Chemistry Commons^™

Electrochemical Behavior Of Benzo[C]Cinnoline And Its Bromo Derivatives, Ni̇lgün Seçken, M. Levent Aksu, Ali̇ Osman Solak, Emi̇ne Kiliç

Turkish Journal of Chemistry

The electrochemical behavior of benzo[c]cinnoline and some of its bromo derivatives was studied. Two discrete 2-electron reduction waves in acidic and only one wave in basic media in ethyl alcohol-BR buffer system (l:5 v/v) were observed. A mechanism for the electrode reaction is proposed. Diffusion coefficients, formal potentials for and the derivatives, the number of electrons transferred were determined by using sampled current polarography, cyclic voltammetry, chronoamperometry, chronocoulometry and constant potential coulometry. Adsorption of the molecules on the surface of the mercury drop was analyzed and this phenomena was exploited to calculate the formal potentials and the diffusion coefficients of …

Observations On Lemon Cells, Jerry Goodisman

Chemistry - All Scholarship

In many general chemistry texts (1), the electrochemistry chapter is introduced with a picture of a “lemon cell”, leads of Zn and Cu piercing a lemon (or sometimes a grapefruit). A voltmeter connected across them shows a potential of about 1 V. (It has been shown how several fruits connected in series can be used to run a calculator [2].) The texts then discuss oxidation–reduction, half-cells, and the rest of what we teach freshmen about electrochemistry, and the lemon is never mentioned again.

It would appear to be questionable scientific pedagogy to present something, even something …

Fabricating And Imaging Carbon-Fiber Immobilized Enzyme Ultramicroelectrodes With Scanning Electrochemical Microscopy, David O. Wipf, Fuyun Ge, Robert C. Tenent

Publications

The scanning electrochemical microscope (SECM) is used to image the activity of enzymes immobilized on the surfaces of disk-shaped carbon-fiber electrodes. SECM was used to map the concentration of enzymatically produced hydroquinone or hydrogen peroxide at the surface of a 33-mm diameter disk-shaped carbon-fiber electrode modified by an immobilized glucose-oxidase layer. Sub-monolayer coverage of the enzyme at the electrode surface could be detected with micrometer resolution. The SECM was also employed as a surface modification tool to produce microscopic regions of enzyme activity by using a variety of methods. One method is a gold-masking process in which microscopic gold patterns …

Impedance Feedback Control For Scanning Electrochemical Microscopy, David O. Wipf, Mario A. Apuche-Avlles

CAS Publications

A new constant-distance imaging method based on the relationship between tip impedance and tip-substrate separation has been developed for the scanning electrochemical microscope (SECM). The tip impedance is monitored by application of a high frequency ac voltage bias between the tip and auxiliary electrode. The high frequency ac current is easily separated from the dc level faradaic electrochemistry with a simple RC filter, which allows impedance measurements during feedback or generation/collection experiments. By employing a piezo-based feedback controller we are able to maintain the impedance at a constant value and, thus, maintain a constant tip-substrate separation. Application of the method …

Electrochemical Evaluation On The Porosity Of Electroless Ni-P Alloy Coatings, Hong-Ying Yu, Dong-Bai Sun, Jing-Bing Huang, De-Jun Yang

Journal of Electrochemistry

By investigating the polarization curves of pure Ni-P alloy, Ni-P alloy coation and carbon steel in nitric acids with different concentrations, the sutable concentration of nitric acid for the evaluation of the porosity of Ni-P alloy coatings has been determined and the coatings with different thickness have been evaluated. The results indicated that the nitric acid with 10 wt% concentration is the most suitable solution for the porosity of the coating by using electrochemical method. The polarization curve of Ni-P alloy coating in 10% nitric acid can accurately reveal the porosity. With the decrease of the porosity of the coating, …

A Study On Stochastic Resonance For The Process Of Active-Passive Transition Of Iron In Sulfuric Acid, Hong-Bo Ding, Bao-Yun Xia, Chun-Sheng Yin, Zhong-Xiao Pan, Renato Seeber

Journal of Electrochemistry

The bistable characteristics of the process of active passive transition of iron in sulfuric acid was described and the stochastic resonance phenomenon in the process was simulated.

Microsystem And Electrochemistry, Zhong-Qun Tian, Jian-Jun Sun

Journal of Electrochemistry

Microsystem or micro electromechanical system (MEMS) is briefly introduced. The electrochemical applications in microsystem are reviewed and prospective applications of microsystem in electrochemistry are discussed. Along with the rapid development of micro_ analytical chemical systems or lab-on-chips in 21st century, electrochemistry may play an increasingly important role in microsystem technology.

The Electrochemical Apparent Effective Thickness Of Alkanethiol Self-Assembled Monolayers, Xiao-Li Cui, Dian-Lu Jiang, Peng Diao, Jun-Xin Li, Ru-Ting Tong, Deng-Ping Gu, Xin-Kui Wang

Journal of Electrochemistry

The electrochemical behavior of octadecanethiol self-assembled monolayers modified gold electrode in different concentration of Fe(CN)6^3-/4- is investigated by cyclic voltammetry and electrochemical impedance spectroscopy. It is determined that the apparent he-terogeneous rate constant k_s is in the order of 10^-6 cm·s^-1, the apparent electron transfer coefficients are 0.15 and 0.22. The apparent effective thickness of the SAMs is established which can be used to describe the molecular ordering degree of self-assembled monolayers.

Effect Of Inhibitor On Electrochemical Behavior Of 1cr18 Stainless Steel In Acidic Solution Under Friction, Jin-Ping Xiong

Journal of Electrochemistry

The electrochemical behavior of 1Cr18 stainless steel had been studied using a reciprocating triboelectrochemical equipment under friction in 0.2 mol/L H₂SO₄ solution with and without addition of thiourea, the frictionized surface of 1Cr18 stainless steel had been examined by the SEM, XPS and IR. The results showed that the loss rate of 1Cr18 stainless steel in the solution could be reduced by addition of thiourea. The adsorption of thiourea on the surface of 1Cr18 stainless steel prohibited the oxidization of Cr³⁺ to form Cr(Ⅵ) and formation of passive film consisting of CrO₄^2- or/and Cr(Ⅵ), …

Study Of Electrochemistry Of Tetrasulphonated Phthalocyanine Zinc In Aqueous And Nonaqueous Solvents, Er-Sheng Liu, Yi-Qun Wu, Jian-Hui Yang, Li-Ying Huang, Jun-Dong Wang, Su-Ling Yang, Nai-Sheng Chen, Jin-Ling Huang

Journal of Electrochemistry

The voltammetry of Tetra-sulphonated phthalocyanine Zn(TSPcZn)in DMSO and DMF solution has been examined and compared with those obtained in aqueous solution. The results showed that three pairs of redox peaks were appear in non-aqueous solvents, exhibiting three quasi-reversible phthalocyanine ligand based one-electron transfers, while in aqueous solution did no quasi-reversible behaviour was observed. The photoelectrochemical effect of light on TSPcZn redox reactions were also discussed.

Use Of Excel To Obtain Voltammetric Information On Microelectrodes, Enda Howard, John Cassidy

Articles

The use of curve fitting for the analysis and interpretation of voltammetric data obtained while working with micro electrodes is discussed as a useful exercise for introducing students to the principle of problem solving using least-squares curve-fitting techniques. The advantages associated with this approach to data processing over the approach where the limiting current (i L) alone is used are discussed and its limitations are highlighted. This technique was applied to the determination of unknown concentrations of ferrocyanide and the most satisfactory recovery of concentrations was found when both the va1ues of the formal potential (EO') and concentration ( C) …

Progress In Intersection Of Modern Electrochemisity And Materials Science, Changjian Lin

Journal of Electrochemistry

A brief introduction to the Joint Conference of Electrochemistry of the 48th Annual Meeting of International Society of Electrochemistry and the 192nd Electrochemistry Society was presented. The progress in intersection of modern electrochemistry and materials science was emphasized in the review.

Fuel Cells, Frederick J. Munster Jr.

Maine Collection

Fuel Cells

by Frederick J. Munster Jr.

Edited by: Mr. Christopher Carroll

Maine Department of Economic Development, Augusta, Maine, 1998.

Contents: Hydrogen / Hydrogen Safety / Electrolysis / Electrolyzers / History of Fuel Cells / How Fuel Cells Operate / Fuel Cell Types / Fuel Cell Electrochemistry / Power Systems / Fuel Cells in Transportation / Hydrogen Powered Internal Combustion Engines / Home, Garden, Education and Industry / For More Information / Glossary / References

Breakdown Of The Iron Passive Layer By Use Of The Scanning Electrochemical Microscope, David O. Wipf, John W. Still

Publications

The scanning electrochemical microscope (SECM) is used to generate localized corrosion at passivating iron surfaces by using the tip to generate Cl^– ions. Use of the SECM allows the rapid establishment of a locally aggressive chemical environment at a pre-selected site on the iron surface. The susceptibility for passive-layer breakdown and corrosion initiation was examined as a function of the time between the start of the passive-layer growth and the formation of Cl^- ions. The breakdown of the passive-layer was found to depend strongly on the passivation potential and the site of Cl^- formation on the iron …

Construction Of Gold Micro-Bead Ultramicroelectrodes, Deon T. Miles, Andrew Knedlik, David O. Wipf

CAS Publications

A new way to construct small electrodes by the use of metal micro-beads is described. Gold beads of 1.5 to 3.0 mm diameter were used to construct inexpensive and disposable microelectrodes with overall structural diameters of £ 6 mm and electrode diameters of £ 5 mm. The voltammetric response of these electrodes is consistent with existing theory and the electrodes exhibited the sigmoidal waves expected at ultramicroelectrodes.

Study Of Electrochemistry Of Octa-Butyl 2,3-Naphthalocyanine Manganese (Ⅲ) In Nonaqeous Solvents, Suling Yang, Ersheng Liu, Naisheng Chen, Jinling Huang, Xiaoyu Wang, Ping Pu, Wubiao Duan, Yiqun Wu, Xia Zuo

Journal of Electrochemistry

The electrochemical behavior of 5,9,14,18,23,27,32,36-Octa-Butyl 2,3-Naphalocyanine Manganese (Ⅲ) [(BuO)₈NPcMn(Ⅲ)Cl] in four nonaqueous solvents was studied by means of cyclic voltammetry, and the corresponding half-wave potentials (E_1/2) of redox reactions were obtained. Four (or five) pairs of redox peaks were assigned. The solvent effect on the electrochemical characteristics of this coordination compound was also discussed preliminarily, and the electrochemical behavior of the complex was compared with that of nonsubstitued naphthalocyanine.

Electrochemical Study And Application Of Cyclodextrin And Its Inclusion Complexes, Shuqin Liu, Zhimin Liu, Jinghao Pan

Journal of Electrochemistry

The electrochemical investigation and application of cyclodextrin and its inclusion complexes in recent years were reviewed. Studies on electrochemical behaviour of cyclodextrin inclusion complexes in our laboratory were introduced.

Applicadons Of Laser In Electrochemistry (Ⅰ), Bin Ren, Zhongqun Tian

Journal of Electrochemistry

This paper is the first part of a comprehensive review of laser applied in electrochemistry. At first, it briefly introduces the advantages, history and exporimental setup of laser electrochamistry. Then it reviews laser applications in electrochemical deposition, polymerization, etching, polishing, corrosion, adsorption/desorption and reactions as well as photoelectrochemical switching and storage.

Ohmic Drop Compensation In Voltammetry:  Iterative Correction Of The Applied Potential, David O. Wipf

CAS Publications

A new method of ohmic potential drop correction for use with potential step and sweep voltammetric methods is described. The method, iterative correction of the applied potential (ICAP), essentially replaces an electronic positive feedback correction with a digital positive feedback correction. This paper will present one form of the ICAP procedure, in which voltammetric current data acquired by a high-speed digital oscilloscope are used to iteratively generate a compensating potential waveform that is then synthesized by an arbitrary waveform generator. The ICAP method is advantageous for high-speed measurements, since many of the difficulties caused by electronic positive feedback compensation are …

Developments Of Fundamental Studies In Modern Electrochemistry──A Lecture For The National Advanced Workshop Of Modern Electrochemistry, Zhaowu Tian, Wenduan Su

Journal of Electrochemistry

This paper is a lecture notes spoken by profesor Tian to the national advanced workshop of modern electrochemistry.

Self-Assembled Monolayers: Preparation,Properties And Application, Xiandui Dong, Juntao Lu, Chuansin Cha

Journal of Electrochemistry

Self-assembling technique is a versatile approach to the preparation of monolayersof well-defined composition, structure, thickness and physicochemical properties. Different aspects, such as wettability, adhesion, corrosion, tribology, electrontransfer, protein adsorption, molecular recognition, and applications of SAMs are widely studied. The developments in the last decade arereviewed, with special attention to the electrochemical studies related to electrodes modified with thiol-derivative-based SAMs.

In Situ Infrared Evidence For The Electrochemical Incorporation Of Hydrogen Into Si And Ge, K. C. Mandal, F. Ozanam, J.-N. Chazalviel

Faculty Publications

No abstract provided.

Electrochemical Machining (Ecm) With Alternating Current, S. J. Shine

Tanzania Journal of Science

Electrochemistry has had several practical uses in industry for a long time; but one of the more recent applications is the machining of metals. Direct current ECM has been applied in industry for the last two decades. However, ECM with alternating current is still in the early stage of research and development. This paper shows that ECM with normal a.c supply is feasible and practicable if special tools are used. ECM with d.c. is first introduced to provide a better insight for the machining with a.c.

Effect Of Sodium Ions On The Electrochemical Reduction Of Diethyl Fumarate In Dimethylsulfoxide And Acetonitrile, Michael D. Ryan, Dennis H. Evans

Chemistry Faculty Research and Publications

No abstract provided.

Analysis Of Solutions For Surface Active Agents, Henry H. Bauer

KWRRI Research Reports

The objective of this study was to obtain a better understanding of the behavior of surfactants in aqueous solutions at electrodes. With this understanding it should be possible to design electrochemical methods for the detection, identification, and quantitative determination of such substances. This study was concerned primarily with the influence of extraneous salts on the behavior of surface active agents when these are examined by the electrochemical technique known as tensammetry.

The tensammetric method consists essentially of the measurement of the electrical impedance of an electrochemical cell. This impedance is characteristically increased in the presence of surfactants at those potentials …