共查询到20条相似文献,搜索用时 31 毫秒
1.
Electrocatalytic properties (towards reduction of bromate in 0.5 mol dm −3 H 2SO 4) of multi-walled carbon nanotubes (CNTs) modified with phosphododecamolybdate (PMo 12) monolayers have been diagnosed using cyclic voltammetry and amperometry. The ability of negatively charged PMo 12-modified CNTs to attract electrostatically ultra-thin, positively charged conducting polymer (PEDOT or polypyrrole) structures is explored to grow in controlled manner hybrid organic-inorganic network electrocatalytic films. Due to the presence of three-dimensionally distributed CNTs, the films’ conductivity and porosity are improved. The hybrid systems utilizing polypyrrole, rather than PEDOT, have produced fairly higher bromate electroreduction catalytic currents. Comparison is also made to Nafion-stabilized dispersion of PMo 12-modified CNTs inks. The latter system is characterized by good stability and relatively the highest sensitivities with respect to bromate concentration. 相似文献
2.
On the basis of the formation and pre-concentration of an α-Keggin-type [PMo 12O 40] 3− complex, a novel voltammetric method was developed for the determination of trace levels of P(V). The α-[PMo 12O 40] 3− complex was formed by heating a 5×10 −4 M Mo(VI)-0.2 M HCl-40% (v/v) CH 3CN system containing a trace amount of P(V) at 70 °C for 30 min. During the electrochemical polymerization of pyrrole in the α-[PMo 12O 40] 3− solution, the α-[PMo 12O 40] 3− complex was accumulated into the polypyrrole film on a glassy carbon electrode. The differential pulse voltammetric peak current due to the α-[PMo 12O 40] 3− complex incorporated in the polypyrrole film was linearly dependent on the P(V) concentration in the range of 5×10 −9-5×10 −7 M; a detection limit of 2×10 −9 M was achieved. 相似文献
3.
Organic/inorganic hybrid films of poly(new fuchsin) and phosphomolybdate (PMo 12O ) have been prepared in acidic aqueous solutions. These new combination films are stable, electrochemically active, and can be produced on glassy carbon, platinum, gold, and transparent semiconductor tin oxide electrodes. An electrochemical quartz crystal microbalance along with cyclic voltammetry and UV‐visible absorption spectroscopy were used to study the in situ growth of the hybrid films. The hybrid poly(new fuchsin) and PMo 12O films showed four obvious redox couples, and when transferred to various acidic aqueous solutions, the formal potentials of the four redox couples were found to be pH dependent. The electrocatalytic reduction of ClO , BrO , IO , SO , S 2O , H 2O 2, and NO by the hybrid poly(new fuchsin) and PMo 12O films was achieved in acidic aqueous solutions. In an aqueous solution at pH 1.5, a hybrid poly(new fuchsin) and PMo 12O film showed a higher electrocatalytic reduction activity of IO than BrO or ClO , and the order of electrocatalytic activity was IO >BrO >ClO . The order of electrocatalytic reduction of SO , S 2O , H 2O 2, and NO by hybrid poly(new fuchsin) and PMo 12O films in an aqueous solution at pH 1.5 was NO >H 2O 2>S 2O and SO . The electrocatalytic reactions of the poly(new fuchsin) and PMo 12O films were investigated using the rotating ring‐disk electrode method. 相似文献
4.
Sulfonated graphene nanosheet/gold nanoparticle (SGN/Au) hybrid was synthesized by electrostatic self-assembly of anionic SGN and positively charged gold nanoparticles. Due to the well-dispersivity of SGN in aqueous solution and its adequate negative charge, Au nanoparticles were assembled uniformly on graphene surface with high distribution. With the advantages of both graphene and Au nanoparticles, SGN/Au hybrid showed enhanced electrocatalytic activity towards O 2 reduction. Furthermore, it provided a conductive and favorable microenvironment for the glucose oxidase (GOD) immobilization and thus promoted its direct electron transfer at the glassy carbon electrode. Based on the consumption of O 2 caused by glucose at the interface of GOD electrode modified with SGN/Au hybrid, the modified electrode displayed satisfactory analytical performance, including high sensitivity (14.55 μA mM ?1 cm ?2), low detection limit (0.2 mM), an acceptable linear range from 2 to 16 mM, and also the prevention from the interference of some species. These results indicated that the prepared SGN/Au hybrid is a promising candidate material for high-performance glucose biosensor. 相似文献
5.
The two-electron two-proton redox reaction of the benzoquinone-hydroquinone (Q/QH 2) couple in aqueous solution has been studied by cyclic voltammetry at platinum electrodes coated with polypyrrole benzensulphonate. In contrast to the behaviour on bare platinum, the voltammetric response of the Q/QH 2 couple on polypyrrole is close to the Nernstian behaviour within pH range from 1 to 7. The heterogeneous rate constant ks determined from the peak separations is in the range of 10 −3 cm s −1. It is independent of the film thickness in a wide range and slightly pH-dependent, with a minimum at pH 4. Compared with related results based on polypyrrole perchlorate-coated gold electrodes, less aging of the catalytic efficiency is observed. Higher peak currents with increasing polypyrrole coverage suggest partial diffusion of the substrate into the bulk of the film. Preliminary studies on more complex quinones, ubiquinone-1, plastoquinone-1 and the bis-quinone of dibenzo [18] crown-6 demonstrate similar catalytic effects of polypyrrole layers. Potential applications of polypyrrole-coated electrodes in organic electrochemistry and bioelectroanalytical chemistry are discussed. 相似文献
6.
Stable electroactive iron tetra( o-aminophenyl)porphyrin (FeTAPP) films are prepared by electropolymerization from aqueous solution by cycling the electrode
potential between −0.4 and 1.0 V vs Ag/AgCl at 0.1 V s −1. The cyclic voltammetric response indicates that polymerization takes place after the oxidation of amino groups, and the
films could be produced on glassy carbon (GC) and gold electrodes. The film growth of poly(FeTAPP) was monitored by using
cyclic voltammetry and electrochemical quartz crystal microbalance. The cyclic voltammetric features of Fe(III)/Fe(II) redox
couple in the film resembles that of surface confined redox species. The electrochemical response of the modified electrode
was found to be dependent on the pH of the contacting solution with a negative shift of 57 mV/pH. The electrocatalytic behavior
of poly(FeTAPP) film-modified electrode was investigated towards reduction of hydrogen peroxide, molecular oxygen, and chloroacetic
acids (mono-, di-, and tri-). The reduction of hydrogen peroxide, molecular oxygen, and dichloroacetic acid occurred at less
negative potential on poly(FeTAPP) film compared to bare GC electrode. Particularly, the overpotential of hydrogen peroxide
was reduced substantially. The O 2 reduction proceeds through direct four-electron reduction mechanism. 相似文献
7.
Electrochemically active hybrid coatings based on cationic films, didodecyldimethylammonium bromide (DDDMAB), and poly(diallyldimethylammonium chloride) (PDADMAC) are prepared on glassy carbon electrode surface by cycling the film‐covered electrode repetitively in a pH 7 solution containing flavin adenine dinucleotide (FAD), and anionic hexacyanometalate (HCM) complexes, Fe(CN) 63? and Ru(CN) 64?. Cyclic voltammetric features of hybrid coatings resemble that of electron transfer process of surface‐confined redox species. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the deposition of FAD on DDDMAB film. Cyclic voltammetric peak potentials of modified electrode were found to be shifted to more negative region with increasing pH of contacting solution with a slope value of 63.3mV per pH unit. The electrocatalytic behavior of FAD‐modified DDDMAB‐coated GCE and hybrid film electrodes was tested towards reduction of oxygen, S 2O 82?, SO 52? and oxidation of SO 32?. The application of FAD‐modified DDDMAB‐coated GCE for S 2O 82? estimation was demonstrated in amperometric mode. The sensitivity and detection limit ( S/ N=3) were 267.6 μA mM ?1 and 2×10 ?6 M, respectively. 相似文献
8.
A hybrid organic-inorganic material composed of poly (3,4-ethylenedioxythiophene), PEDOT, derivatized with 4-(pyrrol-e1-yl) benzoic acid, PyBA, and Keggin-type copper (II)-salt of H3PMo12O40 has been proposed here. Such features as good electronic conductivity of PEDOT, hydrophilic and coordination capabilities of PyBA, the ability of copper (II) ions to link PyBA carboxylic groups, and phosphomolybdate anionic sites, as well as high protonic and mixed-valence conductivities of H3PMo12O40 have been explored here to produce a stable composite material charcterized by reasonable charge propagation dynamics. Characterization and formation of the hybrid ca. 0.6 μm thick PEDOT/PyBA-CuxHyPMo12O40 films have been asessed by FTIR, XRD, AFM, SEM, as well as using electrochemical methods. Among important feautures of the proposed hybrid system is the ability to undergo reversible charging/discharhging (both under voltammetric and galvanostatic conditions) in a manner analogous to what is observed in battery-type cells. Typical parameters, such as specific capacity, energy, and power densities, are provided and discussed. 相似文献
9.
Using the layer-by-layer technique, carbon submicroparticles, that have been modified and stabilized with monolayers of Keggin-type
phosphododecamolybdate (PMo 12O 403−), can be dispersed in multilayer films of organic polymers, poly(3,4-ethylenedioxythiophene), i.e., PEDOT, or poly(diallyldimethylammonium)
chloride, i.e., PDDA, deposited on glassy carbon or indium-tin oxide conductive glass electrodes. The approach involves alternate
treatments in the colloidal suspension of PMo 12O 403−-covered carbon submicroparticles in the solution of monomer, 3,4-ethylenedioxythiophene or in solution of PDDA polymer. Electrostatic
attractive interactions between anionic phosphomolybdate-modified carbon submicroparticles and cationic polymer layers permit
not only uniform and controlled growth of the hybrid organic–inorganic film but also contribute to its overall stability.
The system composed of PMo 12O 403−-covered carbon submicroparticles dispersed in PEDOT is characterized by fast dynamics of charge transport and has been used
to construct symmetric microelectrochemical redox capacitor. The PDDA-based system has occurred to be attractive for electrocatalytic
reduction of hydrogen peroxide. 相似文献
10.
The Lewis acid catalyzed self-condensation of hybrid diheterole (furan-pyrrole and thiophene-pyrrole) precursors has afforded novel Hückel antiaromatic 24π hexaphyrin(1.0.1.0.1.0) and 32π octaphyrin(1.0.1.0.1.0.1.0) structures without β-annulated bridges. Single-crystal X-ray diffraction analysis of the hybrid porphyrinoids ( S 3N 3-ox and O 4N 4-ox ) revealed a nearly planar conformation and the 1H NMR spectra suggest the presence of paratropic ring currents. These antiaromatic macrocycles show characteristic optical features and underwent reversible two-electron reduction to Hückel aromatic 26π- and 34π-electron species, respectively, as is evident from the results of spectroscopic and theoretical studies (nucleus-independent chemical shift (NICS) and anisotropy of the current-induced density (ACID) calculations). The incorporation of hybrid diheteroles alternately into expanded porphyrin skeletons provides a novel approach to the fine-tuning of the electronic structures of planar antiaromatic macrocycles. 相似文献
11.
We explore here the ability of ruthenium hydroxo species to undergo spontaneous deposition on Pt nanoparticles and to form colloidal solutions of oxoruthenium-protected (-stabilized) nanoparticles of Pt. These particles can be spontaneously attracted to carbon substrates, and they form ultrathin self-assembled films. Fabrication of the multilayer network films on electrodes has been achieved by linking the positively charged oxoruthenium-covered Pt clusters with heteropolyanions of tungsten. By repeated alternate treatments in a solution of phosphododecatungstate (PW 12O 403–) and in a colloidal suspension of oxoruthenium-protected (-stabilized) Pt nanoparticles, the film thickness can be increased systematically (layer by layer) to form stable three-dimensional assemblies on carbon electrodes. It is apparent from cyclic voltammetric and chronoamperometric measurements (that were performed at 20 and 60 °C) that the resulting hybrid films show attractive properties towards the oxidation of methanol at fairly low potentials (0.25–0.4 V versus the saturated calomel electrode). With approximately the same loading of oxoruthenium-covered Pt nanoparticles and under analogous conditions, linking or derivatizing the nanoparticles with phosphotungstate leads to the systems higher electrocatalytic activity. It is possible that, in addition to ruthenium hydroxo species, PW 12O 403– exhibits an activating effect on dispersed Pt particles. An alternative explanation may involve the possibility of different morphologies of the catalytic films in the presence and absence of phosphotungstate anions.Dedicated to Zbigniew Galus on the occation of his 70th birthday 相似文献
12.
A Keggin organic-inorganic hybrid polyoxometalate combined with nickel complex [Ni (Dmf) 3(H 2O)][HPMo 12O 40] · (Dmf) · 2H 2O ( I) has been synthesized and structurally characterized by elemental analysis, IR spectrum, TG analysis, cyclic voltammetry,
and single-crystal X-ray diffraction. Interestingly, a two-dimensional supramolecular network is constructed by the [PMo 12O 40] 3− polyanions, [Ni(Dmf) 3(H 2O)] 2+ cations, and water molecules via hydrogen-bonding interactions. The cyclic voltammetric measurements illustrate that the [PMo 12O 40] 3− polyanion is the electrochemical redox active center of I in the solution. 相似文献
13.
Oxidative polymerization of bromoiron(III) meso‐tetrakis(3‐thienyl)porphyrin gave a novel polymeric porphyrin complex randomly crosslinked at the 2,5‐positions of the peripheral thienyl groups. The electrical semiconductivity of ca. 10 ?5 S/cm after I 2 doping indicated that the polymer had a π‐conjugated structure with a moderate delocalization of π electrons over the thienylporphyrin units. PM3 calculations for free‐base models revealed that HOCO (the highest occupied crystal orbital) band width was reduced by introduction of the porphyrin moieties into the thienylene backbone and yet low HOCO‐LUCO (the lowest unoccupied crystal orbital) gap was maintained, which accounted for the relatively low electrical conductivity of the porphyrin polymer. The modified electrode prepared by electropolymerization was redox‐active due to the presence of iron(II/III) couple and the semiconductivity of the film, which served as a novel non‐enzymatic electrochemical sensor for superoxide anion radical based on the facile electrocatalytic oxidation of the superoxide. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
14.
Phosphomolybdate, H 3PMo 12O 40, (PMo 12)-doped-poly(3,4-ethylenedioxythiophene) (PEDOT) coated gold nanoparticles have been synthesized in aqueous solution by reduction of AuCl 4− using hydroxymethyl EDOT as a reducing agent in the presence of polystyrene sulfonate and PMo 12. The resulting PMo 12-doped-PEDOT stabilized Au nanoparticles are water soluble and have been characterized by UV–visible spectroscopy, scanning electron microscopy and electrochemistry. Glassy carbon electrodes modified with these Au nanoparticles show excellent stability and catalytic activity towards the reduction of bromate in an aqueous electrolyte solution containing 10 mM H 2SO 4 and 0.1 M Na 2SO 4. 相似文献
15.
A new hybrid solid, {Ag(phen) 2} 2{[Ag(phen)] 2[PMo 12O 40]} (phen=1,10-phenanthroline) 1, constructed from one-electron-reduced mono-supported α-Keggin polyanions and silver-phenanthroline fragments via either covalent bonds or supramolecular interactions, is described. In the structure of 1, mono-supported {Ag(phen)[PMo 12O 40]} 3− polyanions are connected by {Ag(phen)} + linking fragments to form a hybrid chain structure with engrafted phen ligands. {Ag(phen) 2} + counter-cations occur in pairs trapping in strong inter-chain π- π stacking to form a three-dimensional supramolecular framework. Luminescent investigation of the compound indicates that 1 displays fascinating orange luminescent property at ambient temperature. 相似文献
16.
A photoluminescent multilayer film based on Keggin-type polyoxometalate PMo 12O 403− (PMo 12) and transition metal complex tris(2,2-bipyridine) ruthenium [Ru(bpy) 3] 2+ (Ru(bpy)) was prepared by using layer-by-layer assembly(LBL). The formation of multilayer film was monitored by ultraviolet absorption spectra. The absorption intensity of characteristic peaks increase with a four-layer cycle, indicating that the LBL assembly film grow linearly and reproducibly from layer to layer. The composition of the film was measured by X-ray photoelectron spectrum (XPS). The data of XPS confirmed the presence of the expected elements. The film exhibited photoluminescence arising from π*− t2g ligand-to-metal transition of Ru(bpy) and redox activity attributing to molybdenum-centered redox processes of PMo 12. The surface morphology of multilayer film was characterized by atomic force microscopy (AFM). The result shows that the film had a smooth surface with root-mean-square (rms) roughness ca. 1.363 nm for {PEI/(PSS/PEI/PMo 12/Ru(bpy)) 3}. The grains are homogeneously dispersed in the substrate and have a rather narrow diameter size distribution. 相似文献
17.
A new amperometric biosensor for hydrogen peroxide (H 2O 2) has been developed that is based on direct electrochemistry and electrocatalysis of hemoglobin (Hb) in a multilayer inorganic–organic
hybrid film. o-Phenylenediamine (PDA) was electropolymerized onto a glassy carbon electrode (GCE), and then negatively charged nanogold
particles and positively charged poly(diallyldimethylammonium chloride) (PDDA) were alternately assembled on the PDA/GCE surface.
Finally, Hb was electrostatically adsorbed on the surface of gold nanoparticles. The electrochemical behavior of the resulting
biosensor (Hb/{nanogold/PDDA} n/PDA/GCE) was assessed and optimized. The performance and factors influencing the biosensor were studied in detail. Under
optimal conditions, the immobilized Hb displayed good electrocatalytic response to the H 2O 2 reduction ranging from 1.3 μM to 1.4 mM with a detection limit of 0.8 μM (at 3δ). In addition, the biosensor exhibited rapid
response, good reproducibility, and long-term stability.
Electronic supplementary material to this paper is available in electronic form at
Correspondence: Dianyong Tang, Department of Chemistry and Life Science, Leshan Teachers College, Sichuan (Leshan) 614000,
P.R. China 相似文献
18.
An enhanced amperometric biosensor based on incorporating one kind of unique nanobiocomposite as dopant within an electropolymerized polypyrrole film has been investigated. The nanobiocomposite was synthesized by self-assembling glutamate dehydrogenase (GLDH) and poly(amidoamine) dendrimer-encapsulated platinum nanoparticles (Pt-DENs) onto multiwall carbon nanotubes (CNTs). ζ-Potentials and high-resolution transmission electron microscopy (HRTEM) confirmed the uniform growth of the layer-by-layer nanostructures onto the carboxyl-functionalized CNTs. The size of Pt nanoparticles is approximately 3 nm. The (GLDH/Pt-DENs) n/CNTs/Ppy hybrid film was obtained by electropolymerization of pyrrole onto glassy carbon electrodes and characterized with scanning electron microscopy (SEM), cyclic voltammetry (CV) and other electrochemical measurements. All methods indicated that the (GLDH/Pt-DENs) n/CNTs nanobiocomposites were entrapped within the porous polypyrrole film and resulted in a hybrid film that showed a high electrocatalytic ability toward the oxidation of glutamate at a potential 0.2 V versus Ag/AgCl. The biosensor shows performance characteristics with high sensitivity (51.48 μA mM −1), rapid response (within 3 s), low detection limit (about 10 nM), low level of interference and excellent reproducibility and stability. 相似文献
19.
A 1D zigzag chain compound, [{Nd(NMP) 6}(PMo 12O 40)] n , has been synthesized by reaction of α-H 3PMo 12O 40?·? nH 2O, Nd 2O 3 and NMP (NMP?=? N-methyl-2-pyrrolidone) in acetonitrile–water mixture, and characterized by elemental analysis, IR and UV spectra, and X-ray single crystal structural analysis. The crystal structure indicates that the title compound forms a one-dimensional zigzag chain built from alternating polyanions and cationic units through Mo–O t–Nd–O t–Mo links. In the compound, Nd 3+ are eight-coordinate with a bicapped trigonal prism geometry of oxygen atoms, from six NMP molecules and two adjacent polyanions, and two terminal oxygen atoms of the polyanions occupying the caps. The powder ESR spectrum at 110?K of the title compound after being exposed to sunshine shows the signal of Mo 5+, g?=?1.96. The CV shows that the title compound undergoes five two-electron reversible reductions and that [PMo 12O 40] 3? are active centers for electrochemical redox in solutions; cations have a small effect on electrochemical redox. 相似文献
20.
The analytical prospects of a carbositall electrode modified with a film based on SiO 2, hemoglobin ( Hb), and gold nanoparticles (CSE SiO 2-Hb-Au), prepared by deposition with an electrically generated catalyst, are reported. Hemoglobin on the surface of CSE SiO 2-Hb-Au is shown to possess electrocatalytic activity toward dissolved oxygen, giving a rationale for the development of a
rapid voltammetric procedure of O 2 quantification with a detection limit of 0.1 mg/L. The inhibition activity of a number of nitrogen-containing organic substances
to the catalytic current CSE SiO 2-Hb-Au is studied. A voltammetric procedure is proposed for determination of the anti-flu drug rimantadine, 1-(1-adamantyl)ethylamine
hydrochloride, with a detection limit of 0.4 mg/L. The procedure is applicable to the quantification of rimantadine in blood
serum and saliva. 相似文献
|