupled to the generalized Frumkin-Butler-Volmer boundary equation for the electrochemical charge transfer at the electrodes. Consequently, the model presented here allows for non-zero space charge densities locally at the electrodes, thus extending the frequently used models based on the local electroneutrality condition by including diffuse layer (DL) effects. This extension is necessary since the DLs determine the ion concentration and electrical field at the reaction planes, which uniquely determine the charge transfer at the electrodes.In this work we present numerical results for systems which contain added inert supporting electrolyte using finite element discretization and compare those with semi-analytical results obtained using singular perturbation theory (limit of negligibly thin DLs). In case of negligibly thin DLs the presence of supporting electrolyte will introduce a limiting current below the classical diffusion-limiting current. Just as for systems without supporting electrolyte, the supporting electrolyte induced limiting current formally does not occur for systems having non-negligibly thin double DLs. For thin, however still finite, double layers this limit can still be seen as a steepening of the polarization curve for current vs. voltage.