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1.
Electrocatalytic oxygen reduction was studied on a RuxFeySez(CO)n cluster catalyst with Vulcan carbon powder dispersed into a Nafion film coated on a glassy carbon electrode. The synthesis
of the electrocatalyst as a mixture of crystallites and amorphous nanoparticles was carried out by refluxing the transition
metal carbonyl compounds in an organic solvent. Electrocatalysis by the cluster compound is discussed, based on the results
of rotating disc electrode measurements in a 0.5 M H2SO4. A Tafel slope of −80.00±4.72 mV dec−1 and an exchange current density of 1.1±0.17×10−6 mA cm−2 was calculated from the mass transfer-corrected curve. It was found that the electrochemical reduction reaction follows the
kinetics of a multielectronic (n=4e−) charge transfer process producing water, i.e. O2+4H++4e−→2H2O.
Electronic Publication 相似文献
2.
The metathesis of ethene and 2-butene to propene was studied over WO3/SiO2 catalysts with various WO3 loadings (2, 4, 8, 12, 16, and 24 wt%). The 2-butene conversion and propene selectivity increased greatly with WO3 loading increasing from 2 to 8 wt%, reached maximum at 8–12 wt% WO3 loading, and then decreased when the WO3 loading was higher than 12 wt%. From the above results and taking the economics into account, the optimal amount of WO3 loading was ~8 wt%. The catalysts were characterized by physico-chemical and spectroscopic techniques to elucidate the effect
of different tungsten oxide loadings on the metathesis reactivity of ethene and 2-butene. The characterization data indicated
that three types of tungsten species (i.e., surface tetrahedral tungsten species, surface octahedral polytungstate species,
and WO3 crystallites) were present in the catalysts. It was found that WO3 was not the active centers, and surface tetrahedral tungsten species might be more active than octahedral polytungstate species
in metathesis reaction. The reduced form of tungsten species [W+4, W+5, and W+(6−y) (0 < y < 1)] may be the suitable state of W species acting as metathesis active centers. 相似文献
3.
Yuzhong Zhang Guiying Jin Wangxing Cheng 《Journal of Solid State Electrochemistry》2006,10(4):260-263
The stable electroactive thin film of rhein has been investigated by cyclic voltammetry and electrochemical impedance spectroscopy.
Electrochemical impedance spectroscopy of the electrodeposited film derived from rhein indicated the electrode reaction was
kinetically controlled in the region of higher frequency, the charge transfer resistance was 2.6×103 Ω cm2 and capacitance value was 13.2 μF cm2 . The electrodeposited film derived from rhein exhibited a good electrocatalytic activity for myoglobin (Mb) reduction. In
0.30 mol dm−3 H2SO4solution, the catalysis currents were proportional to the concentrations of Mb over the range of 1.5×10−7–1.3×10−5 mol dm−3. The detection limit is 1.0×10−7 mol dm−3 (S/N=3). The relative standard deviation is 4.8% for eight successive determinations of 5.0×10−7 mol dm−3 Mb. 相似文献
4.
A. D. Chervonnyi 《Russian Journal of Inorganic Chemistry》2010,55(4):556-559
The A1, O, AlO, A12O, Al2O2, WO2, and WO3, partial pressures in the vapor over Al2O3 in a tungsten Knudsen effusion cell between 2300 and 2600 K were derived from A1+, O+, AlO+, A12O+, Al2O2+, WO2+, and WO3+, ion intensities. The mass spectrometer was calibrated against the equilibrium constant of the WO3(g) = WO2(g) + O(g) reaction. Refined values of the ionization cross sections of AlO and A12O2 were used in the partial pressure calculations. The enthalpies of atomization of aluminum suboxides were determined to be
Δat
H
o(AlO, g, 0) = 510.7 ± 3.3 kJ mol−1, Δat
H
o(Al2O, g, 0) = 1067.2 ± 6.9 kJ mol−1, and Δat
H
o(Al2O2, g, 0) = 1556.7 ± 9.9 kJ mol−1. 相似文献
5.
Falong Jia Chuanfang Yu Jingming Gong Lizhi Zhang 《Journal of Solid State Electrochemistry》2008,12(12):1567-1571
Prussian blue-modified nanoporous gold film (PB-NPGF) electrode was fabricated in this study. The fabrication was realized
through electrodeposition of Prussian blue nanoparticles on the skeleton of a nanoporous gold film electrode without destroying
the porous structure of NPGF electrode. The resulting PB-NPGF composite electrode showed very high electrocatalytic activity,
repeatability, and stability to the reduction of H2O2. For instance, its activity was about twenty times that of the PB-modified polished gold electrode. More importantly, the
sensitivity of the PB-NPGF composite electrode reaches as high as 10.6 μA μM−1 cm−2. This PB-NPGF composite electrode is very promising in the fields of catalysis, analysis, and so on. 相似文献
6.
Satoshi Kaneco Kenji Iiba Hideyuki Katsumata Tohru Suzuki Kiyohisa Ohta 《Journal of Solid State Electrochemistry》2007,11(4):490-495
The electrochemical reduction of CO2 with a Cu electrode in methanol was investigated with sodium hydroxide supporting salt. A divided H-type cell was employed;
the supporting electrolytes were 80 mmol dm−3 sodium hydroxide in methanol (catholyte) and 300 mmol dm−3 potassium hydroxide in methanol (anolyte). The main products from CO2 were methane, ethylene, carbon monoxide, and formic acid. The maximum current efficiency for hydrocarbons (methane and ethylene)
was 80.6%, at −4.0 V vs Ag/AgCl, saturated KCl. The ratio of current efficiency for methane/ethylene, r
f(CH4)/r
f(C2H4), was similar to those obtained in LiOH/methanol-based electrolyte and larger relative to those in methanol using KOH, RbOH,
and CsOH supporting salts. In NaOH/methanol-based electrolyte, the efficiency of hydrogen formation, a competing reaction
of CO2 reduction, was suppressed to below 4%. The electrochemical CO2 reduction to methane may be able to proceed efficiently in a hydrophilic environment near the electrode surface provided
by sodium cation. 相似文献
7.
Tanţa Spătaru Maria Marcu Loredana Preda Petre Osiceanu Jose Maria Calderon Moreno Nicolae Spătaru 《Journal of Solid State Electrochemistry》2011,15(6):1149-1157
Polytyramine (PTy) is shown to be a possible alternative to other conducting polymers as a support material for fuel cell
electrocatalysts such as platinum. In this work, a Pt–PTy composite was prepared via potentiodynamic deposition of polytyramine
on graphite substrate, followed by the electrochemical deposition of Pt nanoparticles. The material obtained by this straightforward
method exhibited, for platinum loadings as low as ca. 0.12 mg cm−2, a specific electrochemically active surface area of the electrocatalyst of ca. 54 m2 g−1, together with a good electrocatalytic activity for methanol oxidation in acidic media, thus ensuring better efficiency of
Pt utilization. The system Pt–PTy appears to be worthy of development for methanol fuel cell applications also because the
results suggested that, when deposited as small particles in a PTy matrix, platinum is less sensitive to fouling during CH3OH oxidation. 相似文献
8.
H. López-González M. Jiménez-Reyes M. Solache-Ríos A. Rojas-Hernández 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(1):103-108
Solubility product (Lu(OH)3(s)⇆Lu3++3OH−) and first hydrolysis (Lu3++H2O⇆Lu(OH)2++H+) constants were determined for an initial lutetium concentration range from 3.72·10−5 mol·dm−3 to 2.09·10−3 mol·dm−3. Measurements were made in 2 mol·dm−3 NaClO4 ionic strength, under CO2-free conditions and temperature was controlled at 303 K. Solubility diagrams (pLuaq vs. pC
H) were determined by means of a radiochemical method using 177Lu. The pC
H for the beginning of precipitation and solubility product constant were determined from these diagrams and both the first
hydrolysis and solubility product constants were calculated by fitting the diagrams to the solubility equation. The pC
H values of precipitation increases inversely to [Lu3+]initial and the values for the first hydrolysis and solubility product constants were log10
β*
Lu,H
= −7.92±0.07 and log10
K*sp,Lu(OH)3 = −23.37±0.14. Individual solubility values for pC
H range between the beginning of precipitation and 8.5 were S
Lu3+ = 3.5·10−7 mol·dm−3, S
Lu(OH)2+ = 6.2·10−7 mol·dm−3, and then total solubility was 9.7·10−7 mol·dm−3. 相似文献
9.
Zh. A. Kochkarov M. V. Khubaeva Z. L. Khakulov 《Russian Journal of Inorganic Chemistry》2011,56(5):783-786
This is the first study of the NaBO2-Na2CO3-Na2MoO4-Na2WO4 quaternary system by differential thermal analysis. Na2[MoO4(x)WO4(1 − x)] solid solutions in the quaternary system are found to not decompose. 相似文献
10.
M. H. Pournaghi-Azar H. Dastangoo M. Ziaei 《Journal of Solid State Electrochemistry》2007,11(9):1221-1227
The electrocatalytic activity of a Prussian blue (PB) film on the aluminum electrode by taking advantage of the metallic palladium
characteristic as an electron-transfer bridge (PB/Pd–Al) for electrooxidation of 2-methyl-3-hydroxy-4,5-bis (hydroxyl–methyl)
pyridine (pyridoxine) is described. The catalytic activity of PB was explored in terms of FeIII [FeIII (CN)6]/FeIII [FeII (CN)6]1− system. The best mediated oxidation of pyridoxine (PN) on the PB/Pd–Al-modified electrode was achieved in 0.5 M KNO3 + 0.2 M potassium acetate of pH 6 at scan rate of 20 mV s−1. The mechanism and kinetics of the catalytic oxidation reaction of PN were monitored by cyclic voltammetry and chronoamperometry.
The results were explained using the theory of electrocatalytic reactions at chemically modified electrodes. The charge transfer-rate
limiting reaction step is found to be a one-electron abstraction, whereas a two-electron charge transfer reaction is the overall
oxidation reaction of PN by forming pyridoxal. The value of α, k, and D are 0.5, 1.2 × 102 M−1 s−1, and 1.4 × 10−5 cm2 s−1, respectively. Further examination of the modified electrodes shows that the modifying layers (PB) on the Pd–Al substrate
have reproducible behavior and a high level of stability after posing it in the electrolyte or Pyridoxine solutions for a
long time. 相似文献
11.
A new ternary ion-association complex of tungsten(VI), 4-nitrocatechol (NC), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide (Thiazolyl Blue, MTT) was obtained and studied using an extraction-spectrophotometric method. The optimum pH, reagent
concentrations, and extraction time were determined. The composition of the complex was found to be W(VI): NC: MTT = 1: 2:
2. The extraction process was investigated quantitatively and the key constants were calculated. The molar absorptivity of
the chloroform extract at λmax = 415 nm was 2.8 × 104 dm3 mol−1 cm−1, and the Beer’s law was obeyed up to 8.8 μg cm−3 tungsten(IV). The limit of detection and limit of quantification were calculated to be 0.27 μg cm−3 and 0.92 μg cm−3, respectively. The effect of foreign ions and reagents was studied and a competitive method for determination of tungsten
in products from ferrous metallurgy was developed. The residual standard deviation and the relative error were 0.53 % and
0.2 %, respectively. 相似文献
12.
Camilo A. Angelucci L. Jay Deiner Francisco C. Nart 《Journal of Solid State Electrochemistry》2008,12(12):1599-1603
The electro-oxidation of methanol at supported tungsten carbide (WC) nanoparticles in sulfuric acid solution was studied using
cyclic voltammetry, potentiostatic measurements, and differential electrochemical mass spectroscopy (DEMS). The catalyst was
prepared by a sonochemical method and characterized by X-ray diffraction. Over the WC catalyst, the oxidation of methanol
(1 M in a sulfuric acid electrolyte) begins at a potential below 0.5 V/RHE during the anodic sweep. During potentiostatic
measurements, a maximum current of 0.8 mA mg−1 was obtained at 0.4 V. Measurements of DEMS showed that the methanol oxidation reaction over tungsten carbide produces CO2 (m/z = 44); no methylformate (m/z = 60) was detected. These results are discussed in the context of the continued search for alternative materials for the
anode catalyst of direct methanol fuel cells.
In memoriam 相似文献
13.
Xiu-Bin Ren Hai-Yan Lu Hai-Bo Lin Ya-Nan Liu Yan Xing 《Russian Journal of Electrochemistry》2010,46(1):77-80
WO3 films have been prepared onto IrO2-coated Ti substrate by electro-deposition, and as-deposited and annealed films have been characterized by using Raman spectroscopy.
It was found that the asdeposited film consists of orthorhombic WO3 · H2O phase, which transforms to amorphous WO3 by annealing at 250°C and to monoclinic phase by annealing at and above 350°C. All electrochemical experiments were carried
on Ti/IrO2/WO3 annealed at 450°C. The open-circuit potential could change significantly due to the hydration of the coating film. However
this process is fairly slow. Reproducible voltammograms could be obtained quickly, further revealing high electrochemical
stability of the Ti/IrO2/WO3 electrode. And the shapes of CV show the approximate rectangular mirror image, showing the typical characteristic of capacitive
behavior. The specific capacitance obtained at a scan rate of 50 mV s−1 is 46 F g−1. 相似文献
14.
Elizabeth A. Turner Harald Rösner Yining Huang John F. Corrigan 《Journal of Cluster Science》2007,18(3):764-771
Mercury-selenosulfide (HgSe
x
S
1-x
) nanoparticles have been synthesized using the single-source reagent Me3Si–SeS–SiMe3. The reagent distributes Se2− and S2− to the metal core as the reaction between Me3Si–SeS–SiMe3 and mercury acetate occurs via a redox pathway, ultimately giving rise to Se–S bond cleavage. Particles are characterized
by EDX, TEM and powder X-ray diffraction analysis in conjunction with UV–Visible absorption spectroscopy.
Dedicated to Prof. Dr. Dieter Fenske on the occasion of his 65th birthday. 相似文献
15.
Single-phase LiCoPO4 nanoparticles were synthesized by solid-state reaction method and subsequent high-energy ball milling. The electrochemical
properties of LiCoPO4/Li batteries were analyzed by ac impedance experiments, cyclic voltammetry (CV), and charge/discharge tests. The structural
and morphological performance of LiCoPO4 nanoparticles was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron
microscope (TEM). The XRD result demonstrated that LiCoPO4 nanoparticles had an orthorhombic olivine-type structure with a space group of Pmnb. Different conductive additives including
acetylene black and carbon black (SP270) were used to fabricate electrodes. The morphologies of the electrodes and different
conductive additives were observed by field emission-scanning electron microscopy (FE-SEM). LiCoPO4/Li battery with acetylene black showed the best electrochemical properties, and exhibited a discharge plateau at around 4.7 V
with an initial discharge capacity of 110 mAh g−1 at a discharge current density of 0.05 mA cm−2 at 25 °C. 相似文献
16.
Deuk Yong Lee Kyong-Ho Lee Myung-Hyun Lee Nam-Ihn Cho Bae-Yeon Kim 《Journal of Sol-Gel Science and Technology》2010,53(1):43-49
Ba1−x
Sr
x
TiO3(x = 0–0.5, BST) nanofibers with diameters of 150–210 nm were prepared by using electrospun BST/polyvinylpyrrolidone (PVP) composite
fibers by calcination for 2 h at temperatures in the range of 650–800 °C in air. The morphology and crystal structure of calcined
BST/PVP nanofibers were characterized as functions of calcination temperature and Sr content with an aid of XRD, FT-IR, and
TEM. Although several unknown XRD peaks were detected when the fibers were calcined at temperatures less than 750 °C, they
disappeared with increasing the temperature (above 750 °C) due to its thermal decomposition and complete reaction in the formation
of BST. In addition, the FT-IR studies of BST/PVP fibers revealed that the intensities of the O–H stretching vibration bands
(at 3430 and 1425 cm−1) became weaker with increasing the calcination temperature and a broad band at 540 cm−1, Ti–O vibration, appeared sharper and narrower after calcination above 750 °C due to the formation of metal oxide bonds.
However, no effect of Sr content on the crystal structure of the composites was detected. 相似文献
17.
Exploring advanced electrocatalysts for electrocatalytic hydrogen evolution is highly desired but remains a challenge due to the lack of an efficient preparation method and reasonable structural design. Herein, we deliberately designed novel Ag/WO3?x heterostructures through a supercritical CO2‐assisted exfoliation‐oxidation route and the subsequent loading of Ag nanoparticles. The ultrathin and oxygen vacancies‐enriched WO3?x nanosheets are ideal substrates for loading Ag nanoparticles, which can largely increase the active site density and improve electron transport. Besides, the resultant WO3?x nanosheets with porous structure can form during the electrochemical cycling process induced by an electric field. As a result, the exquisite Ag/WO3?x heterostructures show an enhanced hydrogen evolution reaction (HER) activity with a low onset overpotential of ≈30 mV, a small Tafel slope of ≈40 mV dec?1 at 10 mA cm?2, and as well as long‐term durability. This work sheds light on material design and preparation, and even opens up an avenue for the development of high‐efficiency electrocatalysts. 相似文献
18.
E. Yu. Pikalova V. G. Bamburov A. A. Murashkina A. D. Neuimin A. K. Demin S. V. Plaksin 《Russian Journal of Electrochemistry》2011,47(6):690-696
CeO2-based solid solutions with a fluorite structure are promising materials as electrolytes of medium-temperature electrochemical
devices: electrolytic cells, oxygen sensors, and solid oxide fuel cells. In this work, studies are presented of the effect
of the dopant cation radius and its concentration on the physico-chemical properties of the Ce1 − x
Ln
x
O2 − δ solid solutions (x = 0–0.20; Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb) and also of multicomponent solid solutions of Ce1 − x
Ln
x/2Ln′
x/2O2 − δ (x = 0–0.20; Ln = Sm, La, Gd and Ln′ = Dy, Nd, Y) and Ce1 − x − y
Sm
x
M
y
O2 − δ (M = Ca, Sr, Ba) obtained using the solid-phase synthesis technique. Electric properties of the samples were studied in the
temperature range of 623–1173 K and in the oxygen partial pressure range of 0.01–10−22 MPa. The values of oxygen critical pressure ( pO2 * )\left( {p_{O_2 }^* } \right) are presented, at which the ionic and electron conductivity values are equal. The values were calculated on the basis of
experimental dependences at 1023 K at the assumption that the ionic conductivity value is determined only by the dopant concentration
and its effective ionic radius and is independent of the oxygen partial pressure. 相似文献
19.
The equilibria between tungsten(VI) and iminodiacetic acid (IDA) have been studied in aqueous solution. The stoichiometry
and stability constants of the complexes formed are determined from a combination of potentiometric and Uv spectroscopic measurements.
All measurements are carried out at 25°C, pH 7.5 and different ionic strengths ranging from (0.1 to 1.0) mol dm−3 (NaClO4). According to these results, tungsten(VI) forms a mononuclear complex with IDA of the type (WO3L2−). By introducing two empirical parameters C and D in the complex-formation reaction between tungsten(VI) and IDA, the dependence
of the dissociation and stability constants on ionic strength is described by a modified Debye-Huckel-type equation. Finally,
a pattern for the ionic strength dependence is obtained. 相似文献
20.
The rate constants of the reactions of the chlorine atom with C3F7I (k
1) and CF3I (k
2) have been measured using the resonance fluorescence of chlorine atoms in a flow reactor at 295 K: k
1 = (5.2 ± 0.3) × 10−12 cm3 molecule−1 s−1 and k
2 = (7.4 ± 0.6) × 10−13 cm3 molecule−1 s−1. No iodine atoms have been detected in the reaction products. 相似文献