Papers by Keyword: Electrochemical (EC)

Abstract: A sensitive aptasensor for detection of L-histidine based on switching structure of aptamer and elongated tetrahexaheral gold nanocrystals (ETHH Au NCs) is presented. The introduction of L-histidine induced self-cleavage of aptamer on the ETHH Au NCs / glassy carbon electrode (GCE) into the solution and the ferrocene (Fc) moiety approached the electrode surface and produced measurable electrochemical signals. With the enhancement effect of ETHH Au NCs, a linear electrical response was observed for concentrations ranging from 1 pM to 0.1 μM, a lower detection limit was 0.1 pM. The proposed approach exhibited excellent selectivity against other amino acids. Such an aptasensor provides a promising strategy for screening other amino acids and toxic ions at ultratrace levels on line

Abstract: On condition that the surface of 304 stainless steel has formed passive film, we have done research on the impact that the change of concentration of Cl- and Na+, the temperature, pH of Na+, on 304 stainless steel properties. This experiment is preceded studied with electrochemical method. The results show that along with the increase of temperature, pH improves the repairing capacity of passive film on the surface of 304 stainless steel. However, its stability decreases. Meantime, the pitting corrosion will happen become easier, when the repairing capacity of passive film and stability have been weakened because of the concentration of Na+, Cl- increases.

Abstract: Al/α-PbO2/β-PbO2 electrodes doped with fluoride ion (NaF) were prepared by anodic co-deposition in order to investigate the influence of NaF dopants on the properties of Al/α-PbO2/β-PbO2 electrodes. In our work, we found fluoride ion will benefit for the crystallization of β-PbO2 and change the crystallite size, crystal structure, enhance the catalytic activity, and even change the mechanism of the reaction in the oxidation of the material. The presence of NaF in the β-PbO2 electrolyte could enhance the electrochemical properties of the coating and therefore make itself as a superior anode material.

Abstract: One approach had been developed for the covalent modification of graphene sheets: amidation and esterification of graphene oxide (GO). Graphene oxide was synthesized by oxidizing graphite in strong acid and lots of oxygen-containing groups, such as hydroxyl and carboxyl processed in the carbon layers, made GO strongly hydrophilic activity as well as certain of chemical activity. This work researched a novel DNA biosensor which fabricated by immobilizing GO on Au electrode modified with mercaptoethylamine(MEA), was investigated by cyclic voltammetry. The results showed that graphite oxide was an excellent material and had a promising prospect in biosensor construction.

Abstract: ZnF2 nano-particles were prepared by electrochemical anodization method at room temperature. Zn foil acted as anode and Pb sheet served as cathode, and the complex solution of NH4F-H2O2-C2H5OH was used as electrolyte. The morphology, composition and crystalline structure of the as-prepared product were characterized by SEM, EDS and XRD techniques. The results showed that the product was rhombic nano-particles with the length of 50-200nm and the width of 50-100nm, the crystalline structure of the product was ZnF2 and ZnO, and the ZnF2 was the dominant component. Effects of NH4F concentration, applied voltage and anodization time on the morphology of the product were investigated.

Abstract: In this paper, electrochemical polymerization method was used to prepare electrochromic PANI films with different thicknesses via changing the polymerization time. It is found that the obtained PANI films are uniform and have good adherence with the ITO bases. Scanning electron microscope (SEM) images further show that the obtained films exhibited the tremella like lamellar structures with the diameter of each leaf about 100nm and the thickness of about 20nm at polymerization time of 8min. Optical electronic tests indicated that the films showed a gradient color variation from pale yellow, light yellow to green, blue-green, blue and dark blue among -0.2V and 1.0V. Furthermore, the color saturation increased and the hues became more abundant as polymerization time extended. The optical contrast ratios (ΔT) firstly increased to the maximum of 35% and then decreased, while the response time became longer. The results illustrate that the different shades of color are probably obtained through electrochemical polymerization method, which is important for the preparation of RGB full color system.

Abstract: The preparation of γ-MnOOH nanorod and Mn₃O₄ nanooctahedra have been achieved via hydrothermal reaction between KMnO₄ and DMF in water without the use of any surfactant or template. Various measurements were used to characterize the structure, morphology and electrochemical behavior of the resultant products. A possible growth mechanism has been proposed, the reaction temperature and the concentration of DMF plays a crucial role in the formation of the products. Their electrochemical properties have also been discussed.

Abstract: Real-time monitoring of concrete of rebar in concrete is studied in this paper, electrochemical method is the simplest method, monitoring of corrosion of rebar in concrete. This method is simple in an ever-changing environment, can reflect the corrosion of rebar in a long time.It not only can detect the rebar corrosion rate, also can test the long-term corrosion quantity. With the help of the polarization resistance measured regularly, the quantity of rebar corrosion can be estimated in a certain time.

Abstract: A acrylonitrile (AN)-methyl acrylate (MMA)-methoxy polyethylene glycol(350) monoacrylate (MPGA)-lithium acrylate (LiAc) tetra-copolymer was synthesized by emulsion polymerization, and phase inversion technique was adopted to prepare the as prepared polymer based microporous membrane. The gel polymer electrolytes (GPEs) were obtained by soak the as-prepared microporous membrane into 1M LiPF6/ (EC (ethylene carbonate) + DEC (diethylene carbonate)) (1:1 vol) electrolyte. FTIR, NMR and TGA/DSC measurements are used to character the components and structure of the polymer. The GPE’s ionic conductivity exceeds 3.0×10-3S/cm at ambient temperature, and this system also shows a sufficient electrochemical stability with a decomposition voltage as much as 6.0V vs Lithium(Li)/Li+ to allow far wider operation in the rechargeable lithium-ion polymer batteries. What’s more, this membrane also shows good characters in battery’s charge-discharge cycles.

Abstract: Pd nanoparticles have been prepared on the surface of glassy carbon electrode (GCE) by electrochemical deposition method and applied for the nonenzymatic detection of H₂O₂. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the as-prepared Pd nanoparticles on the surface of GCE. The electrochemical properties of Pd nanoparticles modified GCE were also characterized by cyclic voltammetry and chronoamperometry. The results showed that Pd nanoparticles modified GCE had a favorable catalytic ability for the reduction of H₂O₂ in PBS medium (pH=7.6). At an applied potential of -0.06 V, the nonenzymatic H₂O₂ sensors produce high and reproducible sensitivity to H₂O₂ with 52.45 μA/mmol۰dm–3. Linear responses were obtained over a concentration range from 0.15 mmol۰dm^–3 to 18 mmol۰dm^–3 with a detection limit of 25 μmol۰dm^–3 (S/N=3). Additionally, it exhibited a rapid response time (within 1s), which was much faster than some nonenzymatic H₂O₂ sensors.