Spectroelectrochemical Studies on Silicate Sol‐Gel Matrix‐supported Sub‐10 nm Prussian Blue Nanostructures‐based Electrochromic Device

In this study, spectroelectrochemical (SPE) studies to monitor the electrochromic properties of electrochemically synthesized sub‐10 nm sized Prussian blue (PB) nanostructures (NSs) are employed. At the beginning the dark blue coloured device, shifts reversibly between translucent and dark‐blue while applying an applied bias between +1 to ?1 V with an opposite polarization. Amine functionalized silicate sol‐gel matrix (SSG) is used as a solid support and stabilizer for electrodepositing highly uniform sub‐10 nm PB NSs. The SSG's film thickness is suitably optimized through suitable controlled experiments. It is found that the SPE behaviour of sub‐10 nm sized PB NSs, suitably followed a colour modulation of PB into Prussian white (PW) and vice‐versa. SPE studies are used to investigate the redox switching between the PB and PW and which are responsible for an electrochromic function of a fabricated electrochromic device (ECD). Fabricated ECD has demonstrated an optical modulation at 680 nm with the moderate coloration efficiency of 115.8 cm²/C. Present study validates the SPE feature of sub‐10 nm PB NSs as an active electrochromic nanomaterial and demonstrating the applicability of SPE technique to investigate the variety of electrochromic nanomaterials, with consequences in both spectral and electrochemically active nanomaterials for electrochromic device applications.     

Urea Biosensor Based on Electrochromic Properties of Prussian Blue

Prussian blue (PB) is an electrochromic material, which can be used as a signal transducer in the formation of optical urea biosensors. The previous researches in electrochromic properties of PB demonstrated the optical PB response to ammonium ions, which occurs when ammonium ions are interacting with PB layer at a constant 0.2 V vs Ag|AgCl|KCl_sat potential. In this work PB optical dependence on ammonium ions concentration was applied in the formation of electrochromic urea biosensor. Biosensor was formed by modifying the optically transparent indium tin oxide (ITO) coated glass electrode (glass/ITO) with Prussian blue layer and immobilizing urease (glass/ITO/PB‐urease). Calibration curve showed the linear dependency (R²=0.995) between the change of maximal absorbance (ΔA) and urea concentration in concentration range varying from 3 mM to 30 mM. The highest sensitivity (4 ΔA M^?1) of glass/ITO/PB‐urease biosensor is in the concentration range from 7 mM to 30 mM. It was determined that working principle of the glass/ITO/PB‐urease biosensor is not related to pH changes occurring during enzymatic hydrolysis of urea.     

Nickel-oxide-based electrochromic films with optimized optical properties

Reactive DC magnetron sputtering was used to grow thin films of Ni (93%)-V (7%) oxide and Ni (62%)-Al (38%) oxide. Both films showed electrochromism in KOH. The addition of Al diminished the luminous absorbance significantly, while the charge capacity was maintained. The Al-containing films are superior to the conventional Ni oxide electrodes as regards applications requiring high-bleached-state transmittance.Presented at the 3rd International Meeting on Advanced Batteries and Accumulators, 16–20 June 2002, Brno, Czech Republic     

苯/二联苯为桥的噻吩-吡咯-噻吩结构:分子构型及电致变色性质

A series of multi-branched dithienylpyrrole (SNS) monomers with rigid phenyl (PhSNS) and biphenyl rings (BPhSNS) as bridges were designed and synthesized, and were fabricated to form cross-linked polymers (pPhSNS, pBPhSNS) by electrochemical polymerization. Cyclic voltammetry (CV) results showed that PhSNS and BPhSNS exhibited similar oxidative properties except for one new higher-potential oxidative peak appearing in the curves of PhSNS. Theoretical calculations indicated that it should be attributed to the different steric configuration between the two dithienylpyrrole (SNS) units in PhSNS. One SNS unit possessed a larger twist angle (40.2°) between thiophene and pyrrole rings than the other one (21.2°), which indicated that PhSNS possessed a relatively larger energy gap (~0.4 eV) between HOMO-1 and HOMO than BPhSNS, for which HOMO and HOMO-1 levels were of almost the same energy. However, both PhSNS and BPhSNS showed similar onset oxidation potentials. The CV curves of pPhSNS and pBPhSNS showed that they presented similar oxidative properties, which enabled their corresponding electrochemical polymers to exhibit similar electrochromic properties. The UV-vis spectra of the corresponding polymers showed that both pPhSNS and pBPhSNS possessed similar optical absorption and similar multicolor switching between yellow (-0.8 V), greyish-green (0.9 V) and gray (1.1 V) colors. Besides, pPhSNS and pBPhSNS showed fast switching times of 0.57 s and 0.93 s at 1100 nm, respectively and reasonable contrasts of 46% and 31% at 1100 nm, respectively. These investigations may help understand the relationship between structural configuration and the electrochemistry/electrochromic properties for polymer electrochromic (PEC) materials research.     

电致变色/电控荧光双功能聚合物的合成及性能

将电活性双胺单体4,4'-二氨基二苯醚与1,2,4,5-环己烷四甲酸二酐共聚, 得到电活性聚酰胺酸聚合物. 再通过后功能化方法, 采用酰胺化反应将2-氨基芴引入到聚合物结构中, 合成了荧光聚合物. 通过核磁、 红外和凝胶渗透色谱证实了聚合物的结构. 该聚合物在0~0.8 V的电压下展示出可逆的电化学活性. 在利用电压改变苯胺齐聚物链段的氧化状态的过程中, 聚合物薄膜发生了明显的颜色变化, 展现出良好的电致变色性质. 荧光性质随着施加电压的改变而变化, 展现出优异的电控荧光特性.     

High throughput screening and measurements of proton conductivity of newly developed PEM materials based on proton transport visualization

An electrochemical method for proton transport visualization was developed and applied to the investigation of proton-conducting membrane materials. The method employs the change in the visual appearance of chemo-chromic tungsten oxide WO₃ in the presence of atomic hydrogen. An all-solid electrochemical cell arranged by substituting a fuel cell cathode with a thin film of WO₃-electrode was built and shown to generate both optical and electrical response to hydrogen gas exposure. The design of the cell was extended to a high throughput screening system that was utilized to characterize proton transport properties of samples, including a number of new compounds synthesized in-house by sol–gel wet chemistry. Non-destructive introduction of superacidic groups promoting proton hopping in the membrane materials was achieved by photodecomposition of a photoacid generator just after membrane casting. A model quantitatively describing current–voltage relation in the cell was developed and successfully applied to derive area-specific resistance of proton-conductive membranes from the experimental results. Area-specific resistances of membranes are derived from the slopes of optically reconstructed voltage–current curves. Sensitivity and dynamic range of the screening method are discussed.     

氯醇盐溶胶-凝胶法纳米结构氧化钨薄膜的光谱学特性

由非离子型Gemini表面活性剂TMDD(HO(EO)xC14(EO)yOH)为结构导向模板, 改进EISA(挥发诱导自组装)镀膜工艺经300 ℃焙烧制得具有连续、均一和光学透明特点的蠕虫介孔纳米晶孔壁氧化钨薄膜. 采用SEM、TEM和Raman光谱对此种薄膜的介孔纳米结构进行了表征, 通过光谱电化学、XPS和椭偏谱等方法, 研究了该薄膜在电解质溶液中的电致变色行为. 结果表明, 所制备的纳米结构氧化钨薄膜在633 nm波长处的循环可逆透过率调制幅度可达75%以上, 并且其电致变色机理具有显著的双注入吸收调制特性.     

Effects of film structure on electrochromic properties of the multilayer films containing polyoxometalates

Multilayer films of tungstophosphate anion (P₂W₁₈) and poly(allylamine hydrochloride) (PAH) were fabricated on quartz and ITO substrates by layer-by-layer self-assembly method. These films were characterized by UV–vis spectroscopy, cyclic voltammetry (CV), chronoamperometric (CA), chronocoulometry (CC) and atomic force microscopy (AFM). The effects of film structure on multilayer electrochromic properties were investigated. The electrochromic responses of the composite films were related to the surface coverage of anion and multilayer thickness. It was found that higher concentration of polycation and anion, or adding salt to the polycation solution used for multilayer film preparation led to thicker and denser film structure which improved optical contrast and coloration efficiency whereas prolonged response time.     

Ferrocene clicked poly(3,4-ethylenedioxythiophene) conducting polymer: Characterization, electrochemical and electrochromic properties

The “click” chemistry, Cu(I)-catalyzed azide–alkyne cycloaddition reaction, was applied to covalently functionalize the poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer film with an excellent electron transfer mediator (ferrocene). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy were used to characterize the ferrocene-grafted PEDOT conducting polymer film, and it was proved that the grafting procedure via click reaction had a high efficiency. The ferrocene groups covalently grafted in the polymer films turned out to own a relatively fast electron transfer rate and show multi-color states via adjusting applied potential.     

苯胺链段为侧基的聚酰胺酸的合成及性质

采用三元共聚法制备了苯胺齐聚物为侧链的接枝型聚酰胺酸. 通过红外光谱、核磁共振谱及高效凝胶渗透色谱等技术对聚合物结构进行了表征. 该材料亚胺化后具有十分优异的热稳定性. 紫外-可见光谱和电化学测试结果表明, 该聚合物具有独特的光谱性质和可逆的电化学活性. 聚酰胺酸/ITO电致变色电极具有颜色变化明显, 响应速度较快, 着色效率高等优点, 是一种综合性能较好的电致变色聚合物材料.