EQCM Study of Ru and RuO2 Surface Electrochemistry

The present study represents comparative analysis of voltammetric and microgravimetric behavior of active ruthenium (Ru), electrochemically passivated ruthenium (Ru/RuO₂) and thermally formed RuO₂ electrodes in the solutions of 0.5 M H₂SO₄ and 0.1 M KOH. It has been found that cycling the potential of active Ru electrode within E ranges 0 V–0.8 V and 0 V–1.2 V in 0.5 M H₂SO₄ and 0.1 M KOH solutions, respectively, leads to continuous electrode mass increase, while mass changes observed in alkaline medium are considerably smaller than those in acidic one. Microgravimetric response of active Ru electrode in 0.5 M H₂SO₄ within 0.2 V–0.8 V has revealed reversible character of anodic and cathodic processes. The experimentally found anodic mass gain and cathodic mass loss within 0.2–0.8 V make 2.2–2.7 g F^?1, instead of 17 g F^?1, which is the theoretically predicted value for Ru(OH)₃ formation according to equation: Ru+3H₂O?Ru(OH)₃+3H⁺+3e^?. In the case of Ru/RuO₂ electrode relatively small changes in mass have been found to accompany the anodic and cathodic processes within E range between 0.4 V and 1.2 V in the solution of 0.5 M H₂SO₄. Meanwhile cycling the potential of thermally formed RuO₂ electrode under the same conditions has lead to continuous decrease in electrode mass, which has been attributed to irreversible dehydration of RuO₂ layer. On the basis of microgravimetric and voltammetric study as well as the coulometric analysis of the results conclusions are presented regarding the nature of surface processes taking place on Ru and RuO₂ electrodes.     

Surface Core Level Shifts of Yb Films in the Multilayer,Monolayer and Submonolayer Range

Surface core level shifts in Yb and other rare earth elements, as well as in their compounds, arise from a reduced band width of the 5d band, caused by the reduced coordination at surface sites, with the strength and direction of the shifts depending on the occupation of the 5d band. If the coordination, or more exactly, the local symmetry is considered to be the decisive factor for changing the band width, it is obvious to look for core level shifts even at the interface of two solids. In order to investigate such interface core level shifts, thin Yb films of thicknesses from the multilayer down to the submonolayer range, grown on a polycristalline W substrat, were investigated by photoelectronspectroscopy. It was found, that for decreasing film thicknesses, the ratio of the surface to bulk related 4f intensities increases systematically, and finally, for thicknesses of one up to two monolayers, only the broad, surface related part of the Yb 4f doublet can be observed. For Yb coverages fewer than one monolayer, there is a sudden shift of this remaining doublet towards the Fermi energy, which must result from a reduced occupation of the Yb 5d band due to an electron transfer from Yb to W at the interface.     

TiO2-WO3负载硅钨酸盐聚苯胺膜电极的电化学行为及电催化性能研究

用循环伏安法制备了金属氧化物(TiO2-WO3)负载硅钨酸盐聚苯胺膜修饰玻碳电极(PAn/SiW12/TiO2-WO3/GC),优化了聚合条件,并对该化学修饰电极的电化学行为,包括溶液pH值的影响和电极的稳定性等进行了研究。研究结果表明,此修饰电极聚合物膜不但保持了该杂多酸的电化学活性和电催化性能,又具有良好的稳定性。在0.5 mol/LH2SO4溶液中,该膜电极中的SiW12的第2个还原峰对BrO3-有很好电催化活性,催化过程符合EC平行催化机理。     

电化学联用表面等离子体共振光谱法对苯胺电化学聚合过程的研究

采用双光电池传感器作为检测器件,设计并构建了新型表面等离子体共振( SPR)光谱仪,在一定范围内实现了SPR角度的快速测量。将此SPR光谱仪与电化学工作站联用,构建了电化学联用-时间分辨SPR ( EC-TR-SPR)光谱仪,以聚苯胺电化学制备过程为研究体系,验证了此EC-TR-SPR光谱仪的特性。同时通过对聚苯胺膜的暂态电化学方法测试(计时电流法和差分脉冲法),考察了仪器的时间分辨能力及其响应速度,验证了此仪器系统在小分子反应动力学以及稳态和暂态电化学联用方法研究中的应用价值。实验结果表明,此SPR光谱仪具有高的时间分辨能力,其时间分辨率可达0.1 ms;对聚苯胺膜的暂态电化学测试结果表明,此联用技术可实时监测SO2-4在聚苯胺膜中的掺杂和去掺杂过程,而单纯的电化学电流-时间曲线无法区分。     

Effect of Composition on Surface Properties of Polydimethylsiloxane-based Inorganic/Organic Hybrid Films

Surface properties of the polydimethylsiloxane (PDMS)-based inorganic/organic hybrids films prepared from silanol-terminated PDMS and titanium tetra-isopropoxide (TIP) were investigated with an aim at the application to the thermal-fixation roll for electro-photographic printers. The 300°C-treated hybrid film with the PDMS/TIP molar ratio of 0.5 exerted a relatively high contact angle of water as 115°C. It was found by using Tapping-Mode Atomic Force Microscopy (AFM) that the hybrid film surface changed from lamella structure to sea-island structure with the increase of PDMS content when heat-treated at 150°C, and became homogenous surface over 300°C. The phase-shift detected by AFM was negative shift, showing that hybrid surface became more hydrophobic as the PDMS/TIP molar ratios of 0.35 and 4.0 exhibited excellent toner-offset property of showing no adhesion of toners, suggesting their practical use in the photographic printers.     

Synthesis,Characterization and Electrochemical Polymerization of a Ru2+ Functionalized Pyrrole Monomer

A ruthenium(II) functionalized pyrrole, Ruthenium‐bis‐N,N′‐(2,2′‐bipyridyl)‐N‐(pyridine‐4‐ylmethyl‐(8‐pyrrole‐1‐yl‐octyl)amine)chloride, 1 , has been synthesized and characterized by spectroscopic (UV/vis, ¹H NMR) techniques and cyclic voltammetry. In solution 1 gave a redox couple associated with the Ru^3+/2+ redox system and an irreversible wave associated with the oxidation of the covalently linked pyrrole moiety. What is believed to be homopolymerization, redox active surface films of 1 have been prepared by electrooxidation of the monomeric solution. The resulting polymeric film exhibited clear redox activity associated with the incorporated Ru²⁺ redox centre, which is covalently linked ruthenium centre to the pyrrole moiety in 1. The effect of surface coverage upon the electrochemical behavior of the deposited films has been undertaken. Preliminary investigations into the homogeneous charge transport dynamics of the polymeric film deposited onto platinum microelectrodes has been undertaken. Copolymerization with 3‐methylthiophene was carried out and a clear ruthenium response was seen. Films were formed by both cyclic voltammetry and chronocoulometry and studied. Various ratios were attempted but the ideal was found to be 52 : 5 mmol (3‐methylthiophene: 1 ).     

Surface Properties of Polydimethylsiloxane-Based Inorganic/Organic Hybrid Films Deposited on Polyimide Sheets by the Sol-Gel Method

Polydimethylsiloxane (PDMS)-based inorganic/organic hybrids films were prepared on polyimide sheets by the sol-gel method using silanol-terminated PDMS and titanium tetraisopropoxide as starting materials. The effect of heat-treatment temperature on the surface property of the hybrid films was examined in terms of contact angle of water and Tapping-Mode Atomic Force Microscopy (AFM). AFM phase images showed the presence of domains, 200–500 nm in size, on the surface of these films after heat-treatment below 300°C. These regions were more hydrophilic than the rest of the area. The domains disappeared at 300°C and the surface became homogeneous surface of the peak to valley value, about 10 nm. It is also uniformly hydrophobic and a maximum contact angle (about 115°C) was obtained.     

α-淀粉酶在阴离子化PET表面的自组装膜及其AFM研究

采用分子沉积技术制备了α-淀粉酶的自组装膜,并用AFM研究了在不同的pH值溶液和不同电荷密度基底上得到的自组装膜。结果表明：pH值从6.0变到4.0,形状变得尖细,膜中陷点多;基底的电荷密度增大时,酶分子的外观形状较细,膜中缺陷点少;α-淀粉酶自组装膜的厚度保持约5～10nm。     

PET/PC共混体系的酯交换反应对其高压结晶行为的影响

利用转矩流变仪、DSC、SEM及WAXD等表征手段研究了PET/PC共混体系的酯交换反应对其高压结晶行为的影响.SEM观察表明,PET和PC熔混时的酯交换反应有利于PET/PC体系在高压结晶时生成厚度较大的伸直链晶体,且可以促进其高压下酯交换反应的发生.楔形伸直链晶体和弯曲伸直链晶体的存在证明链滑移扩散和酯交换反应两种机制对体系中聚酯伸直链晶体的增厚有贡献.拟合分峰法和War-ren-Averbach傅里叶分析法的计算结果表明,随PET/PC体系熔混时酯交换反应程度的增加,高压结晶共混物的结晶度降低,PET的平均微晶尺寸增大,点阵畸变平均值则减小,而微晶尺寸分布变宽.提出了在共聚物组分都具备结晶能力时,结晶诱导化学反应和化学反应诱导结晶两种过程在一定条件下可同时发生的观点.     

Recent Progress on Electrode Design for Efficient Electrochemical Valorisation of CO2, O2, and N2

CO₂ reduction, two-electron O₂ reduction, and N₂ reduction are sustainable technologies to valorise common molecules. Their further development requires working electrode design to promote the multistep electrochemical processes from gas reactants to value-added products at the device level. This review proposes critical features of a desirable electrode based on the fundamental electrochemical processes and the development of scalable devices. A detailed discussion is made to approach such a desirable electrode, addressing the recent progress on critical electrode components, assembly strategies, and reaction interface engineering. Further, we highlight the electrode design tailored to reaction properties (e.g., its thermodynamics and kinetics) for performance optimisation. Finally, the opportunities and remaining challenges are presented, providing a framework for rational electrode design to push these gas reduction reactions towards an improved technology readiness level (TRL).     

聚酰胺-胺接枝PPO-PEO两亲嵌段树状分子的合成与表面性质

合成了一系列以1.0 代(G1)聚酰胺-胺(PAMAM)为核心、以聚环氧丙烷-聚环氧乙烷(PPO-PEO)为辐射臂的新型树状分子, 通过傅里叶变换红外(FTIR)光谱、质谱(MS)、核磁共振谱(1H NMR)和凝胶渗透色谱(GPC)等方法对其结构进行了表征与分析. 用表面张力与稳态荧光法对其表面性质与聚集行为进行研究, 结果表明, 临界聚集浓度(CAC)随PPO-PEO两亲嵌段长度的增加而增大, 同时聚集体的生成对芘探针有增溶作用, 并使其微环境的极性明显减弱. 通过动态激光光散射(DLS)法得到聚集体的尺寸分布均为窄分布, 其平均尺寸约为100 nm. 对该体系水溶液pH效应的研究发现, 两亲嵌段的长度对于质子化进程有着较大影响.     

NiO阳极薄膜制备与电化学性能

NiO阳极薄膜制备与电化学性能;NiO薄膜;真空蒸发;热氧化     

溶剂对SEBS/PMMA共混物薄膜形态的影响

采用原子力显微镜研究了聚（苯乙烯嵌-乙烯／丁烯嵌-苯乙烯）（SEBS）和聚甲基丙烯酸甲酯（PMMA）共混物不同溶剂旋转涂膜的表面形态和相分离行为。结果表明,用共混物的氯仿溶液旋转涂膜,可见明显的共混物的宏观相分离和SEBS的微观相分离形态。改变选择性溶剂可使旋涂膜具有不同的均匀度和形态结构,其相区的尺寸和形状相差甚大,有海岛型、网状、双连续状结构。AFM显示用环己烷／丁酮混合溶剂旋转涂膜,共混物的相分离最为彻底;用选择性溶剂氯仿时次之,但有明显的相分离;对SEBS和PMMA均无选择性的单一溶剂或混合溶剂则无明显相分离。     

Surface film formation on a graphite electrode in Li‐ion batteries: AFM and XPS study

The formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO₂/graphite lithium‐ion cells using LiPF₆ (1M ) in carbonate solvents as electrolyte was investigated by means of x‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The analyses were carried out at different potentials of the first and the fifth cycles, showing the potential‐dependent character of the surface‐film species formation. These species were mainly identified as Li₂CO₃ up to 3.8 V and LiF up to 4.2 V. This study shows the formation of the SEI during charging and its partial dissolution during discharge. Copyright © 2005 John Wiley & Sons, Ltd.     

Photophysical and Photochemical Properties of Ru(bpy)3 2+ in Si-Ti Mixed Oxides Xerogels Prepared by the Sol-Gel Process

The luminescence spectra and lifetime of tris(2,2-bipyridine)ruthenium(II), Ru(bpy)₃ ²⁺, were studied in sol-gel reaction systems of tetramethoxysilane (TMOS) and titanium(IV) isopropoxide (TTIP) with HCl. Luminescence lifetime in the TMOS system increased as the sol-gel reaction proceeded, because diffusion-controlled luminescence quenching such as oxygen and collisional quenching with solvent molecules were suppressed in the rigid matrices. On the other hand, luminescence lifetime in the TTIP system decreased during the sol-gel reaction. The decrease in lifetime was ascribed to electron transfer from photoexcited Ru(bpy)₃ ²⁺ to the conduction band of the TiO₂ xerogels. Extended X-ray absorption fine structure (EXAFS) measurements were done to associate lifetime in the Si-Ti xerogels with the structures of Ti⁴⁺ sites in the xerogels.     

二氧化钛薄膜的低温制备及其性能表征

通过水煮法在较低温度下制备了均匀、透明的TiO2-SiO2复合薄膜,利用XRD、AFM和UV-Vis光谱等手段对薄膜的物相、表面形态结构和透明性进行了表征,分析了SiO2的添加对薄膜性质的影响.并利用紫外光照降解罗丹明B溶液评价了薄膜的光催化活性及其影响因素.实验结果表明,通过水煮法在较低温度下制备的薄膜具有较高的光催化活性,适量SiO2的添加能够提高薄膜的光催化活性.     

Hybrid Electrochromic Multilayer Films Based on Fe(II)-Metalloviologens and TiO2 Nanoparticles

Metallosupramolecular coordination polyelectrolyte, Fe(II)-metalloviologen(FEN), was prepared by the reaction of Fe(II) with a novel bisterpyridine ligand. As active components, FENs could be assembled into electrochromic multilayer films with negative charged polystyrene sulfate(PSS) by the sequential deposition layer-by-layer technique. Numerous analytical instruments, such as UV-Vis spectroscopy, atomic force microscopy(AFM), tunneling electron microscopy(TEM), zeta-potential measurement and electrochemical measurement have been utilized to characterize their morphology, optical and electrochromic properties. It has been observed that as-prepared films exhibited multi-colour changes by triggering with different potentials. However, the low optical contrast of multilayer films would limit their further applications. In order to overcome this problem, semiconductor TiO₂ nanoparticles(TiO₂) were incorporated into FEN multilayers by layer-by-layer approach. By carefully optimizing the film structure, as-resulted hybrid films containing FEN, TiO₂ and PSS exhibited high optical contrast, suitable response time and long-term stability. Such hybrid films should be promising candidates to meet the requirements for deve- loping flexible displays and electrochromic devices.     

铅铈和铅钙锡合金阳极腐蚀膜的性能研究

利用叠加交流伏安法、线性电位扫描法、交流阻抗技术和XPS研究了铅铈合金和铅钙锡合金在阳极1.28 V, 4.5 mol/L的硫酸溶液中所形成的阳极腐蚀膜. 结果表明: 稀土铈能抑制阳极膜中高阻抗的Pb(II)化合物的生长, 降低腐蚀膜的阻抗, 并增加膜的孔隙率. 同时可以提高合金的析氢过电位, 有利于电池免维护性能的提高.     

Surface and Catalytic Properties of K/V Catalysts Coating on Porous Al2O3 Substrate

The morphology of different ratio K/V catalysts supported on porous α‐alumina substrate was investigated by atomic force microscopy (AFM). Changes in the particle size distribution, pore size distribution were analyzed respectively using AFM software. In addition, their catalytic activities and compositions for carbon oxidation were studied by x‐ray diffraction (XRD), differential scanning calorimetry (DSC), and temperature‐programmed reactions (TPR). As a result, with the increase of K concentration, the mean particle size gradually increased and the mean pore size decreased. According to the catalytic activity studies, the catalytic activity of the KVO₃ and K₃V₅O₁₄ phases are more effective than KCl.     

Excited-State Dynamics of [Ru(bpy)3]2+ Thin Films on Sensitized TiO2 and ZrO2

The excited state dynamics of Tris(2,2′-bipyridine)ruthenium(II) hexafluorophosphate, [Ru(bpy)₃(PF₆)₂], was investigated on the surface of bare and sensitized TiO₂ and ZrO₂ films. The organic dyes LEG4 and MKA253 were selected as sensitizers. A Stern–Volmer plot of LEG4-sensitized TiO₂ substrates with a spin-coated [Ru(bpy)₃(PF₆)₂] layer on top shows considerable quenching of the emission of the latter. Interestingly, time-resolved emission spectroscopy reveals the presence of a fast-decay time component (25±5 ns), which is absent when the anatase TiO₂ semiconductor is replaced by ZrO₂. It should be specified that the positive redox potential of the ruthenium complex prevents electron transfer from the [Ru(bpy)₃(PF₆)₂] ground state into the oxidized sensitizer. Therefore, we speculate that the fast-decay time component observed stems from excited-state electron transfer from [Ru(bpy)₃(PF₆)₂] to the oxidized sensitizer. Solid-state dye sensitized solar cells (ssDSSCs) employing MKA253 and LEG4 dyes, with [Ru(bpy)₃(PF₆)₂] as a hole-transporting material (HTM), exhibit 1.2 % and 1.1 % power conversion efficiency, respectively. This result illustrates the possibility of the hypothesized excited-state electron transfer.