共查询到20条相似文献,搜索用时 15 毫秒
1.
Shaolin Mu 《Electrochemistry communications》2009,11(7):1519-1522
It was found that the copolymer poly(aniline-co-o-aminophenol) (PANOA) can strongly catalyze the reduction of arsenate in a NaCl solution, which was proved by cyclic voltammetry and the determination of activation energy. On the basis of the electrocatalytic reduction of arsenate, the PANOA copolymer was used as a probe to determine directly arsenate. The electrocatalytic activity of the PANOA electrode toward As(V) reduction strongly depended on the pH and the applied potential. Under the optimal conditions, the PANOA electrode can be used to determine directly As(V) concentration in a wide linear range (n = 19) of 0.949 and 495 μM with a correlation coefficient of 0.995 and a limit of detection of 0.495 μM. The sensitivity of the electrode was 0.192 μA μM?1 cm?2. The PANOA electrode had the good storage stability and a less negative operation potential of ?0.15 V (vs. SCE). 相似文献
2.
Xiaopei Miao Lu Liu Shukuan Wang Hong Lin Baoyun Sun Jingbo Hu Meixian Li 《Electrochemistry communications》2010,12(1):90-93
A new ferrocenecarboxylic acid–C60 composite (Fc–C60) has been synthesized by controlled potential electrolysis. A composite modified glassy carbon electrode has been prepared based on its good electrochemical activity. The modified electrode in 0.1 M NaClO4 solution shows a reversible oxidation wave at E1/2 = 0.32 V (vs. SCE) attributed to the oxidation of the ferrocene entity and a quasi-reversible reduction wave of C60 entity at E1/2 = ?0.54 V (vs. SCE). Electrocatalytic studies show that Fc–C60 at the modified electrode can mediate the reduction of hydrogen peroxide (H2O2), and a broad linear range from 1.2 μM to 21.9 mM for H2O2 were obtained with a determination limit of 2.5 × 10?7 M by amperometry. 相似文献
3.
Catalytic activity of a polycrystalline gold electrode toward oxygen reduction reaction (ORR) in aqueous alkaline media in the presence of various alkali-metal sulfates (M2SO4, M = Li, Na, K, Rb and Cs) was investigated by hydrodynamic voltammetry. The fraction of 4e? pathway in low overpotentials (? 0.1 to ? 0.3 V) depended on the alkali-metal cations (Rb ? Na, K, Cs, Li). A complete 4e? reduction of O2 was only attained in the presence of Rb+ cation in the solution, which was comparable or even superior to that reported at the Au(100) single crystal electrode. 相似文献
4.
《Electrochemistry communications》2008,10(2):298-301
Electrochemical oxidation of thermally denatured single-stranded DNA (ssDNA) was studied on a room temperature ionic liquid N-butylpyridinium hexafluorophosphate (BPPF6) modified carbon paste electrode (IL-CPE). A distinct oxidation peak appeared at +0.772 V (vs. SCE) on the IL-CPE after preconcentration of ssDNA at +0.35 V for 160 s in pH 7.0 phosphate buffer solution (PBS), which was attributed to the oxidation of guanine residue on the ssDNA molecular structure. The results showed an apparent negative shift of the oxidation peak potential and a great enhancement of the oxidation peak current on the IL-CPE compared with that of CPE. The electrochemical parameters of ssDNA on the IL-CPE were further calculated. Under the selected conditions, a linear calibration curve for ssDNA detection was obtained in the concentration range from 10.0 to 110.0 μg mL−1 with the detection limit of 1.5 μg mL−1(3σ). 相似文献
5.
Poly-anionic deoxyribonucleic acid (DNA) was accumulated on the positively charged surface of carbon ionic liquid electrode (CILE) with N-butylpyridinium hexafluorophosphate (BPPF6) as binder, and then myoglobin (Mb) was immobilized onto the DNA film by electrostatic interaction to form Mb/DNA/CILE electrode. The direct electrochemistry of Mb was then investigated in detail. A pair of well-defined, quasi-reversible cyclic voltammetric peaks of Mb was obtained with the formal potentials (E0′) at ?0.304 V (vs. SCE) in phosphate buffer solution (PBS, pH 7.0). The Mb/DNA/CILE electrode showed excellent electrocatalytic activity to H2O2 and trichloroacetic acid (TCA) in the range of 1.0–160 μmol/L and 0.5–40.0 mmol/L, respectively. The apparent Michaelis–Menten constants (KM) toward H2O2 and TCA were calculated as 0.42 and 0.82 mmol/L. So, the DNA/CILE had potential to study other proteins. 相似文献
6.
Francisco de Assis dos Santos Silva Cleylton Bezerra Lopes Erivaldo de Oliveira Costa Phabyanno Rodrigues Lima Lauro Tatsuo Kubota Marília Oliveira Fonseca Goulart 《Electrochemistry communications》2010,12(3):450-454
This paper describes, for the first time, the development of a simple and highly sensitive chemical sensor based on a new electroactive material, electrogenerated in situ from xanthurenic acid on an electrode modified with MWCNT. The modified electrode shows efficient electrocatalytic oxidation activity towards NADH at an applied potential of 0.1 V vs. Ag/AgCl. The kinetic constant, kkin, for the electrocatalytic oxidation of NADH, evaluated by chronoamperometry and voltammetry using RDE, provided values close to 105 mol?1 L s?1. 相似文献
7.
《Electrochemistry communications》2007,9(8):2027-2031
We characterized the electrocatalytic activity of platinum electrode modified by underpotential deposited lead (PtPbupd) for a formic acid (HCOOH) oxidation and investigated the influence on the power performance of direct formic acid fuel cells (DFAFC). Based on the electrochemical analysis using cyclic voltammetry and chronoamperometry, PtPbupd electrode modified by underpotential deposition (UPD) exhibited significantly enhanced catalytic activity for HCOOH oxidation below anodic overpotential of 0.4 V (vs. SCE). Multi-layered PtPbupd electrode structure of Pt/Pbupd/Pt resulted in more stable and enhanced performance using 50% reduced loading of anode catalyst. The performance of multi-layered PtPbupd anode is about 120 mW/cm2 at 0.4 V and it also showed a sustainable cell activity of 0.52 V at an application of constant current loading of 110 mA/cm2. 相似文献
8.
We report the preparation and electrochemical properties of Na3V(PO3)3N made by ammonolysis. Na3V(PO3)3N is reversibly oxidized to Na2V(PO3)3N at high voltage (4.0 V vs. Na+/Na0 and 4.1 V vs. Li+/Li0) with an unusually small difference in the insertion/extraction voltage between both alkali metal reference electrodes. In both cases, the voltage hysteresis is extremely small (~ 0.035 V vs. sodium and ~ 0.065 V vs. lithium), which suggests facile migration of alkali cations within the structure. Further oxidation to NaV(PO3)3N is predicted to occur beyond the voltage stability window of the electrolytes. 相似文献
9.
In this communication, a hydrogen peroxide (H2O2) sensor based on self-assembled Prussian Blue (PB) modified electrode was reported. Thin film of PB was deposited on the electrode by self-assembly process including multiple sequential adsorption of ferric ions and hexacyanoferrate ions. The as-prepared PB modified electrode displayed sufficient stability for practical sensing application. At an applied potential of ?0.05 V vs. Ag/AgCl (sat. KCl), PB modified electrode with 30 layers exhibited a linear dependence on H2O2 concentration in the range of 1 × 10?6–4 × 10?4 M (r = 0.9998) with a sensitivity of 625 mA M?1 cm?2. It was found that the sensitivity of H2O2 sensors could be well controlled by adjusting the number of deposition cycles for PB preparation. This work demonstrates the feasibility of self-assembled PB modified electrode in sensing application, and provides an effective approach to control the sensitivity of PB-based amperometric biosensors. 相似文献
10.
Farhana S. Saleh Mohammad R. Rahman Takeyoshi Okajima Lanqun Mao Takeo Ohsaka 《Bioelectrochemistry (Amsterdam, Netherlands)》2011,80(2):121-127
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 ? 0.365 ± 0.002 V vs. SHE at pH 7.0. As for the bare carbon electrodes, the oxidation of NADH at the BPPG electrode was found to be enhanced compared with the GC electrode. For the PPS-modified electrodes, it was found that the electrocatalysis of PPS-modified electrodes for the oxidation of NADH largely depends on the carbon substrate and electrolyte solution employed for their preparation, i.e., the PPS-modified BPPG electrode prepared in 0.2 M NaClO4/acetonitrile solution exhibits an excellent and persistent electrocatalytic property toward NADH oxidation in phosphate buffer solution (pH 7.0) with a diminution of the overpotential of about 740 and 670 mV compared with those at the bare GC electrode and the PPS-modified GC electrode prepared in 0.2 M H2SO4 solution, respectively. A quantitative analysis of the electrocatalytic reaction based on rotating disk voltammetry gave the electrocatalytic reaction rate constants of the order of 103–104 M?1 s? 1 depending on the preparation conditions of the PPS-modified electrodes. 相似文献
11.
Jacques Simonet 《Electrochemistry communications》2010,12(11):1475-1478
Smooth gold is easily palladized by means of very thin galvanostatic deposits of Pd0. Such chemically modified materials are mainly tested in acetonitrile in the presence of tetraalkylammonium salts (TBABF4). All exhibit large usable electrochemical windows: between ? 1.8 V and + 1.5 V vs. saturated calomel electrode (SCE). When employed as cathodic material, they show exceptional catalytic capabilities especially for achieving the one-electron cleavage of organic halides (RX). Thus, these modified surfaces, found to be chemically and electrochemically stable, lead to amazing potential shifts compared to those obtained with glassy carbon, smooth platinum, or gold cathodes under the same experimental conditions. Specifically, these palladium-doped gold interfaces were preliminarily used for the reduction of alkyl iodides RIs. The presence of gold is expected to boost up the catalytic effect of palladium already reported with such compounds. 相似文献
12.
A composite electrode of Ni-ferrite/TiOx/Si(111) was synthesized by grafting Ni2+Fe2+Fe3+–LDH–TiCl3 (LDH: Layered Double Hydroxides) on n-Si(111) surface and calcined under 1100 °C. Photoelectric research results indicated that the electrode had good photovoltaic effects in an electrolyte solution containing 7.6 M HI and 0.05 M I2, while platinum plate was used as counter-electrode. The observed photo-voltages (Upv) and photocurrent densities (jpc) of the electrode were at ?0.75 V and 5.35 mA/cm2, respectively. Compared with electrodes of oxidized n-Si(111) crystal and n-Si(111) wafer covered by Ni-ferrites, jpc of the electrode Ni-ferrite/TiOx/Si(111) was increased greatly. 相似文献
13.
A flow electrochemical sensor for trace analysis of lead, using TETRAM-modified graphite felt electrode is reported here. TETRAM ligands are covalently immobilized on the graphite felt by chemical reactions on amino acid linkers, previously attached to the electrode by an electrochemical process. The detection is performed in two steps: the preconcentration of Pb2+ ions by complexation with immobilized TETRAM and the analysis by linear sweep stripping voltammetry. A calibration curve typical of at least two equilibrium processes is obtained. A limit of detection of 2.5 × 10?8 mol L?1 is reached for a total analysis time of 35 min. Interestingly, the flow sensor shows a good selectivity toward lead in presence of Cu2+, Cd2+, Ni2+, Zn2+ and Co2+ ions. This new sensor exhibits improved sensitivity and selectivity compared to the previously reported sensor using cyclam-modified electrode. It is stable after three uses, using strong acidic medium for the regeneration step. 相似文献
14.
Square-wave adsorptive stripping voltammetry technique was used to determine rosiglitazone (ROS) on the hanging mercury dropping electrode (HMDE) surface, in Britton Robinson buffer, pH = 5. The voltammetric cathodic peak was observed at ?1520 mV vs. Ag/AgCl reference electrode. The voltammetric peak response was characterized with respect to pH, supporting electrolyte, accumulation potential, preconcentration time, scan rate, frequency, pulse amplitude, surface area of the working electrode and the convection rate. Under optimal conditions, the voltammetric current is proportional to the concentration of ROS over the concentration range of 5 × 10?8–8 × 10?7 mol l?1 (r = 0.9899) with a detection limit of 3.2 × 10?11 mol l?1 using 120 s accumulation time. The developed SW-AdSV procedure showed a good reproducibility, the relative standard deviation RSD% (n = 10) at a concentration level of 5 × 10?7 mol l?1 was 0.33%, whereas the accuracy was 101% ± 1.0. The proposed method was successfully applied to assay the drug in the human urine and plasma samples with mean recoveries of 90 ± 0.71% and 86 ± 1.0%, respectively. 相似文献
15.
Visible light active hydrogen modified n-type titanium oxide (HM-n-TiO2) thin films were synthesized by thermal oxidation of Ti metal sheet (Alfa Co. 0.25 mm thick) in an electric oven followed by incorporation of hydrogen electrochemically under cathodic polarization at ?1.6 V vs Pt. The photoresponse of the HM-n-TiO2 was evaluated by measuring the rate of water splitting reaction to hydrogen and oxygen in terms of photocurrent density, Jp. The optimized electric oven-made n-TiO2 and HM-n-TiO2 photoelectrodes showed photocurrent densities of 0.2 mA cm?2 and 1.60 mA cm?2, respectively, at a measured potential of ?0.4 V vs Pt at illumination intensity of 100 mW cm?2 from a 150 W xenon lamp. This indicated an eightfold increase in photocurrent density for HM-n-TiO2 compared to oven-made n-TiO2 at the same measured electrode potential. The band-gap energy of HM-n-TiO2 was found to be 2.7 eV compared to 2.82 eV for electric oven-made n-TiO2 and a mid-gap band at 1.67 eV above the valence band was also observed. The HM-n-TiO2 thin film photoelectrodes were characterized using photocurrent density under monochromatic light illumination and UV–Vis spectral measurements. 相似文献
16.
Daniel A. Lutterman Laurie A. Lazinski-Melanson Yogen Asher Dean H. Johnston Judith C. Gallucci Claudia Turro 《Journal of photochemistry and photobiology. A, Chemistry》2011,217(1):100-107
Two new Ru(II) complexes, [Ru(bpy)2(1-COO-iqu)]+ (2; bpy = 2,2′-bipyridine, 1-COO-iqu? = isoquinoline-1-carboxylate) and [Ru(bpy)2(3-COO-iqu)]+ (3; 3-COO-iqu? = isoquinoline-3-carboxylate), were prepared and their crystal structures solved. The ground and excited state properties of 2 and 3 were characterized and compared to those of [Ru(bpy)3]2+ (1). The presence of the oxygen atom in the Ru(II) coordination sphere makes 2 and 3 easier to oxidize than 1. The Ru → bpy MLCT absorption and emission of 2 and 3 are red-shifted relative to that of 1 in CH2Cl2, and the E00 energies were estimated to be 1.89 eV and 1.95 eV from the low temperature emission of 2 and 3, resulting in excited state oxidation potentials of ?1.03 V and ?1.10 V vs SCE, respectively. In addition to the short-lived emissive 3MLCT state, a long-lived species is observed in the transient absorption of 3 in DMSO (τ = 49 μs) and pyridine (τ = 44 μs), assigned to a solvent-coordinated complex. This intermediate is not observed for 3 in non-polar solvents or for 2. The absence of the solvent coordinated intermediate in 2 is explained by the stronger Ru–O bond afforded by the lower conjugation in that extends onto the carboxylic acid in the 1-COO-iquo?ligand, compared to that in the 3-COO-iqu?ligand in 3. Transient absorption experiments also show that the 3MLCT excited state of 3 is able to reduce methyl viologen. 相似文献
17.
PbO2 thin films were prepared by pulse current technique on Ti substrate from Pb(NO3)2 plating solution. The hybrid supercapacitor was designed with PbO2 thin film as positive electrode and activated carbon (AC) as negative electrode in the 5.3 M H2SO4 solution. Its electrochemical properties were determined by cyclic voltammetry (CV), charge–discharge test and electrochemical impedance spectroscopy (EIS). The results revealed that the PbO2/AC hybrid supercapacitor exhibited large specific capacitance, high-power and stable cycle performance. In the potential range of 0.8–1.8 V, the hybrid supercapacitor can deliver a specific capacitance of 71.5 F g?1 at a discharge current density of 200 mA g?1(4 mA cm?2) when the mass ratio of AC to PbO2 was three, and after 4500 deep cycles, the specific capacitance remains at 64.4 F g?1, or 32.2 Wh Kg?1 in specific energy, and the capacity only fades 10% from its initial value. 相似文献
18.
《Electrochemistry communications》2007,9(5):1159-1164
A room temperature ionic liquid (RTIL) modified carbon paste electrode was constructed based on the substitute of paraffin with 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) as binder for carbon paste. Direct electrochemistry and electrocatalytic behaviors of hemoglobin (Hb) entrapped in the sodium alginate (SA) hydrogel film on the surface of this carbon ionic liquid electrode (CILE) were investigated. The presence of IL in the CILE increased the electron transfer rate and provided a biocompatible interface. Hb remained its bioactivity on the surface of CILE and the SA/Hb modified electrode showed a pair of well-defined, quasi-reversible cyclic voltammetric peaks with the apparent standard potential (E0′) at about −0.344 V (vs. SCE) in pH 7.0 Britton–Robinson (B–R) buffer solution, which was attributed to the Hb Fe(III)/Fe(II) redox couple. UV–Vis absorption spectra indicated that heme microenvironment of Hb in SA film was similar to its native status. Hb showed a thin-layer electrochemical behavior in the SA film with the direct electron transfer achieved on CILE without the help of electron mediator. Electrochemical investigation indicated that Hb took place one proton with one electron electrode process and the average surface coverage of Hb in the SA film was 3.2 × 10−10 mol/cm2. The immobilized Hb showed excellent electrocatalytic responses to the reduction of H2O2 and nitrite. 相似文献
19.
《Electrochemistry communications》2001,3(2):102-106
The deposition and dissolution of palladium(0) at non-modified carbon paste electrode (CPE) is studied in aqueous chloride solution. During the dissolution one or two Pd oxidation peaks are observed at + 0.1 V and about + 0.45 V vs. SCE, indicating the existence of different states of Pd0 at the CPE. In accordance with the experimental results it is assumed that a palladium monolayer is formed when low amounts of Pd are deposited and that multilayers are formed in the case of larger amounts of deposited palladium. The formation of a metal monolayers at CPE is described for the first time. 相似文献
20.
Ajay Kumar Yagati Taek Lee Junhong Min Jeong-Woo Choi 《Bioelectrochemistry (Amsterdam, Netherlands)》2011,80(2):169-174
A protein-based electrochemical sensor for hydrogen peroxide (H2O2) was developed by an easy and effective film fabrication method where spinach ferredoxin (Fdx) containing [2Fe–2S] metal center was cross linked with 11-mercaptoundecanoic acid (MUA) on a gold (Au) surface. The surface morphology of Fdx molecules on Au electrodes was investigated by atomic force microscopy (AFM). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to study the electrochemical behavior of adsorbed Fdx on Au. The interfacial properties of the modified electrode were evaluated in the presence of Fe(CN)63?/4? redox couple as a probe. From CV, a pair of well-defined and quasi-reversible redox peaks of Fdx was obtained in 10 mM, pH 7.0 Tris–HCl buffer solution at ?170 and ?120 mV respectively. One electron reduction of the [2Fe-2S]2+ cluster occurs at one of the iron atoms to give the reduced [2Fe-2S]+. The formal reduction potential of Fdx ca. ?150 mV (vs. Ag/AgCl electrode) at pH 7.0. The electron-transfer rate constant, ks, for electron transfer between the Au electrode and Fdx was estimated to be 0.12 s?1. From the electrochemical experiments, it is observed that Fdx/MUA/Au promoted direct electron transfer between Fdx and electrode and it catalyzes the reduction of H2O2. The Fdx/MUA/Au electrode displays a linear increase in amperometric current for increasing concentration of H2O2.The sensor calibration plot was linear with r2 = 0.998 with sensitivity approximately 68.24 μAm M?1 cm?2. Further, the effect of nitrite on the developed sensor was examined which does not interfere with the detection of H2O2. Finally, the addition of H2O2 on MUA/Au electrode was observed which has no effect on amperometric current. 相似文献