Papers by Keyword: Electrochemical (EC)

Abstract: X80 pipeline steel specimens were treated by electrochemical hydrogen charging under various current density and charging time. The polarization resistance and corrosion rate of X80 steel were analyzed in Yingtan simulated soil solution under the different hydrogen charging conditions. The results showed that hydrogen accelerated anodic dissolution and enhanced corrosion sensitivity. With hydrogen in the steel, the charge transfer resistance and polarization resistance decreased, double electric layer capacitor and corrosion current increased. The effects were enhanced with the increase of hydrogen charging time and current density.

Abstract: Electropolishing, the anodic dissolution process without contact with tools, is a surface Treatment method to make a surface planarization using an electrochemical reaction with low current density. Stainless steel can be put various applications which require purity and high precision surface of products. The aim of this study is to investigate the characteristic of electropolishing effect for stainless steel workpieces. In order to analyze the characteristics of electropolishing effect, surface roughness and micro-burr size were measured in terms of machining conditions such as current density, machining time and electrode gap. The tendencies about improvement of surface roughness by electropolishing for stainless steel workpieces were determined.

Abstract: The PANI-CNTs composite material was synthesized through emulsion polymerization, and then the composite had been modified by the oxygen plasma to get the electrode material for super-capacitor. The influences of the modification time on the electrode material surface property and the electrochemical performance were investigated. And based on the analysis of the scanning electron microscope(SEM) and fourier transform-infrared spectroscopy (FT-IR), the results revealed that the particle size of the composite material become smaller, more micro pores were etched by the oxygen plasma and some active functional groups were introduced. The electrochemical tests demonstrated that the PANI/CNTs composite material modified by the oxygen material after 10 min has perfect capacitive properties, the specific capacitance is 287.8 Fg-1, and the ESR is 0.320 Ω.

Abstract: A novel DNA biosensor based on layer-by-layer self-assembled multi-walled carbon nanotubes (MWNTs) functionalized with a mercapto group (SH-MWNTs) and gold nano-particles (GNPs) was presented, where anthraquinone-2-sulfonic acid sodium salt (AQMS) was used as hybridization indicator. The differential pulse voltammetry responses demonstrated that this DNA/GNPs/SH-MWCNTs/Au biosensor was enabled to specifically detect the single-base mismatch DNA sequence in phosphate buffer solution with pH 7.4 containing 0.3 mol/L Na+ and 1.0 mmol/L AQMS. The result showed that when the target DNA concentration was 1.0×10-10 to 1.6×10-5 mol/L, the cathodic peak current of Au electrode system with AQMS as indicator was linearly related to complementary NDA concentration, and the detection limit was about 3.82×10-11 mol/L and had good stability and specificity.

Abstract: The construction and performance of a novel electrochemical (EC) surface plasmon resonance (SPR) instrument based on a mini three electrode flow cell that was designed and manufactured by MEMS technology is described. The working electrode is 50nm gold and counter and reference electrodes, made of Au and Ag/AgCl separately, are 0.6 mm in diameter. The flow channel is made of polydimethylsiloxane (PDMS) with 1mm in width, 200μm in depth, 5μL in volume. The process for activating and modifying the working electrode is given by the real-time SPR detection. The Cyclic voltammetry (CV) and SPR detection are conducted simultaneously in potassium ferricyanide solution system. It is proved that the signal of redox reaction and the change of refractive index have a well correlation by the potential sweep experiment. Four kinds of concentration of potassium ferricyanide are analyzed and the peak oxidizing current, obtained from the curve, is proportional to the respective concentration of the sample. The EC-SPR experiment is also carried out in CuSO₄ system and the results is similar to potassium ferricyanide.

Abstract: Silver nanoparticles protected by Tetradecyltrimethyl Ammonium Bromide (TTAB) were prepared in a one-phase electrochemical system. Electrochemical procedure, based on the dissolution of a metallic anode in an appropriate solvent, has been used to get silver nanoparticles. It is possible to get different particle size by changing the current density. The optical properties of the silver Nanoparticles were investigated by UV-Vis and Photoluminescence (PL) Spectroscopy. Absorption peak were found 424 nm which confirm the presence of Ag nanoparticles. The structural properties of the samples were carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. XRD confirmed the preferential growth of Ag nanoparticles whose average size is ≈ 20 nm in the <111> orientation as well as purity of silver clusters.

Abstract: HRB400 reinforcing steel due to high strength and high ductibility is as the main reinforcing steel in “Code for design of concrete structures (GB50010-2002)” in China. Cyclic potentiodynamic polarization technique was used to investigate the electrochemical corrosion bebavior of HRB400 reinforcing steel in Simulated Concrete Pore solutions (SCP solutions) differently contaminated by bicarbonate ions and/or chloride ions. The evolution feature of the corrosion parameters was analyzed and was compared with that of HPB235 reinforcing steel. The results show that the corrosion characteristics of HRB400 and HPB235 were exceedingly similar before the destruction of the passivation film. However, HRB400 is remarkedly more susceptible to chloride ions and carbonation than HPB235 during the failure of the passivation films. The pH threshold for HRB400 is larger than that for HPB235, and the chlorides threshold for the former is smaller than that of the latter. When HRB400 and HPB235 were connected and exposed to an aggressive environment, the galvanic corrosion will occur where HRB400 is anode and HPB235 is cathode. To ensure the durability of the reinforcing concrete structures, it is necessary to make the connection points insulate.

Abstract: The solubility of different commercially available sodium salts was measured at 120°C for the potential use in the production of sodium metal by electrochemical processes in Ionic liquids (ILs) at relatively moderate temperatures. The results showed that the anion, cation, and substituents on the cation of the IL have a great effect on the solubility of the salts. It was found that the solubility of the salts in some ILs is higher than the value required in the production of sodium metal. An electrochemical method was used to measure the electrical conductivity of the selected ILs. Moreover, the effect of sodium salts on the conductivity of the ILs was studied. The conductivity of IL increased with the dissolution of sodium salts. In general, the conductivity of the studied ILs with/without sodium salts was suitable for the use in the production of metal sodium.

Abstract: A new unsymmetrical photochromic diarylethene [1-(2-methyl-5-(3-methoxyphenyl)-3-thienyl), 2-(2-methyl-3-benzothienyl)] perfluorocyclopentene (1a), was synthesized, and its photochromic properties such as photochromism, kinetics and electrochemical properties were investigated in detail. The results showed that the compound exhibited excellent photochromism both in solution and in PMMA film with alternating irradiation by UV/Vis light. The kinetic and electrochemical experiments indicated that the cyclization/cycloreversion process of the compound was determined to be the zeroth/first order reaction, and the electrochemcial switching property can be potential use for electrochemistry data storage. At last, using this dithienylethene as recording medium was performed successfully.

Abstract: The behavior of an electrochemical cell for anodic formation of titanium oxide nanotubes is calculated from an electrical model obtained from the DC Current-time plot. The result can predict the behavior beyond the voltage source used in the experiment and in conditions that are impossible to achieve in a real experiment. This clarifies the speculation around the cell voltage versus cell current limited experimental data and its behavior is explained in terms of the source used in the experiment.