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Electrochemistry
Kinds of Electrochemistry Selected AbstractsDirect Electrochemistry of Hemoglobin Immobilized on Colloidal Gold-Hydroxyapatite Nanocomposite for Electrocatalytic Detection of Hydrogen PeroxideELECTROANALYSIS, Issue 2 2009Juan You Abstract A novel nanocomposite of colloidal gold (GNPs) and hydroxyapatite nanotubes (Hap) was prepared for immobilization of a redox protein, hemoglobin (Hb), on glassy carbon electrode. The immobilized Hb showed fast direct electron transfer and excellent electrocatalytic behavior toward reduction of hydrogen peroxide. A synergic effect between GNPs and Hap for accelerating the surface electron transfer of Hb was observed, which led to a pair of redox peaks with a formal potential of (,340±2) mV at pH,7.0, and a new biosensor for hydrogen peroxide with a linear range from 0.5 to 25,,M and a limit of detection of 0.2,,M at 3,. Owing to the good biocompatibility of the nanocomposite, the biosensor exhibited good stability and acceptable reproducibility. The as-prepared nanocomposite film provided a good matrix for protein immobilization and biosensor preparation. [source] Preparation, Electrochemistry, and Electrocatalytic Activity of Lead Pentacyanonitrosylferrate Film Immobilized on Carbon Ceramic ElectrodeELECTROANALYSIS, Issue 21 2008H. Razmi Abstract Lead pentacyanonitrosylferrate (PbPCNF), a new Prussian blue analog, was immobilized on the surface of a carbon ceramic electrode (CCE) prepared by sol-gel method. The immobilization process consists of adding a certain amount of metallic lead to the electrode matrix before gelation, and chemical derivatization of Pb on the electrode surface to a PbPCNF solid film by immersing the electrode in a solution of sodium pentacyanonitrosylferrate (PCNF). The composition of the synthesized PbPCNF was characterized by FTIR, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques. The resulting modified electrode showed electroactivity at two redox centers. The electrochemical behavior of the PbPCNF modified carbon ceramic electrode (PbPCNF|CCE) was studied by cyclic voltammetry. Under optimized conditions the peak-to-peak separation is only 39,mV, indicative of a surface reaction. Ion effects of the supporting electrolyte suggest that cations have a considerable effect on the electrochemical behavior of the modified electrode. The transfer coefficient (,) and the charge transfer rate constant at the modifying film|electrode interface (ks) were calculated. The electrocatalytic activity of the modified electrode toward the electro-reduction of peroxodisulfate was studied in details. [source] Direct Electrochemistry and Electrocatalysis of Hemoglobin in Lipid Film Incorporated with Room-Temperature Ionic LiquidELECTROANALYSIS, Issue 20 2008Gaiping Li Abstract A facile phospholipid/room-temperature ionic liquid (RTIL) composite material based on dimyristoylphosphatidylcholine (DMPC) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) was exploited as a new matrix for immobilizing protein. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were adopted to characterize this composite film. Hemoglobin (Hb) was chosen as a model protein to investigate the composite system. UV-vis absorbance spectra showed that Hb still maintained its heme crevice integrity in this composite film. By virtue of the Hb/DMPC/[bmim]PF6 composite film-modified glassy carbon electrode (GCE), a pair of well-defined redox peaks of Hb was obtained through the direct electron transfer between protein and underlying GCE. Moreover, the reduction of O2 and H2O2 at the Hb/DMPC/[bmim]PF6 composite film-modified GCE was dramatically enhanced. [source] Direct Electrochemistry and Electrocatalysis of Myoglobin Immobilized on Gold Nanoparticles/Carbon Nanotubes Nanohybrid FilmELECTROANALYSIS, Issue 17 2008Wei Cao Abstract A novel nanohybrid material, constructed by gold nanoparticles (GNPs) and multiwalled carbon nanotubes (MWNTs), was designed for immobilization and biosensing of myoglobin (Mb). Morphology of the nanohybrid film was characterized by SEM. UV-vis spectroscopy demonstrated that Mb on the composite film could retain its native structure. Direct electrochemistry of Mb immobilized on the GNPs/MWNTs film was investigated. The immobilized Mb showed a couple of quasireversible and well-defined cyclic voltammetry peaks with a formal potential of about ,0.35,V (vs. Ag/AgCl) in pH,6.0 phosphate buffer solution (PBS) solution. Furthermore, the modified electrode also displayed good sensitivity, wide linear range and long-term stability to the detection of hydrogen peroxide. The experiment results demonstrated that the hybrid matrix provided a biocompatible microenvironment for protein and supplied a necessary pathway for its direct electron transfer. [source] Electrochemistry of Mitochondria: A New Way to Understand Their Structure and FunctionELECTROANALYSIS, Issue 14 2008Jing Zhao Abstract In this article, electrochemistry of mitochondria is achieved. Cyclic voltammograms of freshly prepared mitochondria were obtained by immobilizing mitochondria together with glutaraldehyde and bovine serum albumin on the surface of a pyrolytic graphite electrode. Two pairs of redox peaks could be observed which were ascribed to the electron transfer reactions of cytochrome c and FAD/FADH2. Study of submitochondrial particles was also conducted, which could confirm the results of the study of the entire mitochondria. The redox wave of NADH could be obtained due to the destruction of the membrane of mitochondria. We have also checked the function of succinate in mitochondria by employing the electrochemical method. This work is not only the first to be able to obtain the direct electrochemistry of mitochondria, but is also beneficial to the further understanding of the structure and function of mitochondria in vitro. [source] Electrochemistry of Cytochrome P450 2B6 on Electrodes Modified with Zirconium Dioxide Nanoparticles and Platin ComponentsELECTROANALYSIS, Issue 7 2008Lei Peng Abstract The direct electrochemical and electrocatalytic behavior of the immobilized cytochrome P450 2B6 (CYP2B6) on zirconium dioxide nanoparticles (ZrO2) was investigated. The film of nano-structured ZrO2 that incorporated cytochrome P450 2B6 (CYP2B6) with colloidal paltin, which was stabilized by poly-lysine (Pt-PLL), was prepared on glassy carbon electrodes. In anaerobic solutions, the immobilized CYP2B6 exhibited a reversible electron transfer between the heme electroactive center of CYP2B6 and electrodes with a formal potential of ,(0.449±0.004) V at pH,7.4. In air-saturated solutions, an increased bioelectrocatalytic reduction current could be obtained with the CYP2B6-modified electrode with the addition of anticancer drugs, such as lidocaine. This leads to the construction of disposable biosensors for drugs by utilizing the electrochemical activity and catalytic reactions of the immobilized CYP2B6. [source] Reagentless Glucose Biosensor Based on the Direct Electrochemistry of Glucose Oxidase on Carbon Nanotube-Modified ElectrodesELECTROANALYSIS, Issue 11 2006Xiliang Luo Abstract The direct electrochemistry of glucose oxidase (GOD) was revealed at a carbon nanotube (CNT)-modified glassy carbon electrode, where the enzyme was immobilized with a chitosan film containing gold nanoparticles. The immobilized GOD displays a pair of redox peaks in pH,7.4 phosphate buffer solutions (PBS) with the formal potential of about ,455,mV (vs. Ag/AgCl) and shows a surface-controlled electrode process. Bioactivity remains good, along with effective catalysis of the reduction of oxygen. In the presence of dissolved oxygen, the reduction peak current decreased gradually with the addition of glucose, which could be used for reagentless detection of glucose with a linear range from 0.04 to 1.0,mM. The proposed glucose biosensor exhibited high sensitivity, good stability and reproducibility, and was also insensitive to common interferences such as ascorbic and uric acid. The excellent performance of the reagentless biosensor is attributed to the effective enhancement of electron transfer between enzyme and electrode surface by CNTs, and the biocompatible environment that the chitosan film containing gold nanoparticles provides for immobilized GOD. [source] Direct Electrochemistry of Cytochrome c at Gold Electrode Modified with Fumed SilicaELECTROANALYSIS, Issue 20 2005Hongjun Chen Abstract Direct electrochemistry of horse heart cytochrome c (cytc) has been obtained at a gold electrode constructed by self-assembling fumed silica particles (FSPs) onto a silane monolayer. A pair of well-defined and nearly symmetrical redox peaks of cytc is obtained at the FSPs film modified gold electrode. Cyclic voltammetry (CV) and tapping-mode atomic force microscopy (AFM) are used to characterize the FSPs film modified electrode, showing that the FSPs can provide a favorable microenvironment for cytc and facilitate the direct electron transfer between the cytc and the gold electrode, which may propose an approach to realize the direct electrochemistry of other proteins. [source] Immobilization and Electrochemistry of Negatively Charged Proteins on Modified Nanocrystalline Metal Oxide ElectrodesELECTROANALYSIS, Issue 12 2005Emmanuel Topoglidis Abstract The immobilization of two acidic, low isoelectric point proteins, green fluorescence protein and ferredoxin (FRD) is investigated on nanocrystalline, mesoporous TiO2 and SnO2 electrodes. Modification of these electrodes with a cationic polypeptide (poly- L -lysine) or an aminosilane prior to protein immobilization is found to enhance protein binding at least ten fold, attributed to more favorable protein/electrode electrostatic interactions. Cyclic voltammetry studies of FRD-modified SnO2 electrodes indicate reversible protein electrochemistry with a midpoint potential of ,0.59,V (vs. Ag/AgCl) and an interfacial electron transfer rate constant of 0.45,s,1. [source] Electrochemistry of Nucleic Acids at Solid Electrodes and Its ApplicationsELECTROANALYSIS, Issue 15 2004Patricia de-los-Santos-Álvarez Abstract The knowledge of the redox chemistry of nucleic acids (NA) is of paramount importance in cancer and aging research. Charge migration through DNA is also involved in biologically relevant functions such as DNA damage and repair. In the first part of this article the main aspects of the electrochemistry of nucleic acids at solid electrodes are revised, including redox processes, photoelectroactivity and electrical conductivity. In the second part, an overview of its applications is presented. Methods for electrochemical detection of NA, NA-based biosensors for detection of nonnucleic acid molecules, studies on the nature and dynamics of interactions and structural conformations of NA, are some applications that take advantage of NA electrochemistry at solid electrodes. [source] Electrochemistry at High Pressures: A ReviewELECTROANALYSIS, Issue 10 2004Debora Giovanelli Abstract High pressure electrochemical studies are potentially dangerous and less immediately implemented than conventional investigations. Technical obstacles related to properties of the working electrode material, preparation of its surface, availability of suitable reference electrodes, and the need for specially designed high pressure equipment and cells may account for the relative lack of experimental data on electrochemistry at high pressures. However, despite the stringent requirements for system and equipment stability, significant developments have been made in recent years and the combination of electrochemical methods with high hydrostatic pressure has provided useful insights into the thermodynamics, kinetics, and other physico-chemical characteristics of a wide range of redox reactions. In addition to fundamental information, high pressure electrochemistry has also lead to a better understanding of a variety of processes under non-classical conditions with potential applications in today's industrial environment from extraction and electrosynthesis in supercritical fluids to measurement of the pH at the bottom of the ocean. The purpose of this article is to detail the experimental pressurizing apparatus for electroanalytical measurements at high pressures and to review the relevant literature on the effect of pressure on electrode processes and on the properties of aqueous electrolyte solutions. [source] High-Temperature Electrochemistry: A ReviewELECTROANALYSIS, Issue 6 2004Gregory Abstract High-temperature electrochemistry remains a relatively unexplored field of research, although in recent years significant developments have been made. This report details the main experimental methods and approaches to heating an electrochemical system under both isothermal and non-isothermal conditions and gives an insight into the experimental and electroanalytical results obtainable under such conditions. It has been shown that the promotion of mass transport at high-temperatures, through diffusion or convection, often results in increased current signals. This increase benefits electroanalytical measurements by lowering detection limits. High temperatures also usefully enhance the sensitivity of systems with sluggish kinetics. [source] The Influence of Doping Levels and Surface Termination on the Electrochemistry of Polycrystalline DiamondELECTROANALYSIS, Issue 6 2004Matthew Abstract The influence of surface chemistry and boron doping density on the redox chemistry of Fe(CN) at CVD polycrystalline diamond electrodes is considered. It is demonstrated that for this couple both the doping density and the surface chemistry are important in determining the rate of charge transfer at the electrode/electrolyte interface. For hydrogen terminated CVD diamond metallic electrochemical behavior is always observed, even at boron doping densities as low as 7×1018,cm,3. In contrast, the electrochemical behavior of oxygen terminated CVD diamond varies with doping density, a metallic response being observed at high doping density and semiconductor behavior at low doping density. It is shown that the results attained may be explained by a surface state mediated charge transfer mechanism, thus demonstrating the importance of controlling surface chemistry in electroanalytical applications of diamond. [source] Studies on Nickel(II) Complexes with Amide-Based Ligands: Syntheses, Structures, Electrochemistry and Oxidation ChemistryEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2008Jyoti Singh Abstract The present work discusses the nickel chemistry in a set of amide-based open-chain ligands with subtle differences in the backbone or terminal amine substituents. The ligands coordinate to the Ni2+ ion through the Namide and Namine atoms maintaining a square-planar geometry. Absorption spectra and NMR studies reveal that the solid-state square-planar geometry is retained in solution. The electrochemical results suggest that the NiIII/NiII redox couple primarily depends on the N4 donors, which is composed of two Namide and twoNamine atoms and not on the peripheral substituents. All four ligands with variable backbone and substituents are equally competent in stabilizing the NiIII state. On the basis of electrochemical findings, chemical oxidations were carried out, and they reveal generation of the NiIII state in two cases, whereas decomposition was observed in others. Preliminary alkene epoxidation reactions suggest that the present nickel complexes transiently stabilize the higher oxidation state of the nickel ion that possibly participates in the oxidation of the substrates.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis, X-ray Crystal Structures and Electrochemistry of (Indenyl)ruthenium Complexes Containing dppf and Heterocyclic Thiolato/Thione LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2008Sin Yee Ng Abstract A number of (indenyl)ruthenium complexes containing dppf [1,1,-bis(diphenylphosphanyl)ferrocene] and heterocyclic thiolato/thione ligands have been synthesized. All the complexes were fully characterized by microanalytical and spectroscopic techniques, together with X-ray diffraction analyses for those containing the benzothiazolato (thiolato) and the thiadiazole (thione) ligands. Cyclic voltammetry (CV) experiments indicated that these complexes can be oxidized in three one-electron processes at positive potentials. Differences in chemical reversibility observed during variable-temperature CV experiments indicated that it was likely that the oxidation processes occurred at two electronically noncommunicating sites within the molecules. One site could be assigned as the oxidation of the Ru ion (two one-electron processes), whilst the second site was assigned as the oxidation of the dppf (one one-electron process). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Nitrate- and Nitrite-Assisted Conversion of an Acetonitrile Ligand Into an Amidato Bridge at an {Mo2(Cp)2(,-SMe)3} Core: Electrochemistry of the Amidato Complex [Mo2(Cp)2(,-SMe)3{,-,1,,1 -OC(Me)NH}]+EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2005Marc Le Hénanf Abstract Treatment of [Mo2(Cp)2(,-SMe)3(MeCN)2]+ (1+) with NO3, or NO2, results in the conversion of one terminally bound acetonitrile ligand into an amidato bridge. The reaction produces [Mo2(Cp)2(,-SMe)3{,-,1,,1 -OC(Me)NH}]0/+ (20/+) and involves the formation of an intermediate, which was detected by cyclic voltammetry but which could not be isolated, and which likely arises from the substitution of the NOx anion for one MeCN ligand. The electrochemical behaviour of 2+ was studied by cyclic voltammetry in THF and MeCN. The reduction of 2+ in the presence of acid (HBF4/H2O or HBF4/Et2O) in these solvents leads to the release of the amidate bridge. Controlled-potential electrolysis of 2+ in MeCN in the presence of acid produces 1+ quantitatively; the charge consumed (>1 F,mol,1 of 1+) indicates that electrons are also used to reduce protons. This was confirmed by the formation of 2+ (in variable amounts depending on the conditions) on treating 2 with acid. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Structure, Electrochemistry and Hydroformylation Catalytic Activity of the Bis(pyrazolylborato)rhodium(I) Complexes [RhBp(CO)P] [P = P(NC4H4)3, PPh3, PCy3, P(C6H4OMe-4)3]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2004Anna M. Trzeciak Abstract Rhodium complexes of formula [RhBp(CO)P] [Bp = bis(pyrazolylborate), P = P(NC4H4)31, PPh32, PCy33, P(C6H4OMe-4)34] have been prepared by exchange of the acetylacetonate (acac,) ligand in [Rh(acac)(CO)P] complexes. The spectroscopic and electrochemical properties as well as X-ray data of [Rh(acac)(CO)P] and [RhBp(CO)P] complexes have been compared with the aim to estimate the relative donor properties of both anionic ligands (acac, and Bp,). The cyclic voltammetric results indicate that the Bp, ligand behaves as a much stronger electron donor than acac, and a value of the Lever EL ligand parameter identical to that of the pyrazolate ligand (,0.24 V vs. NHE for each coordinating arm) is proposed for the bis- and tris(pyrazolyl)borate ligands, whereas P(C6H4OMe-4)3 is also shown to have an identical EL value (0.69 V) to that of P(NC4H4)3. An improved linear relationship between the oxidation potential and the sum of the ligand EL values for square-planar RhI complexes is also obtained and adjusted values for the Lever SM and IM parameters for the RhI/RhII redox couple are given. The trans influence of phosphanes was not observed in crystals of complexes 2 and 3, in contrast to analogous acetylacetonato complexes in which the Rh,O bonds differ by ca. 0.04,0.06 Å. Complexes 1,4 are very attractive precursors for hydroformylation catalysts and yields of aldehydes of 80,87% have been obtained with all complexes without extra phosphane as co-catalyst. During the hydroformylation reaction, however, small amounts of a catalytically inactive [RhBp(CO)2] complex were formed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis, Characterization and Electrochemistry of the Novel Dawson-Type Tungstophosphate [H4PW18O62]7, and First Transition Metal Ions DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2004Israel-Martyr Mbomekalle Abstract Following the synthesis of pure [H4PW18O62]7, (PW18), its derivatives monosubstituted with M (M = MoVI, VIV, VV, MnII, FeIII, CoII, NiII CuII and ZnII) were obtained. All compounds were characterized by elemental analysis, IR, UV/visible and 31P NMR spectroscopy. Their cyclic voltammetry properties were studied as a function of pH and systematically compared with those of their analogs derived from the symmetrical species, [P2W18O62]6,(P2W18). Comparison of the two unsubstituted precursors revealed that the merging of the first two waves of the monophosphate occurred in a less acidic medium than for the diphosphate. The observations point to the higher basicity of the reduced forms of PW18 compared with those of P2W18. The fingerprint pattern observed for ,2 -P2W17M derivatives in media of pH = 3 consisted of the splitting of the third W redox system into two one-electron closely spaced waves which is in contrast to the same system in ,1 -P2W17M. This peculiarity was also obtained for several of the present ,2 -PW17M systems in media of pH = 3 and confirmed that ,2 -substituted derivatives were indeed formed. The absence of this peculiar behavior in some other derivatives is consistent with smooth variations of acid-base properties from one derivative to the next. The electrocatalytic properties of all the compounds are illustrated by the reduction of nitrite by reduced PW18 and of nitrate by reduced ,2 -PW17Cu. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Cimetidine: antioxidant and metal-binding propertiesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2002Zaynab Lambat ABSTRACT Cimetidine is one of the most potent H2 receptor antagonists for inhibiting excessive histamine-induced acid secretion and is currently used worldwide to treat peptic ulcers. In this study, levels of free radicals were assessed and the ability of cimetidine to act as an antioxidant was determined using nitroblue-tetrazolium assay and lipid peroxidation assays. Free radical generation in the brain is promoted by the presence of iron, as occurs in the Fenton reaction. The results show that cimetidine reduces the generation of superoxide anion formed in the nitroblue-tetrazolium assay. In addition, cimetidine (1 mm) is able to reduce the iron-induced rise in lipid peroxidation in rat brain homogenates. Electrochemistry, UV/Vis spectroscopy and HPLC experiments show metal-ligand interactions between cimetidine and transition metals. The results imply that cimetidine provides a neuroprotective effect by binding to iron and copper, thus making them unavailable for free radical production. [source] Factors that prevent learning in electrochemistryJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 2 2007Hans-Jürgen Schmidt Electrochemistry plays an important role in curricula, textbooks, and in everyday life. The purpose of the present study was to identify and understand secondary-school students' problems in learning electrochemistry at an introductory chemistry level. The investigation covered four areas: (a) electrolytes, (b) transport of electric charges in electrolyte solutions, (c) the anode and the cathode, and (d) the minus and plus poles. Written tests were given to high-school students in five cycles. The population from which random samples were drawn totalled 15,700 subjects. Students were asked to select the correct answers and to justify their choices. It was found that students based their reasoning on four alternative concepts: (a) During electrolysis, the electric current produces ions; (b) electrons migrate through the solution from one electrode to the other; (c) the cathode is always the minus pole, the anode the plus pole; and (d) the plus and minus poles carry charges. The results suggest a teaching strategy in which students first experience and learn about electrochemistry concepts. In the second step, appropriate concept terms are added, and students then are confronted with the alternative concepts described in this article. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 44: 258,283, 2007 [source] Poly(3,4-ethylenedioxythiophene) (PEDOT)-Coated MWCNTs Tethered to Conducting Substrates: Facile Electrochemistry and Enhanced Coloring EfficiencyMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2008Shweta Bhandari Abstract Composite films of poly(3,4-ethylenedioxythiophene) (PEDOT)-coated over functionalized multiwalled coiled and linear carbon nanotubes (CNTs) have been fabricated by a simple oxidative electropolymerization route. The nanotubular morphology of the polymer,CNT composite is responsible for the lower charge transfer impedance, lower internal resistance, and superior capacitive response in comparison to that shown by the control PEDOT film doped by trifluoromethanesulfonate ions. This facile electrochemistry exhibited by the PEDOT,CNT composite film ensues in a remarkably high coloration efficiency of 367 cm2,·,C,1 at 550 nm, hitherto unrealized for PEDOT; thus demonstrating the huge potential the PEDOT,CNT composite film has as cathode for the entire spectrum of electrochromic devices. [source] Electrochemistry and XPS study of an imidazoline as corrosion inhibitor of mild steel in an acidic environmentMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 1 2009O. Olivares-Xometl Abstract The effect of 2-(2-heptadec-8-enyl-4,5-dihydro-imidazol-1-yl)-ethylamine on the corrosion behavior of mild steel in aqueous hydrochloric acid was investigated using weight loss measurements, polarization scans, electrochemical impedance, and X-ray photoelectron spectroscopy (XPS). The inhibition efficiencies and coverage degrees increased with the concentration of inhibitor but decreased proportionally with temperature. It appears that the steric hindrance of the aliphatic chain on the imidazoline ring adsorption may affect inhibitor efficiency. Polarization curves showed that the oleic imidazoline (OI) acted essentially as a mixed type inhibitor, in which the blocking of active sites occurred. As a result of film formation, impedance spectra revealed a considerable increase in the charge transfer resistance as indicated by the second capacitive loop. XPS depth profile analysis observed the presence of nitrogen and carbon species on the inhibitor film, which were associated to the OI. [source] Electrochemistry of graphene: new horizons for sensing and energy storageTHE CHEMICAL RECORD, Issue 4 2009Martin Pumera Abstract Graphene is a new 2D nanomaterial with outstanding material, physical, chemical, and electrochemical properties. In this review, we first discuss the methods of preparing graphene sheets and their chemistry. Following that, the fundamental reasons governing the electrochemistry of graphene are meaningfully described. Graphene is an excellent electrode material with the advantages of conductivity and electrochemistry of sp2 carbon but without the disadvantages related to carbon nanotubes, such as residual metallic impurities. We highlight important applications of graphene and graphene nanoplatelets for sensing, biosensing, and energy storage. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 211,223; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900008 [source] Electrochemical Quartz Crystal Microbalance Studies on Enzymatic Specific Activity and Direct Electrochemistry of Immobilized Glucose Oxidase in the Presence of Sodium Dodecyl Benzene Sulfonate and Multiwalled Carbon NanotubesBIOTECHNOLOGY PROGRESS, Issue 1 2008Yuhua Su The electrochemical quartz crystal microbalance (EQCM) technique was utilized to monitor in situ the adsorption of glucose oxidase (GOD) and the mixture of GOD and sodium dodecyl benzene sulfonate (SDBS) onto Au electrodes with and without modification of multiwalled carbon nanotubes (MWCNTs) or SDBS/MWCNTs composite, and the relationship between enzymatic specific activity (ESA) and direct electrochemistry of the immobilized GOD was quantitatively evaluated for the first time. Compared with the bare gold electrode at which a little GOD was adsorbed and the direct electrochemistry of the adsorbed GOD was negligible, the amount and electroactivity of adsorbed GOD were greatly enhanced when the GOD was mixed with SDBS and then adsorbed onto the SDBS/MWCNTs modified Au electrode. However, the ESA of the adsorbed GOD was fiercely decreased to only 16.1% of the value obtained on the bare gold electrode, and the portion of adsorbed GOD showing electrochemical activity exhibited very low enzymatic activity, demonstrating that the electroactivity and ESA of immobilized GOD responded oppositely to the presence of MWCNTs and SDBS. The ESA results obtained from the EQCM method were well supported by conventional UV-vis spectrophotometry. The direct electrochemistry of redox proteins including enzymes as a function of their biological activities is an important concern in biotechnology, and this work may have presented a new and useful protocol to quantitatively evaluate both the electroactivity and ESA of trace immobilized enzymes, which is expected to find wider applications in biocatalysis and biosensing fields. [source] Book Review: Encyclopedia of Electrochemistry: Bioelectrochemistry, Volume 9.CHEMBIOCHEM, Issue 12 2003Edited by George S. Wilson No abstract is available for this article. [source] ChemInform Abstract: Rational Synthesis, Structure, Magnetism and Electrochemistry of Mixed Iron,Nickel-Containing Wells,Dawson-Fragment-Based Sandwich-Type Polyoxometalates.CHEMINFORM, Issue 7 2010Israel M. Mbomekalle Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis, Characterization and Electrochemistry of the Novel Dawson-Type Tungstophosphate [H4PW18O62]7- and First Transition Metal Ions Derivatives.CHEMINFORM, Issue 16 2004Israel-Martyr Mbomekalle Abstract For Abstract see ChemInform Abstract in Full Text. [source] Evidence for the Formation of Singly Bonded Dimers During the Reductive Electrochemistry of Methanofullerenes.CHEMINFORM, Issue 2 2004Maitena Ocafrain No abstract is available for this article. [source] Structure, Magnetism, and Electrochemistry of the Multinickel Polyoxoanions [Ni6As3W24O94 (H2O)2]17- , [Ni3Na(H2O)2 (AsW9O34)2]11- , and [Ni4Mn2P3W24O94 (H2O)2]17- .CHEMINFORM, Issue 44 2003Israel M. Mbomekalle Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: New Crown-Anellated Tetrathiafulvalenes (I): Synthesis, Electrochemistry, Self-Assembly of Thiol Derivatives, and Metal Cation Recognition.CHEMINFORM, Issue 11 2001Adrian J. Moore Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] | |||||||||||||||||||||||||||||||