Enhancement in Kinetics of the Oxygen Reduction Reaction on a Nitrogen-Doped Carbon Catalyst by Introduction of Iron via Electrochemical Methods.

The iron (Fe) electrodeposition-electrochemical dissolution has been employed on nitrogen-doped carbon material (P-PI) prepared via multi-step pyrolysis of a polyimide precursor to achieve the introduction of Fe species, and its influence on the oxygen reduction reaction (ORR) is investigated by cyclic and rotating ring-disk electrode voltammetry in 0.5 M H2SO4. After the electrochemical treatment, the overpotential and H2O2 production percentage of ORR on the P-PI are decreased and the number of electrons transferred is increased in the meanwhile.

A novel fabrication of a polymeric ionic liquid hybrid film modified electrode and its successful application to the electrogeneration of a superoxide anion in aqueous media.

A novel polymeric ionic liquid hybrid film-modified electrode, in which the electrode surface is coated with a hydrophobic hybrid material composed of an ionene polymer with quaternary ammonium sites in its polymeric backbone and ionic liquids, was fabricated by electropolymerization of N,N-dimethylaniline in a hydrophobic ionic liquid, which can be applied for the electrogeneration of a superoxide anion via one-electron reduction of O2 in aqueous media.

Characterization by electrochemical and X-ray photoelectron spectroscopic measurements and quantum chemical calculations of N-containing functional groups introduced onto glassy carbon electrode surfaces by electrooxidation of a carbamate salt in aqueous solutions.

The present paper deals with characterization of an aminated glassy carbon electrode (GCE) surface obtained by electrooxidation of ammonium carbamate in its aqueous solution (amination reaction) using electrochemical and XPS methods. From the XPS analysis, it was found that not only the primary amine group (i.e.

Direct electrochemistry and intramolecular electron transfer of ascorbate oxidase confined on L-cysteine self-assembled gold electrode.

A direct electrochemistry and intramolecular electron transfer of multicopper oxidases are of a great importance for the fabrication of these enzyme-based bioelectrochemical-devices. Ascorbate oxidase from Acremonium sp. (ASOM) has been successfully immobilized via a chemisorptive interaction on the l-cysteine self-assembled monolayer modified gold electrode (cys-SAM/AuE).

Electroless deposition of platinum nanoparticles in room-temperature ionic liquids.

The electroless deposition of Pt nanoparticles (Pt-NPs) could be carried out by dissolving potassium tetrachloroplatinate(II) (K2[PtCl4]) in 1-ethyl-3-methylimidazolium (EMI(+)) room-temperature ionic liquids (RTILs) containing bis(trifluoromethylsulfonyl) imide (NTf2(-)) or tetrafluoroborate (BF4(-)) anion and small cations, such as H(+), K(+), and Li(+). In this case, no deposition of Pt-NPs occurred in RTILs without such small cations. The formation of Pt-NPs was only observed in RTILs containing trifluoromethanesulfonimide (HNTf2) and protons at high temperature (≥80 °C) when potassium hexachloroplatinate(IV) (K2[PtCl6]) was dissolved in the RTILs.

Electrodeposition of platinum nanoparticles in a room-temperature ionic liquid.

The electrochemistry of the [PtCl(6)](2-)-[PtCl(4)](2-)-Pt redox system on a glassy carbon (GC) electrode in a room-temperature ionic liquid (RTIL) [i.e., N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEMEBF(4))] has been examined.

Generation of gaseous sulfur-containing compounds in tumour tissue and suppression of gas diffusion as an antitumour treatment.

Background And Aims: The mechanisms of cancer cell growth and metastasis are still not entirely understood, especially from the viewpoint of chemical reactions in tumours. Glycolytic metabolism is markedly accelerated in cancer cells, causing the accumulation of glucose (a reducing sugar) and methionine (an amino acid), which can non-enzymatically react and form carcinogenic substances. There is speculation that this reaction produces gaseous sulfur-containing compounds in tumour tissue.

pH Dependence of the size and crystallographic orientation of the gold nanoparticles prepared by seed-mediated growth.

The effect of the pH of the growth solution on the size and crystallographic orientation of gold nanoparticles (GNPs) was studied during the course of the preparation of surface-confined spherical GNPs following a two-step protocol (electrochemical and chemical). GNPs were first electrodeposited onto a clean glassy carbon (GC) electrode and these GNPs were used as seeds. Seed-mediated growth of the electrodeposited GNPs was performed in a solution of H[AuCl(4)] at various pHs (5.

Selective detection of As(III) at the Au(111)-like polycrystalline gold electrode.

Selective electrochemical detection of As(III) using a highly sensitive platform based on a Au(111)-like surface is described. The Au(111)-like surface was achieved for the first time by the partial reductive desorption of n-butanethiol (n-BT) from polycrystalline gold (poly-Au), on which a self-assembled monolayer (SAM) of n-BT was formed previously, which allows the selective blockage of the Au(100) and Au(110) surface domains by n-BT while the Au(111) domain remains bare. Square wave anodic stripping voltammetry (SWASV) using the Au(111)-like poly-Au electrode confirms the successful detection of As(III) without any interference from Cu(II).

Determination of formal potential of NADH/NAD+ redox couple and catalytic oxidation of NADH using poly(phenosafranin)-modified carbon electrodes.

The electrochemical regeneration of NADH/NAD(+) redox couple has been studied using poly(phenosafranin) (PPS)-modified carbon electrodes to evaluate the formal potential and catalytic rate constant for the oxidation of NADH. The PPS-modified electrodes were prepared by electropolymerization of phenosafranin onto different carbon substrates (glassy carbon (GC) and basal-plane pyrolytic graphite (BPPG)) in different electrolytic solutions. The formal potential was estimated to be -0.

Fabrication of Au(111) nanoparticle-like electrode through a seed-mediated growth.

We demonstrate a seed-mediated growth of electrodeposited gold-nanoparticles (GNPs) onto a glassy carbon (GC) electrode from a solution of H[AuCl(4)] containing NH(2)OH at pH 0.5, resulting in a Au(111) facet ratio as high as 97%.

EQCM study of the [Au(III)Cl4](-)-[Au(I)Cl2](-)-Au(0) redox system in 1-ethyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquid.

The electrochemical behavior of the [Au(III)Cl(4)](-)-[Au(I)Cl(2)](-)-Au(0) redox system in room temperature ionic liquid (RTIL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF(4)) has been investigated quantitatively using an in situ electrochemical quartz crystal microbalance (EQCM) technique based on a Pt film-coated quartz crystal electrode (Pt-QCE). A series of two-electron (2e) and one-electron (1e) reductions of the [Au(III)Cl(4)](-) to [Au(I)Cl(2)](-) and [Au(I)Cl(2)](-) to Au metal were recognized at the Pt surface. Besides, the disproportionation reaction of [Au(I)Cl(2)](-) (i.

Enhanced catalytic reduction of oxygen at tantalum deposited platinum electrode.

A tantalum deposited platinum electrode that offers an enhanced catalytic four-electron reduction of oxygen over the bare platinum electrode in acidic solution is explored.

Stability of superoxide ion in imidazolium cation-based room-temperature ionic liquids.

The stability of superoxide ion (O(2)(*-)) generated chemically by dissolving KO(2) in dried dimethyl sulfoxide solutions containing imidazolium cation [e.g., 1-ethyl-3-methylimidazolium (EMI(+)) and 1-n-butyl-2,3-dimethylimidazolium (BMMI(+))] based ionic liquids (ILs) was investigated with UV-visible spectroscopic, NMR, and voltammetric techniques and an ab initio molecular orbital calculation.

Water electrolysis: an excellent approach for the removal of water from ionic liquids.

An electrochemical system based on platinum cathode and glassy carbon anode was assembled for a successful removal of water from ionic liquids via the water electrolysis strategy.

Electrochemical, HPLC and electrospray ionization mass spectroscopic analyses of peroxycitric acid coexisting with citric acid and hydrogen peroxide in aqueous solution.

We successfully determined the molecular structure of peroxycitric acid (PCA) coexisting in the aqueous equilibrium mixture with citric acid (CA; 1,2,3-tricarboxylic-2-hydroxy propane) and hydrogen peroxide (H(2)O(2)) by a combined use of reversed-phase HPLC (RP-HPLC), potentiometric, hydrodynamic chronocoulometric (HCC) and electrospray ionization mass spectroscopic (ESI-MS) methods. Firstly, the RP-HPLC was employed to separate CA, PCA and H(2)O(2) coexisting in the equilibrium mixture and the concentration of CA consumed (DeltaC(CA)) in the formation of PCA that was evidenced to be fairly stable during the RP-HPLC measurement was quantitatively measured based on the standard calibration curve of CA. Secondly, the total oxidant concentration (C(Ox)) corresponding to peroxycarboxylic (-COOOH) group in PCA in the equilibrium mixture was determined using potentiometric measurement.

Nonlinear phenomena at mercury Hg electrode/room-temperature ionic liquid (RTIL) interfaces: polarographic streaming maxima and current oscillation.

The polarographic streaming maxima and cyclic voltammetric anodic current oscillation (CVACO) at a hanging mercury drop electrode (HMDE) in room-temperature ionic liquid (RTIL) have been studied for the first time using cyclic voltammetric, potential step chronoamperometric and pulse voltammetric techniques. The reversible redox reaction of the 2,1,3-benzothiadiazole (BTD)/BTD*- (an anion radical of BTD) couple with a formal potential (E0') of -1.36 V versus Ag/AgCl/NaCl(saturated) in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) RTIL was typically employed for this purpose.

Eccentric phenomena at liquid mercury electrode/solution interfaces: upward, downward, and circular motions.

The present paper describes a visualization of unidirectional and circular motions triggered by an electrochemical redox reaction at a charged, bent, and streamed liquid electrode/liquid solution interface. The novel circular motion that induces a conversion of electrochemical energy into mechanical energy could be visualized for the first time at a hanging mercury drop electrode (HMDE)/dimethyl sulfoxide (DMSO) solution interface via the electrochromic reaction of 2,1,3-benzothiadiazole (BTD) by using a CCD-color video camera. The observed motions are self-insisting in nature and are tunable into upward, downward, clockwise, and anticlockwise ones by an appropriate choice of the experimental conditions.

Fabrication and electrochemical application of three-dimensional gold nanoparticles: self-assembly.

Multilayers film of nanostructured citrate-stabilized gold particles (AuNPs) has been fabricated based on the layer-by-layer (LBL) technique using a self-assembled monolayer of 1,4-benzenedimethanethiol (BDMT). The formation of AuNPs and BDMT self-assemblies as alternative multilayers was confirmed by transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), and quartz crystal microbalance (QCM). The formation of uniform AuNP layers with an average monolayer thickness of 5-6 nm was obvious in the TEM images.

A carbon fiber microelectrode-based third-generation biosensor for superoxide anion.

Implantable and miniature carbon fiber microelectrode (CFME)-based third-generation biosensor for superoxide anion (O(2)(-)) was fabricated for the first time. The CFME-based biosensor was constructed by electro-deposition of Au nanoparticles on the CFMEs and then modification of the Au nanoparticles by cysteine followed by immobilization of superoxide dismutase (SOD) on the electrodes. The direct electrochemistry of the SOD immobilized on the CFME-based electrodes was efficiently realized by electron transfer promoter - cysteine molecules confined on the Au nanoparticles deposited on the CFMEs.

Electrochemistry and electrocatalytic activities of superoxide dismutases at gold electrodes modified with a self-assembled monolayer.

In this article, the electrochemical properties and electrocatalytic activity of three kinds of superoxide dismutases (SODs), that is, bovine erythrocyte copper-zinc superoxide dismutase (Cu/Zn-SOD), iron superoxide dismutase from Escherichia coli (Fe-SOD), and manganese superoxide dismutase from E. coli (Mn-SOD), in the SOD family were studied. It was revealed that the direct electron transfer of the three kinds of SODs could be efficiently promoted by a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA) confined on a gold electrode.

Simultaneous electroanalysis of dopamine and ascorbic acid using poly (N,N-dimethylaniline)-modified electrodes.

Glassy carbon (GC) electrode is modified with an electropolymerized film of N,N-dimethylaniline (DMA). This polymer (PDMA) film-coated GC electrode is used to electrochemically detect dopamine (DA) in the presence of ascorbic acid (AA). Polymer film has the positive charge in its backbone, and in neutral solution DA exists as the positively charged species whereas AA exists as the negatively charged one.

Chemiluminescence of lucigenin by electrogenerated superoxide ions in aqueous solutions.

The chemiluminescence reaction of lucigenin (Luc(2+)c2NO(3) (-), N,N'-dimethyl-9,9'-biacridinium dinitrate) at gold electrodes in dioxygen-saturated alkaline aqueous solutions (pH 10) was investigated in detail by the use of electrochemical emission spectroscopy. We noted that both O(2) and Luc(2+) are reduced on a gold electrode in aqueous solution of pH 10 in almost the same potential region. From this fact, we expected chemiluminescence based on a radical-radical coupling reaction of superoxide ion (O(2).

A superoxide dismutase-modified electrode that detects superoxide ion.

A superoxide dismutase (SOD)-modified electrode, in which SOD is oriented on the gold electrode via a self-assembled monolayer of cysteine so as to allow its direct electrode reaction, possesses a bi-directional electrocatalysis for both the oxidation of superoxide ion (O2-) to O2 and the reduction of O2- to H2O2 and functions as a third generation O2- biosensor.

Superoxide dismutase-based third-generation biosensor for superoxide anion.

A third-generation biosensor for superoxide anion (O2-) was developed by immobilizing superoxide dismutase (SOD) on a self-assembled monolayer of cysteine on gold electrode; i.e., a SOD/cysteine-modified gold electrode (SOD/Cys/Au) was fabricated.