Welcome to Visit Journal of Electrochemistry,Today is Share:

Table of Content

    28 November 2004, Volume 10 Issue 4
    Studies on the Electrochemical Preparation and Electrochemical Properties of Conducting Polymers——Brief Introduction to the Research Work of Electrochemistry of Conducting Polymers in CAS Key Laboratory of Organic Solids(I)
    LI Yong-fange Academy of Sciences, Beijing 100080, China)
    2004, 10(4):  369-378. 
    Asbtract ( 3610 )   PDF (379KB) ( 4250 )  
    References | Related Articles | Metrics
    Conducting polymers have drawn much attention since the discovery of conducting polyacetylene in 1977, due to the novelty and curiosity of their structure and properties as well as their promising applications in many aspects. Among the studies of conducting polymers, the electrochemical preparation and electrochemical properties of conducting polymers are of special importance, because the electropolymerization is a main method for preparing conducting polymer films and the electrochemical properties are the basis for their applications in the fields of electrode materials for batteries, electrocatalysis, electrochromic display, etc. We are one of the earliest research groups in the world to perform the studies of electrochemistry of conducting polymers. Starting from 1980s, we mainly studied the electrochemical polymerization processes of pyrrole and the electrochemical properties of conducting polypyrrole. The main achievements we obtained are as follows:In the studies on the electropolymerization processes of pyrrole: 1) An anion-participated electropolymerization mechanism of pyrrole was proposed and a kinetic equation of the electropolymerization was firstly deduced based on the mechanism; 2) Smooth, flexible and strong conducting polypyrrole (PPy) films (tensile strength reaches 127 MPa) were prepared electrochemically in aqueous solution by adding non-ionic surfactant OP_(10); 3) Effects of the electropolymerization conditions (anions, solvents, pH values of the eletropolymerization solutions, and the polymerization current, potential and temperature etc.) on the conductivity and mechanical strength of the as-prepared PPy films were investigated and optimized systematically. It was found that surfactant anions with concentration higher than 0.1 mol/L, low DN (donor number) solvent, acidic aqueous solution, lower temperature, appropriate current (~ 1 mA/cm) are the optimized conditions for the electropolymerization of highly conductive and flexible and strong PPy films. 4) A proton-acid doping structure was proposed and confirmed in the PPy prepared electrochemically, in addition to the doping structure with its oxidized conjugated chain. In the studies on the electrochemical properties of PPy: 1) Two redox processes of PPy corresponding to its two doping structures were observed, and the mechanisms of the electrochemical redox processes in aqueous and organic solutions were studied and elucidated by means of cyclic voltammetry, spectroelectrochemical measurement, electrochemical quartz crystal microbalance (EQCM) etc; 2) The over-potential phenomenon in the first cycle of the cyclic voltammograms of PPy prepared and measured in organic solutions was investigated and elucidated. 3) The electrochemical overoxidation degradation of PPy in aqueous solutions was studied. It was found that the overoxidation potential depends on the pH values of the aqueous solutions, the higher the pH value is, the lower the overoxidation potential will be. The mechanism of the overoxidation was proposed to be related to the oxygen produced by the electrolysis of the aqueous solutions.In addition, the stabilities of conducting polymers in aqueous solutions and in air were elucidated from the electrochemical point of view, and the electrochemical properties of polyaniline (PAn) were also studied and the mechanisms of the redox processes of PAn were elucidated by spectroelectrochemical measurement.
    Investigation of Pulse Potential-modulated Coulometry for CO_2 Detection
    WANG Hai-chuan, WU Bing-liang~*
    2004, 10(4):  379-383. 
    Asbtract ( 2411 )   PDF (294KB) ( 1016 )  
    References | Related Articles | Metrics
    A pulse potential-modulated technique was applied to measure the concentration of CO_2 in gas samples. In the first step, an anodic pulse and a consequent cathodic pulse were used to remove the organic pollutant and surface oxide on the surface of the platinized Pt gauze electrode before each experiment. As following, a given potential step was used to reduce the CO_2 into adsorbed intermediate on Pt surface, and the adsorbates produced were oxidized by a following anodic potential step. At same time the oxidation current of adsorbates were measured. A certain relation exists between the concentration of CO_2 and the oxidation charge within the concentration range of (0.015)% to 20%. The approximate linear concentration-charge relation appears during a shorter reduction period and at a lower concentration of CO_2. It's wide convenient and effective for the detection of CO_2 in a relatively wide concentration range.
    Electrocatalytic Performances of Carbon Nanotube Air Electrode for Oxygen Reduction
    ZHAO Feng-ming, MA Chun-an~
    2004, 10(4):  384-390. 
    Asbtract ( 2420 )   PDF (313KB) ( 1412 )  
    References | Related Articles | Metrics
    The air electrodes with different mass ratio of Pt/active carbon or carbon nanotube as catalyst layer material have been prepared. The electrocatalytic performances for oxygen reduction were evaluated by means of polarization curve and electrochemical impedance spectroscopy (EIS). The results disclosed that carbon nanotubes dealt with nitric acid in the catalyst layer had been improved obviously on the electrocatalytic activity. After the surface of carbon nanotube was oxygenated and aggraded with platinum, the catalyst had obviously effects on the electrocatalytic activity. The air electrode with the mass ratio of active carbon to Pt/carbon nanotube in 4∶1 showed better electrocatalytic activity, e.g., the output current density reached 600~700 mA cm~(-2) when the overpotential was 500~600 mV. The EIS showed that the addition of Pt/carbon nanotube in the catalyst decreased greatly ohmic and kinetic impedance and thereby produced greater enhancement in performances.
    The Investigation of BaFeSi/C Alloy Composite as Anode Materials for Li-ion Battery
    FENG Rui-xiang, DONG Hua, AI Xin-ping~*,YANG Han-xi
    2004, 10(4):  391-396. 
    Asbtract ( 2079 )   PDF (265KB) ( 1147 )  
    References | Related Articles | Metrics
    A novel BaFeSi/C composite was prepared by mechanical ball milling, and lithium insertion reactions on the composite electrode were investigated by cyclic voltammetry ,charge-discharge measurements, XRD and XPS spectroscopy. It is demonstrated that the capacity retention with indiscernible capacity decas during charge-discharge cycling. The improved cycling ability of the composite is suggested from a cooperative action by inactive FeSi_(2 )and BaSi_2 matrix and outer graphite shell, which both buffer the volumetric changes of the active Si phase and provide a good connection for electronic and ionic conduction during lithium insertion and extraction processes.
    Electrochemical Investigations on Pitting Susceptibility of Iron-based Alloy
    LI Wei-shan~*,CHEN Hong-yu ,YUAN Zhong-zhi, LI Hong, HUANG Qi-ming, LV Dong-sheng
    2004, 10(4):  397-403. 
    Asbtract ( 2184 )   PDF (428KB) ( 1190 )  
    References | Related Articles | Metrics
    The formation process of passive film on iron and electronic properties and pitting susceptibility of an iron-based alloy are investigated by using linear potential sweep, alternative current impedance and electrochemical nose technologies. The relationship between reciprocal square capacitance and potential following the Mott-Schottky behavior is limited at a narrow rang of low potentials. At higher potentials, linear relationship between reciprocal capacitance and potential is obtained, which is ascribed to the increasing thickness of the passive film with potential. The donor density of the passive film is influenced by the formation potential of the film, passivator and microstructure. The decrease in the formation potential of the passive film and the existence of reduced or deposited passivator can increase the donor density of the passive film and lead to low resistance to pitting corrosion. The high-to-low order of pitting susceptibility for the individual microstructure is ferrite> martensite>pearlite. There exists interaction between different microstructures with different donor density, which results in pitting initiation and propagation on the weak microstructure.
    Electrochemical Behaviours of Hemoglobin-DDAB-Modified Powder Microelectrode and the Application of the Powder Microelectrode in Determination of Nitric Oxide
    GUO Zhi-mou,LIU Huan,CHEN Jian~* ,ZHANG Wen-ting
    2004, 10(4):  404-408. 
    Asbtract ( 2465 )   PDF (234KB) ( 1100 )  
    References | Related Articles | Metrics
    The electrochemical behaviours of DDAB-Hb-PME were studied in this paper. The (apparent) surface concentration of Hb was enhanced greatly by using the powder microelectrode (technique). NO reacts with Hb and absorbs on the surface of the modified carbon powder. Therefore, the output of the electrode was enhanced greatly by employing PME with higher reaction surface (area). The sensitivity of DDAB-Hb-PME is 3.1 mA/μmol·L~(-1)·cm~(2), which is much larger than the values obtained with the traditional electrodes. The detection limit is 9 nmol·L~(-1) and the linear response range is 9~100 nmol·L~(-1).
    LiCo_(x)Ni_(1-x)O_2 Cathode Materials Prepared by Electrolysis of Co and Ni
    WEI Jin-ping~*, SUN Xin, WANG Xiao-yu, BIAN Xi-kui, ZHAI Jin-ling, YAN-Jie
    2004, 10(4):  409-414. 
    Asbtract ( 2183 )   PDF (336KB) ( 1097 )  
    References | Related Articles | Metrics
    A new electrolytic method was developed to prepare LiCo_(x)Ni_(1-x)O_2 as a cathode material of lithium-ion battery. Contrary to the traditional method, electrolytic method is a potential method with simple process to industrialization and no pollution. Metal cobalt and nickel were electrolysed in parallel to prepare the precursor of Co_( x )Ni_(1- x )(OH)_2.Different compositional precursors could be conveniently prepared by changing electrolytic current. The LiCo_(0.3)Ni_(0.7)O_2 cathode prepared by this method was found favorable charge-discharge and cycle properties. For the LiCo_(0.3)Ni_(0.7)O_(2 )cathode material, the discharge capacities in the 1st and 50th cycles were 163 mAh/g and 140 mAh/g with charge retention of 86%.
    Study on Mass Transport in Liquid Layer Adjacent to the Electrode Through Transmission Vop-Spectroellipsometry
    ZHU Wei, YANGYu-ru, HUANG Zong-qing~*
    2004, 10(4):  415-419. 
    Asbtract ( 1791 )   PDF (102KB) ( 970 )  
    References | Related Articles | Metrics
    In electrochemical system, the mass transport process in liquid layer adjacent to electrode is studied through theoretical analysis only.The diffusion process can be analyzed theoretically by Fick's law for homogeneous media. Up to now, none of satisfied experimental method has been reported for studying mass transport of a whole process in liquid media yet. This paper described the experimental approach to explore mass transport in electrochemical system by transmission Vop-spectroellipsometry briefly.
    Effect of Fe~(3+) Dopen of Titanium Dioxide Film on Absorption Spectra and Photo Catalysis
    XIAO Mei-qun~*,SHEN Jia-nian , LI Moucheng , WU Peng-fei , LIU Dong , ZHANG Yu-juan
    2004, 10(4):  420-424. 
    Asbtract ( 2389 )   PDF (156KB) ( 1072 )  
    References | Related Articles | Metrics
    Photo-catalytic titanium dioxide film in nano crystalline has been prepared by electrochemical oxidation process and adding different amount of ferric ion into the electrolyte during the anodic oxidation.The effects of Fe~(3+) dopen on absorption spectra and photo-catalytic of the titanium dioxide films have been studied. It shows that the Fe~(3+) dopen caused the red shife of the absorption edge for the incoming light and exhibited the improved photocatalytic reactivity.
    Improvement and Its Mechanism of Storage Performance of Ni-MH Battery
    LI Xiao-feng~
    2004, 10(4):  425-429. 
    Asbtract ( 2272 )   PDF (216KB) ( 1097 )  
    References | Related Articles | Metrics
    The storage performance of nickel-metal-hydride (Ni-MH) battery was studied by using galvanostatic charge-discharge and cyclic voltammetry. The experimental results indicated that CoOOH could not be completely restored after its being thoroughly reduced at lower potential, which might weaken electric conduction network in the positive electrode and result in fading of electrochemical properties of Ni-MH battery. Addition of nickel powder as a conductive agent into the positive electrode was beneficial to the capacity recovery after storage.
    Anodic Dissolution of Aluminum in KOH-Ethanol Solutions
    SHAO Hai-bo, WANG Jian-ming~*, WANG Xiao-yan,ZHENG Yi, ZHANG Jian-qing
    2004, 10(4):  430-434. 
    Asbtract ( 2524 )   PDF (124KB) ( 1163 )  
    References | Related Articles | Metrics
    The feasibility of employing aluminum in KOH ethanol solution as a battery anode system was discussed. Weight loss measurement showed that the corrosion rate of Al is low enough to be used in sealed batteries. Through the measurements done by anodic polarization, EIS and galvanostatic discharge, it was found that A1 is electrochemical active in a wide potential range in this system, and its discharge mechanism is similar to that of A1 in aqueous solution. The discharge potential increased rapidly after a period of time, which might be caused by the discharge products depositing on the electrode surface.
    Electrochemical Behavior of Aluminized Steel in Seawater Environment
    LIANG Cheng-hao~
    2004, 10(4):  435-439. 
    Asbtract ( 2641 )   PDF (257KB) ( 1253 )  
    References | Related Articles | Metrics
    The electrochemical behavior of aluminized steel in seawater has been studied by immersion test and electrochemical technology. The results indicate that compared with 20# steel, the aluminized steel has lower corrosion potential and stronger anodic activity in seawater. Its anodic solution will occur at low potential. The immersion test shows that the corrosion rates of aluminized steel and 20# steel are 5.80 mg/dm~2 dand 3.36 mg/dm~2 d, respectively. Through the X-ray diffraction patternanalysis, it was found that chloride ions exit in the corrosion products of aluminized steel. It proves the participation of chloride ions in the process of corrosion, which are the main reason resulting in the corrosion. The research reveals that Aluminized steel's excellent corrosion resisting property in seawater is attributed to the combined action of the shutoff on the surface and couple protection. Besides the compact and uniform films of Al-Fe compound and the oxide of Al formed on the aluminized steel's surface, the aluminized layer as sacrificial anode can also protect the matrix.
    The Inhibition Synergistic Effect Between Imidazoline Derivative and Thiourea
    ZHAO Jing-mao, LIU He-xia, DI Wei,ZUO Yu~*
    2004, 10(4):  440-445. 
    Asbtract ( 2707 )   PDF (307KB) ( 1748 )  
    References | Related Articles | Metrics
    The inhibition synergistic effect between imidazoline and thiourea for carbon steel in CO_2 saturated brine solution was investigated by using weight-loss method, polarization curves measureament and XPS. The results showd that the inhibition efficiency increased significantly when imidazoline derivative was added as a corrosion inhibitor in the solution together with thiourea. The N and S atoms in the inhibitor film adsorbed on the surface of carbon steel, and N atoms predominated in the film near the solution and decreased gradually with the film depth and finally S atoms were the major element in the film near the matrix. It was concluded that imidazoline and thiourea could form a cage complex which adsorbed on the surface of steel and provided a compact film and a better inhibition.
    The Electrochemical Performance of Modified Spinel at Elevated Temperature
    CAI Zhen-ping~﹡, CHEN Xiao-hong, LU Shi-gang, LI Ming-xun, JIN Wei-hua
    2004, 10(4):  446-451. 
    Asbtract ( 2331 )   PDF (238KB) ( 1160 )  
    References | Related Articles | Metrics
    The modified LiMn_2O_4 cathode materials for lithium ion batteries have been synthesized by solid-state reaction. The crystal structure and electrochemical performance of products have been investigated by SEM、XRD and electrochemical measurements. The XRD analysis indicated that all the synthesized products possess Fd3m spinel LiMn_2O_4 structure. Those modified LiMn_2O_4 materials showed improved cycling capacity over pure spinels at high temperature and room temperature.
    Preparation and Photo-catalyst Properties of the α-Fe_2O_3-TiO_2 Films on Sodium Alginate Polymer
    CHEN Li-qin, ZHONG Huai-zhen, CHEN Ri-yao, ZHENG Xi, CHEN Zhen~*
    2004, 10(4):  452-459. 
    Asbtract ( 2408 )   PDF (214KB) ( 1911 )  
    References | Related Articles | Metrics
    Three new nano thin films of α-Fe_2O_(3)、TiO_2 and α-Fe_2O_(3)-TiO_2 by doping their powder with sodium alginate polymer were prepared. Surface structure and catalytic activities of the films were characterized by FTIR、XRD、PL、TEM and I-V techniques. The results of UV-visible absorption showed that the methylene blue was mineralized in aqueous of α-Fe_2O_(3)/SA、TiO_2/SA and (α-(Fe_2O_(3)))-TiO_2 /SA upon radiation with ultra violet light. α-Fe_2O_(3) enhanced their photo-decolorized-activities by doping 15% TiO_2.
    Preparation and Electrochemical Magnesium Insertion Behaviors of MgV_2O_6
    YUAN Hua-tang~*,JIAO Li-fang, CAO Jian-sheng, LIU Xiu-sheng, ZHAO Ming, WANG Yong-mei
    2004, 10(4):  460-463. 
    Asbtract ( 2582 )   PDF (220KB) ( 2035 )  
    References | Related Articles | Metrics
    MgV_2O_6was synthesized by conventional solid-state reaction from MgO and V_2O_(5)as starting materials. X-Ray diffraction analysis showed that the prepared sample belongs to the monoclinic structure. Electrochemical magnesium insertion from aprotic electrolytes such as organomagnesium halides into this host was found possible and exhibited charge/discharge circulation.
    Applications of New Activated Carbon Meterials in the Electric Double-layer Capacitor
    ZHANG Jian-jun~
    2004, 10(4):  464-467. 
    Asbtract ( 2282 )   PDF (220KB) ( 1272 )  
    References | Related Articles | Metrics
    A new type activated carbon whose precursor was coconut shell could be obtained using specific physics-chemistry activation, and the activated carbon was applied as the material of electrode in EDLC(electrical double-layer capacitor),which had a large specific capacitance,and could charge and discharged in some large currents. Carbon dioxide and acid were used to modify carbon,and the effects of post-treatment on surface area and pore volume were investigated. A moulding method which has influence on some properties of carbon electrode with PTFE additive was researched in the paper.