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1.
A simple and efficient route to decorate carbon nanotubes (CNTs) with nanocrystalline RuO2 has been developed. In this method, RuCl3 · 3H2O was oxidized into RuO2 by oxygen in supercritical diethyl amine, and the produced RuO2 deposited on CNTs, resulting in RuO2/CNT nanocomposites. The as-prepared composites were structurally and morphologically characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). TEM images showed that RuO2 nanoparticles attached on CNTs had uniform shape and a narrow particle size distribution. The loading content and the size of RuO2 particles on CNTs could be tuned by changing the mass ratio of RuCl3 · 3H2O/CNT. Electrochemical measurements by cyclic voltammetry demonstrated a substantial increment of the specific capacitance of CNTs due to a pseudocapacitance originated from the deposited RuO2 nanoparticles. 相似文献
2.
Fernando Pico Teresa A. Centeno Rosa M. Rojas Jose M. Rojo 《Electrochimica acta》2006,51(22):4693-4700
RuO2·xH2O/NiO composites having RuO2 contents in the range 0-100 wt.% have been prepared by a co-precipitation method. Structural, microstructural and textural transformations after heating the as-prepared composites at 200 and 600 °C have been followed by X-ray diffraction, scanning electron microscopy (SEM) and nitrogen adsorption/desorption isotherms. At 200 °C the composites are made of micrometric particles in which nanometric crystallites of the two oxides are aggregated. The composites show microporosity (0.02-0.10 cm3/g), mesoporosity (0.07-0.12 cm3/g) and relatively high specific surface area (62-309 m2/g). At 600 °C the composites are fully dehydrated and RuO2 has crystallized and segregated. Microporosity and mesoporosity as well as specific surface area are strongly decreased. Specific capacitance and specific surface area of the composites heated at 200 and 600 °C have been measured and discussed on the basis of the RuO2 content. For comparison the specific capacitance and specific surface area of mixtures of NiO and RuO2·xH2O (or RuO2) have been taken as references. The higher specific capacitance of the 200 °C-heated composites compared to the 600 °C-heated ones is due to the higher specific surface area of the former and the higher pseudocapacitance of RuO2·xH2O compared to RuO2. The discussion reported in this work can be applied to other composites such as RuO2·xH2O/carbon and RuO2·xH2O/other oxides. 相似文献
3.
Sub-micron Bi2Ru2O7+x + RuO2 oxide sensing electrodes (SE) for water quality sensors were prepared on platinised ceramic substrate of the sensor. Their morphology was analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Sensing properties of the Bi2Ru2O7+x + RuO2-SE were investigated for potentiometric detection of pH and dissolved oxygen (DO) in water in the temperature range of 4–30 °C. Sensor was capable to measure DO from 0.5 to 8.0 ppm and pH from 2.0 to 13.0, respectively. The obtained results show acceptable linearity of the measuring characteristics. Long-term stability trial for Bi2Ru2O7+x + RuO2-SE revealed that bio-fouling can be one of the main destructive factors affecting the performance of the sensors in the long run. The screen-printing technology used in the multi-sensory implementation provides fundamental properties of miniaturization, reasonable accuracy and low cost. 相似文献
4.
The electrochemical energy storage and delivery on the electrodes composed of hydrous ruthenium oxide (RuOx·nH2O) or activated carbon-hydrous ruthenium oxide (AC-RuOx) composites are found to strongly depend on the substrate employed. The contact resistance at the active material-graphite interface is much lower than that at the active material-stainless steel (SS) mesh interface. Thin films of gold plus RuOx·nH2O deposited on SS meshes (RuOx/Au/SS) are found to greatly improve the poor contact between SS meshes and electrode materials. The maximum specific capacitance (CS,RuOx) of RuOx·nH2O, 1580 F g−1 (measured at 1 mV s−1), very close to the theoretic value, was obtained from an AC-RuOx/RuOx/Au/SS electrode with 10 wt.% sol-gel-derived RuOx·nH2O annealed in air at 200 °C for 2 h. The highly electrochemical reversibility, high-power characteristics, good stability, and improved frequency response of this AC-RuOx/RuOx/Au/SS electrode demonstrate its promising application potential in supercapacitors. The ultrahigh specific capacitance of RuOx·nH2O probably results from the uniform size distribution of RuOx·nH2O nanoparticles, ranged from 1.5 to 3 nm which is clearly observed from the high-resolution transmission electron microscopy (HRTEM). 相似文献
5.
Bin Xu 《Electrochimica acta》2010,55(8):2859-1590
In this work, a novel type electrode based on RuO2 nanoparticles-modified vertically aligned carbon nanotubes (RuO2/MWCNTs) was prepared by magnetron sputtering deposition. This RuO2/MWCNTs electrode not only shows a high capacity nature, but also possesses a good response to the pH value. The pH sensor based on the RuO2/MWCNTs nanocomposite electrode exhibits some advantages over the conventional pH sensors. It shows good reproducibility, long-term storage stability (over 1 month) and linear response in the whole pH range (2-12) of Britton-Robinson (B-R) buffer solutions with near-Nernstian response (about −55 mV/pH). The hysteretic widths of the nanocomposite electrode are 6.4 mV, 5.1 mV and 10.2 mV in pH 7-4-7-10-7, pH 7-10-7-4-7 and pH 2-8-12-8-2 loop cycles, respectively. Moreover, the RuO2/MWCNTs electrode displays an excellent anti-interference property and fast response time (less than 40 s). According to the electrochemical impedance measurements, the pH sensing properties of the RuO2/MWCNTs electrode were also discussed. 相似文献
6.
Hydrous RuO2 particles were electrochemically loaded into poly(3,4-ethylenedioxythiophene) doped poly(styrene sulfonic acid), PEDOT-PSS, matrix by employing various potential cycles in cyclic voltammetry and to fabricate the PEDOT-PSS-RuO2·xH2O electrode. The amount of hydrous RuO2 particles loaded into the PEDOT-PSS matrix was easily controlled by varying the number of potential cycles. Scanning electron microscopy photographs reveal a uniform dispersion of hydrous RuO2 particles in the porous structure of PEDOT-PSS matrix. Raman spectrum confirms the incorporation of hydrous RuO2 into PEDOT-PSS matrix. Chronopotentiometry and cyclic voltammetry were employed in 0.5 M H2SO4 to evaluate the capacitor properties. Specific capacitance values were determined by chronoamperometry. An increasing trend in specific capacitance with loaded amount of hydrous RuO2 particles in PEDOT-PSS was noticed. A maximum specific capacitance of 653 F/g was achieved. 相似文献
7.
Bo Gao 《Electrochimica acta》2010,55(11):3681-11258
Amorphous RuO2·xH2O was well coated on the benzenesulfonic functionalized multi-wall carbon nanotubes (f-MWCNTs) successfully via hydrothermal method. The decorated benzenesulfonic groups served as a bifunctional role both for solubilizing and dispersing MWCNTs into aqueous solution and for tethering Ru3+ precursor to facilitate the following uniform chemical deposition of RuO2·xH2O. The electrochemical performance of RuO2/f-MWCNTs and utilization of RuO2·xH2O were evidenced by cyclic voltammetry and galvanostatic charge/discharge tests. The specific capacitance of 1143 Fg−1 for RuO2·xH2O was obtained from RuO2/f-MWCNTs with 32 wt.% RuO2·xH2O, which was much higher than that of just 798 Fg−1 for the RuO2/p-MWCNTs. Even though the RuO2·xH2O loading increases to 45 wt.%, the utilization of RuO2·xH2O still possesses as high as 844.4 Fg−1, indicating a good energy capacity in the case of high loading. 相似文献
8.
Hydrous ruthenium dioxide (RuO2·xH2O) prepared in a modified sol-gel process was subjected to annealing in air and water at various temperatures for supercapacitor applications. The textural and pseudocapacitive characteristics of RuO2·xH2O annealed in air and water were systematically compared to show the benefits of annealing in water (denoted as hydrothermal annealing). An important concept that hydrothermal annealing effectively restricts condensation of hydroxyl groups within nanoparticles, inhibits crystal growth, and maintains high water content of RuO2·xH2O is demonstrated in this work. The unique textural characteristics of hydrothermally annealed RuO2·xH2O are attributable to the high-pressured, water-enriched surroundings which restrain coalescence of RuO2·xH2O nanocrystallites. The crystalline, hydrous nature of hydrothermally annealed RuO2·xH2O favors the utilization of active species in addition to a merit of minor dependence of specific capacitance on the scan rate of CV for pseudocapacitors. As a result, RuO2·xH2O with hydrothermal annealing at 225 °C for 24 h exhibits 16 wt.% water, an average particle size of about 7 nm, and specific capacitance of ca. 390 F g−1. 相似文献
9.
Composites are prepared by deposition of nanoparticles of RuO2·xH2O (1-4 nm) on two carbons: microporous carbon (1.3 nm of average micropore size) and mesoporous carbon (11 nm of average mesopore size). Two-preparation procedures are used: (i) procedure A consisting of repetitive impregnations of the carbons with RuCl3·0.5H2O solutions, and (ii) procedure B based on impregnation of the carbons with Ru(acac)3 vapour. The procedure B leads to supported RuO2·xH2O particles that appear more crystalline than those obtained by the procedure A. Specific capacitance and specific surface area of the composites are discussed as functions of the RuO2 content, and different dependences for the composites derived from the two carbons are found. Mesoporous carbon is better support than microporous carbon. Procedure A leads to supported RuO2·xH2O particles with higher specific capacitance than the particles deposited by procedure B. 相似文献
10.
Improvement in both sensor's characteristics and antifouling resistance has been achieved by utilising Cu2O as a dopant to the sub-micron-sized RuO2 sensing electrode (SE) of the water quality sensors. 20 mol% Cu2O-doped RuO2-SE has exhibited a linear response to dissolved oxygen (DO) between 0.5 and 8.0 ppm at various temperatures with the sensitivity slope of −46 mV/decade. This paper describes the structural properties and characteristics of thin-film Cu2O-doped RuO2-SE subjected to a field trial in sewerage environment for three months. Selectivity measurements revealed that the presence of PO43−, SO42−, Ca2+, Mg2+, Li+, NO3−, F−, Na+, K+ and Cl− in the test solution had no significant effect on the sensor's emf. Long-term stability test in harsh sewerage environment demonstrated that the Cu2O-doped RuO2-SE possesses improved antifouling resistance compared to RuO2-SE. Morphology and crystalline structure of Cu2O-doped RuO2-SE were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and Raman spectroscopy. 相似文献
11.
Two-step hydrothermal synthesis of Ru-Sn oxide composites for electrochemical supercapacitors 总被引:1,自引:0,他引:1
A two-step hydrothermal process was developed to synthesize hydrous 30RuO2-70SnO2 composites with much better capacitive performances than those fabricated through the normal hydrothermal process, co-annealing method, or modified sol-gel procedure. A very high specific capacitance of RuO2 (CS,Ru), ca. 1150 F g−1, was obtained when this composite was synthesized via this two-step hydrothermal process with annealing in air at 150 °C for 2 h. The voltammetric currents of this annealed composite were found to be quasi-linearly proportional to the scan rate of CV (up to 500 mV s−1), demonstrating its excellent power property. From Raman, UV-vis spectroscopic and TEM analyses, the reduction in mean particulate size is clearly found for this two-step oxide composite, attributable to the co-precipitation of (RuδSn1−δ)O2·xH2O onto partially dissolved SnO2·xH2O and the formation of (RuδSn1−δ)O2·xH2O crystallites in the second step. This effect significantly promotes the utilization of RuO2 (i.e., very high CS,Ru). The excellent capacitive performances, very similar to that of RuO2·xH2O, suggest the deposition of RuO2-enriched (RuδSn1−δ)O2·xH2O onto SnO2·xH2O seeds as well as the individual formation of (RuδSn1−δ)O2·xH2O crystallites in the second hydrothermal step. 相似文献
12.
Effects of the sodium acetate (NaCH3COO, denoted as NaAcO) concentration, plating temperature, and oxide loading on the pseudocapacitive characteristics of hydrous ruthenium oxide (denoted as RuO2·xH2O) films anodically plated from aqueous RuCl3·xH2O media were systematically investigated in this work. The electrochemical behavior of RuO2·xH2O with annealing in air at 200 °C for 2 h is approximately independent of the NaAcO concentration and plating temperature although a negative shift in the onset and peak potentials of deposition with rising the plating temperature is found. The morphologies and adhesion of RuO2·xH2O deposits strongly depend on the deposition rate which is obviously influenced by varying the above two deposition variables. The specific capacitance of RuO2·xH2O is monotonously decreased from 760 to 505 F g−1 when the oxide loading is gradually increased from 0.34 to 1.0 mg cm−2, due to the longer pathways of both electrons and protons during the redox transitions. The XRD and Raman spectroscopic analyses reveal the extremely localized crystalline nature of as-deposited RuO2·xH2O. All RuO2·xH2O deposits show the ideal pseudocapacitive characteristics, definitely illustrating the merits of RuO2·xH2O prepared by anodic deposition without considering the advantages of its simplicity, one-step, reliability, low cost, and versatility for electrode preparation. 相似文献
13.
Wataru Sugimoto 《Electrochimica acta》2004,49(2):313-320
The pseudocapacitance of nanocrystalline RuO2 with BET surface area of 42 m2 g−1 was evaluated using a RuO2 modified Glassy Carbon (RuO2/GC) thin film electrode. The charge storage behavior of the RuO2/GC thin film electrode was studied from fast to slow scan cyclic voltammetry between various potential windows. The utilization of the thin film electrode method for nanocrystalline RuO2 with known specific surface area allowed a semi-quantitative understanding of the electric double-layer capacitance (Cdl), adsorption related charge (Cad), and the irreversible redox related charge (Cirr) per unit mass and surface area of RuO2. Comparison of the cyclic voltammograms between different voltage windows revealed that the contribution from Cirr is especially dominant below 0.4 V (versus RHE) at slow scan rates. 相似文献
14.
Tm3+ doped KF–YbF3 nanocrystals were synthesized by a hydrothermal method using oleic acid as a stabilizing agent at 190 °C. The influence of Gd3+ and Sm3+ content on the phase structure and upconversion (UC) emission of the final products was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UC spectra. XRD analyses and TEM observations evidence that the phase and size of the as prepared Tm3+ doped KF–YbF3 nanocrystals are closely related to the Gd3+ doping content. Without Gd3+ impurity, the undoped nanocrystals crystallize in orthorhombic KYb2F7 with an average diameter of 42 nm. When the Gd3+ doping is below 10 mol%, the orthorhombic KYb2F7 nanocrystals grow up. However, with Gd3+ addition beyond about 30 mol%, the complete phase transformation from orthorhombic KYb2F7 to cubic KGdF4 occurs in the final products. Under the excitation of a 980 nm laser diode, the as prepared Tm3+ doped nanocrystals exhibit strong near-infrared UC emission at 800 nm. Particularly, the intensity of high energy UV and blue UC emissions of Tm3+ ions in Tm3+ doped KYb2F7 nanocrystals are selectively reduced compared to the NIR emission at 800 nm by co-doping a small amount of Sm3+ ions into the host matrix. Possible dynamic processes for UC emissions in Tm3+ doped nanocrystals are discussed in detail. 相似文献
15.
Graphene oxide nano-platelets were produced from helical-ribbon carbon nanofibers by oxidation with KMnO4/H2SO4 and further exfoliation by ultrasonication. The KMnO4 to carbon nanofiber ratio is 1:1. TEM and AFM were used to characterize the samples. TEM shows individual nanocrystals with straight edges and SAED yields a hexagonal spot pattern arrangement, attributed to graphene layers. The thickness of the nanocrystals, measured by AFM, is approximately 1.7 nm, which corresponds to a single layer of hydrated graphene oxide. 相似文献
16.
SnO2/multi-walled carbon nanotube (MWCNT) composites were prepared by the solvothermal method and subsequent heat treatment at 360 °C. The samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Results on the higher SnO2 content composite sample indicate that a uniform layer of SnO2 nanocrystals with crystal size around 5 nm was deposited on the surface of the carbon nanotubes. The composite demonstrates a reversible lithium storage capacity of 709.9 mAh g−1 at the first cycle and excellent cyclic retention up to 100 cycles as anode for lithium ion batteries. 相似文献
17.
Ping Shen Xinping LiuShenghui Jiang Ling WangLing Yi Dandan YeBin Zhao Songting Tan 《Dyes and Pigments》2012,92(3):1042-1051
Four novel D-π-A hydrazone dyes (HT, HM, HE, and HO) with an N, N-diphenylhydrazone moiety as the electron donor, different thiophene-derived π-conjugated bridges and a cyanoacrylic acid moiety as the electron acceptor have been designed and synthesized for the application in dye-sensitized solar cells. The influences of thiophene-derived bridges on the photoelectrochemical and photovoltaic performance of these hydrazone dyes were investigated. Results demonstrate that the introduction of 3,4-dialkyloxythiophene could red-shift the dye’s absorption spectrum due to the enhancement of the electron-donating ability of π-conjugated bridges. Importantly, electrochemical impedance spectroscopy analysis reveal that 3,4-dialkyloxythiophene bridge could change the charge recombination resistance at the TiO2/dye/electrolyte interface and as a result to improve the open-circuit photovoltage. Among the four dyes, HO exhibits the maximum power conversion efficiency of 5.83% (Voc = 0.65 V, Jsc = 12.69 mA/cm2, FF = 0.707) under simulated AM 1.5 irradiation (100 mW/cm2). 相似文献
18.
Yang Liu 《Electrochimica acta》2008,53(8):3296-3304
Co3O4/RuO2·xH2O composites with various Ru content (molar content of Ru = 5%, 10%, 20%, 50%) were synthesized by one-step co-precipitation method. The precursors were prepared via adjusting pH of the mixed aqueous solutions of Co(NO3)2·6H2O and RuCl3·0.5H2O by using Pluronic123 as a soft template. For the composite with molar ratio of Co:Ru = 1:1 annealed at 200 °C, Brunauer-Emmet-Teller (BET) results indicated that the composite showed mesoporous structure, and the specific surface area of the composite was as high as 107 m2 g−1. The electrochemical performances of these composites were measured in 1 M KOH electrolyte. Compared with the composite prepared without template, the composite with P123 exhibited a higher specific capacitance. When the molar content of Ru was rising, the specific capacitance of the composites increased significantly. It was also observed that the crystalline structures as well as the electrochemical activities were strongly dependent on the annealing temperature. A capacitance of 642 F/g was obtained for the composite (Co:Ru = 1:1) annealed at 150 °C. Meanwhile, the composites also exhibited good cycle stability. Besides, the morphologies and textural characteristic of the samples were also investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM). 相似文献
19.
Carbon-supported IrO2 and RuO2 were prepared using an incipient wetness method and were then calcinated at various temperatures. IrO2/C and RuO2/C are less expensive than the conventional Pt/C material and more stable than metal Ni in an acidic electrolyte. Moreover, IrO2/C and RuO2/C are not influenced by under potential deposition (UPD) and show lower sensitivity to poisoning by Ni or Fe impurities. The physical properties of IrO2/C and RuO2/C were investigated via XRD and TEM. Cyclic voltammograms (CV) and Tafel plots were used to provide information regarding surface redox reaction and electrocatalytic activity. The activity and durability of IrO2/C and RuO2/C were studied after prolonged potential cycling between −0.3 and 0.3 VSCE. After comparison of Tafel plots of Pt/C and IrO2/C after activation, it was observed that they have similar electrocatalytic activities in a hydrogen evolution reaction (HER). A single cell test with solid polymer electrolyte (SPE) proved that the performance of IrO2/C (0.5 mg cm−2) was similar to that of Pt/C (0.5 mg cm−2). 相似文献
20.
The 3D mesoporous, well crystalline RuO2 film prepared via the evaporation-induced self-assembled method (EISA) successfully demonstrates the extremely high power performances (e.g., excellent capacitive behavior at 10,000 mV s−1, ultrahigh-frequency capacitive responses (the absence of a knee point in the Nyquist plot), and 2.6 MW kg−1 with an acceptable energy density of 4.6 Wh kg−1). These excellent capacitive performances were identified by means of voltammetric and electrochemical impedance spectroscopic (EIS) analyses. The mesoporous (with mean pore spacing of 18.1 nm) and crystalline nature of this film was characterized by means of the field emission scanning electron microscopy (FE-SEM), Brunaur-Emmett-Teller (BET) method, small-angle X-ray scattering (SAXRS), high-resolution transmission electron microscopy (HR-TEM), electron diffraction (ED), and X-ray diffraction (XRD) analyses. This mesoporous, well crystalline RuO2 film constrains the redox transition to the superficial region meanwhile the tailored mesoporous structure increases the electrochemically active centers, promotes the penetration of electrolytes, provides the “proton reservoirs”, and enhances the rate of electron transport simultaneously for the ultrahigh power application. The specific capacitance of this mesoporous RuO2 can be enhanced from 84 to 185 F g−1 after the microwave-assisted hydrothermal treatment. 相似文献