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1.
Multiwalled carbon nanotubes and TiO2 nanoparticles were used for the improvement of a hyoscine butylbromide (HYBB) potentiometric carbon paste electrode response. The electrode was based on the ammonium reineckate-hyoscine ion association complex as an ion-exchange site dissolved in 2-nitrophenyloctyl ether as pasting liquid. The characteristics of the suggested potentiometric nanocomposite-modified HYBB carbon paste electrode in comparison with the PVC membrane sensor show better responses in terms of sensitivity, dynamic concentration range, detection limit, Nernstain slope, low potential drift, response time, lifetime, and mechanical stability. The electrode exhibits good selectivity for HYB ion with respect to a large number of cations. For investigation of the effects of carbon nanotubes and TiO2 nanoparticles on the conductivity property of the electrode surface, electrochemical impedance spectroscopy measurements were done. The prepared electrode was successfully applied to the determination of hyoscine butylbromide in pharmaceutical formulations and biological samples. 相似文献
2.
《Journal of Electron Spectroscopy and Related Phenomena》1987,44(1):65-78
A Fourier Transform infrared spectrometer has been attached to an ultrahigh vacuum (UHV) apparatus in order to perform reflection-absorption infrared Spectroscopy (RAIRS) of adsorbed species on well-defined surfaces.An infrared spectrum of carbon monoxide (CO) adsorbed at 90 K on Cu(111) has been measured using a resolution of 2 cm−1 and a measuring time of 60 s. Coverages below 1 % of a monolayer are easily detectable.Tetracyanoethylene (TCNE) has been adsorbed at various coverages at 100 K on Cu(111). Strongly red-shifted CN stretchings modes due to charged TCNE adspecies are observed at low coverage. The RAIRS spectrum of the condensed phase is characteristic of crystalline TCNE.Finally, isotopically labeled 12C and 13C acetonitrile (CH3CN) has been adsorbed on Cu(111) as multilayers. Shifts caused by isotopic labeling as small as 3 cm−1 are easily detected. 相似文献
3.
Highly microporous carbon obtained by KOH etching of carbohydrates exhibited enhanced specific capacitance due to the increased adsorption of electrolyte ions on its large surface, which renders it a promising electrode material. However, the KOH-activated carbon electrode did not achieve its optimum charge capacity in organic electrolytes due to the limited accessibility of the electrolyte ions to the micropores, which hindered the adsorption of ions. The electrode performance was enhanced by enlarging the micropores of KOH-activated carbon to mesopores via reactivation in a stream of CO2, which allowed the mesopore/micropore ratio to be increased without compromising the originally high specific surface area. The extended amount of mesopores increased the charge capacity of the electrode by enabling the large organic electrolyte ions to access the porous surface, as compared to untreated KOH-activated carbon. 相似文献
4.
L. Eliad E. Pollak N. Levy G. Salitra A. Soffer D. Aurbach 《Applied Physics A: Materials Science & Processing》2006,82(4):607-613
In order to maximize the capacitance of electrical double layer (EDL) capacitors per unit electrode volume, higher surface
areas are required. This leads to an increasingly greater subdivision of the carbon electrode, namely to pore systems of smaller
pore size. When the pore size approaches the ion size, the EDL charging kinetics lows down because of multiple interactions
of the ions with the surrounding pore walls. On the other hand, the ion electroadsorption capacity increases just because
of this enhanced interaction. Therefore, there is a conflict between improving discharge kinetics and improving capacity.
Knowing the effective ion size relative to the pore size can be helpful in optimizing the pore system design in electrodes
for EDL capacitors. A thorough technique based on the adsorption of molecular probes in the gas phase and the electroadsorption
of different ions was developed to assess pore dimensions. In this report, the technique is applied to the unique case of
polyvinylidene chloride (PVDC) based carbon electrodes in an attempt to elucidate its extraordinary high EDL capacitance,
in terms of the relation between effective ion size and pore size.
PACS 82.47.Uv; 73.22.-f; 73.30.+y; 82.75.-z 相似文献
5.
One-dimensional fluid model for a planar sheath in front of a negative ion-emitting electrode surface immersed in a collision-less, non-magnetized, electronegative plasma is presented. It was found that the positive ion speed at the plasma–sheath boundary (PSB) increases linearly with negative ion emission from the electrode but attains a saturation value as soon as a virtual cathode is formed near the electrode surface. The effect of negative ion emission on the pre-sheath region shows that the potential drop increases across the pre-sheath in accordance with the rise in positive ion speed at the PSB. The sheath width obtained using the present model shows a similar trend as the Child-Langmuir law, but its magnitude is found to be consistently higher compared with a non-emitting electrode. A plausible explanation has been given to explain these effects. 相似文献
6.
Şadan Korkmaz Saliha Elmas Naci Ekem Suat Pat M. Zafer Balbağ 《Optics Communications》2012,285(9):2373-2376
In this study, optical and surface properties of MgF2 thin films produced by thermionic vacuum arc (TVA) technique have been investigated. By means of this technique the MgF2 thin film produced by condensing the plasma of anode material generated by using TVA under high vacuum conditions on the glass. The optical properties have been investigated by using Filmetrics F20 and UV/VIS spectrometer. For surface properties of produced thin films EDS, SEM and AFM have been used. Our analysis shows that MgF2 thin films produced by using TVA are proper single and multi layer anti-reflective (AR) coating and TVA technique brings very important advantages for ophthalmic glass coating and industrial applications' optical purposes. 相似文献
7.
The adsorption and reconstruction of strong electron-acceptor TCNE on the Si(001)-(2 × 1) surface are investigated by density functional theory (DFT). The results show that TCNE prefers to adsorb on the trench between two adjacent dimer rows and the CC double bond is parallel to dimer rows. Charge density difference calculation and Bader charge analysis indicate that abundant negative charge transfers from dimer Si to TCNE. Strong interaction makes it difficult for TCNE to move on Si(001), which is confirmed by nudged elastic band (NEB) analysis. In addition, the correlations between simulated STM images and molecular orbitals are discussed and two surface reconstructions of (2 × 1) and (4 × 2) are predicted at different TCNE coverages. 相似文献
8.
To date, the lithium ion battery has become the focus of secondary battery studies. A considerable capacity loss during the first lithiation of its carbon electrode is a severe drawback of this kind of battery. It has been suggested frequently that the capacity loss was caused by the decomposition of the electrolyte on the surface of the carbon electrode. However, the contribution of binder reduction to this capacity loss has never been considered until now. This paper deals with the binder polytetrafluorethylene (PTFE) reduction and finds that it plays an important part in the capacity loss. It is found that (1) the capacity loss increased with increasing PTFE binder content, (2) the X-ray diffraction peaks corresponding to the PTFE, binder became weaker, while more of the lithium was consumed by the carbon electrode, and disappeared when the consumed amount of lithium exceeded the theoretical value of 1070 mAh per gram of PTFE and (3) the height of the high voltage plateau of the electrochemical titration curves was just a function of storage time, and the length of the plateau was a function of the PTFE content. 相似文献
9.
Amino ion implantation was carried out at the energy of 80 keV with fluence of 5 × 1015 ions cm−2 for indium tin oxide film (ITO) coated glass, and the existence of amino group on the ITO surface was verified by X-ray photoelectron spectroscopy analysis and Fourier transform infrared spectra. Scanning electron microscopy images show that multi-wall carbon nanotubes (MWCNTs) directly attached to the amino ion implanted ITO (NH2/ITO) surface homogeneously and stably. The resulting MWCNTs-attached NH2/ITO (MWCNTs/NH2/ITO) substrate can be used as electrode material. Cyclic voltammetry results indicate that the MWCNTs/NH2/ITO electrode shows excellent electrochemical properties and obvious electrocatalytic activity towards uric acid, thus this material is expected to have potential in electrochemical analysis and biosensors. 相似文献
10.
《Ultrasonics sonochemistry》2014,21(6):1954-1957
A sonochemical approach was employed to prepare Vulcan carbon XC-72R supported by Sn nanoparticles at room temperature in the presence of ethylene glycol. The reduction of metallic Sn ion and ethylene glycol takes place and in turn the glycolate ion as formed acts as a stabilizing agent. Transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy have illustrated that the metallic Sn nanoparticles are successfully embedded on the carbon. The significantly observed reduction over potential for oxygen reduction reaction displays a higher catalytic activity of carbon supported by Sn nanoparticles due to the large surface area of the modified electrode. 相似文献
11.
Hadi Beitollahi Alireza Mohadesi Mortaza Mostafavi Hassan Karimi-Maleh Mehdi Baghayeri Ali Akbari 《Ionics》2014,20(5):729-737
A novel carbon paste electrode modified with carbon nanotubes and 5-amino-2′-ethyl -biphenyl-2-ol was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for electrocatalytic oxidation of ascorbic acid (AA), is described. The electrode was employed to study the electrocatalytic oxidation of AA, using cyclic voltammetry, chronoamperometry, and square-wave voltammetry (SWV) as diagnostic techniques. It has been found that the oxidation of AA at the surface of modified electrode occurs at a potential of about 250 mV less positive than that of an unmodified carbon paste electrode. SWV exhibits a linear dynamic range from 2.0?×?10?7 to 5.0?×?10?4 M and a detection limit of 1.0?×?10?7 M for AA. In addition, this modified electrode was used for simultaneous determination of AA, acetaminophen (AC), and tryptophan (TRP). Finally, the modified electrode was used for determination of AA, AC, and TRP in pharmaceutical products. 相似文献
12.
A flow injection catechol biosensor based on tyrosinase entrapped in carbon nanotube modified polypyrrole biocomposite film on a glassy carbon surface has been developed. Amperometric response was measured as a function of concentration of catechol, at a fixed bias voltage of −50 mV at a flow rate of 1 mL/min. The proposed biosensor exhibited impressive analytical performance such as a linear range between 3 and 50 μM, a short response time (10 s), a detection limit of 0.671 μM and an excellent operational (with a relative standard deviation of 0.54%) and long-term stability (85% remained after 10th week). A comparison of the analytical parameters of the developed biosensor with polypyrrole/tyrosinase film electrode was performed in the study. CNT was shown to enhance the electron transfer between the electrode and enzyme and capable to carry higher bioactivity owing to its intensified surface area. 相似文献
13.
V. Ciupina J. Sullivan S. Saied R. Vladoiu G. Prodan I.M. Oancea‐Stanescu A. Mandes M. Contulov V. Dinca M. Prodan D. Manole 《等离子体物理论文集》2011,51(6):546-553
Carbon thin films were synthesized using the original Thermionic Vacuum Arc (TVA) method. Mechanical properties were investigated using Micro Materials NanoTest 500 instrument using a NT Berkovich indenter. XPS provides a quantitative analysis of the surface composition and X‐ray generated Auger electron spectroscopy (XAES) performed by Thermoelectron ESCALAB 250 revealed information about the sp3:sp2 ratio of the carbon bondings. Structure and morphology was studied by Transmission Electron Microscope CM120ST, providing information on the grain size distribution of the crystalline diamond structures (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
R. Vladoiu V. Dinca G. Musa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):433-437
The aim of this paper is concerned with the surface energy evaluation by contact angle measurements of DLC films deposited
by thermionic vacuum arc (TVA) on different substrates: glass plate, zinc foil, stainless steel and alumina foil. TVA is an
original method based on a combination of the evaporation by electron bombardment and anodic arc. The evaluation of the surface
free energy has been carried out by surface energy evaluation system (SEE System). The influence of the experimental conditions
is also investigated. 相似文献
15.
A simple and low-cost strategy is developed to fabricate three-dimensional (3D) nitrogen-doped carbon cloth electrode through surface activation and nitrogen-doping process. The process can exfoliate the smooth surfaces of micro carbon fibers into nanostructures together with the doping of nitrogen-containing species. The as-fabricated carbon cloth electrode shows excellent areal capacitances of 882.36 and 706.68 mF cm?2 at the current density of 1 and 60 mA cm?2, respectively, exhibiting good rate performance. It also exhibits outstanding cycling stability with 98.7 % retention of its initial capacitance after 30,000 continuous charging/discharging tests. When the electrodes were assembled and tested as a symmetric supercapacitor, it also demonstrates superior electrochemical performance. It is believed that the 3D carbon structures with enlarged surface area, improved conductivity and electrode/electrolyte wettability, and enhanced pseudocapacitance by doping of nitrogen lead to the vast improvement of electrochemical performance. 相似文献
16.
Thin films of molecule-based charge transfer magnet, cobalt tetracyanoethylene [Co(TCNE)x, x ~ 2] consisting of the transition metal Co, and an organic molecule viz. tetracyanoethylene (TCNE) have been deposited by using physical vapor deposition method under ultra-high vacuum conditions at room temperature. X-ray photoelectron spectroscopy (XPS) technique has been used extensively to investigate the electronic properties of the Co(TCNE)x thin films. The XPS measurements show that the prepared Co(TCNE)x films are clean, and oxygen free. The stoichiometries of the films, based on atomic sensitive factors, are obtained, and yields a ~ 1:2 ratio between metal Co and TCNE for all films. Interestingly, the positive shift of binding energy position for Co(2p), and negative shifts for C(1s) and N(1s) peaks suggest a charge-transfer from Co to TCNE, and cobalt is assigned to its Co(II) valence state. In the valence band investigation, the highest occupied molecular orbital (HOMO) of Co(TCNE)x is found to be at ~ 2.4 eV with respect to the Fermi level, and it is derived either from the TCNE? singly occupied molecular orbital (SOMO) or Co(3d) states. The peaks located at ~ 6.8 eV and ~ 8.8 eV are due to TCNE derived electronic states. The obtained core level and valence band results of Co(TCNE)x, films are compared with those of V(TCNE)x thin film magnet: a well known system of M(TCNE)x type of organic magnet, and important points regarding their electronic properties have been brought out. 相似文献
17.
18.
Carbon-based OTFT devices were fabricated using a plasma process for the gate electrode and gate insulators. A nanocrystalline carbon (nc-C) film was used as the gate electrode, and three different layers, cyclohexene, diamond-like carbon (DLC), and cyclohexene/DLC (hybrid insulator), were used as the gate insulator. The surface and electrical properties of the three different gate insulators on the nc-C gate electrode were investigated using the SPM method, and the leakage current density and dielectric constant of the metal-insulator-metal (MIM) structures with three different insulator layers were evaluated. The hybrid insulator layer had a very smooth surface, approximately 0.2 nm, a uniform surface without defects, and good adhesion between the layers. Overall, it is believed that the hybrid insulator lead to a decrease in the electrical leakage current and an improvement in the device performance. 相似文献
19.
Hollow Silica Spheres Embedded in a Porous Carbon Matrix and Its Superior Performance as the Anode for Lithium‐Ion Batteries
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Xi Cao Xiuyun Chuan Shuang Li Dubin Huang Guozhong Cao 《Particle & Particle Systems Characterization》2016,33(2):110-117
Silica (SiO2) is regarded as one of the most promising anode materials for lithium‐ion batteries due to the high theoretical specific capacity and extremely low cost. However, the low intrinsic electrical conductivity and the big volume change during charge/discharge cycles result in a poor electrochemical performance. Here, hollow silica spheres embedded in porous carbon (HSS–C) composites are synthesized and investigated as an anode material for lithium‐ion batteries. The HSS–C composites demonstrate a high specific capacity of about 910 mA h g?1 at a rate of 200 mA g?1 after 150 cycles and exhibit good rate capability. The porous carbon with a large surface area and void space filled both inside and outside of the hollow silica spheres acts as an excellent conductive layer to enhance the overall conductivity of the electrode, shortens the diffusion path length for the transport of lithium ions, and also buffers the volume change accompanied with lithium‐ion insertion/extraction processes. 相似文献
20.
S. S. Chebotarev L. A. Pesin I. V. Gribov N. A. Moskvina V. L. Kuznetsov S. E. Evsyukov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(4):553-559
The modification of x-ray photoelectron spectra (XPS) and C KVV spectra of a partially crystalline polyvinylidene fluoride (PVDF) film under the long action of soft x-rays and secondary electrons followed by argon ion bombardment of its surface is investigated. Deep radiative carbonization leads to the formation of carbynoid structures (chain carbon) on the PVDF surface. Hence, the carbon XPS of the carbonized sample differs from those obtained for graphite and PVDF. Ion bombardment shows the instability of the carbonized sample surface, giving rise to formation of sp 2 hybrid bonds of carbon atoms. The obtained results are indirect experimental evidence that, before ion bombardment, sp-type bonds are dominant on the carbonized PVDF surface. 相似文献