Synthesis and Characterization of Flexible Hydrogel Electrodes for Electrochemical Impedance Measurements of Protective Coatings on Metal Sculptures

A novel conductive anionic hydrogel was synthesized for use as a solid electrolyte for electrochemical impedance spectroscopy (EIS) characterization of the barrier properties of protective coatings on outdoor metalworks, such as bronze sculptures. The AMPS‐co‐PAA hydrogel was soaked in a variety of aqueous salt solutions and characterized by swelling capacity and conductivity in order to determine the most appropriate gel/liquid electrolyte combination for use on culturally significant objects. K₂PIPES‐equilibrated hydrogels were selected as the preferred electrodes for this particular application and were used to measure the impedance of a coated substrate, yielding spectra similar to those from standard liquid cells.     

Synthesis of core-shell structured Au@Bi2S3 nanorod and its application as DNA immobilization matrix for electrochemical biosensor construction

The core-shell structured Au@Bi2S3 nanorods have been prepared through direct in-situ growth of Bi2S3 at the surface of pre-synthesized gold nanorods.The product was characterized by X-ray diffraction,transmission electron microscopy and energy-dispersive X-ray spectroscopy.Then the obtained Au@Bi2S3 nanorods were coated onto glassy carbon electrode to act as a scaffold for fabrication of electrochemical DNA biosensor on the basis of the coordination of-NH2 modified on 5’-end of probe DNA and Au@Bi2S3.Electrochemical characterization assays demonstrate that the Au@Bi2S3 nanorods behave as an excellent electronic transport channel to promote the electron transfer kinetics and increase the effective surface area by their nanosize effect.The hybridization experiments reveal that the Au@Bi2S3 matrix-based DNA biosensor is capable of recognizing complementary DNA over a wide concentration ranging from 10 fmol/L to 1 nmol/L.The limit of detection was estimated to be 2 fmol/L(S/N=3).The biosensor also presents remarkable selectivity to distinguish fully complementa ry sequences from basemismatched and non-complementary ones,showing great promising in practical application.     

A Novel Chronoimpedimetric Glucose Sensor in Real Blood Samples Modified by Glucose‐imprinted Pyrrole‐Aminophenylboronic Acid Modified Screen Printed Electrode

In this study, a molecularly imprinted sensor technology is engineered to detect glucose in real blood samples by chronoimpedimetrically. The imprinting process of glucose (Glc) was carried out by electrochemical polymerization of aminophenylboronic acid (APBA) and pyrrole (Py) by performing cyclic voltammetry (CV). Afterwards, glucose molecule was removed from imprinted surface by 5 % acetic acid to reveal glucose imprinted cavities. Electrochemical Impedance Spectroscopy (EIS) was used to characterize sensor modification steps and glucose removal. Glucose monitoring process was carried out chronoimpedimetrically(CI) for the first time in real blood samples. Calibration curve was prepared between 20–800 mg/dL. The standard deviations of the 18 calibration curves R² were calculated as 0.9866±0.0066 to assess reproducibility. Recovery was calculated by using 105 mg/dL Glc Serum Sample, which was monitored by auto analyzer and into this sample 50 mg/dL Glc added and our sensor response was 147.92±2.43 mg/dL, 98.6±1.62 % (n=5). Non‐imprinted (NIP) sensor gave no signal for the glucose concentration.     

Molecularly Imprinted Impedimetric Sensor for Determination of Mycotoxin Zearalenone

The mycotoxin zearalenone (ZEA) prompts reproductive toxicity due to its strong estrogenic effects. In this work, an electrochemical sensor for determination of ZEA was developed by electropolymerization of a molecularly imprinted poly (o‐phenylenediamine) (PPD) film on screen‐printed gold electrode (SPGE) surface. The sensor was examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using K₃[Fe(CN)₆]/K₄[Fe(CN)₆] as redox probe. The molecularly imprinted polymer (MIP) sensor showed a wide determination range from 2.50 to 200.00 ngmL^?1 for ZEA. The Limit of detection (LOD) was calculated to be 0.20 ngmL^?1, based on the signal to noise (S/N) ratio equal to 3.0. The sensor displayed good repeatability, with RSD values≤4.6 %, and maintained 93.2 % of its initial response after storage for 10 days in air at room temperature. The developed method was successfully applied for the determination of ZEA in corn flakes with mean recoveries ranged from 96.2 % to 103.8 % and RSDs within the interval of 2.1 % to 3.8 %.     

Electrochemical behavior of PbO2/PbSO4 electrode in the presence of surfactants in electrolyte

The electrochemical behavior of PbO₂/PbSO₄ electrode is investigated in 4.5 M H₂SO₄ in presence of three surfactants, Sodium Dodecyl Sulfate (SDS), Cetyltrimethylammonium bromide (CTAB) and Sodium tripolyphosphate (STPP), using cyclic voltametry, electrochemical spectroscopy impedance and galvanostatic discharge as techniques. The micro morphology of the surface of the modified PbO₂ electrodes is examined by scanning electron microscopy. The results show that SDS and CTAB when added in the electrolyte could refine the coating particles and change the roughness of the surface of the electrode leading to a thin film of PbO₂ with amorphous character. In addition, SDS and CTAB shift the hydrogen evolution potential towards more negative values, improve the discharge capacity of the anodic layer and accelerate the charge transfer. Under cathodic polarization, CTAB presents the lowest value of the charge transfer resistance R_ct. In the contrary, STPP shifts the oxygen evolution potential towards more positive values, passivates the surface of the electrode and inhibits completely the reaction of PbO₂ formation.     

Electrochemical characteristics of the blended polymer electrolytes containing lithium salts

Blend-based polymer electrolytes composed of poly(ethylene oxide), poly(oligo[oxyethylene]oxysebacoyl), and lithium salts have been prepared. These polymer electrolytes have been investigated in terms of ionic conductivity, transport number, and interfacial characteristics of the lithium electrode in contact with the polymer electrolyte. The influences of the blend composition, the salt used, and its concentration on the electrochemical behavior were studied. © 1996 John Wiley & Sons, Inc.     

NaOH电解液改善MH/Ni电池自放电性能的机理研究

以NaOH电解液代替KOH能够明显改善MH/N i电池的自放电性能和高温(60℃)充电效率.电化学阻抗和循环伏安测试表明,NaOH电解液的作用可能是改变了H原子于负极表面的吸(脱)附行为,并在一定程度上抑制了负极的析氢过程,从而改善了电池的自放电性能.     

基于电化学发光和阻抗技术研究DNA单碱基错配

单碱基错配的识别和稳定性差异在核酸多态性研究中至关重要。在同一电化学传感器平台上,采用电化学发光（ECL）和电化学阻抗（EIS）2种技术,协同研究DNA链中不同类型和不同位点的单碱基错配识别和稳定性差异。电极表面具有茎环构象的探针DNA与完全互补DNA、不同类型或不同位点单碱基错配DNA杂交前后的ECL和EIS信号强度变化有显著差异。信号强度变化可揭示单碱基错配识别的稳定性。结果表明,DNA链中心位点的C-A单碱基错配稳定性低于链两端的,靠近键合电极表面双链链端的C-A单碱基错配稳定性低于非键合电极表面双链链端的,同一中心位点C-X碱基对的稳定性顺序为C-G?C-T>C-A≥C-C。研究结果可为核酸多态性研究提供参考。     

聚乙撑二氧噻吩阳极降解的研究

研究了聚乙撑二氧噻吩(PEDOT)膜在水溶液中的阳极降解过程. 研究发现PEDOT的阳极过程可以分为p掺杂区[电位范围－0.3～0.5 V (相对于饱和甘汞电极; vs. SCE)]、过渡区[电位范围0.6～1 V (vs. SCE)]、过氧化区[电位范围1.2～1.6 V (vs. SCE)]三个电位区域. 用电化学阻抗谱法、循环伏安法、红外光谱技术、膜电阻测量以及电子自旋共振技术分别研究了PEDOT膜在这三个电位区域的行为. 结果表明: PEDOT膜在这三个电位区域的性质有明显不同. 在p掺杂区PEDOT膜的官能团、共轭结构、导电性均保持, 即在这个电位区发生可逆的掺杂/脱掺杂反应, 膜几乎不降解. 在过渡区和过氧化区, PEDOT膜均发生了降解. 与传统的导电聚合物在高电位的阳极降解的过氧化过程不同, 我们认为膜在较高电位(过渡区)发生一个驰豫过程, 该过程使得膜的官能团改变, 但是膜的共轭结构和导电性均保持; 而在更高的电位区(过氧化区)膜的降解和一般意义的过氧化降解相同, 此时膜的官能团、共轭结构、导电性均发生不可逆的破坏.     

基于器件结构提高TADF-OLED器件的发光性能

为了提高以TADF材料作为主体、天蓝色荧光材料作为客体的混合薄膜的OLED器件光电性能,我们调整了器件结构,使主体材料发挥其优势。制备了基本结构为ITO/NPB(40 nm)/DMAC-DPS∶x%BUBD-1(40 nm)/Bphen(30 nm)/LiF(0.5 nm)/Al的OLED器件。研究了主-客体材料在不同掺杂浓度下的OLED器件的光电特性。为了提高主体材料的利用率,在空穴传输层和发光层之间加入10 nm的DMAC-DPS作为间隔层;然后,在阳极和空穴传输层之间加入HAT-CN作为空穴注入层,形成HAT-CN/NPB结构的PN结,有效降低了器件的启亮电压(2.7 V)。测量了有无HAT-CN的单空穴器件的阻抗谱。结果表明,在最佳掺杂比例(2%)下,器件的外量子效率(EQE)达到4.92%,接近荧光OLED的EQE理论极限值;加入10 nm的DMAC-DPS作为间隔层,使得器件的EQE达到5.37%;HAT-CN/NPB结构的PN结有效地降低了器件的启亮电压(2.7 V),将OLED器件的EQE提高到5.76%;HAT-CN的加入提高了器件的空穴迁移率,降低了单空穴器件的阻抗。TADF材料作为主体材料在提高OLED器件的光电性能方面具有很大的潜力。