5(6)羧基荧光素敏化TiO2纳米粒子的光致电子转移的荧光特性研究

通过水解TiCl₄制备了锐钛矿结构TiO₂纳米粒子, 并用时间分辨荧光光谱研究了5(6)CFL(5(6)-Carboxyfluorescein, 简称5(6)CFL)染料敏化TiO₂纳米粒子体系的光致电子转移动力学. 5(6)CFL染料敏化TiO₂纳米粒子能形成电荷转移复合物, 这归因于染料分子的激发电子态波函数Ψ(D^*)与电荷分离态波函数Ψ(D⁺ +e^-)之间的耦合作用. 当激发5(6)CFL染料敏化TiO₂纳米粒子体系时, 电子以两种不同方式注入TiO₂纳米粒子导带: 第一, 通过5(6)CFL染料分子的激发态注入; 第二, 从电荷转移复合物(5(6)CFL/TiO₂)直接注入. 时间分辨荧光光谱表明, 在水溶液中纯5(6)CFL染料的荧光以寿命为τ₁=41 ps (74.4%) 和τ₂=3.22 ns (25.6%) 的双e指数衰减, 而5(6)CFL染料敏化TiO₂纳米粒子体系的荧光分别以时间常数为τ₁=44 ps (90.4%), τ₂=478 ps (8.6%) 和τ₃=2.41 ns (1.0%) 的三e指数衰减. 本文的研究工作能够为染料敏化太阳能电池的光致电子转移机理提供有价值的参考.     

由纳米管和纳米颗粒构成的TiO2膜的制备与机理研究

采用聚苯乙烯小球修饰Ti片表面,并进行阳极氧化,制备出一种由纳米颗粒和纳米管构成的TiO₂膜．通过数值模拟,分析了氧化表面附近的局部电场分布对TiO₂膜形貌的影响．结果表明,覆盖物增强了局部电场,从而加快了O^2-与Ti的反应速率,有利于TiO₂的生长;与此同时,[TiF₆]^6-的扩散受到阻碍,使得TiO₂的溶解速率减慢．可见,覆盖物打破了TiO₂纳米管形成的平衡条件,导致纳米颗粒的生成．此外,通过X射线衍射和Raman光谱的测试分析发现,所制备的TiO₂为锐钛矿结构.     

TiO2表面质子化对染料敏化太阳能电池性能及吸附染料稳定性的影响

采用致密平整TiO₂薄膜作为染料敏化太阳能电池光电极,并研究了HCl处理表面质子化对电池性能的影响. 结果表明,HCl处理后电池的短路电流显著提升,电池的开路电压则有轻微的下降,电池电流提升了31%,而能量转化效率则提升了25%. 这是因为TiO₂的表面质子化增强了吸附染料与TiO₂间的电学耦合,提高了染料中激发电子向TiO₂导带的注入速率. 而电压的下降,一方面是由于质子化会引起TiO₂导带能级     

基于薄膜电极溶胶修饰的染料敏化太阳电池光电特性研究

染料敏化太阳电池(DSC)中的纳米薄膜电极 是决定太阳电池光电转换性能的重要组成部分. 为改善薄膜电极特性, 采用了不同浓度的TiO₂溶胶对DSC光阳极导电玻 璃和纳米TiO₂多孔薄膜进行不同方式的界面处理. 利用X射线衍射方法对制备得到的多孔薄膜以及溶胶经高温处理 后致密层中纳米TiO₂颗粒的尺寸及晶型进行了测试. 采用高分辨透射电子显微镜和场发射扫描电子 显微镜观察了纳米颗粒及薄膜微结构形貌. 采用强度调制光电流谱/光电压谱分析了TiO₂溶 胶的不同处理方式对电子传输和复合的影响. 在100 mW· cm^-2光强以及暗环境下分别测试了DSC的伏安输出性能以及暗电流. 结果表明, 不同浓度和处理方式均能较好地抑制暗电流. 溶胶处理后光生电子寿命τ_n延长, 电子传输平均时间τ_d相应缩短. 采用浓度为0.10 mol·L^-1的 溶胶对导电玻璃和多孔膜同时处理, DSC的宏观输出特性最佳, 短路电流密度J_sc提高了10.9%, 光电转换效率η提高了11.9%.     

多孔TiO2/Al/SiO2纳米复合结构的紫外光吸收特性研究

在SiO₂玻璃衬底上用脉冲激光沉积(PLD)技术，分别沉积Ti和Ti/Al膜，经电化学阳极氧化成功制备了多孔TiO₂/SiO₂和TiO₂/Al/SiO₂纳米复合结构. 其中TiO₂薄膜上的微孔阵列高度有序，分布均匀. 实验研究了Al过渡层对多孔TiO₂薄膜光吸收特性的影响. 结果表明：无Al过渡层的多孔TiO₂薄膜其紫外吸收峰在27     

飞秒瞬态吸收技术研究有机/无机异质结的超快电荷转移过程

本文检测SQ02在氯苯溶液、Al₂O₃薄膜和TiO₂薄膜中的弛豫过程,从而探究SQ02在单分散态和聚集态下的光物理性质以及相应过程中界面电荷转移过程.实验数据表明,单分散态下SQ02 的寿命约为2 ns,但是,在Al₂O₃薄膜中显著减小到21 ps.电子从激发态SQ02转移到TiO₂薄膜的时间约为2.6 ps,摄入电子量约为89.1%,与基于SQ02的染料敏化太阳能电池光电效应的效率相匹配.此外,一些染料和其他染料一起嵌入纳米晶薄膜中的弛豫时间可达到60 ps.由于其远离TiO₂界面,因此不参与界面电荷转移.     

宽带隙半导体TiO2纳米溶胶原位变温的X射线小角散射研究

对宽带隙半导体TiO₂纳米粒子水溶液,开展了原位变温SAXS研究.采用Shull-Roess方法,我们确定了TiO₂纳米粒子在水溶液中的回转半径的尺寸分布,M(R_g).结果表明,在常温25°C下,M(R_g)的极大峰位于2.3nm,对应于2.9nm的球形粒子直径,在80°C时增加到3.2nm,对应于8.2nm的球形粒子直径.这些结果有利于理解染料敏化TiO₂纳米太阳能电池的光-电子特性及其转换效率随温度的变化规律.     

多种金属/TiO2核壳纳米棒阵列的通用制备方法

使用了一种具有较大通用性的方法制备了金属/二氧化钛(TiO₂)核壳纳米结构. 采用电沉积方法在多孔氧化铝模板(AAO)孔洞中沉积壁厚均一的TiO₂纳米管,TiO₂纳米管的壁厚可以通过沉积时间来控制,而纳米管的直径和长度则由模板孔洞大小和模板厚度决定. 采用这种方法制备的TiO₂纳米管顶端是开放的,而底端连接在电沉积前溅射在AAO模板背面的金膜上. 这种TiO₂纳米管阵列结构适合进行二次电沉积,以它为模板将Pd、Cu、Fe等金属沉积到纳米管中形成核壳纳米棒结构. 这是一种可以用于制备多种金属/TiO₂核壳纳米结构的通用方法,采用这种方法制备的金属/TiO₂核壳纳米棒结构具有填充率高和取向性好的特点,而且它们的壁厚和长度可以通过分别改变两步电沉积的时间来控制.     

[Au25(SR)18]-团簇的相干振动动力学研究

利用飞秒时间分辨光谱,可观测叠加在电子态动力学上的相干振动动力学. 从金团簇的相干振动中,不仅能提取电子与振动的耦合信息,也能得到力学性质和电子结构,进而有望实现微小质量探测等应用. 本文利用飞秒时间分辨的瞬态吸收探测了[Au₂₅(SR)₁₈]^-团簇的相干振动动力学,通过对相干振动的频率、相位、波长分布的详细分析进一步揭示了其来源. 在[Au₂₅(SR)₁₈]^-团簇的飞秒瞬态吸收动力学中可以观测到频率为40 cm^-1和80 cm^-1的两种振动,均来源于团簇中心Au₁₃核的振动. 通过对相干振动的相位分析发现频率为80 cm^-1的振动来自于对电子态之间吸收频率的调制,而频率为40 cm^-1的振动来源于对电子态之间吸收强度的调制. 同时,研究发现[Au₂₅(SR)₁₈]^-团簇相干振动的频率对其表面配体不敏感,该振动是来源于Au₁₃核的本征性质.     

Ag-Cu纳米颗粒修饰的N掺杂TiO2纳米棒阵列及其高效光催化CO2还原应用

本文采用微纳加工方法制备了负载高密度Ag-Cu纳米颗粒的N掺杂TiO₂纳米棒阵列样品. 通过TiO₂的N掺杂,可将其吸光范围调控至与Ag纳米颗粒的等离激元吸收频率相匹配的波段,从而实现复合材料中肖特基结与共振能量转移过程的协同作用. 与此同时,Cu纳米颗粒可以为CO₂还原提供活性位点. 在全谱光照射下,复合样品光催化CO₂还原的活性显著提高,CH₄生成速率可达720 μmol·g^-1·h^-1.     

Electrochemical properties of compacts of nano-and microdisperse diamond powders in aqueous electrolytes

The electrochemical behavior of compacts of micro-and nanodisperse diamond powders were studied by using model redox K₃[Fe(CN)₆]-K₄[Fe(CN)₆] and Ce(SO₄)₂-Ce₂(SO₄)₃ systems in aqueous electrolytes. The current-voltage curves for compacts of microdisperse diamonds and the kinetics of reactions on these compacts in a solution of the [Fe(CN)₆]^3-/4- system are similar to those obtained by using a metal electrode. For nanodisperse diamonds, the same reactions are essentially irreversible.     

Electrochemical Studies on Substituted Iron-Hexacyanoiron(III) Bi-Layered Thin Films at Glassy Carbon Electrode/Electrolyte Interface

Thin films (30–50 nm) of bilayered HCM (hexacyanometalates) were prepared using direct electrodeposition or electrochemically driven insertion-substitution of PB (Prussian Blue) or InHCF (Indium Hexacyanoferrate) or K..In _x [Fe{CN}₆] _y , as starting material. The redox behavior of the immobilized counter/central ions at GCE/electrolyte interface have been investigated in aqueous KCl (pH 1) electrolytes using dynamic voltammetric techniques. Studies show that when the counter Fe or In ion is replaced by expandable partially filled d orbits elements such as Ru³⁺ a redox wave of the inserted counter ion is observed. Furthermore, the substitution of Fe as a counter ion with other poly-valent cations was found to be reversible if PB was the starting material. Studies were extended to include the EC (electrochemical) behavior of related HCM compounds such as K...Al _x [Fe{CN}₆] _y K, Ni _x [Fe{CN}₆] _y Cu _x [Fe{CN}₆] _y , K..Zn _x [Fe{CN}₆] _y and, K..Ru[Fe{CN}₆]₃. Unlike studied 3d cations, GCE modified with thin films of copper-hexacyanoiron (III) KCu _x [Fe{CN}₆] _y or CHF showed two redox waves with E^o _f 0.6, 0.9 V vs Ag/AgCl. Studies showed that even immobilized Cu ions were capable of catalyzing the oxidation of hydrazine and sulfite. The mechanism for electro-oxidation is also included.     

Photophysical studies of xanthene dye in alkanols and in presence of inorganic ions

Eosin Y belongs to a xanthene group. It is an anionic fluorescent dye. The absorbance and fluorescence of Eosin Y have been investigated in a series of alkanols (methanol to propanol). When the solvents are added to the aqueous solution of Eosin Y (EY) the absorbance and fluorescence intensity are enhanced. The alkanols are found to affect the absorption and fluorescence spectra of the dye. On the basis of solvent adsorption model the binding constants of the dye with alkanols have been estimated. The interaction of solvent molecule with dye in aqueous solution is specific in nature. The fluorescence quenching of Eosin Y by the inorganic ions [Fe(CN)₆]⁻³, [Fe(CN)₆]⁻⁴ and Cl⁻ was also observed. The ions influenced the quenching process to different extents. The rate constants of quenching were calculated using the Stern-Volmer equation. The equilibrium constant of dye in presence of inorganic ions are determined by Scott equation.     

Mössbauer studies of photochemical reaction products of Ru(bpy)3 2+ iron cyanide double complexes

The reductive and the oxidative electron-transfer photochemical reaction system of light-irradiated the mix solutions of Ru(bpy)₃ ²⁺ with [Fe(CN)₆]^4–, [Fe(CN)₆]^3–, [Fe(CN)₅NO]^2– and PB (Prussian Blue) have been studied. The double complexes which isolated from the precipitates of the photochemical reaction have been identified by means of Mössbauer spectroscopy. In order to clarify the chemical states of these isolated double complexes, we have (prepared and) studied Mössbauer spectra of the double complexes such as [Ru(bpy)₃]₃[Fe(CN)₆]₂.14H₂O, [Ru(bpy)₃]₂[Fe(CN)₆].10H₂O, [Ru(bpy)₃][Fe(CN)₅NO].4H₂O, and [Ru(bpy)₃][PB]₂.xH₂O.     

Electrochemical immune bioassay for the antigen–antibody interaction based on [Fe(CN)<Subscript>6</Subscript>]<Superscript>4-/3-</Superscript> and [AuCl<Subscript>4</Subscript>]<Superscript>-</Superscript> ions-derivated biomimetic interface

A simple and sensitive electrochemical immune bioassay for the detection of hepatitis B surface antigen (HBsAg), as a model, was developed based on [Fe(CN)₆]^4-/3- and [AuCl₄]^- ions-derivated biomimetic interface in this study. A layer of [Fe(CN)₆]^4-/3- film (i.e., Prussian blue, PB) was initially electrodeposited onto a glassy carbon electrode, and then [AuCl₄]^- ions were reduced under the potentiostat to form gold nanoparticles on the PB film. Finally, hepatitis B surface antibody (HBsAb) was adsorbed onto the nanogold surface. The performance and factors influencing the immunosensor were assessed and optimized. The proposed immunosensor exhibits a specific response to HBsAg in the range of 2.13–314.3 ng∙ml^-1 with a detection limit of 0.42 ng∙ml^-1. In addition, the developed immunosensor shows high sensitivity, good reproducibility, and long-term stability. Importantly, the ions-derivated biomimetic interface could be further extended for the immobilization of other proteins and biocompound.     

Characterization of T-55 sorbent using 57Fe Mössbauer spectroscopy with a high velocity resolution

A new sorbent T-55 with mixed ferrocyanide surface modification developed for Cs⁺ sorption was characterized using Mössbauer spectroscopy with a high velocity resolution in comparison with K₂Ni[Fe(CN)₆] and K₄[Fe(CN)₆ samples. The main sorption active component of T-55 sorbent was determined as K₂Ni[Fe(CN)₆].     

Laser induced breakdown spectroscopy surface analysis correlated with the process of nanoparticle production by laser ablation in liquids

Linkage isomerism is the coexistence of iso-compositional molecules or solids differing by connectivity of the metal to a ligand. In a crystalline solid state, the rotation is possible for asymmetric ligands, e.g., for cyanide ligand. Here we report on our observation of a phase transition in anhydrous RbMn[Fe(CN)₆] (nearly stoichiometric) and on the effect of linkage isomerism ensuing our interpretation of the results of Mössbauer study in which we observe the iron spin state crossover among two phases involved into this transition. The anhydrous RbMn[Fe(CN)₆] can be prepared via prolonged thermal treatment (1 week at at 80 °C) of the as-synthesized hydrated RbMn[Fe(CN)₆]·H₂O. The latter compound famous for its charge-transfer phase transition is a precursor in our case. As the temperature is raising above 80 °C (remaining below 100 °C) we observe RbMn[Fe(CN)₆] that inherited its F-43 m symmetry from RbMn[Fe(CN)₆]·H₂O transforming to a phase of the Fm-3 m symmetry. In the latter, more than half of Fe^3?+? ions are in high-spin state. We suggest a plausible way to explain the spin-crossover that is to allow the linkage isomerism by rotation of the cyanide ligands.     

Magnetic and Mössbauer studies of cyanide-bridged bimetallic assembly [Mn(cyclam)][Fe(CN)6]·3H2O

Cyanide-bridged bimetallic assembly [Mn(cyclam)][Fe(CN)₆]·3H₂O (cyclam=1,4,8,11-tetraazacyclotetradecane) was synthesized from the reaction of trans-[MnCl₂(cyclam)]Cl with K₃Fe(CN)₆. A linear chain structure consisting of alternating [Mn(cyclam)]³⁺ and [Fe(CN)₆]³⁻ units was indicated by the IR and Mössbauer spectra. The variable-temperature magnetization and Mössbauer measurements revealed that this complex exhibited a long-range ordering below 6.8 K. The magnetic behavior of the complex was based on intrachain ferromagnetic and interchain antiferromagnetic interactions.     

High‐pressure studies of the micro‐Raman spectra of iron cyanide complexes: Prussian blue (Fe4[Fe(CN)6]3), potassium ferricyanide (K3[Fe(CN)6]), and sodium nitroprusside (Na2[Fe(CN)5(NO)]·2H2O)

The pressure dependences of the peaks observed in the micro‐Raman spectra of Prussian blue (Fe₄[Fe(CN)₆]₃), potassium ferricyanide (K₃[Fe(CN)₆]), and sodium nitroprusside (Na₂[Fe(CN)₅(NO)]·2H₂O) have been measured up to 5.0 GPa. The vibrational modes of Prussian blue appearing at 201 and 365 cm⁻¹ show negative dν/dP values and Grüneisen parameters and are assigned to the transverse bending modes of the Fe C N Fe linkage which can contribute to a negative thermal expansion behavior. A phase transition occurring between 2.0 and 2.8 GPa in potassium ferricyanide is shown by changes in the spectral region 150–700 cm⁻¹. In the spectra of the nitroprusside ion, there are strong interactions between the FeN stretching mode and the FeNO bending and the axial CN stretching modes. The pressure dependence of the NO stretching vibration is positive, 5.6 cm⁻¹ GPa⁻¹, in contrast to the negative behavior in the iron(II)‐meso‐tetraphenyl porphyrinate complex. Copyright © 2011 John Wiley & Sons, Ltd.     

Self-Indicating Surfactants: Potentially Micellar Solvatochromic Iron(II) Complexes

The preparation of ternary iron(II) complexes [Fe(CN)₂(LL)₂] and [Fe(CN)₄(LL)]^2-, where LL = a Schiff base derived from 2-acetyl pyridine and a long chain amine 1-Me(CH₂)_nNH₂ (n = 11, 15, 17), is described. These complexes exhibit strong solvatochromism and can thus be used to probe solvation in organised aqueous media, as in ternary water - Aerosol OT- hexanol mixtures. They also have a dramatic effect on the micellisation behaviour of the uncharged surfactant Triton X-100.