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1.
《Electroanalysis》2004,16(9):724-729
Interdigitated ultramicroelectrode arrays (IDUAs) were fabricated on glass wafers and investigated to obtain optimal oxidation and reduction reactions of potassium ferro/ferrihexacyanide, Fe2+/3+(CN)6, when using a 2‐electrode set up. These electrodes will be used as transducers in portable microfluidic‐based biosensors in the future for the detection in an aqueous, biocompatible matrix. IDUAs were designed to maximize the signal‐to‐noise ratio (S/N) investigating electrode height, gap size, finger width, and material. Interesting differences in the electrode materials gold and platinum were found, which were due to the oxidization of platinum and gold during the IDUA fabrication process. It resulted in gold IDUAs being by far superior in respect to signal‐to‐noise ratio and overall signal magnitude to those made of platinum. The effects of gap size, electrode width and number of electrode fingers were as expected. Optimal electrode heights were in the range of 70 nm–140 nm, much larger and smaller electrodes had lower signal‐to‐noise ratios due to overall reduced signal or increased background. The optimized IDUA was made out of gold, had 400 fingers with a finger width of 2.7 μm, a finger height between 70 nm and 140 nm and a gap size of 0.9–1 μm. A detection limit of as low as 0.1 μM ferro/ferrihexacyanide measured in a simple 2‐electrode set up was obtained with a signal‐to‐noise ratio of 9.7. 相似文献
2.
Amir Hatamie Ehsan Rezvani Armin Sedighian Rasouli Abdolreza Simchi 《Electroanalysis》2019,31(3):504-511
In this work, a porous and flexible three‐dimensional (3D) nickel/gold nanoparticle electrode (NiF/AuNPs) is presented as an efficient electrocatalyst for ethanol oxidation in alkaline media. The 3D nanocomposite electrode consists of interconnected porous nickel foam (NiF) with large pores (500±200 μm diameter) surrounded by interconnected struts (~100 μm) that are decorated with gold nanoparticles (AuNPs, 37±8 nm) through in‐situ electrochemical deposition. The catalytic performance of the 3D electrode was evaluated by different electrochemical methods. An enhancement in the performance (about 253 %) and a remarkable decline in onset potential (about ~0.63 V) in comparison with pristine NiF for ethanol oxidation are demonstrated. This potential is lower than many reported results except palladium‐ and platinum‐based catalysts, which are expensive. It is shown that both hydroxyl anions and cations affect the ethanol oxidation on the 3D electrode. The interconnected porous structure provides efficient mass diffusivity, which along with its high specific surface area combined with the catalytic nature of AuNPs, may open new opportunities for in‐inexpensive and highly efficient electro‐oxidation of ethanol for energy applications. 相似文献
3.
Chih‐Ching Huang Prof. Yu‐Lun Hung Yen‐Chun Shiang Tai‐Yuan Lin Prof. Yu‐Shen Lin Chao‐Tsen Chen Prof. Huan‐Tsung Chang Prof. 《化学:亚洲杂志》2010,5(2):334-341
We have employed mannose‐modified gold nanodots (Man–Au NDs) as a luminescence sensor for the detection of the thyroid‐cancer marker thyroglobulin (Tg) in homogeneous solutions. The luminescent Man–Au NDs are prepared through the reaction of 2.9 nm‐diameter gold nanoparticles (Au NPs) with 11‐mercapto‐3,6,9‐trioxaundecyl‐α‐D ‐mannopyranoside (Man‐RSH) under the irradiation of a light‐emitting diode (LED). We have found that the irradiation enhances the quantum yield (~11 %), alters the emission wavelength and lifetimes, and shortens the preparation time. A luminescence assay has been developed for Tg based on the competition between Tg and Man–Au NDs for the interaction with the concanavalin A (Con A). Because luminescence quenching of the Man–Au NDs by Con A is inhibited by Tg selectivity, we have obtained a highly sensitive and selective assay for Tg. 相似文献
4.
Morphology Tailoring of Sulfonic Acid Functionalized Organosilica Nanohybrids for the Synthesis of Biomass‐Derived Alkyl Levulinates
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Sai An Daiyu Song Bo Lu Dr. Xia Yang Prof. Yi‐Hang Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(30):10786-10798
Morphology evolution of sulfonic acid functionalized organosilica nanohybrids (Si(Et)Si‐Pr/ArSO3H) with a 1D tubular structure (inner diameter of ca. 5 nm), a 2D hexagonal mesostructure (pore diameter of ca. 5 nm), and a 3D hollow spherical structure (shell thickness of 2–3 nm and inner diameter of ca. 15 nm) was successfully realized through P123‐templated sol–gel cocondensation strategies and fine‐tuning of the acidity followed by aging or a hydrothermal treatment. The Si(Et)Si‐Pr/ArSO3H nanohybrids were applied in synthesis of alkyl levulinates from the esterification of levulinic acid and ethanolysis of furfural alcohol. Hollow spherical Si(Et)Si‐Pr/ArSO3H and hexagonal mesoporous analogues exhibited the highest and lowest catalytic activity, respectively, among three types of nanohybrids; additionally, the activity was influenced by the ?SO3H loading. The activity differences are explained in terms of different Brønsted acid and textural properties, reactant/product diffusion, and mass transfer rate, as well as accessibility of ?SO3H sites to the reactant molecules. The reusability of the nanohybrids was also evaluated. 相似文献
5.
Erfan Mafakheri Abdollah Salimi Rahman Hallaj Abdolali Ramazani Mohamad Almasi Kashi 《Electroanalysis》2011,23(10):2429-2437
For the first time iridium oxide (IrO2) nanotubes are synthesized by electrodeposition in a polycarbonate (PC) template. Potential cycling (90 cycles) between 0.0 and 0.9 V is used for the preparation of IrOx nanotubes onto the PC template with a pore diameter of 100 nm. Field‐emission scanning electron microscopy (FESEM) images show, that IrO2 nanotubes with uniform diameters of 110±10 nm and an estimated length of 1–3 µm are formed. The electrochemical properties and the electrocatalytic activity of a glassy carbon‐IrOx nanotube modified electrode toward Cr3+ and As3+ oxidation are investigated. Finally, the modified electrode is used for micromolar detection of the proposed analytes using differential pulse voltammetry. 相似文献
6.
One‐Pot Synthesis of Pomegranate‐Structured Fe3O4/Carbon Nanospheres‐Doped Graphene Aerogel for High‐Rate Lithium Ion Batteries
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Dr. Dafang He Lixian Li Fengjuan Bai Chenyang Zha Prof. Liming Shen Prof. Harold H. Kung Prof. Ningzhong Bao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(13):4454-4459
A unique hierarchically nanostructured composite of iron oxide/carbon (Fe3O4/C) nanospheres‐doped three‐dimensional (3D) graphene aerogel has been fabricated by a one‐pot hydrothermal strategy. In this novel nanostructured composite aerogel, uniform Fe3O4 nanocrystals (5–10 nm) are individually embedded in carbon nanospheres (ca. 50 nm) forming a pomegranate‐like structure. The carbon matrix suppresses the aggregation of Fe3O4 nanocrystals, avoids direct exposure of the encapsulated Fe3O4 to the electrolyte, and buffers the volume expansion. Meanwhile, the interconnected 3D graphene aerogel further serves to reinforce the structure of the Fe3O4/C nanospheres and enhances the electrical conductivity of the overall electrode. Therefore, the carbon matrix and the interconnected graphene network entrap the Fe3O4 nanocrystals such that their electrochemical function is retained even after fracture. This novel hierarchical aerogel structure delivers a long‐term stability of 634 mA h g?1 over 1000 cycles at a high current density of 6 A g?1 (7 C), and an excellent rate capability of 413 mA h g?1 at 10 A g?1 (11 C), thus exhibiting great potential as an anode composite structure for durable high‐rate lithium‐ion batteries. 相似文献
7.
《Electroanalysis》2004,16(19):1583-1591
Micro‐wire electrodes were made from gold and silver wires (diameter: 25 μm; length: 3–21 mm) and sealed in a polyethylene holder; micro‐disk electrodes were made from the same wires and polished. The gold electrodes were electrochemically coated with mercury before use; the silver wires were used without coating. Comparative measurements demonstrated that the micro‐wire electrodes had much higher sensitivity, and a much (10–100×) lower limit of detection, than micro‐disk electrodes, and the sensitivity increased linearly with the area and length of the electrodes. Using a gold micro‐wire electrode of 21 mm and a deposition time of 300 s the limit of detection was 0.07 nM Pb in seawater of natural pH, compared to a limit of detection of 10 nM Pb (more than 100×greater) using a gold micro‐disk electrode of the same diameter. Using the silver micro‐wire electrode the limit of detection of lead was improved by a factor of 10 to 0.2 nM in acidified seawater. It is expected that the improved sensitivity of micro‐wire electrodes will lead to successful in situ detection of metals in natural waters. 相似文献
8.
A novel nanocomposite electrode based on hierarchical 3D porous MnO2?TiO2 for the application in hydrogen peroxide (H2O2) sensors has been explored. This electrode was fabricated by growing TiO2 cross‐linked nanowires on a commercial fluorine tin oxide (FTO) glass via a hydrothermal process and subsequent deposition of 3D honeycomb‐like MnO2 nanowalls using an electrodeposition method (denoted as 3D MNS‐TNW@FTO). The obtained 3D MNS‐TNW@FTO electrode was characterized by scanning electron microscopy (SEM), Raman spectroscopy, X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). Based on such a unique 3D porous framework and the existence of MnO2, the electrode demonstrates a good performance in the detection of H2O2, with two linear ranges from 9.8 to 125 μM and 125 μM–1.0 mM, a good selectivity of 8.02 μA mM?1 cm?2, and a low detection limit of 4.5 μM. In addition, the simplicity of the developed low‐cost fabrication process provides an efficient method for the mass production of electrocatalytical MnO2?TiO2 nanocomposites on commercial FTO glass for H2O2 sensing applications and can be adapted for other electrochemical sensors for various biochemical targets. It thus is beneficial for the practical usage in bioanalysis. 相似文献
9.
Zhenzhen Lu Shanli Yang Qiong Yang Shenglian Luo Chengbin Liu Yanhong Tang 《Mikrochimica acta》2013,180(7-8):555-562
We have modified a glassy carbon electrode by single-step electrodeposition of graphene (GR), gold nanoparticles (AgNPs), and chitosan (CS) directly from a solution containing graphene oxide, tetrachloroauric acid, and chitosan. The surface and electrochemical properties of the film-modified electrode were investigated by SEM and TEM images. The AuNPs have a diameter of about 20 nm and are uniformly dispersed in the matrix. Combining the advantages of GR (i.e., high surface area and conductivity), of AuNPs (excellent electrical conductivity) and CS (excellent film-forming ability and good water permeability), the hybrid film effectively enhances electron-transfer and promotes the response to lead(II) ion. Under the optimum conditions, a linear relationship exists between electrical current and the concentration of lead (II) ion in the range between 0.5 to 100 μg?L-1, with a detection limit of 1 ng?L-1 (at an SNR of 3). The electrode was successfully applied to the detection of lead(II) in spiked samples of river water. Figure
Graphene–Au nanoparticles–chitosan (GR–AuNPs–CS) was fabricated by one-step electrodeposition. The obtained GR–AuNPs–CS hybrid was used for trace analysis of the lead (II). 相似文献
10.
《Electroanalysis》2006,18(11):1105-1113
We report for the first time the effective catalytic electrooxidation of nicotinamide adenine dinucleotide (NADH) on the pencil 8B‐scrawled gold electrode of an electrochemical quartz crystal microbalance (EQCM). The EQCM allowed us to quantitatively evaluate the catalytic activity of the pencil‐scrawled Au electrode. With increasing the mass of modified pencil powders, the peak potential for NADH oxidation shifted negatively, with maximum shift of ?0.35 V at saturated pencil modification; the NADH‐oxidation peak current density (jp) was also notably increased, and the jp at saturated pencil modification was found to be larger than those at conventional pencil 8B and bare Au electrodes. Sensitive amperometric detection of NADH was achieved at the gold electrode with saturated pencil modification, with low detection potential (0.4 V versus SCE), low detection limit (0.08 μmol L?1) and wide linear range (0.2–710 μmol L?1). The fluoroelectrochemical measurements of NADH at bare and pencil‐modified gold electrodes were also conducted with satisfactory results. The convenient and low‐cost modification of pencil powders on the Au electrode may have presented a new functional surface of the EQCM, which is recommended for wider applications to bioelectrochemical studies, especially in view of the EQCM's capability of providing abundant in situ information in relevant processes. 相似文献
11.
Mirghasem Hosseini Mohamad Mohsen Momeni 《Journal of Solid State Electrochemistry》2010,14(6):1109-1115
Au/TiO2/Ti electrode was prepared by a two-step process of anodic oxidation of titanium followed by cathodic electrodeposition of
gold on resulted TiO2. The morphology and surface analysis of Au/TiO2/Ti electrodes was investigated using scanning electron microscopy and EDAX, respectively. The results indicated that gold
particles were homogeneously deposited on the surface of TiO2 nanotubes. The nanotubular TiO2 layers consist of individual tubes of about 60–90 nm in diameter, and the electrode surface was covered by gold particles
with a diameter of about 100–200 nm which are distributed evenly on the titanium dioxide nanotubes. This nanotubular TiO2 support provides a high surface area and therefore enhances the electrocatalytic activity of Au/TiO2/Ti electrode. The electrocatalytic behavior of Au/TiO2/Ti electrodes in the glucose electro-oxidation was studied by cyclic voltammetry. The results showed that Au/TiO2/Ti electrodes exhibit a considerably higher electrocatalytic activity toward the glucose oxidation than that of gold electrode. 相似文献
12.
A poly(3,4‐ethylenedioxypyrrole)–gold nanoparticle (Au)–tungsten oxide (PEDOP–Au@WO3) electrochromic supercapacitor electrode capable of optically modulating solar energy while simultaneously storing/releasing energy (in the form of charge) was fabricated for the first time. WO3 fibers, 50 to 200 nm long and 20 to 60 nm wide, were synthesized by a hydrothermal route and were electrophoretically deposited on a conducting substrate. Au nanoparticles and PEDOP were coated over WO3 to yield the PEDOP–Au@WO3 hybrid electrode. The inclusion of Au in the hybrid was confirmed by X‐ray diffraction, Raman spectroscopy, and energy‐dispersive X‐ray analyses. The nanoscale electronic conductivity, coloration efficiency, and transmission contrast of the hybrid were found to be significantly greater than those of pristine WO3 and PEDOP. The hybrid showed a high specific discharge capacitance of 130 F g?1 during coloration, which was four and ten times greater than the capacitance achieved in WO3 or PEDOP, respectively. We also demonstrate the ability of the PEDOP–Au@WO3 hybrid, relative to pristine PEDOP, to perform as a superior counter electrode in a solar cell, which is attributed to a higher work function. The capacitance and redox switching capability of the hybrid decreases insignificantly with cycling, thus establishing the viability of this multifunction hybrid for next‐generation sustainable devices such as electrochromic psuedocapacitors because it can concurrently conserve and store energy. 相似文献
13.
Ultrathin FeSe2 Nanosheets: Controlled Synthesis and Application as a Heterogeneous Catalyst in Dye‐Sensitized Solar Cells
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Shoushuang Huang Qingquan He Wenlong Chen Prof. Qiquan Qiao Dr. Jiantao Zai Prof. Xuefeng Qian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):4085-4091
Two‐dimensional (2D) semiconducting nanosheets have emerged as an important field of materials, owing to their unique properties and potential applications in areas ranging from electronics to catalysis. However, the controlled synthesis of ultrathin 2D nanosheets remains a great challenge, due to the lack of an intrinsic driving force for anisotropic growth. High‐quality ultrathin 2D FeSe2 nanosheets with average thickness below 7 nm have been synthesized on large scale by a facile solution method, and a formation mechanism has been proposed. Due to their favorable structural features, the as‐synthesized ultrathin FeSe2 nanosheets exhibit excellent electrocatalytic activity for the reduction of triiodide to iodide and low charge‐transfer resistance at the electrolyte–electrode interface in dye‐sensitized solar cells (DSSCs). The DSSCs with FeSe2 nanosheets as counter electrode material achieve a high power conversion efficiency of 7.53 % under a simulated solar illumination of 100 mW cm?2 (AM 1.5), which is comparable with that of Pt‐based devices (7.47 %). 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(4):1007-1011
The direct reaction between copper nitrate, thymine‐1‐acetic acid, and 4,4′‐bipyridine in water leads to the formation of a blue colloid comprising uniform crystalline nanoribbons (length >1 μm; width ca. 150–185 nm; diameter ca. 15–60 nm) of a coordination polymer. The polymer displays a thymine‐based structure freely available for supramolecular interactions. These nanostructures show significant selective interaction with single‐stranded oligonucleotides based on adenine. Remarkably, they present low cell toxicity in three cell lines–despite the copper(II) content–and can be used as nanocarriers of oligonucleotides. These results suggest the potential of these types of nanostructures in several biological applications. 相似文献
15.
A bipotentiostatic gold electrodeposition process is developed to grow gold junctions between two adjacent 100 μm diameter platinum disc electrodes. Gold is electrodeposited simultaneously on both electrodes with an automated termination mechanism close to short‐circuit conditions. Gap junctions (average gap width ca. 4 μm) are obtained reproducibly and the behavior of the resulting generator–collector electrode system is investigated for two relevant redox systems. First, the chemically reversible oxidation of 1,1′‐ferrocenedimethanol in aqueous 0.1 M KCl is studied. Well‐defined feedback currents across the electrode junction in generator–collector mode are recorded down to sub‐micromolar analyte concentration. Electrochemically reversible voltammetric responses suggest fast heterogeneous electron transfer and this allows further gap geometry analysis. Second, the (apparently) chemically irreversible oxidation of nitric oxide in 0.1 M phosphate buffer solution (pH 7) at gold electrodes is re‐investigated and, perhaps surprisingly, generator–collector feedback currents are observed for a solution phase intermediate, here tentatively assigned to nitrosonium phosphate, NO+H2PO . The life time of this intermediate, ca. 10 ms, is surprisingly long, given a typical decay time for free NO+ in water of only nanoseconds. The results are consistent with an estimated nitrosonium phosphate association equilibrium constant, K≈107 mol?1 dm3. Without further optimization of the electrode junction gap geometry, the determination of nitric oxide down to ca. 10 μM concentration is achieved. The benefits of smaller junctions and potential analytical applications of paired nanojunction electrodes are discussed. 相似文献
16.
Some porous titanium dioxide (TiO2) films were prepared on flexible substrates by the method of micro‐arc oxidation (MAO) combined with magnetron sputtering (MS). The original material of MAO was Ti films prepared by MS, which was composed of columnar crystals with a diameter of less than 150 nm. The results indicated that the phase of the oxide films was mainly anatase structure, and the pore diameter of the films was about 100–300 nm. However, the phases of the oxide films prepared on Ti plates, which composed of equiaxed crystals with a diameter of 2–5 µm, were anatase and rutile structure. The pore diameter of those films was about 4–10 µm. It was suggested that the changes of the grain boundary structure of the original material could have a significant impact on the phase structure and surface morphology of the resultant TiOx films. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
Hai‐Long Jiang Dr. Tetsuo Umegaki Dr. Tomoki Akita Dr. Xin‐Bo Zhang Dr. Masatake Haruta Prof. Dr. Qiang Xu Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(10):3132-3137
Gold–nickel nanoparticles (NPs) of 3–4 nm diameter embedded in silica nanospheres of around 15 nm have been prepared by using [Au(en)2Cl3] and [Ni(NH3)6Cl2] as precursors in a NP‐5/cyclohexane reversed‐micelle system, and by in situ reduction in an aqueous solution of NaBH4/NH3BH3. Compared with monometallic Au@SiO2 and Ni@SiO2, the as‐synthesized Au–Ni@SiO2 catalyst shows higher catalytic activity and better durability in the hydrolysis of ammonia borane, generating a nearly stoichiometric amount of hydrogen. During the generation of H2, the synergy effect between gold and nickel is apparent: The nickel species stabilizes the gold NPs and the existence of gold helps to improve the catalytic activity and durability of the nickel NPs. 相似文献
18.
Xiaoyu Song Xinyue Wang Yusen Li Chengzhi Zheng Bowen Zhang Chong‐an Di Feng Li Chao Jin Wenbo Mi Long Chen Wenping Hu 《Angewandte Chemie (International ed. in English)》2020,59(3):1118-1123
2D conductive metal–organic frameworks (2D c‐MOFs) feature promising applications as chemiresistive sensors, electrode materials, electrocatalysts, and electronic devices. However, exploration of the spin‐polarized transport in this emerging materials and development of the relevant spintronics have not yet been implemented. In this work, layer‐by‐layer assembly was applied to fabricate highly crystalline and oriented thin films of a 2D c‐MOF, Cu3(HHTP)2, (HHTP: 2,3,6,7,10,11‐hexahydroxytriphenylene), with tunable thicknesses on the La0.67Sr0.33MnO3 (LSMO) ferromagnetic electrode. The magnetoresistance (MR) of the LSMO/Cu3(HHTP)2/Co organic spin valves (OSVs) reaches up to 25 % at 10 K. The MR can be retained with good film thickness adaptability varied from 30 to 100 nm and also at high temperatures (up to 200 K). This work demonstrates the first potential applications of 2D c‐MOFs in spintronics. 相似文献
19.
This work proposes a vibrating microwire electrode as working electrode in stripping voltammetry. The vibration was found to maintain a constant and thin (1–2 μm) diffusion layer during the deposition step. The electrode vibration eliminated the need for external stirring of the solution, thus facilitating in situ detection in the environment. The vibration was effected by fixing a low‐voltage (3 V), asymmetric, electrical rotor to the working electrode (a gold microwire of either 5 or 25 μm). The sensitivity of the vibrated electrode was ca. 22×greater than stationary. Measurements of copper (4 nM) by anodic stripping voltammetry using the vibrating electrode had a low standard deviation (1% for n=6) indicating that the diffusion layer had only minor variability. The agitation mechanism was unaffected by water moving at >2 m s?1 and by water pressure equivalent to a depth of >40 m, indicating its suitability for in situ measurements. The vibrating probe was used for in situ detection of copper by anodic stripping voltammetry to a depth of 6 m. Using a 5 min deposition time, the limit of detection for labile copper was 38 pM. 相似文献
20.
Eu2O3nanorods were synthesized and characterized. The crystallites of Eu2O(CO3)2·H2O nanorods and Eu2O3 nanorods were obtained by means of surfactant assistance, with aqueous butanol solution as the solvent and hexamethylene tetramine as the base. The characteristics of the nanorods were analyzed by transmission electron microscopy, high‐resolution transmission electron microscopy, scanning electron microscopy and X‐ray diffraction. The Eu2O3 nanorod is about 80–300 nm in diameter and 1–5 µm in length. The formation mechanism of the 1D products was also proposed. 相似文献