112 research outputs found
Maximizing Ru-YSZ-Au battery capacity using an interfacial Ru:YSZ intermixed layer
In the advanced materials and technology landscape, pursuing high-performance energy storage solutions for operating at elevated temperatures remains challenging. This study investigates the enhancement of a Ru-YSZ-Au energy storage device by incorporating an intermixed Ru:YSZ1:1 layer at the Ru/YSZ interface via atomic layer deposition. The structural and optical characterization through transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and ellipsometry confirmed the presence of metallic Ru within the YSZ matrix. Electrical measurements showed that this intermixed layer enhances the energy capacity, achieving a 230 % improvement in energy density compared to the reference device. However, introducing this layer also causes a voltage drop of 0.5 V, potentially due to defects formed during the atomic layer deposition of the Ru:YSZ1:1 layer. Despite this, the Ru-Ru:YSZ1:1-YSZ-Au device exhibits superior performance, demonstrating longer discharge times and higher energy densities, rivaling solid-state Li-ion micro-batteries across a wide temperature range
Effect of gold electronic state on the catalytic performance of nano gold catalysts in n-octanol oxidation
UIDB/50006/2020 project VIU-RSCBMT-65/2019 project 18-29-24037 (Russia) MINECO project CTQ2017-86170-R (Spain)This study aims to identify the role of the various electronic states of gold in the catalytic behavior of Au/MxOy/TiO2 (where MxOy are Fe2O3 or MgO) for the liquid phase oxidation of n-octanol, under mild conditions. For this purpose, Au/MxOy/TiO2 catalysts were prepared by deposition-precipitation with urea, varying the gold content (0.5 or 4 wt.%) and pretreatment conditions (H2 or O2), and characterized by low temperature nitrogen adsorption-desorption, X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDX), scanning transmission electron microscopy-high angle annular dark field (STEM HAADF), diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy of CO adsorption, temperature-programmable desorption (TPD) of ammonia and carbon dioxide, and X-ray photoelectron spectroscopy (XPS). Three states of gold were identified on the surface of the catalysts, Au0, Au1+ and Au3+, and their ratio determined the catalysts performance. Based on a comparison of catalytic and spectroscopic results, it may be concluded that Au+ was the active site state, while Au0 had negative effect, due to a partial blocking of Au0 by solvent. Au3+ also inhibited the oxidation process, due to the strong adsorption of the solvent and/or water formed during the reaction. Density functional theory (DFT) simulations confirmed these suggestions. The dependence of selectivity on the ratio of Brønsted acid centers to Brønsted basic centers was revealed.publishersversionpublishe
Homogeneidade e heterogeneidade nos sistemas educacionais: Argentina, Brasil, Chile e México
Fabrication of macro-mesoporous zirconia-alumina materials with a one-dimensional hierarchical structure
A series of one dimensional (1D) zirconia/alumina nanocomposites were prepared by the deposition of zirconium species onto the 3D framework of boehmite nanofibres formed by dispersing boehmite nanofibres into butanol solution. The materials were calcined at 773K and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), N2 adsorption/desorption, infrared emission spectroscopy (IES). The results demonstrated that when the molar percentage X=100*Zr/(Al+Zr) was > 30 %, extremely long ZrO2/Al2O3 composite nanorods with evenly distributed ZrO2 nanocrystals on the surface were formed. The stacking of such nanorods gave rise to a new kind of macroporous material without the use of any organic space filler\template or other specific technologies. The mechanism for the formation of long ZrO2/Al2O3 composite nanorods was proposed in this work
pH-Sensitive electrical behavior of 4-vinylpyridine grafts on poly(propylene) films
AbstractAn interesting, electrical behavior of Poly(4-vinylpyridine) was observed at different pH values. 4-vinylpyridine was grafted onto mechanically durable poly(propylene) films to synthesize a pH responsive hydrogel. We have focused on the influence of temperature and pH on the electrical behavior response of hydrogel. An abrupt increase of its electrical resistance from 5 to 20 X106 Ω was observed when the hydrogel (100% grafted) was swelled on phosphate buffer solutions with pH value of 4 and 8 respectively
Onset of electronic conductivity in nanometer thick films of yttria stabilized zirconia (YSZ) at high electric fields
Onset of electronic conductivity in nanometer thick films of yttria stabilized zirconia (YSZ) at high electric fields
Understanding the first half-ALD cycle of the ZnO growth on hydroxyl functionalized carbon nanotubes
Initial stages of the ZnO growth on hydroxyl functionalized carbon nanotubes: the first half-ALD reaction mediated by a ligand exchange reaction.</p
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