Examinando por Autor "Torquemada, M. C."

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Acceso Abierto
2-D organization of silica nanoparticles on gold surfaces: CO2 marker detection and storage
(Royal Society of Chemistry, 2020-08-27) Cueto Díaz, E. J.; Gálvez Martínez, S.; Torquemada, M. C.; Valles González, M. P.; Mateo Martí, Eva; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Torquemada, M. C. [0000-0002-0438-3120]; Mateo Martí, E. [0000-0003-4709-4676]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
A single layer of silica nanoparticles with an average size of ∼200 nm was deposited over the surface of pristine gold wafers, aided by (3-mercaptopropyl)trimethoxysilane. The nanoparticle immobilization was driven by covalent bonding rather than a self-assembly process, leading to a cluster-assembled material which has CO2 sensing features. Here, we show how this device can be used for CO2 physisorption and chemisorption. We analyse the device, both spectroscopically and morphologically, before and after exposure to an atmosphere of 7 mbar of CO2, inside a planetary atmospheres and surfaces simulation chamber, (PASC) mimiking Martian atmospheric conditions. Our studies demonstrate that these clusters are suitable for CO2 detection and storage, under well controlled experimental Martian conditions. Their high sensitivity at a very low concentration of CO2, 12.4 ppm, makes them ideal candidates in the nanosensor field.
Acceso Abierto
APTES-Based Silica Nanoparticles as a Potential Modifier for the Selective Sequestration of CO2 Gas Molecules
(Multidisciplinary Digital Publishing Institute, 2021-10-10) Cueto Díaz, Eduardo J.; Valles González, M. P.; Torquemada, M. C.; Gálvez Martínez, Santos; Suárez García, Fabián; Castro Muñiz, Alberto; Mateo Martí, Eva; Agencia Estatal de Investigación (AEI)
In this work, we have described the characterization of hybrid silica nanoparticles of 50 nm size, showing outstanding size homogeneity, a large surface area, and remarkable CO2 sorption/desorption capabilities. A wide battery of techniques was conducted ranging from spectroscopies such as: UV-Vis and IR, to microscopies (SEM, AFM) and CO2 sorption/desorption isotherms, thus with the purpose of the full characterization of the material. The bare SiO2 (50 nm) nanoparticles modified with 3-aminopropyl (triethoxysilane), APTES@SiO2 (50 nm), show a remarkable CO2 sequestration enhancement compared to the pristine material (0.57 vs. 0.80 mmol/g respectively at 50 °C). Furthermore, when comparing them to their 200 nm size counterparts (SiO2 (200 nm) and APTES@SiO2 (200 nm)), there is a marked CO2 capture increment as a consequence of their significantly larger micropore volume (0.25 cm3/g). Additionally, ideal absorbed solution theory (IAST) was conducted to determine the CO2/N2 selectivity at 25 and 50 °C of the four materials of study, which turned out to be >70, being in the range of performance of the most efficient microporous materials reported to date, even surpassing those based on silica.
Restringido
Steam-Resistant Optical Materials for Use in Diagnostic Mirrors for ITER
(Institute of Electrical and Electronics Engineers, 2020-01-30) Pereira, A.; Martín, P.; López Heredero, R.; Torquemada, M. C.; Rodrigo, M. T.; Gómez, L. J.; Vila, R.; Belenguer, T.; Medrano, M.; Piqueras, J. J.; Le Guern, F.; Pastor, C.; Rodríguez, M. C.; Quintana, J. A.; Carrasco, R.; Lapayese, F.; De la Peña, A.; Alén Cordero, C.; Pereira, A. [0000-0001-7945-6569]
The need for a steam ingress environmental experiment is very significant to understand the impact of accidental in-vessel coolant leaks at ITER and to study the exposure of optical diagnostics to steam and humid conditions. This could happen as a result of the damage to the cooling pipes due to runaway electrons generated during plasma disruptions in ITER. In order to know the scope of this potential impact, an assessment was carried out to simulate and to study the exposure of optical elements to strong and hostile moisture conditions. After test, different measurements on optical mirrors were performed to characterize the reflectance properties, observed both in the visible and infrared spectral ranges, as well as the analysis of wavefront error, coating adherence test, and X-ray spectroscopy. Modification of properties and fluctuations in the physical behavior of optical materials and components were observed. Substrates and coatings were affected at different levels due to corrosion and oxidative depositions that modify their optical performances. In general, there are large differences in the results obtained for the same material manufactured by different manufacturing processes. Steam and humidity affected, especially substrates and metal coatings. Substrates made of silicon carbide and stainless steel were the least affected by corrosion. Rhodium coating suffered less damage than the molybdenum coating.