排序方式: 共有64条查询结果,搜索用时 15 毫秒
31.
Gelines Moreno-Fernández Christoph Schütter José M. Rojo Stefano Passerini Andrea Balducci Teresa A. Centeno 《Journal of Solid State Electrochemistry》2018,22(3):717-725
This study is essentially based on innovative electrolytes such as the organic salt N-methyl-N-butylpyrrolidinium tetrafluoroborate (Pyr14BF4) dissolved in propylene carbonate (PC) and the pure ionic liquid (N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) and its solution in PC. Activated carbon cloths were used as self-standing binder-free electrodes. It is found that the presence of impurities in carbon electrodes may lead to electrolyte decomposition and electrode degradation which notably affect the electrochemical double-layer capacitor (EDLC) performance. Such processes greatly depend on the composition of both the electrode and the electrolyte, being much less significant with solvent-containing electrolytes. By raising the operation temperature to 60 °C, the EDLC performance in the ionic liquid Pyr14TFSI is notably improved due to a relevant decrease in the viscosity and increase in ionic conductivity. By contrast, the presence of impurities, e.g., Zn and Al, in the electrodes remarkably reduces the electrolyte stability and a thick layer of decomposition products completely covers the carbon fibers after cycling at high temperature. The ionic liquid in solution maintains the high maximum operative voltage of the net ionic liquid whereas its viscosity and ionic conductivity are close to those of the conventional Et4NBF4/PC. Furthermore, the presence of propylene carbonate as solvent prevents to some extent the ionic liquid degradation. 相似文献
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Arlandis J Centeno E Pollès R Moreau A Campos J Gauthier-Lafaye O Monmayrant A 《Physical review letters》2012,108(3):037401
We demonstrate a mesoscopic self-collimation effect in photonic crystal superlattices consisting of a periodic set of all-positive index 2D photonic crystal and homogeneous layers. We develop an electromagnetic theory showing that diffraction-free beams are observed when the curvature of the optical dispersion relation is properly compensated for. This approach allows us to combine slow-light regime together with self-collimation in photonic crystal superlattices presenting an extremely low filling ratio in air. 相似文献
34.
Centeno SP López-Tocón I Arenas JF Soto J Otero JC 《The journal of physical chemistry. B》2006,110(30):14916-14922
Surface-enhanced Raman spectra (SERS) of pyrimidine recorded on a silver electrode have been analyzed on the basis of a resonant Raman (RR) process involving photoexcited charge transfer (CT) states of the metal-adsorbate surface complex. The main feature of the SERS of benzene and azine derivatives is the enhancement of the totally symmetric ring stretching mode 8a due to Franck-Condon contributions related to the CT transition. Although this behavior is observed in the SERS of pyrimidine, its spectrum is also characterized by the strong enhancement of the nontotally symmetric mode 8b. This peculiar feature can be explained only by the redistribution of the Franck-Condon factors between the 8ab pair of vibrations originated by the descent in symmetry occurring when pyrimidine is bonded to silver nanoclusters. This conclusion is a new evidence of the main role of the RR-CT enhancement mechanism in the SERS of aromatic molecules and shows once again the usefulness of the methodology developed by our group in order to analyze these complex spectra. 相似文献
35.
The study of 28 porous carbons shows that the specific capacitance in the electrolyte (C(2)H(5))(4)NBF(4)/acetonitrile is relatively constant between 0.7 and 15 nm (0.094 ± 0.011 F m(-2)). The increase in pores below 1 nm and the lower values between 1 and 2 nm reported earlier are not observed in the present work. 相似文献
36.
Silvia A. Centeno Franziska Schulte Nora W. Kennedy Alejandro G. Schrott 《Applied Physics A: Materials Science & Processing》2011,105(1):55-63
The daguerreotype image, composed of nanosized silver–mercury or silver–mercury–gold amalgam particles formed on a polished
silver substrate, is particularly sensitive to deterioration by chlorine-containing compounds resulting in the formation of
AgCl that generates redeposited silver upon exposure to UV and visible lights. In the present study, alterations caused by
chlorides on daguerreotype test samples prepared following 19th century recipes were studied. The dependence of variations
in the production steps of daguerreotypes, such as multiple sensitization and gilding, on the impact of the exposure to chlorine
were analyzed by scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS) and atomic force microscopy (AFM),
complemented by X-ray fluorescence (XRF) and Raman spectroscopy. It was observed that AgCl nucleates on the image particles
and in the substrate defects, regardless of the particle density or the sensitization process. In gilded samples, Au was observed
over the image particles and the polished silver substrate as a tightly packed grainy layer, which conformably follows the
polishing irregularities. For the first time it is shown that Au preferentially accumulates on top of the image particles.
This gold layer does not protect the image from chlorine-induced deterioration. 相似文献
37.
L.F. Bobadilla C. García J.J. Delgado O. Sanz F. Romero-Sarria M.A. Centeno J.A. Odriozola 《Journal of magnetism and magnetic materials》2012
The influence of PVP on the magnetic properties of NiSn nanoparticles prepared by polyol method has been studied. NiSn nanoparticles exhibit superparamagnetic behavior although there is a ferromagnetic contribution due to particles agglomerated below the blocking temperature. The particle size is controlled by the addiction of PVP in varying amounts. The addition of PVP also favours the particles isolation, narrow the particle size distribution and decrease the interparticle interaction strength increasing the superparamagnetic contribution. 相似文献
38.
E. Centeno B. Vitoriano A. Campos A. Muñoz J. Villar E.F. Sánchez-Úbeda 《Annals of Operations Research》2003,120(1-4):45-57
In deregulated electrical systems, production schedule for power plants is the result of an auction process. In the Spanish case, this schedule includes two main concepts: energy production (to be actually produced) and secondary reserve (to maintain available). The generation company faces the problem of converting energy schedule into a power schedule, respecting the reserve schedule as well as technical constraints, and trying to accomplish different goals: to minimise the production costs, to obtain smooth shapes for the power schedules and to optimise eventual compensation in schedules. A weighted goal mixed integer programming model with a real-size application to deal with this problem is presented. 相似文献
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Modelling shows that the pore size distribution of microporous carbons determined by NLDFT only hides relatively small variations of the surface-related capacitance C/S between 0.7 and 1.3 nm. This suggests again that C/S in TEABF(4)-AN is 0.09 ± 0.01 F m(-2) for our typical carbons, including carbide-based samples. 相似文献