Noncovalent nanohybrid of ferrocene with single-walled carbon nanotubes and its enhanced electrochemical property

The nanoscale hybridization adduct of ferrocene (Fc) and single-walled carbon nanotubes (SWNTs) was prepared and it shows high stability and greatly enhanced sensitivity toward hydrogen peroxide reduction. The electrochemical and hydrolysis results suggest that the strong π–π stacking interaction between Fc and SWNTs play a critical role for its enhanced electrochemical catalytic property. The combined advantages from SWNTs and Fc and the cooperative effect due to this π–π stacking could make this adduct an excellent choice for ultrasensitive electrochemical detections.     

CuS–MWCNT based electrochemical sensor for sensitive detection of bisphenol A

The rapid and simple detection of bisphenol A is very important for the safety and reproduction of organisms. Here, a sensitive and reliable electrochemical sensor was established for bisphenol A detection based on the high amplification effect of copper sulfide-multi-walled carbon nanotube (CuS–MWCNT) nanocomposites. The flower-like CuS–MWCNT were successfully synthesized by a simple hydrothermal method accompanied by polyvinylpyrrolidone (PVP). Compared with bare glassy carbon electrode (GCE), CuS–MWCNT modified GCE could amplify the electrochemical signals in about ten times, which was attributed to the synergistic effect of CuS and MWCNT. The MWCNT could increase the specific surface area of electrodes and improve the electrode activity. The integration of CuS could further enhance the electrode conductivity as well as accelerate the electron transfer rate. Raman spectra and transmission electron microscope (TEM) were used to characterize the successful fabrication of CuS–MWCNT nanocomposites and its uniform and monodispersed morphology. Under optimizing conditions, the oxidation currents of bisphenol A via the differential pulse voltammetric (DPV) showed a good linear relationship with its concentration in a wide range of 0.5–100 μM, with a detection limit of 50 nM. This electrochemical sensor of bisphenol A provided a convenient and economical platform with high sensitivity and reproducibility, which had great potential in environmental monitoring.     

Effect of High Humidity Exposure to Wheat Starch Based High Conducting Flexible Polymer-in-Salt-Electrolyte

Polymer-in-salt-electrolytes (PISEs) are an important class of electrolytes as they carry the promise of faster and single ion transport. Unfortunately, due to unavailability of a suitable polymer host PISE has still not reached to commercial level. In the present work, using a novel synthesis protocol developed by the group, glutaraldehyde crosslinked wheat starch has been successfully modified with sodium iodide (NaI) to synthesize a flexible PISE membrane with desired electrochemical properties. Present paper reports the effect of crosslinker and exposure to high humidity ambience on electrochemical and morphological properties. It has been established that on exposure to higher humidity atmosphere starch-based PISEs stabilize at lower resistance value, but with higher ion relaxation time, which indicates that effect of high humidity treatment is more on salt dissociation instead of assisting the ion transport. The studied materials have conductivity ≈0.01 S cm⁻¹ range with ESW >2.5 V, ensuring its usability in electrochemical devices. The developed synthesis protocol does not require any complicated synthesis route and/or sophisticated instrument hence the overall process is economical also, adding up to its potentiality for energy device fabrication.     

钛酸钠纳米管-碳复合材料用作钠离子电容电池负极材料

以二氧化钛、氢氧化钠溶液和葡萄糖作为初始原料,通过水热方法合成了钛酸钠纳米管-碳复合材料。 使用XRD和TEM等方法测试了材料的结晶情况和形貌, 通过氮气吸-脱附和热重实验测试了材料的孔结构和碳含量。 采用复合材料作为负极材料,和石墨正极材料配伍,组装成不对称型电容电池,在钠基有机系电解液中其电压可高达3.5 V。 探讨了负极材料的储能机理,并考察了正负极质量比对负极储钠容量的影响。 电化学性能测试结果显示,电容电池具有较高能量密度和功率密度,其数值分别为72 Wh/Kg和1256 W/Kg,电容电池也表现出了较好的循环稳定性,在0.17 A/g电流密度下,经1000次循环后容量保持率高达100%。     

PVDF/PU blend membrane separator for lithium-ion batteries via non-solvent-induced phase separation (NIPS)

Membrane separator based on the polyvinylidene fluoride (PVDF) is prepared via the non-solvent-induced phase separation (NIPS) method with water and ethanol as non-solvent and a mixture of dimethylformamide (DMF) and acetone as solvent. The effect of various acetone/DMF ratios and non-solvent material on the physical and electrochemical properties of the separator is studied by FE-SEM, tensile strength, electrochemical AC-impedance spectroscopy (EIS), thermal stability, and linear sweep voltammetry (LSV). The charge-discharge studies are carried out by fabricating a lithium foil/polymer electrolyte membrane/LiFePO4 cell. The results show that with the change of solvent and non-solvent, the structure and morphology of the separator change and its physical and electrochemical properties. The results indicate that the membrane sample with non-solvent ethanol, acetone/DMF: 80/20 (wt/wt), and PVDF/PU: 95/5 (wt/wt) shows high porosity (66.3%) and high ionic conductivity (1.34 mS/cm) as well as excellent thermal stability.

     

The Effect of Electrochemical and Gas Phase Activation of High Surface Area Carbon Black Ketjen Black EC 600 DJ on Its Surface Composition,Electrochemical Capacitance,and Stability

The effect of electrochemical and gas-phase activation of high-surface-area carbon black Ketjen Black EC 600 DJ on its stability and electrochemical capacitance is studied. The electrochemical activation is carried out according to the “start–stop” protocol (1–1.5 V, 0.5 V/s). The stability of samples is assessed based on variation of their effective resistance (based on the results of cyclic voltammetry (CVA)) and electrochemical capacitance (based on CVA and galvanostatic data) with the cycle number. The changes in the texture and surface properties of activated samples are studied by the methods of nitrogen low-temperature adsorption and X-ray photoelectron spectroscopy. The gas-phase activation of high-surface-area carbon black Ketjen Black EС 600 DJ is shown to impair its stability, while the electrochemical oxidation of carbonblack samples leads to a considerable (two-fold) increase in their electrochemical capacitance.     

IrO2电极在4-氯苯酚水溶液中的电化学活性

研究了在4-氯苯酚(简称氯酚)电化学稳定窗口内氯酚对Ti基IrO2电极在酸性水溶液中电化学活性的影响. 循环伏安(CV)与电化学阻抗谱(EIS)测试均显示, 几乎在整个氯酚的电化学稳定电位区间内, 氯酚对氧化物电极均起到活化作用. 以金属Ir电极为对比试样的测试结果却显示, 由于氯酚易于在金属表面吸附, 氯酚在其电化学稳定窗口内对金属电极的活性产生抑制作用. 基于氯酚对上述两类电极电化学行为影响的差异, 提出活性氧化物自身在上述电位区间内发生从低价态到高价态的转变, 进而用于氧化去除吸附在电极表面的有机分子, 可能是氯酚对IrO2电极造成活化的主要原因.     

Electrochemical behavior of levodopa at multi-wall carbon nanotubes-quantum dots modified glassy carbon electrodes.

A multi-wall carbon nanotubes (MWNTs)-quantum dots (QDs) composite-modified glassy carbon electrode (GCE) was prepared. The complex was characterized by transmission electron microscopy (TEM). The electrochemical behavior of levodopa at MWNTs and QDs-modified GCEs (MWNTs-QDs/GCE) was studied by cyclic voltammetry (CV) and chronocoulometry (CC). It was found that its electrochemical behavior was a two-charge-two-proton process. The modified electrode had high electrocatalytic activity for levodopa with a standard heterogeneous rate constant of 0.595 cm s(-1), which was greatly increased compared with the values for bare GCE and individual MWNTs modified GCE. The better electrocatalytic activity for levodopa at MWNTs-QDs/GCE may due to a synergistic effect between MWNTs and QDs. This result provides a novel way to promote research on biomicromolecules at nano-dimensions.     

Disposable Electrochemical Aptasensor for Ultrasensitive Determination of Aflatoxin B1 Using Copper Nanoparticles as Probes

An electrochemical aptasensor for aflatoxin B1 (AFB1) detection was constructed based on the copper nanoparticles (CuNPs) and gold nanoflowers modified screen-printed carbon electrodes as electrochemical probes and substrates, respectively. In the range of 100 aM to 100 pM, a good linear relationship between oxidation peak current of CuNPs and concentration of AFB1 was obtained. The high sensitivity could be ascribed to the amplified electrochemical signals by CuNPs. The high affinity of AFB1 with aptamer endowed its high selectivity. The above advantages and disposable traits made this aptasensor as an ideal platform for evaluation of AFB1 level in food samples.     

Amperometric NADH Biosensor Based on Magnetic Chitosan Microspheres/Poly(thionine) Modified Glassy Carbon Electrode

Novel magnetic chitosan‐coated microspheres (MCMSs) were prepared by modifying carbon‐coated iron magnetic nanoparticles with chitosan. An amperometric dihydronicotinamide adenine dinucleotide (NADH) sensor was constructed based on immobilizing MCMS on the surface of a polythionine (PTH) modified glassy carbon electrode (GCE). The fabrication of MCMS/PTH film and its electrocatalytic effect on electrochemical oxidation of NADH were investigated by electrochemical impedance spectroscopy (EIS) and voltammetric methods. It was found that the resulting integrated films of PTH and MCMS exhibit high electrocatalytic response to NADH by significantly reduce its overpotential. The effects of the experimental variables on the amperometric determination of NADH such as solution pH and working potential were investigated for optimum analytical performance. This electrochemical sensor had a fast response to NADH which was less than 10 s. Linear response ranges of 2–10 μM and 10–100 μM and a detection limit of 0.51 μM (S/N=3) were obtained under the optimum conditions. Moreover, the selectivity, stability and reproducibility of this biosensor was evaluated with satisfactory results.     

Feasibility studies for the detection of volatile organic compounds in the gas phase using microelectrode sensors

The use of microelectrode sensors to detect volatile organic compounds (VOCs) in air is demonstrated. In general, VOCs that oxidize easily to form protons gave a larger electrochemical response. The use of voltammetry for speciation and the effect of electrode size on the electrochemical response are discussed. We demonstrate that surface enhanced Raman spectroscopy (SERS) can be used to monitor the electrochemical reactions in situ and discuss its applicability in identifying the electroactive species.     

Highly Sensitive and Selective Fluorometric/Electrochemical Dual‐Channel Sensors for TNT and DNT Explosives

A novel electro‐active compound, TCAC , is synthesized and its electrochemical polymerized film is used to detect 2,4,6‐trinitrotoluene (TNT) and 2,4‐dinitrotoluene (DNT) explosives through a fluorometric/electrochemical dual‐channel sensor with high sensitivity and selectivity. In particular, the electrochemical sensor for the analysis of TNT had an enhanced sensitivity of 0.5 μM . The detection limit of the sensor was calculated to be 15 nM .     

Preparation of polymer phthalocyanine electrodes and their electrochemical properties

Phthalocyanine coated electrodes are of interest due to their high electrochemical and electrocatalytical activities. Several possibilities to prepare electrodes coated by polymeric phthalocyanine and its precursor are described. Examples of electrochemical (reduction/reoxidation of the films) as well as electrocatalytical properties are presented.     

Influence of lanthanum on morphology and electrochemical performance of nano-platinum-based catalytic membrane electrode

The current research of platinum (Pt)–based catalysts focuses on reducing Pt loading in the catalysts while enhancing the catalytic activity. As a rare-earth element, lanthanum (La) has demonstrated good synergistic effect with Pt-based catalysts, because of its catalytic promoting capability and high dispersibility. Here, we fabricated La-doped nano-Pt-based catalytic membrane electrode using ion beam sputtering method. The effect of La on the morphology and electrochemical performance of the catalytic membrane electrode was investigated by scanning electron microscope, X-ray photoelectron spectroscopy, and electrochemical measurements. Compared with pure Pt-based sample, the electrochemical activity specific area of the La-doped sample increases by 74.59%, with 63.95% increase in exchange current density. The results also show that La₂O₃ enhances oxygen enrichment of the membrane electrode and reduces interfacial energy among Pt grains while pinning the grain boundaries. In addition, the inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurement shows that the Pt loading in the membrane electrodes is below 0.1 mg/cm². Thus, enhanced catalytic performance is achieved in catalysts with lower Pt loading.     

掺硼金刚石电极电催化氧化酚类有机物的取代基效应

本文主要以当前水环境中存在酚类有机污染物为研究对象,探讨酚类有机污染物在掺硼金刚石(BDD)电极上的取代基效应,具体研究具有不同位置及种类官能团的取代酚类有机污染物在BDD电极上的电催化氧化过程,通过化学需氧量和浓度变化考察有机污染物在电催化降解过程中的降解趋势,深入分析电极种类、官能团位置与种类与电催化氧化活性之间的联系的同时,研究阳极材料电催化氧化有机污染物的机理及动力学。结果表明,有机物在电极表面的电催化过程以电产生羟基自由基为媒介,对苯二酚在不同电极上的电催化活性与电极析氧电位及表面产生羟基自由基量有着重要的联系,BDD电极拥有最强的电催化氧化活性;不同取代基团的对位取代酚在BDD电极上的电化学降解实验显示电催化反应速率受取代官能团自身的电子效应制约,有机物矿化过程中羟基自由基首先进攻苯环的对位发生取代反应,同时取代基脱离苯环过程成为整个取代酚类电化学降解过程的决速步骤,且有机物的电催化反应速率与取代基特征Hammett常数σ呈近似线性关系。     

甲酸在钯微粒修饰聚苯胺电极上氧化的协同效应研究

Electrochemical oxidation of formic acid on PAN(Pd) electrode has been studied using conventional electrochemical techniques and the electrochemical in-situ FTIR. The process of electrochemical oxidation of PAN(Pd) electorde has been put forward. The kinetic parameters of different thickness of PAN film such as diffusion coefficient (D0) and reaction rate constant(k0) have been calculated. Furthermore, the causes of the difference between PAN(Pd) and pure Pd(or Pt) electrodes as well as the high electrocatalytic activation of PAN(Pd) electrode for oxidation of fomic acid have also been discussed. The high catalytic activation of PAN(Pd) electrode for oxidation of formic acid probably comes from the synergistic effect of the subcatalytic interaction of PAN and the catalytic interaction of the palladium microparticles.     

中空碳球合成方法及其电化学应用进展

中空碳球由于具有大的比表面积、良好的导电性以及高的化学稳定性等优异性能,现已被广泛地用于电化学储能、电化学催化和电化学传感领域。基于此,本文主要概述了中空碳球的各种合成方法及在电化学领域的研究进展,并对该领域面临的挑战及未来的发展方向进行了讨论。     

Nucleosides and ODN electrochemical detection onto boron doped diamond electrodes

Boron doped diamond (BDD) is a promising material for electroanalytical chemistry due mainly to its chemical stability, its high electrical conductivity and to the large amplitude of its electroactive window in aqueous media. The latter feature allowed us to study the direct oxidation of the two electroactive nucleosides, guanosine and adenosine. The BDD electrode was first activated by applying high oxidizing potentials, allowing to increase anodically its working potential window through the oxidation of CH surface groups into hydroxyl and carbonyl terminations. Guanosine (1.2 V vs. Ag/AgCl) and adenosine (1.5 V vs. Ag/AgCl) could then be detected electrochemically with an acceptable signal to noise ratio. The electrochemical signature of each oxidizable base was assessed using differential pulse voltammetry (DPV), in solutions containing one or both nucleosides. These experiments pointed out the existence of adsorption phenomena of the oxidized products onto the diamond surface. Scanning electrochemical microscopy (SECM) was used to investigate these adsorption effects at the microscopic scale. The usefulness of BDD electrodes for the direct electrochemical detection of synthetic oligonucleotides is also evidenced.     

Molten-Salt Media Synthesis of N-Doped Carbon Tubes Containing Encapsulated Co Nanoparticles as a Bifunctional Air Cathode for Zinc-Air Batteries

Cost efficient bifunctional air cathodes possessing high electrocatalytic activity are of great importance for the development of secondary Zn-air batteries. In this work, cobalt nanoparticles are encapsulated within a 3D N-doped open network of carbon tubes (Co@N-CNTs) by a molten-salt synthesis procedure conducted at a high temperature. Physical characterization demonstrates that Co@N-CNTs are comprised of Co particle inserted carbon tubes with mesoporous tube walls, providing significant active surface area for electrochemical reactions. High electrocatalytic activity of Co@N-CNTs towards both oxygen evolution and oxygen reduction reactions is due to its well-developed active surface and a synergistic effect between N-doped carbon and Co nanoparticles. Both primary and secondary Zn-air battery cells assembled using Co@N-CNTs as an air cathode show higher electrochemical performance than similar cells containing commercial Pt/C and Pt/C +RuO₂, making the newly developed material a promising alternative to existing metal-based air cathodes.     

钛/活细胞界面原位EIS研究

设计了原位电解池用于生物材料/活细胞界面电化学交流阻抗谱(EIS)的测量, 原位观测了钛/MG63细胞界面EIS行为及其随时间的变化. 原位电解池中引入Ag/AgCl作为参比电极, 解决了EIS测量过程中高频部分信号失真的问题. 钛/MG63细胞界面EIS研究初步结果表明: 活细胞在钛电极表面附着, 可改变界面双电层结构和电极的表面状态, 进而影响界面的电化学性质. 实验发现, 由于钛电极表面氧化层的阻抗信号处于中低频段, 而细胞膜层自身的电化学阻抗响应位于高频范围, 由此, 可分别分析不同的电极过程, 解析其相互关系, 研究活细胞在生物材料表面的作用机理.