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1.
Gold (Au) films with open interconnected macroporous walls and nanoparticles have been successfully sculptured using the hydrogen bubble dynamic template synthesis followed by a galvanic replacement reaction. Copper (Cu) films with open interconnected macroporous walls and nanoparticles were synthesized using the electrochemically generated hydrogen bubbles as a dynamic template. Then through a galvanic replacement reaction between the porous Cu sacrificial templates and KAu(CN)2 in solution, the porous Cu films were converted to porous Au films with the similar morphologies. Additional electrochemical dealloying process was introduced to remove the remaining Cu from the porous Au films. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), X-ray diffraction (XRD) and electrochemical methods were adopted to characterize the porous Au films. The resulted porous Au films show excellent catalytic activity toward the electrooxidation of glucose. A nonenzymatic glucose sensor based on those Au film electrodes shows a linear range from 2 to 10 mM with a sensitivity of 11.8 μA cm−2 mM−1, and a detection limit of 5 μM.  相似文献   

2.
《Comptes Rendus Chimie》2015,18(4):438-448
A highly sensitive method was investigated for the simultaneous determination of acetaminophen (AC), dopamine (DA), and ascorbic acid (AA) using a PbS nanoparticles Schiff base-modified carbon paste electrode (PSNSB/CPE). Differential pulse voltammetry peak currents of AC, DA and AA increased linearly with their concentrations within the ranges of 3.30 × 10−8–1.58 × 10−4 M, 5.0 × 10−8–1.2 × 10−4 M and 2.50 × 10−6–1.05 × 10−3 M, respectively, and the detection limits for AC, DA and AA were 5.36 × 10−9, 2.45 × 10−9 and 1.86 × 10−8 M, respectively. The peak potentials recorded in a phosphate buffer solution (PBS) of pH 4.6 were 0.672, 0.390, and 0.168 V (vs Ag/AgCl) for AC, DA and AA, respectively. The modified electrode was used for the determination of AC, DA, and AA simultaneously in real and synthetic samples.  相似文献   

3.
MnO2 nanowires were electrodeposited onto carbon nanotube (CNT) paper by a cyclic voltammetric technique. The as-prepared MnO2 nanowire/CNT composite paper (MNCCP) can be used as a flexible electrode for electrochemical supercapacitors. Electrochemical measurements showed that the MNCCP electrode displayed specific capacitances as high as 167.5 F g−1 at a current density of 77 mA g−1. After 3000 cycles, the composite paper can retain more than 88% of initial capacitance, showing good cyclability. The CNT paper in the composite acted as a good conductive and active substrate for flexible electrodes in supercapacitors, and the nanowire structure of the MnO2 could facilitate the contact of the electrolyte with the active materials, and thus increase the capacitance.  相似文献   

4.
This work reports on a novel chitosan–hematite nanotubes composite film on a gold foil by a simple one-step electrodeposition method. The hybrid chitosan–hematite nanotubes (Chi–HeNTs) film exhibits strong electrocatalytic reduction activity for H2O2. Interestingly, two electrocatalytic reduction peaks are observed at −0.24 and −0.56 V (vs SCE), respectively, one controlled by surface wave and the other controlled by diffusion process. The Chi–HeNTs/Au electrode shows a linear response to H2O2 concentration ranging from 1 × 10−6 to 1.6 × 10−5 mol L−1 with a detection limit of 5 × 10−8 mol L−1 and a sensitivity as high as 1859 μA μM−1 cm−2.  相似文献   

5.
In this study, new xanthine biosensors, XO/Au/PVF/Pt and XO/Pt/PVF/Pt, based on electroless deposition of gold(Au) and platinum(Pt) nanoparticles on polyvinylferrocene(PVF) coated Pt electrode for detection of xanthine were presented. The amperometric responses of the enzyme electrodes were measured at the constant potential, which was due to the electrooxidation of enzymatically produced H2O2. Compared with XO/PVF/Pt electrode, XO/Au/PVF/Pt and XO/Pt/PVF/Pt exhibited excellent electrocatalytic activity towards the oxidation of the analyte. Effect of Au and Pt nanoparticles was investigated by monitoring the response currents at the different deposition times and the different concentrations of KAuCl4 and PtBr2. Under the optimal conditions, the calibration curves of XO/Au/PVF/Pt and XO/Pt/PVF/Pt were obtained over the range of 2.5 × 10?3 to 0.56 mM and 2.0 × 10?3 to 0.66 mM, respectively. The detection limits were 7.5 × 10?4 mM for XO/Au/PVF/Pt and 6.0 × 10?4 mM for XO/Pt/PVF/Pt. The effects of interferents, the operational and the storage stabilities of the biosensors and the applicabilities of the proposed biosensors to the drug samples analysis were also evaluated.  相似文献   

6.
Metal-oxygen systems are an attractive option to enhance the specific energy of secondary batteries. However, their power is limited by the oxygen electrode. In this communication we address the issue of the sluggish kinetics of the oxygen cathode in the aprotic Li–O2 batteries. The electrochemical performances of newly designed carbon electrodes coated with 50 Å thick Au layer are evaluated and compared with those of unmodified electrodes. Despite the low noble metal content (~ 2 wt.%), the Li–O2 batteries built with the abovementioned Au-coated cathodes show considerably enhanced kinetics as demonstrated by the higher onset potentials for the oxygen reduction reaction (~ 2.6 V at a current rate of 1000 mA g 1), together with reduced oxygen evolution potentials.  相似文献   

7.
Novel nano-structured Pd+yttrium doped ZrO2 (YSZ) electrodes have been developed as cathodes of intermediate temperature solid oxide fuel cells (IT-SOFCs). Nano-sized Pd particles were introduced into the rigid and porous YSZ structure by PdCl2 solution impregnation. The results show that Pd nanoparticles (20–80 nm) were uniformly distributed in the porous YSZ structure; and such nano-structured composite cathodes were highly active for the O2 reduction reaction, with polarization resistances (RE) of 0.11 and 0.22 Ω cm2 at 750 and 700 °C and activation energy of 105 kJ mol−1 that is significantly lower than those for the conventional perovskite-based cathodes (130–201 kJ mol−1).  相似文献   

8.
Nano-sized insoluble iron, cobalt and nickel hexacyanoferrates (Mhcf) were prepared by a simple co-precipitation method. The potential of using these materials for supercapacitor was examined by cyclic voltammogram and constant charge/discharge. Due to the different types of the second metal (M), the Mhcf electrodes showed different electrochemical capacitive performances. The specific discharge capacitances of Fehcf, Nihcf and Cohcf electrodes at the current density of 0.2 A g−1 were 425 F g−1, 574.7 F g−1 and 261.56 F g−1, respectively. Meanwhile, the Mhcf electrodes showed good cyclic performance.  相似文献   

9.
A simple electrochemical method for the determination of association constants between carbohydrates and carbohydrate-binding proteins using cyclic voltammetry (CV) is described. The binding of concanavalin A (Con A) and cholera toxin (CT) to their specific α-mannose and β-galactose derivatives self-assembled on gold electrodes is electrochemically monitored with a redox probe of K3Fe(CN)6/K4Fe(CN)6. Upon binding of the proteins to the carbohydrate-modified electrodes, the redox current in CV decreases. The binding-induced change in electrochemical signal is thus used to construct Langmuir adsorption isotherm for the carbohydrate–protein interactions and to obtain the association constants. The association constants of carbohydrate–protein interactions determined by CV ((5.8 ± 1.2) × 107 M 1 for mannose–Con A, (2.6 ± 0.5) × 108 M 1 for galactose-CT) were in good agreement with those measured with electrochemical impedance spectroscopy and quartz crystal microbalance.  相似文献   

10.
《Vibrational Spectroscopy》2010,52(2):283-288
The far-infrared and Raman spectra of binuclear molecules [Me2AuX]2 (X = Cl, Br, I) and [Me2Au(OOCR)]2 (R = Me, CF3, But, Ph) in the 600–70 cm−1 region are reported. The experimentally measured vibrational frequencies of [Me2AuX]2 are in a good agreement with density functional theory predictions. The Au…Au vibrational interactions predicted to be in the 270–60 cm−1 region of [Me2AuX]2 far-IR and Raman spectra have been observed. The Raman-active Au…Au vibrations of the [Me2Au(OOCR)]2 molecules were found to be in the same region as those of [Me2AuX]2. The Au–X stretching modes were observed between 100 and 250 cm−1 in accordance with the DFT predictions. Their frequencies in the IR spectra of [Me2AuX]2 increase in the sequence I < Br < Cl while the AuC2 stretching frequencies decrease in the same order. This fact might be an evidence of the decreasing covalent character of the gold-halogen bridges. The Au–O stretching bands of dimethylgold(III) carboxylates have been observed in the 500–250 cm−1 region, and Au–C stretching frequencies of both [Me2AuX]2 and [Me2Au(OOCR)]2 compounds have been found between 600 and 500 cm−1.  相似文献   

11.
In this study, Nb2O5 nanobelts, with a ca. ∼15 nm in thickness, ca. ∼60 nm in width and several tens of mircrometers in length, have first been used as the electrode material for lithium intercalation over the potential window of 3.0–1.2 V (vs. Li+/Li). It delivers an initial intercalation capacity of 250 mA hg−1 at 0.1 Ag−1 current density, corresponding to x = 2.5 for LxNb2O5, and can still keep relative stable and reaches as large as 180 mA hg−1 after 50 cycles. Surprisingly, the electrodes composed of Nb2O5 nanobelts can work smoothly even at high current density of 10 Ag−1, and shows higher specific capacity and excellent cycling stable, as well as sloped feature in voltage profile. Cycling test indicates Nb2O5 nanobelts electrode shows a high reversible charge/discharge capacity, high rate capability with excellent cycling stability.  相似文献   

12.
We have obtained spinel-type Co3O4 and La-doped Co3O4 in the form of thin film on Ni, using microwave-assisted synthesis, which dramatically exhibit very low overpotentials for the oxygen evolution reaction (OER). Investigations have shown that at the apparent current density of 100 mA cm−2 in 1 mol dm−3 KOH at 25 °C, the new electrodes, Co3O4 (oxide loading = 3.4 ± 0.3 mg cm−2) and La-doped Co3O4 (oxide loading = 2.8 ± 0.4 mg cm−2), produce overpotentials, 235 ± 7 and 224 ± 8 mV, respectively. Such low overpotentials for the OER, to our knowledge, have not been found on any mixed oxide electrode material reported in literature till today. Small La addition improved the BET surface area and porosity of the oxide catalyst powder and reduced the charge transfer resistance for the OER on the electrode made of oxide powder.  相似文献   

13.
The determination of cysteine by means of square wave cathodic stripping voltammetry (SWCSV) is reported here for the first time at Bi-modified carbon paste electrodes (CPEs). The modified electrodes are 17% w/w metallic Bi powder mixed with CP (Bi-CPEs) and the technique is based on the enhancement of Bi surface oxidation in the presence of cysteine at a carefully chosen accumulation potential and the subsequent reduction-stripping of the product (proposed to be bismuth(III) cysteinate) by potential scanning to more negative values. The wide concentration range of 1 × 10−6–5 × 10−5 M for cysteine can be assessed by SWCSV using Bi-CPEs and, by appropriate choice of accumulation times, two linear response concentration regimes could be identified: 1 × 10−6–1 × 10−5 M (accumulation for 600 s) and 1 × 10−5–5 × 10−5 M (accumulation for 100 s), with estimated detection limits of 3 × 10−7 and 2 × 10−6 M, respectively.  相似文献   

14.
Vanadium dioxide (VO2) nano-sheets were directly synthesized via a continuous hydrothermal process and were investigated as electrodes in a wide potential range of 0.05–3 V vs. Li/Li+. The nano-sheets showed excellent capacity retention, with a specific capacity of 350 mAh g 1 at an applied current of 0.1 A g 1 and 95 mAh g 1 at 10 A g 1. Further electrochemical testing suggested that a significant proportion of the charge storage in the cells was due to pseudocapacitive processes.  相似文献   

15.
A novel photoelectrochemical (PEC) sensor for mercury ions (Hg2 +) was fabricated based on the energy transfer (ET) between CdS quantum dots (QDs) and Au nanoparticles (NPs) with the formation of T–Hg2 +–T pairs. In the presence of Hg2 + ions, a T-rich single-strand (ss) DNA labeled with Au NPs could hybridize with another T-rich ssDNA anchored on the CdS QDs modified electrode, through T–Hg2 +–T interactions, rendering the Au NPs in close proximity with the CdS QDs and hence the photocurrent decrease due to the ET between the CdS QDs and the Au NPs. Under the optimal condition, the photocurrent decrease was proportional to the Hg2 + concentration, ranging from 3.0 × 10 9 to 1.0 × 10 7 M, with the detection limit of 6.0 × 10 10 M.  相似文献   

16.
This work introduces an effective, inexpensive, and large-scale production approach to the synthesis of Fe2O3 nanoparticles with a favorable configuration that 5 nm iron oxide domains in diameter assembled into a mesoporous network. The phase structure, morphology, and pore nature were characterized systematically. When used as anode materials for lithium-ion batteries, the mesoporous Fe2O3 nanoparticles exhibit excellent cycling performance (1009 mA h g 1 at 100 mA g 1 up to 230 cycles) and rate capability (reversible charging capacity of 420 mA h g 1 at 1000 mA g 1 during 230 cycles). This research suggests that the mesoporous Fe2O3 nanoparticles could be suitable as a high rate performance anode material for lithium-ion batteries.  相似文献   

17.
The thermodynamic properties, including activity coefficients, osmotic coefficients and excess Gibbs free energy for RbCl and Rb2SO4 aqueous mixtures at T=298.15 K and in 0.01 mol · kg−1 to 5 mol · kg−1 ionic strength, were determined by emf measurements. The Rb–ISE and Ag–AgCl electrodes used in this work were prepared in our laboratory and had a reasonably good Nernst response. The experimental data were fitted by using the Harned rule and Pitzer model. The Harned coefficients and the Pitzer binary and ternary interaction parameters for the system have been evaluated. The experimental results obey the Harned rule. The Pitzer model can be used to describe this aqueous system satisfactorily.  相似文献   

18.
Carbon nanofibers embedded with ultrafine zirconia nanoparticles (ZrO2-CNFs) are fabricated via a new methodology. Polyvinylpyrrolidone (PVP) and polymethylmethacrylate (PMMA) binary polymers containing zirconium n-butoxide are first dissolved in dimethylformamide, and the resulting solution is electrospun and heat-treated. The tetragonal zirconia nanoparticles formed, with a size of 5 ± 2 nm in diameter, are uniformly distributed in the carbon nanofibres. Using Nafion as an additive, ZrO2-CNFs are drop-cast onto the glassy carbon electrode (ZrO2-CNF/GCE) and the modified electrode is then applied to detect methyl parathion (MP) using differential pulse voltammetry. Two linear relationships are found at the concentration ranges of 1 × 10 9–2 × 10 8 g/L and 2 × 10 8–2 × 10 7 g/L, with a detection limit of 3.4 × 10 10 g/L (S/N > 3). The electrospun-based ZrO2-CNF is a very promising coating material for electrochemical sensing of organophosphorus compounds.  相似文献   

19.
Nano-sized nickel ferrite (NiFe2O4) was prepared by hydrothermal method at low temperature. The crystalline phase, morphology and specific surface area (BET) of the resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen physical adsorption, respectively. The particle sizes of the resulting NiFe2O4 samples were in the range of 5–15 nm. The electrochemical performance of NiFe2O4 nanoparticles as the anodic material in lithium ion batteries was tested. It was found that the first discharge capacity of the anode made from NiFe2O4 nanoparticles could reach a very high value of 1314 mAh g−1, while the discharge capacity decreased to 790.8 mAh g−1 and 709.0 mAh g−1 at a current density of 0.2 mA cm−2 after 2 and 3 cycles, respectively. The BET surface area is up to 111.4 m2 g−1. The reaction mechanism between lithium and nickel ferrite was also discussed based on the results of cycle voltammetry (CV) experiments.  相似文献   

20.
An interesting mode of reactivity of MnO2 nanoparticles modified electrode in the presence of H2O2 is reported. The MnO2 nanoparticles modified electrodes show a bi-direction electrocatalytic ability toward the reduction/oxidation of H2O2. Based on this property, a choline biosensor was fabricated via a direct and facile electrochemical deposition of a biocomposite that was made of chitosan hydrogel, choline oxidase (ChOx) and MnO2 nanoparticles onto a glassy carbon (GC) electrode. The biocomposite is homogeneous and easily prepared and provides a shelter for the enzyme to retain its bioactivity. The results of square wave voltammetry showed that the electrocatalytic reduction currents increased linearly with the increase of choline chloride concentration in the range of 1.0 × 10−5 –2.1 × 10−3 M and no obvious interference from ascorbic acid and uric acid was observed. Good reproducibility and stability were obtained. A possible reaction mechanism was proposed.  相似文献   

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