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1.
Huimin Wu David Wexler Guoxiu Wang Huakun Liu 《Journal of Solid State Electrochemistry》2012,16(3):1105-1110
Nanoscale Cocore–Ptshell particles were successfully synthesized based on a successive reduction strategy. The as-prepared core–shell nanoparticles
were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, transmission electron microscope, and electrochemical
methods. It was found that the catalytic reactivity of Cocore–Ptshell/C catalysts toward oxygen reduction was enhanced. It is believed that the prepared Cocore–Ptshell/C nanoparticles could be promising for cathode catalysis in proton exchange membrane fuel cells with much reduced Pt content,
but significantly increased catalytic activity. 相似文献
2.
Stuart M. Macdonald Katarzyna Szot Joanna Niedziolka Frank Marken Marcin Opallo 《Journal of Solid State Electrochemistry》2008,12(3):287-293
A hydrophilic carbon nanoparticle–sol-gel electrode with good electrical conductivity within the sol-gel matrix is prepared.
Sulfonated carbon nanoparticles with high hydrophilicity and of 10–20 nm diameter (Emperor 2000) are co-deposited onto tin-doped
indium oxide substrates employing a sol-gel technique. The resulting carbon nanoparticle-sol-gel composite electrodes are
characterized as a function of composition and salt (KCl) additive. Scanning electron microscopy and voltammetry in the absence
and in the presence of a solution redox system suggest that the composite electrode films can be made electrically conducting
and highly porous to promote electron transport and transfer. The effect of the presence of hydrophilic carbon nanoparticles
is explored for the following processes: (1) double layer charging, (2) diffusion and adsorption of the electrochemically
reversible solution redox system 1,1′-ferrocenedimethanol, (3) electron transfer to the electrochemically irreversible redox
system hydrogen peroxide, and (4) electron transfer to the redox liquid tert-butylferrocene deposited into the porous composite
electrode film. The extended electrochemically active hydrophilic surface area is beneficial in particular for surface sensitive
processes (1) and (3), and it provides an extended solid|organic liquid|aqueous solution boundary for reaction (4). The carbon
nanoparticle–sol-gel composite electrodes are optimized to provide good electrical conductivity and to remain stable during
electrochemical investigation. 相似文献
3.
Wenjiao Wang Jinlong Zhang Feng Chen Masakazu Anpo Dannong He 《Research on Chemical Intermediates》2010,36(2):163-172
Ag nanoparticles encapsulated by TiO2 shells have the ability to catalyze redox reactions on their surface. By continually monitoring by use of UV–visible spectroscopy
it was found that the surface charge of both TiO2-coated and uncoated colloidal silver particles changed after chemical electron injection. The charging and discharging process
of Ag@TiO2 vary, depending on the different Ag content of the core–shell nanoparticles. In order to enhance the stability of Ag@TiO2 colloids, Fe3+ was doped into the lattice of the TiO2 shells. The experimental results showed that the Fe3+ ions have the capacity to store and transfer electrons. Furthermore, the charging and discharging rate can be controlled
by changing the thickness of the TiO2 shells, because they are limited by the diffusion distance of electrons through the TiO2 shells. 相似文献
4.
Silica and core–shell structured titania/silica (TiO2/SiO2) nanoparticles with particles size ranging from tens to hundreds of nanometers were prepared and deposited onto cotton fabric
substrates by sol–gel process. The morphologies of the nanoparticles were characterized by field-emission scanning electron
microscope (FE-SEM). The photocatalytic decomposition properties as well as UV-blocking properties of the fabrics treated
with SiO2 and TiO2/SiO2 nanoparticles were investigated. 相似文献
5.
Yingchang Yang Wei Huang Jufang Zheng Zelin Li 《Journal of Solid State Electrochemistry》2012,16(2):803-809
We report here a facile electrochemical method on the preparation of antimony nanoparticles (NPs) by dispersing a bulk antimony
electrode under highly cathodic polarization in different media at room temperature, requiring neither precursor ions nor
organic capping agents. The dispersion of bulk antimony in a tetrabutyl ammonium bromide (TBAB) acetonitrile solution involved
the formation and oxidation of an unstable Zintl compound of antimony, and the as-prepared Sb NPs were readily transferred
into Sb–Sb2O3 core–shell NPs during the post treatment and characterization because of the surface oxidation of Sb NPs by oxygen in the
air. In contrast, Sb NPs prepared by dispersing the bulk antimony cathode in a blank aqueous NaOH solution were oxygen-resistant
in the air because the strongly adsorbed hydroxide ions from the solution could stabilize the Sb NPs. The incorporation of
sodium, the formation/oxidation of polyanions of antimony (Zintl ions), and the formation/decomposition of unstable antimony
hydrides may all take effect for the cathodic dispersion of bulk antimony electrodes in the NaOH solution. Transmission electron
microscope, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy were used to characterize these NPs. 相似文献
6.
Palanisamy Venkatachalam Njathumkalayil George Joby Narendran Krishnakumar 《Journal of Sol-Gel Science and Technology》2013,67(3):618-628
Dye-sensitized solar cells (DSSCs) have established themselves as an alternative to conventional solar cells owing to their remarkably high power conversion efficiency, longtime stability and low-cost production. DSSCs composed of a dyed oxide semiconductor photoanode, a redox electrolyte and a counter electrode. In these devices, conversion efficiency is achieved by ultra-fast injection of an electron from a photo excited dye into the conduction band of metal oxide followed by subsequent dye regeneration and holes transportation to the counter electrode. The energy conversion efficiency of DSSC is to be dependent on the morphology and structure of the dye adsorbed metal oxide photoanode. Worldwide considerable efforts of DSSCs have been invested in morphology control of photoanode film, synthesis of stable optical sensitizers and improved ionic conductivity electrolytes. In the present investigation, a new composite nano structured photoanodes were prepared using TiO2 nano tubes (TNTs) with TiO2 nano particles (TNPs). TNPs were synthesized by sol–gel method and TNTs were prepared through an alkali hydrothermal transformation. Working photoanodes were prepared using five pastes of TNTs concentrations of 0, 10, 50, 90, and 100 % with TNPs. The DSSCs were fabricated using Indigo carmine dye as photo sensitizer and PMII (1-propyl-3-methylimmidazolium iodide) ionic liquid as electrolyte. The counter electrode was prepared using Copper sulfide. The structure and morphology of TNPs and TNTs were characterized by X-ray diffraction and electron microscopes (TEM and SEM). The photocurrent efficiency is measured using a solar simulator (100 mW/cm2). The prepared composite TNTs/TNPs photoanode could significantly improve the efficiency of dye-sensitized solar cells owing to its synergic effects, i.e. effective dye adsorption mainly originated from TiO2 nanoparticles and rapid electron transport in one-dimensional TiO2 nanotubes. The results of the present investigation suggested that the DSSC based on 10 % TNTs/TNPs showed better photovoltaic performance than cell made pure TiO2 nanoparticles. The highest energy-conversion efficiency of 2.80 % is achieved by composite TNTs (10 %)/TNPs film, which is 68 % higher than that pure TNPs film and far larger than that formed by bare TNTs film (94 %). The charge transport and charge recombination behaviors of DSSCs were investigated by electrochemical impedance spectra and the results showed that composite TNTs/TNPs film-based cell possessed the lowest transfer resistances and the longest electron lifetime. Hence, it could be concluded that the composite TNTs/TNPs photoanodes facilitate the charge transport and enhancing the efficiencies of DSSCs. 相似文献
7.
M. Mallouki F. Tran-Van C. Sarrazin P. Simon B. Daffos A. De C. Chevrot J. F. Fauvarque 《Journal of Solid State Electrochemistry》2007,11(3):398-406
We report on the synthesis and electrochemical characterization of nanohybrid polypyrrole (PPy) (PPy/Fe2O3) materials for electrochemical storage applications. We have shown that the incorporation of nanoparticles inside the PPy
notably increases the charge storage capability in comparison to the “pure” conducting polymer. Incorporation of large anions,
i.e., paratoluenesulfonate, allows a further improvement in the capacity. These charge storage modifications have been attributed
to the morphology of the composite in which the particle sizes and the specific surface area are modified with the incorporation
of nanoparticles. High capacity and stability have been obtained in PC/NEt4BF4 (at 20 mV/s), i.e., 47 mAh/g, with only a 3% charge loss after one thousand cyles. The kinetics of charge–discharge is also
improved by the hybrid nanocomposite morphology modifications, which increase the rate of insertion–expulsion of counter anions
in the bulk of the film. A room temperature ionic liquid such as imidazolium trifluoromethanesulfonimide seems to be a promising
electrolyte because it further increases the capacity up to 53 mAh/g with a high stability during charge–discharge processes. 相似文献
8.
Well‐Dispersed CoS Nanoparticles on a Functionalized Graphene Nanosheet Surface: A Counter Electrode of Dye‐Sensitized Solar Cells
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Dr. Xiaohuan Miao Prof. Kai Pan Prof. Guofeng Wang Dr. Yongping Liao Dr. Lei Wang Dr. Wei Zhou Dr. Baojiang Jiang Prof. Qingjiang Pan Prof. Guohui Tian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):474-482
With a facile electrophoretic deposition and chemical bath process, CoS nanoparticles have been uniformly dispersed on the surface of the functionalized graphene nanosheets (FGNS). The composite was employed as a counter electrode of dye‐sensitized solar cells (DSSCs), which yielded a power conversion efficiency of 5.54 %. It is found that this efficiency is higher than those of DSSCs based on the non‐uniform CoS nanoparticles on FGNS (4.45 %) and built on the naked CoS nanoparticles (4.79 %). The achieved efficiency of our cost‐effective DSSC is also comparable to that of noble metal Pt‐based DSSC (5.90 %). Our studies have revealed that both the exceptional electrical conductivity of the FGNS and the excellent catalytic activity of the CoS nanoparticles improve the conversion efficiency of the uniformly FGNS‐CoS composite counter electrode. The electrochemical impedance spectra, cyclic voltammetry, and Tafel polarization have evidenced the best catalytic activity and the fastest electron transport. Additionally, the dispersion condition of CoS nanoparticles on FGNS plays an important role for catalytic reduction of I3?. 相似文献
9.
Xiaodong Li Dingwen Zhang Xi Jiang Yin Si Chen Jianhua Shi Zhuo Sun Sumei Huang 《Journal of Solid State Electrochemistry》2011,15(6):1271-1277
Polymer gel electrolytes based on poly(acrylic acid)-poly(ethylene glycol) (PAA–PEG) hybrid have been prepared and applied
to developed quasi-solid-state dye-sensitized solar cells (DSCs). PAA–PEG hybrid was synthesized by polymerization reaction.
Quasi-solid-state DSCs were fabricated with synthesized PAA–PEG electrolyte. The effects of alkali iodides LiI, KI, and I2 concentrations on liquid electrolyte absorbency and ionic conductivity of PAA–PEG were investigated. The evolution of the
solar cell parameters with polymer gel electrolyte compositions was revealed. DSCs based on PAA–PEG with optimized KI/I2 concentrations showed better performances than those with optimized LiI/I2 concentrations. The electrochemical impedance spectroscopy technique was employed to examine the electron lifetime in the
TiO2 electrode and quantify charge transfer resistances at the TiO2/dye/electrolyte interface and the counter electrode in the solar cells based on the PAA–PEG hybrid gels. A maximum conversion
efficiency of 4.96% was obtained for DSCs using KI based quasi-solid electrolyte under 100 mW cm−2. Our work suggests that KI can be the promising alkali metal iodide for improving the performance of PAA–PEG hybrid gel DSCs. 相似文献
10.
Electrorheological properties of suspensions of hollow globular titanium oxide/polypyrrole particles
Hollow globular clusters of titanium oxide (TiO2) nanoparticles were synthesized by a simple hydrothermal method. The prepared particles were consequently coated by in situ
polymerization of conductive polymer polypyrrole (PPy) to obtain novel core–shell structured particles as a dispersed phase
in electrorheological (ER) suspensions. The X-ray diffraction analysis and scanning electron microscopy provided information
on particle composition and morphology. It appeared that PPy coating improved the compatibility of dispersed particles with
silicone oil which results in higher sedimentation stability compared to that of mere TiO2 particles-based ER suspension. The ER properties were investigated under both steady and oscillatory shears. It was found
that TiO2/PPy particles-based suspension showed higher ER activity than that of mere TiO2 hollow globular clusters. These observations were elucidated well in view of their dielectric spectra analysis; a larger
dielectric loss enhancement and faster interfacial polarization were responsible for a higher ER activity of core–shell structured
TiO2/PPy-based suspensions. Investigation of changes in ER properties of prepared suspensions as a function of particles concentration,
viscosity of silicone oil used as a suspension medium, and electric field strength applied was also performed. 相似文献
11.
Xiang Shen Yan Xin Wang Li Qiang Lu Yan Ling Chen Yong Xia Yuan Hao Li 《Journal of Sol-Gel Science and Technology》2010,54(3):340-346
A nitrogen doped TiO2/Ni0.5Zn0.5Fe2O4 core–shell structure nanoparticles was prepared by low temperature sol–gel-hydrothermal process. The characterizations of
the catalyst indicate that the Ni0.5Zn0.5Fe2O4 nanocrystals of about 25 nm are well-coated with crystalline N-doped titania. The absorption edges in the diffusion reflectance
spectra of TiO0.98N1.02 and TiO1.37N0.63/Ni0.5Zn0.5Fe2O4 shift to visible light region. The core–shell nanocatalysts can effectively photodegrade organic pollutants in the dispersion
system and can be recycled easily by an external magnetic field. 相似文献
12.
Platinum nanoparticles were successfully deposited within a multiwalled carbon nanotube (MWCNT)–Nafion matrix by a cyclic
voltammetry method. A Pt(IV) complex was reduced to platinum nanoparticles on the surface of MWCNTs. The resulting Pt nanoparticles
were characterized by scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy.
The Pt–MWCNT–Nafion nanocomposite film-modified glassy carbon electrode had a sharp hydrogen desorption peak at about −0.2 V
vs. Ag/AgCl (3 M) in a solution of 0.5 M H2SO4, which is directly related to the electrochemical activity of the Pt nanoparticles presented on the surface of MWCNTs. The
electrocatalytic properties of the Pt–MWCNT–Nafion nanocomposite-modified glassy carbon electrode for methanol electrooxidation
were investigated by cyclic voltammetry in a 2 M CH3OH + 1 M H2SO4 solution. In comparison with the Pt-coated glassy carbon electrode and the Pt–Nafion modified glassy carbon electrode, the
Pt–MWCNT–Nafion-modified electrode had excellent electrocatalytic activity toward methanol electrooxidation. The stability
of the Pt–MWCNT–Nafion nanocomposite-modified electrode had also been evaluated. 相似文献
13.
Jie Cai Jia Guo Minglei Ji Wuli Yang Changchun Wang Shoukuan Fu 《Colloid and polymer science》2007,285(14):1607-1615
Fe3O4/SiO2/poly (N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate) [P(NIPAM-co-DMA)] multiresponsive composite microspheres with core–shell structure were synthesized by template precipitation polymerization.
First, the magnetite nanoparticles were coated with silica and then modified with 3-(trimethoxysilyl)-propyl methacrylate
(MPS). Subsequently, the Fe3O4/SiO2 particles grafted with MPS were used to seed the precipitation copolymerization of NIPAM and DMA. The composite microspheres
with core–shell structure were superparamagnetic, pH-sensitive, and thermoresponsive. The swelling ratio (D25 °C,
pH = 3/D50 °C,
pH = 9)3 coupling of pH and temperature increased up to 21.2, which was much higher than that without comonomer DMA. 相似文献
14.
G. A. Kovalenko L. G. Tomashevskaya T. V. Chuenko N. A. Rudina L. V. Perminova A. N. Reshetilov 《Kinetics and Catalysis》2011,52(4):564-572
The carbon-carbon composite materials obtained via the synthesis of catalytic filamentous carbon (CFC) on a Ni/graphite supported
catalyst in the process of the pyrolysis of C3–C4 alkanes in the presence of hydrogen were systematically studied. The effects of the following conditions on the catalytic
activity expressed as the yield of carbon (g CFC)/(g Ni) and on the character of CFC synthesis on graphite rods were studied:
procedures for supporting Ni(II) compounds (impregnation and homogeneous precipitation), the concentrations of impregnating
compouds (nickel nitrate, urea, and ethyl alcohol) in solution, graphite treatment (oxidation) conditions before supporting
Ni(II) compounds, and the pyrolysis temperature of C3–C4 alkanes in the range of 400–600°C. Optimum conditions for preparing CFC/graphite composite materials, which are promising
for use as electrodes in microbial fuel cells (MFCs), were chosen. The electrochemical characteristics of an MFC designed
with the use of a CFC/graphite electrode (anode) and Gluconobacter oxydans glycerol-oxidizing bacteria were studied. The morphology of the surfaces of graphite, synthesized CFC, and also bacterial
cells adhered to the anode was studied by scanning electron microscopy. 相似文献
15.
Horseradish peroxidase (HRP) was immobilized onto a polyion complex membrane containing positively charged silver nanoparticles
(nanosilver), double stranded DNA and poly(thionine) to fabricate highly sensitive and selective electrochemical hydrogen
peroxide (H2O2) biosensor on a glassy carbon electrode. The presence of nanosilver provided a biocompatible microenvironment for enzyme
molecules, greatly amplified the surface coverage of HRP on the electrode surface, and most importantly could act as a charge
carrier. The process of the biosensor construction was characterized by scanning electron microscopy. Voltammetric and time-based
amperometric techniques were employed to characterize the properties of the derived biosensor. Under optimal conditions, the
biosensor has an electrocatalytic behavior towards the H2O2 reduction, and exhibits a linear range from 1.1 μM to 5.2 mM, with a lower detection limit of 0.2 μM. The apparent Michaelis–Menten
constant of the biosensor to H2O2 was estimated to be 1.02 mM. Furthermore, the biosensor exhibited high sensitivity, good reproducibility, and acceptable
stability. Importantly, the properties of composite film, together with the bioelectrochemical catalytic activity, could make
them useful in the development of bioelectronic devices and investigation of protein electrochemistry at functional interface.
Correspondence: Yan Liu, College of Chemistry, Chongqing Normal University, Chongqing 400047, P.R. China 相似文献
16.
Following previous works [1, 2], silica–polystyrene core–shell particles have been synthesized by dispersion polymerization
of styrene in an ethanol/water mixture in the presence of a poly(styrene-b-ethylene oxide) block copolymer as stabilizer. Besides the formation of composite core–shell particles, a large number of
free latex particles that do not contain silica were also formed. This number decreases as the size of the silica beads decreases
from 300 to 29 nm in diameter, and becomes very low compared to the number of composite particles for the smallest silica
beads used. In every case, the composite particles could be easily separated from the free latex particles by centrifugation,
providing a material made of regular core–shell composite particles. On the basis of the mechanisms involved in dispersion
polymerization, hypotheses were formulated to account for the formation of the silica–polystyrene composite particles.
Received: 6 May 1999 Accepted in revised form: 29 June 1999 相似文献
17.
A magnetocontrolled immunosensing strategy based on flow-injection electrochemical impedance spectroscopy (EIS) was developed
for the determination of carcinoembryonic antigen (CEA) in human serum. The immunosensor was fabricated by immobilizing anti-CEA
on epoxysilane-modified core–shell magnetic Fe3O4/SiO2 nanoparticles. The detection principle is based on the difference between the resistances measured before and after the antigen–antibody
interaction. The performance of the immunosensor and factors influencing this performance were also proposed. The resistance
response depended linearly on the CEA concentration over the range 1.5–60 ng/ml, and the immunosensor gave a detection limit
of 0.5 ng/ml (S/N = 3). Coefficients of variance (CVs) of <9.8% were obtained for the intra- and interassay precisions. The method was successfully
applied to the analysis of CEA in human serum. The recoveries obtained by spiking CEA standards into normal serum were 87–113%.
The performance of the immunosensor was compared with a commercially available CEA ELISA. Satisfactory results were obtained
according to a paired t-test method (t value < t
critical at the 95% confidence level). Importantly, the proposed immobilization protocol could be further developed to immobilize
other antigens or biocompounds.
Figure This study introduced a magnetocontrolled electrochemical immunosensing strategy based on antibody-functionalized magnetic
core–shell Fe3O4/SiO2 nanoparticles for the determination of carcinoembryonic antigen in human serum 相似文献
18.
A one-step electrochemical approach for synthesis of Pt nanoparticles/reduced graphene oxide(Pt/RGO) was demonstrated.Graphene oxide(GO) and chloroplatinic acid were reduced to RGO and Pt nanoparticles(Pt NPs) simultaneously,and Pt/RGO composite was deposited on the fluorine doped SnO 2 glass during the electrochemical reduction.The Pt/RGO composite was characterized by field emission-scanning electron microscopy,Raman spectroscopy and X-ray photoelectron spectroscopy,which confirmed the reduction of GO and chloroplatinic acid and the formation of Pt/RGO composite.In comparison with Pt NPs and RGO electrodes obtained by the same method,results of cyclic voltammetry and electrochemical impedance spectroscopy measurements showed that the composite electrode had higher catalytic activity and charge transfer rate.In addition,the composite electrode had proved to have better performance in DSSCs than the Pt NPs electrode,which showed the potential application in energy conversion. 相似文献
19.
多壁纳米碳管空气电极的交流阻抗研究 总被引:10,自引:0,他引:10
研究了多壁纳米碳管、活性炭和石墨等空气电极的交流阻抗特性.结果表明,纳米碳管空气电极的阻抗谱由两个半圆组成,高频区半圆对应欧姆极化阻抗,低频区半圆对应电化学极化阻抗.催化剂Pt以纳米颗粒的形式沉积在碳管的外表面,明显减小了电极的欧姆阻抗和电化学极化阻抗,提高了氧还原反应的电催化活性.活性炭电极除存在电化学阻抗外,还存在薄液膜扩散阻抗(Nernst扩散),石墨电极形成的薄液膜反应区域较小,电极反应呈Warburg扩散阻抗特征,相应的电催化活性较低.采用交流阻抗等效电路分析方法,对拟合的动力学数据进行了解释. 相似文献
20.
We reported previously the superiority of electrochemical characteristics of the mechanical mixtures of micrometer LiMn2O4 spinel with multiwall carbon nanotubes (MCNT) over those of spinel compositions with natural graphite in the prototypes of the Li-ion batteries. In the presented work, we extended the investigation of the kinetic and interfacial characteristics of the spinel in the redox reaction with the Li ion. Slow-rate scan cyclic voltammetry and impedance spectroscopy were used. Carbon electroconductive fillers, their nature, and particle sizes play the key role in the efficiency of the electrochemical transformation of spinel in Li-ion batteries. Electrodes based on the composition of the spinel and MCNT show a good cycling stability and efficiency at the discharge rate of 2C. Chemical diffusion coefficients of Li ion, which were determined in spinel composite with MCNT and graphite near potentials of peak activity in deintercalation/intercalation processes, change within one order of 10?12 cm2 s?1. The value of this chemical diffusion coefficient for the composition of the spinel with MCNT and with graphite change within one order of 10?12 cm2 s?1. The data of the impedance spectroscopy shows that the resistance of surface films on the spinel (R s) is low and does not considerably differ from R s in composites of the spinel with MCNT and graphite. The investigation shows that the resistance of charge transport (R ct) through the boundary of surface film/spinel composite is dependent on the conductive filler. Value of R ct in spinel electrode decreases by the factor of thousand in the presence of carbon filler. Exchange current of spinel electrode increases from the order of 10?7 to 10?4 A cm?2 under the influence of MCNT. At the potentials of maximum activity in deintercalation processes, exchange current of spinel composite electrode with MCNT is 2.2–3.0 times more than one of the composite with graphite. Determining role of the resistance of charge transport in electrode processes of spinel is established. The value of R ct is dependent on the resistance in contacts between spinel particles and also between particles and current collectors. Contact resistance decreases under the influence of MCNT with more efficiency than under the influence of graphite EUZ-M because of small the size of its particles with high surface area of the MCNT. 相似文献