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    28 April 2018, Volume 24 Issue 2
    Table of Contents
    Table of Contents-2018,Vol 24(2)
    2018, 24(2):  0. 
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    Preparation of Ni(dpim)2Cl2 Complex for the Electrocatalytic Reduction of CO2
    ZHANG Li-pu, NIU Dong-fang, ZHANG Xin-sheng
    2018, 24(2):  103-110.  doi:10.13208/j.electrochem.170401
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    A new Ni(dpim)2Cl2complex using 2-(diphenylphosphino)-1-methylimidazole (dpim) as ligand was prepared and served as a catalyst for the electrochemical reduction of CO2. The electrochemical redox behavior of Ni(dpim)2Cl2 in CH3CN/TPABF4 solution under nitrogen atmosphere showed the two-electron irreversible reduction at -0.7 V and one-electron quasi-reversible reduction at -1.3 V. After bubbling CO2 into the electrolyte, the reduction peak appeared at -1.3 V became irreversible and the peak current increased from 0.48 mA·cm-2 to 0.55 mA·cm-2. Moreover, the peak current at -1.3 V could further increase to 0.72 mA·cm-2 in the presence of proton source (CH3OH). These observations indicate that the Ni(dpim)2Cl2 exhibited a good electrocatalytic performance toward CO2 reduction and the electrocatalytic reduction process followed the ECE mechanism. The reduction products obtained by the potentiostatic electrolysis (at -1.3 V) were identified to be mainly CO with the catalytic conversion frequency  of 0.17 s-1.

    Preparations and Corrosion Protection Investigations of Diethylene Triamine Penta(Methylene Phosphonic Acid)-Zn2+ Conversion Coatings on Cold Rolled Steel Substrates
    HE Wei, YAN Ru, WANG Ying-qi, GAO Xiang, MA Hou-yi
    2018, 24(2):  111-121.  doi:10.13208/j.electrochem.170622
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    Novel diethylene triamine penta(methylene phosphonic acid) (DTPMPA)-zinc ion (Zn2+) conversion coatings with uniform blue color and excellent corrosion protection were directly formed on the cold rolled steel (CRS) substrates by immersing a CRS plate into the film-forming solutions containing the appropriate concentrations of DTPMPA and Zn2+ ion at the proper pH. In this paper, surface morphologies and elemental compositions of DTPMPA-Zn2+ conversion coatings were characterized by SEM and EDS, respectivey. The surface functional groups, chemical constituents and binding modes to the substrates were investigated by means of FTIR and XPS methods. The influences of DTPMPA concentrations and pH values on the corrosion protection properties of the DTPMPA-Zn2+ conversion coatings were studied using electrochemical impedance spectroscopy (EIS) and polarization measurements. The results revealed that DTPMPA reacted with Zn2+ ions, forming the DTPMPA-Zn2+ chelate under the coexistence condition of both substances. Moreover, the chelate would be deposited onto the CRS substrate through the cross-linking of Zn2+ ions and form three-dimensional DTPMPA-Zn2+ thin films with uniform blue color and thickness. This kind of conversion coating exhibited the best corrosion resistance performance with the protection efficiency of 91.6% when the concentrations of DTPMPA and Zn2+ ion were 0.2wt% and 0.044wt%, respectively, in the film-forming solutions at pH = 3.0.

    Preparation of Co3O4/Ti Electrocatalytic Membrane Electrode for Catalytic Oxidation of Benzyl Alcohol
    ZHENG Yu-mei, YIN Zhen, WANG Hong, LI Jian-xin
    2018, 24(2):  122-128.  doi:10.13208/j.electrochem.170407
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    The cobalt oxide(Co3O4) nanoparticles were loaded on microporous Ti membrane to prepare Co3O4/Ti electrocatalytic membrane electrode by dip-coating method. The microstructures and electrochemical properties of Co3O4/Ti electrocatalytic membrane were investigated. The Co3O4/Ti electrocatalytic membrane reactor (ECMR) assembled by using the Co3O4/Ti electrocatalytic membrane as an anode was adopted for catalytic oxidation of benzyl alcohol to produce benzaldehyde and benzoic acid.The effects of different operation parameters on benzyl alcohol conversion, and selectivity to benzaldehyde and benzoic acid of ECMR were studied. The results indicated that the electrochemical performance and catalytic activity of Co3O4/Ti membrane were improved significantly. The values of 49.8% for the conversion of benzyl alcohol, 51.5% for the selectivity to benzaldehyde and 23.6% for the selectivity to benzoic acid were obtained under the operating conditions with the benzyl alcohol concentration of 10 mmol·L-1, pH of 7.0, residence time of 5.0 min, current density of 2.5 mA·cm-2 at ambient temperature and pressure.

    Electrochemical Oxidation of p-Chlorophenol on Porous Ti/BDD Electrode Cooperated with Cathode Dechlorination
    CHEN Rong-ling, HUANG Wei-min, HE Ya-peng, SHI Jun, LIN Hai-bo
    2018, 24(2):  129-136.  doi:10.13208/j.electrochem.170310
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    The electrochemical oxidation of p-chlorophenol on porous Ti/BDD electrode cooperated with synergistic effect of cathode dechlorination was studied. Electrochemical degradation tests of p-chlorophenol were conducted in single and double compartment electrolytic cells separately, and the results showed that the mineralization happened mainly in the anode region. The product of chloride ions produced from the cathodic reduction of 4-chlorophenol in the single cell migrated to the anode region and further generated active chlorine toward electro-catalytic oxidation. At the same time, the chloride ion produced from the cathode of the double cell was difficult to be migrated to the anode region, which led to better degradation efficiency in the single compartment electrolytic cell. Combining with high performance liquid chromatography, the intermediate products in the anode region, including benzoquinone, catechol and phenol, were determined, while the major product in the cathode region was phenol. The degradation pathway of p-chlorophenol on BDD electrode was suggested based on the detected intermediate products

    Preparation and Properties of  Manganese Oxide and Polyaniline-Carbon Composite Electrode
    ZHOU Tian-tian, WU Bing, DENG Chao, GAO Ying
    2018, 24(2):  137-142.  doi:10.13208/j.electrochem.170510
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    The polyaniline-carbon (PAnC) electrode was prepared by the polymerization of aniline monomer and activated carbon in ice water bath, and followed by chemical deposition of manganese dioxide MnO2-PAnC composite material. The specific capacitance of MnO2-PAnC reached 459 F•g-1. The cyclic voltammetric results showed a small deformation in the voltammogram curve obtained with the MnO2-PAnC electrode at high scan rate, indicating good reversibility and capacitive properties. The AC impedance results revealed that the MnO2-PAnC electrode displayed the smallest charge transfer resistance and the fastest diffusion
    rate of surface ions than other two materials of MnO2 and MnO2-C. After 500 cycles of charging and discharging processes, the capacitance retention rate of MnO2-PAnC was still higher than 60%. The MnO2-PAnC is promising as a good electrode material for supercapacitors.

    One-Step Co-deposition of ZSM-5/PANI/PSS Electroactive Film and Its Kinetics Characteristics of Electrochemical Control Selective Separation for Pb2+ Ions
    QIAO Wen-lei, DU Xiao, GAO Feng-feng, ZHENG Jun-lan, LI Sha-sha, HAO Xiao-gang
    2018, 24(2):  143-153.  doi:10.13208/j.electrochem.170517
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    A novel electroactive composite film consisting of ZSM-5/polyaniline/polystyrene sulfonate(ZSM-5/PANI/PSS) was prepared by double pulse one step co-deposition method. The ZSM-5/PANI/PSS composite film was characterized by FT-IR, SEM, XRD, and XPS techniques. The highly crystalline nano-ZSM-5 was synthesized by hydrothermal method, which could be evenly dispersed in aqueous solution by ultrasonic treatment. The synthesis condition of composite film was optimized through changing the pH value of solution. The ZSM-5/PANI/PSS composite film showed higher adsorption capacity for Pb2+ ions. Langmuir model was applied to analyze the adsorption process. The adsorption capacity of composite film for Pb2+ ions was 235 mg·g-1. The adsorption kinetics of Pb2+ ions could be described properly by the pseudo-first-order kinetic mode.Furthermore, the pseudo-first-order rate constant was determined to be 0.0227 g·mg-1·min-1 in ESIX process, which is higher than that of 0.0117 g·mg-1·min-1 in IX process. Therefore, the ZSM-5/PANI/PSS composite film is expected to be a promising material in the field of waste treatment.
    A Label-free Immunosensor Based on K3[Fe(CN)6] and Aldehyde-Functionalized Pyridinium
    HU Xia, SHEN You-ming, SHEN Guang-yu
    2018, 24(2):  154-159.  doi:10.13208/j.electrochem.170406
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    A novel aldehyde-functionalized pyridinium was successfully synthesized. Using K3[Fe(CN)6] as a redox species modified on the surface of the electrode through Poly(diallyldimethylammonium chloride), we developed a label-free immunosensor based on aldehyde-functionalized pyridinium that was applied to simplify antibody immobilization on the electrode surface, in which no additional chemical cross-linking was required. In addition, the introduction of K3[Fe(CN)6] on the surface of electrode avoided the use of other redox species in the electrolyte solution. Under the optimal experimental conditions, differential pulse voltammetry (DPV) signals corresponding to different α-Fetoprotein (AFP) concentrations were measured. After antigens with different concentrations reacted with antibodies immobilized on the electrode surface, the peak current of DPV gradually decreased with increasing concentrations of AFP. The calibration curve showed a good linear relation in the range from 0.01 to 20 ng·mL-1 with the linear regression equation of y = -3.23x + 22.42 (R2=0.9943). The detection limit is 0.004 ng·mL-1 based on a signal-to-noise ratio of 3. The constructed immunosensor is simple, label-free and specific, thus, provides a good diagnostic tool for detection of α-Fetoprotein and other cancer markers.
    Electrochemical Performance of MoO2-C Composite Coatings
    LI Quan-yi, YANG Qi, ZHAO Yan-hong
    2018, 24(2):  160-165.  doi:10.13208/j.electrochem.170409
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    The molybdenum dioxide-carbon(MoO2-C)composite coatings on the surface of Cu foils were prepared by simple knife coating route and followed by sintering in vacuum. The morphology, composition, structure and electrochemical performance of the MoO2-C composite coatings were investigated. The results demonstrated that the MoO2-C composite coatings consist of MoO2 nano-particles with monoclinic crystal structure and amorphous carbon. Some MoO2 nano-particles with a size range of 5-30nm were loaded on the surface of carbon matrices; while some MoO2 nano-particles with a size of ~5nm were encapsulated inside. The composite coatings showed porous structure with the pore size ranging 1~3nm. The composite coatings attached firmly on the surface of Cu foils without any cracks accurred at their interface. The Cu-supported MoO2-C composite coatings delivered high capacity and good cyclic performance with a capacity of 814 mAh·g-1 at a current density of 100mA·g-1 after 100 cycles without apparent capacity fading during cycling, and good rate performance with a capacity of 188mAh·g-1 even at a high current density of 5000mA·g-1.

    Simulation Analysis in Dynamic Performance of Proton Exchange Membrane Fuel Cell under Starting Condition
    XIAO Yan,CHANG Ying-jie,ZHANG Wei,JIA Qiu-hong
    2018, 24(2):  166-173.  doi:10.13208/j.electrochem.170607
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    Based on the equivalent circuit model, by considering both the dynamic gas pressure model and the dynamic heat transfer model, a lumped parameter model is developed. The start process of the fuel cell is simulated by using SIMULINK software. The undershoot of the voltage is observed from the simulation results, and the response time of the voltage is basically the same as that of the fuel cell temperature, which indicates that the temperature has great influence on the dynamic performance of the fuel cell. From the perspective of the temperature, the dynamic responses of the thermodynamic potential, the activation overvoltage, the ohmic overvoltage and the concentration overvoltage of the fuel cell iare analyzed. It is found that the overshoot of the activation overvoltage and the ohmic overvoltage cause the voltage undershoot. When the temperature is input in the form of a step signal, the output voltage response of the fuel cell is fast, and thus, undershoot and overshoot do not occur. Therefore, it can improve the dynamic performance of the fuel cell with the increasing of temperature response speed.
    Synthesis and Electrochemical Properties of Li3V2(BO3)3/C Anode Materials for Lithium-Ion Batteries
    WANG You, ZENG Yi-wen, ZHONG Xing, LIU Xing, TANG Quan
    2018, 24(2):  174-181.  doi:10.13208/j.electrochem.170328
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    The Li3V2(BO3)3/C (LVB/C) composite materials were successfully synthesized in two steps:Firstly, a stoichiomertric mixture of Li2C2O4, V2O5, H3BO3, H2C2O4•H2O and ethanol was thoroughly ball-milled to get the precursors. Secondly, the precursors were post-calcinated to get the ultimate products. The calcination temperatures of 750 ℃, 800 ℃ and 850 ℃ were selected based on TG-DTA analyses. The crystal structures, surface morphologies and carbon contents of the samples calcinated at five conditions, namely, a(750 ℃, 10 h), b(800 ℃, 10 h), c(850 ℃, 10 h), d(800 ℃, 5 h) and e(800 ℃, 15 h), were characterized by XRD, SEM and EDS, respectively. The results showed that the dominant phase of all the samples was (Li0.31V0.69)3BO5 with the impure Li3VO4 phase in Samples a, b, c, and LiVO2 phase in Samples a, b, d and e. All of the samples consisted of many cylindrical particles, polygonal particles and agglomerations, among which Sample b showed better crystallized and less-agglomerated particles. EDS data demonstrated that the carbon, oxygen and vanadium elements were uniformly distributed in Sample b, and the carbon contents in Samples a, b, c, d, e were 2.64 %, 1.17 %, 1.51 %, 1.97 %, 1.30 %, respectively. The electrochemical performances of Samples a, b, c, d and e were compared by obtaining the galvanostatic charge/discharge, cycling ability, cyclic voltammetry curves, and electrochemical impedance spectra. The results revealed that Sample b achieved the optimal electrochemical performance. The initial charge/discharge capacities at a current density of 50 mA•g-1 were 427.6 mAh•g-1 and 669.1 mAh•g-1, respectively. However, after 10 cycles, only 55.4 % and 35.2 % of the initial charge/discharge capacities were retained, which might be related to the phase transformation from crystalline to amorphous during the insertion and extraction of lithium ions.
    Numerical Simulation of Output Performance in PEMFC
    LUO Xin,CHEN Shi-zhong, WU Yu-hou
    2018, 24(2):  182-188.  doi:10.13208/j.electrochem.170505
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    The COMSOL software was used to analyze the output performances in proton exchange membrane fuel cell(PEMFC) under three kinds of flow fields. Under the same operating conditions, the performance differences among single serpentine flow field, interdigitated flow field and mixed flow field are compared, and the causes of the differences in the output performances of PEMFC under three kinds of flow fields were analyzed. The simulation results showed that the output performance of the mixed flow field was the best, the output performance of the interdigitated flow field the second and the output performance of single serpentine flow field the worst. In addition, the drainability capacity of the mixed flow field was the best, and the oxygen concentration distribution was the most uniform. The mixed flow field exhibited minimun oxygen concentration difference between inlet and outlet. The simulation results have provieded an important guiding significance in the optimization of the structure and design of PEMFC.
    Effects of Rotating Magnetic Fields on PEM Fuel Cell Performance
    WU Mao-liang,WANG En-ze,PAN Guang-de,LIU Zhong-jun,XIE Fei
    2018, 24(2):  189-193.  doi:10.13208/j.electrochem.160815
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    Proton Exchange Membrane (PEM) fuel cell performance may be improved by application of additional magnetic fields. In this work, one square permanent magnet, made of either 16 combination cylinder magnets with homopolarity or 16 combination cylinder magnets with heteropolarity, was exerted on the fuel cell surface to produce additional magnetic field affecting PEM fuel cell performance. The influences of magnetic field status (rotating, static and none) on polarization and power density curves measured in a PEM fuel cell were investigated. The results verified the benefit of magnetic field, proving that the magnetic field distribution could improve the fuel cell output. Especially, the rotating combination magnet with heteropolarity enlarged the power density by 21.27%, which has advantage to the static magnetic field of 11.70% enhancement. Finally, the rotating speed was related to the fuel cell output power. High rotating speed was beneficial to the performance improvement, and the maximum power density was obtained at 30 r·min-1. However, the performance became worse upon further acceleration.
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    ZHAN Dongping
    2018, 24(2):  197-198. 
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