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1.
This communication studies the CO2 reduction reaction in H2O/CH3CN mixtures on nanostructured copper. It was found that the nanostructured copper electrode presents a well-defined voltammogram in acetonitrile, where it can be seen three signals related to adsorbed or surface attached (thin films) species. Also, it was found that the current density of CO2 reduction in mixtures H2O/CH3CN on nanostructured copper electrodes with a mole fraction around 0.25 is higher than those observed with mole fractions lower than 0.15 or higher than 0.35. Finally, nanostructured Cu electrodes show higher catalytic activity towards the CO2 reduction than copper electrode. 相似文献
2.
YX Chen A Lavacchi SP Chen F di Benedetto M Bevilacqua C Bianchini P Fornasiero M Innocenti M Marelli W Oberhauser SG Sun F Vizza 《Angewandte Chemie (International ed. in English)》2012,51(34):8500-8504
Improved performance through milling: A method for enhancing the catalytic activity of supported metal nanoparticles is reported. This method enhances the activity for the ethanol electro-oxidation of a supported palladium catalyst. The much higher catalytic performance is ascribed to the increased electrochemically active surface area as well as the generation of high-index facets at the milled nanoparticle surface. 相似文献
3.
Neutralization of the positive charge of the pyridinium cation (Pyr+)ads adsorbed at the mercury/water interface following electrochemical reduction is likely to provoke a very fast flat-to-perpendicular reorientation of the adsorbed species, thus rendering the perpendicularly adsorbed radical (Pyr)ads electrochemically inactive. Therefore, it cannot be ascertained by means of cyclic voltammetry whether dimerization of the (Pyr)ads radicals, which occurs in solution, also occurs at the mercury/water interface. 相似文献
4.
We present theoretical and experimental evidence for CO(2) adsorption on different sites of single walled carbon nanotube (SWNT) bundles. We use local density approximation density functional theory (LDA-DFT) calculations to compute the adsorption energies and vibrational frequencies for CO(2) adsorbed on SWNT bundles. The LDA-DFT calculations give a range of shifts for the asymmetric stretching mode from about -6 to -20 cm(-1) for internally bound CO(2), and a range from -4 to -16 cm(-1) for externally bound CO(2) at low densities. The magnitude of the shift is larger for CO(2) adsorbed parallel to the SWNT surface; various perpendicular configurations yield much smaller theoretical shifts. The asymmetric stretching mode for CO(2) adsorbed in groove sites and interstitial sites exhibits calculated shifts of -22.2 and -23.8 cm(-1), respectively. The calculations show that vibrational mode softening is due to three effects: (1) dynamic image charges in the nanotube; (2) the confining effect of the adsorption potential; (3) dynamic dipole coupling with other adsorbate molecules. Infrared measurements indicate that two families of CO(2) adsorption sites are present. One family, exhibiting a shift of about -20 cm(-1) is assigned to internally bound CO(2) molecules in a parallel configuration. This type of CO(2) is readily displaced by Xe, a test for densely populated adsorbed species, which are expected to be present on the highest adsorption energy sites in the interior of the nanotubes. The second family exhibits a shift of about -7 cm(-1) and the site location and configuration for these species is ambiguous, based on comparison with the theoretical shifts. The population of the internally bound CO(2) may be enhanced by established etching procedures that open the entry ports for adsorption, namely, ozone oxidation followed by annealing in vacuum at 873 K. Xenon displacement experiments indicate that internally bound CO(2) is preferentially displaced relative to the -7 cm(-1) shifted species. The -7 cm(-1) shifted species is assigned to CO(2) adsorbed on the external surface based on results from etching and Xe displacement experiments. 相似文献
5.
V. P. Kadysh Ya. P. Stradyn' E. L. Khanina G. Ya. Dubur D. Kh. Mutsenietse 《Chemistry of Heterocyclic Compounds》1985,21(1):95-99
A rotating disk-ring, graphite electrode was used to show that the first step in the electrochemical oxidation of substituted 2-oxo-1,2,3,4-tetrahydropyrimidines in anhydrous acetonitrile corresponds to a two-electron process and leads to the formation of the corresponding substituted 2-oxo-1,2-dihydropyrimidines. The electroreduction wave of 2-oxo-1,2-dihydropyrimidines on the ring electrode which appears at about –1.0 V is related to the reduction of the protonated oxidized species arising in the electrolysis. The electrochemical oxidation potentials of 11 hydrogenated 2-pyrimidones and electrochemical reduction-potentials of two 2-pyrimidines were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 117–121, January, 1985. 相似文献
6.
Yeung LK Lee CT Johnston KP Crooks RM 《Chemical communications (Cambridge, England)》2001,(21):2290-2291
Dendrimer-encapsulated nanoparticles are shown to be versatile catalysts for both the hydrogenation of styrene and Heck heterocoupling of iodobenzene and methacrylate in supercritical CO2 (scCO2). 相似文献
7.
Presented are two newly observed adstructures of adsorbed CO onto Pt(111), (2 x 2)-3CO-beta and (2 x 2)-4CO, observed during the structural evolution from the well-known (2 x 2)-3CO-alpha structure to the (square root 19 x square root 19)-13CO structure. 相似文献
8.
D. A. Matveev E. A. Arbuzova P. B. Kraikivskii N. F. Aprelkova V. A. Khutoryanskii K. M. Kryukova 《Russian Journal of Electrochemistry》2011,47(9):1022-1028
The methods of classical and ac polarography were used to study the electrochemical behavior of dihydroquercetin on a mercury
dropping electrode. This process occurs only in protonic media. The protonated and nonprotonated forms of dihydroquercetin
undergo electroreduction. The amount of electrons and protons participating in electroreduction of the studied flavonoid is
determined. The nature of currents measured in the processes of electrochemical reduction of dihydroquercetin is studied. 相似文献
9.
Qinggong Zhu Jun Ma Xinchen Kang Xiaofu Sun Jiayin Hu Guanying Yang Buxing Han 《中国科学:化学(英文版)》2016,59(5):551-556
Electrochemical reduction of CO2 to CO is an interesting topic. In this work, we prepared metal-free electrodes by depositing graphene oxide (GO), multi-walled carbon nanotube (MWCNT), and GO/MWCNT composites on carbon paper (CP) using electrophoretic deposition (EPD) method. The electrodes were characterized by different methods, such as X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical reduction of CO2 to CO was conducted on the electrodes in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4)/acetonitrile (MeCN) electrolyte, and the composition of the electrolyte influenced the reaction significantly. It was demonstrated that GO/MWCNT-CP electrode was very effective for the reaction in IL (90 wt%)/MeCN binary mixture, the Faradaic efficiency of CO and current density were even higher than those on Au and Ag electrodes in the same electrolyte. 相似文献
10.
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11.
The surface dynamics of adsorbed CO molecules formed by dissociative adsorption of HCHO at a polycrystalline Pt electrode/electrolyte solution interface was studied by picosecond time-resolved sum-frequency generation (TR-SFG) spectroscopy. A SFG peak at 2050-2060 cm(-1) was observed at the Pt electrode in HClO(4) solution containing HCHO at 0-300 mV (vs Ag/AgCl), indicating the formation of adsorbed CO at an atop site of the Pt surface as a result of dissociative adsorption of HCHO. The peak position varied with potential by approximately 33 cm(-1)/V, as previously found in an infrared reflection absorption spectroscopy (IRAS) study. Irradiation of an intense picosecond visible pulse (25 ps, 532 nm) caused an instant intensity decrease and broadening of the CO peak accompanied by the emergence of a new broad peak at approximately 1980 cm(-1) within the time resolution of the system. These results suggest a decrease and increase in the populations of CO adsorbed on atop and bridge sites, respectively, upon visible pump pulse irradiation. 相似文献
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13.
通过循环伏安法(CV)研究了玻碳电极上邻仲丁基苯酚(OSBP)的电化学行为.结果显示:在pH=8.0的磷酸盐缓冲液中,OSBP在玻碳电极上发生的氧化反应是受扩散控制的不可逆等电子、质子转移过程,且氧化产物部分被还原.氧化峰电流与浓度在5.0×10~(-6)~2.0×10~(-4)mol·L~(-1)之间呈良好的线性关系,检出限(S/N=3)为6.60×10~7mol·L~(-1).重复测定的相对标准偏差(RSD)为4.48%(n=7),加标回收率为86.2%~100.5%.结果令人满意. 相似文献
14.
Luisa F. Cueto Gustavo A. Hirata Eduardo M. Sánchez 《Journal of Sol-Gel Science and Technology》2006,37(2):105-109
The effect of electrochemical reduction of CO2 on the structure and morphology of titanium(IV) oxide thin films was examined after a fixed-potential bulk electrolysis process.
Films deposited on ITO (Indium-Tin Oxide) substrates were used as the working electrodes and 1-butyl-3-methylimidazolium tetrafluoroborate
([BMIm][BF4]) as solvent and as supporting electrolyte. Grazing incidence X-ray diffraction analysis performed before and after the electrolysis
process indicated no microstructural changes of the anatase films. X-ray photoelectron spectroscopy revealed peaks associated
with adsorbed carbonate ions at 288 eV and CO2 species at 293 eV, whereas Ti2p peaks displacements for CO2-saturated TiO2/ITO surfaces in [BMIm][BF4] revealed chemical bonding effects. Auger electron spectroscopy revealed a high carbon content on CO2-exposed films, and suggested a strong chemisorption of CO2 and CO32− species on the TiO2/ITO surface in [BMIm][BF4] solvent system. A significant decrease in carbon content after bulk electrolysis indicated that the CO2 electroreduction process is not controlled by either diffusion or by adsorption of CO2 on the TiO2/ITO electrode surface. 相似文献
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Cui Yanshuai Liang Bo Zhang Jin Wang Ran Sun Haotian Wang Longgang Gao Dawei 《Transition Metal Chemistry》2019,44(7):655-662
Transition Metal Chemistry - Palladium nanoparticles (Pd NPs) have been drawing great interest as catalysts for water treatment. Herein, high molecular weight polyethyleneimine (PEI) (molecular... 相似文献
17.
Dukštienė N. Sinkevičiūtė D. Tatariškinaitė L. 《Journal of Solid State Electrochemistry》2016,20(3):813-825
Journal of Solid State Electrochemistry - Preliminary results regarding the electrochemical behavior of Se(IV) in sodium citrate solution on a polycrystalline SnO2 electrode are presented. A... 相似文献
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V. V. Yanilkin N. V. Nastapova R. R. Fazleeva G. R. Nasretdinova E. D. Sultanova A. Yu. Ziganshina A. T. Gubaidullin A. I. Samigullina V. G. Evtugin V. V. Vorobev Yu. N. Osin 《Russian Chemical Bulletin》2018,67(2):215-229
Efficient mediated electrosynthesis of nanocomposite Au@р(MVCA8+-co-St) (~6 nm), in which ultrasmall Au nanoparticles (Au-NP) were bound in nanocapsules of water-soluble nanoparticles of соpolymer р(MVCA8+-co-St) of tetraviologen calix[4]resorcinol (MVCA8+) with styrene (St), was accomplished by the reduction of AuI in aqueous medium. The quanti- tative reduction of AuI was carried out using the theoretically necessary amount of electricity and was not accompanied by the deposition of metal on the electrode. Radical cations of viologen units MV?+ of the molecule р(MVCA4?+-co-St) adsorbed on the electrode and π-dimers MV?+···MV?+ of π-polymers [р(MVCA4?+-co-St)] n deposited on the electrode act- ed as the reducing agents with respect to AuI. During electrolysis, the nanoparticles agglo- merated to 37—50 nm. The nanocomposite particles dispersed in ethanol had sizes of 72±16 nm and also contained Au-NP with sizes of 51±8 and 19±3 nm. The catalytic activity of the nanocomposite in the reduction of p-nitrophenol with sodium borohydride was demon- strated. A similar reduction of AgCl nanoparticles (~250 nm) led to the formation of silver nanoparticles with crystallite sizes in the range of 7—11 nm, the process was inefficient, however, even when using 250% of electricity, an incomplete reduction of AgCl was still observed. 相似文献
20.
采用循环伏安法和示差脉冲伏安法研究了三磷酸腺苷(ATP)在TiO2掺杂碳纳米纤维(TiO2@CNF)修饰的碳离子液体电极表面(TiO2@CNF/CILE)的电化学行为。结果表明,ATP在TiO2@CNF/CILE表面有一个明显的氧化峰,在pH 3.0的Britton-Robinson(BR)缓冲溶液中修饰电极对ATP具有显著的电催化作用。纤维状的TiO2@CNF能够有效促进电子转移,增加电化学信号。当ATP浓度分别在4.0×10^-9~2.0×10^-6mol/L和2.0×10^-6~1.0×10^-4mol/L范围时,氧化峰电流与ATP浓度呈良好的线性关系,检测限为1.4 nmol/L。修饰电极可用于注射液中ATP的测定。 相似文献