Scientific Papers in SCI
2023
2023
Química de Superficies y Catálisis
Formic Acid Dehydrogenation over a Monometallic Pd and Bimetallic Pd:Co Catalyst Supported on Activated Carbon
Pelaez, MR; Ruiz-Lopez, E; Dominguez, MI; Ivanova, S; Centeno, MACatalysts, 13 (2023) 977
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In this study, palladium is proposed as an active site for formic acid dehydrogenation reaction. Pd activity was modulated with Co metal with the final aim of finding a synergistic effect that makes possible efficient hydrogen production for a low noble metal content. For the monometallic catalysts, the metal loadings were optimized, and the increase in the reaction temperature and presence of additives were carefully considered. The present study aimed, to a great extent, to enlighten the possible routes for decreasing noble metal loading in view of the better sustainability of hydrogen production from liquid organic carrier molecules, such as formic acid.
June, 2023 | DOI: 10.3390/catal13060977
Nanotecnología en Superficies y Plasma
Structure and Void Connectivity in Nanocolumnar Thin Films Grown by Magnetron Sputtering at Oblique Angles
Alvarez, R; Regodon, G; Acosta-Rivera, H; Rico, V; Alcala, G; Gonzalez-Elipe, AR; Palmero, ACoatings, 13 (2023) 991
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The morphology and void connectivity of thin films grown by a magnetron sputtering deposition technique at oblique geometries were studied in this paper. A well-tested thin film growth model was employed to assess the features of these layers along with experimental data taken from the literature. A strong variation in the film morphology and pore topology was found as a function of the growth conditions, which have been linked to the different collisional transport of sputtered species in the plasma gas. Four different characteristic film morphologies were identified, such as (i) highly dense and compact, (ii) compact with large, tilted mesopores, (iii) nanocolumns separated by large mesopores, and (iv) vertically aligned sponge-like coalescent nanostructures. Attending to the topology and connectivity of the voids in the film, the nanocolumnar morphology was shown to present a high pore volume and area connected with the outside by means of mesopores, with a diameter above 2 nm, while the sponge-like nanostructure presented a high pore volume and area, as well as a dense network connectivity by means of micropores, with a diameter below 2 nm. The obtained results describe the different features of the porous network in these films and explain the different performances as gas or liquid sensors in electrochromic applications or for infiltration with nanoparticles or large molecules.
June, 2023 | DOI: 10.3390/coatings13060991
Materiales Nanoestructurados y Microestructura
Microstructural characterization and thermal stability of He charged amorphous silicon films prepared by magnetron sputtering in helium
Fernández, A; Sauvage, T; Diallo, B; Hufschmidt, D; de Haro, MCJ; Montes, O; Martínez-Blanes, JM; Caballero, J; Godinho, V; Ferrer, FJ; Ibrahim, S; Brault, P; Thomann, ALMaterials Chemistry and Physics, 301 (2023) 127674
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_423.png)
Sputtering of silicon in a Helium magnetron discharge has been reported as a bottom-up procedure to obtain amorphous Si films containing high amounts of gas-filled nanopores. Here we compare the microstructure and composition of Si-He nanocomposite films deposited by magnetron sputtering (MS) with 4He in DC or RF and 3He in RF operation modes. Electron microscopy (SEM and TEM), X-ray diffraction (XRD) and ion beam analysis (IBA) have been used to analyze the films and to investigate the in-situ and ex-situ thermal evolution. Depending on deposition conditions different in depth compositions, nanopore size and shape distributions, porosity and He content could be obtained. The presence of impurities (i.e. oxygen) has shown to promote He diffusivity reducing He accumulation. The start temperature of He-release varied in the range 473-723 K without films crystallization. Films grown in RF mode reached contents of 32 and 29 at% of 4He and 3He and were respectively stable up to 573 and 723 K both in vacuum and under inert gas flow. In-situ p-EBS (proton Elastic Back Scattering) allowed monitoring the He release accompanied by blistering/delamination effects visualized by SEM. These results show the potentiality of annealing to hold nano-porous structures after liberation of trapped gas.
June, 2023 | DOI: 10.1016/j.matchemphys.2023.127674
Reactividad de Sólidos
Direct comparison of surface crystal growth kinetics in chalcogenide glass measured by microscopy and DSC
Shanelova, J; Honcova, P; Malek, J; Perejon, A; Perez-Maqueda, LAJournal of the American Ceramic Society, 106 (2023) 6051-6061
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Surface crystallization in fine powder Se70Te30 chalcogenide glass was studied by differential scanning calorimetry (DSC) and optical microscopy. A complex kinetic analysis of these experimental data reveals that the contracting sphere mechanism (R3 model) is the rate determining step of crystal growth, and the conventional Johnson-Mehl-Avrami-Kolmogorov model cannot be used in this case. Moreover, it is clearly shown that the particle size distribution should be considered in crystallization studies. Actually, when the particle size effect is taken into account, the simulated DSC curves for the R3 model agree very well with the experimental data over the entire temperature range. The crystallization kinetics determined from the nonisothermal DSC data are consistent with previously reported isothermal crystallization data for the same powder fraction. The crystal growth rate calculated from isothermal and nonisothermal DSC data agrees very well with the microscopically measured surface and bulk crystal growth rate.
May, 2023 | DOI: 10.1111/jace.19204
Nanotecnología en Superficies y Plasma
Strontium/zinc phytate-based self-assembled monolayers on titanium surfaces enhance osteogenesis and antibacterial performance in vitro
Asensio, G; Hernández-Arriaga, AM; Martin-del-Campo, M; Prieto, MA; González-Elipe, AR; Rojo, L; Vázquez-Lasa, BApplied Surface Science, 620 (2023) 156818
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_380.png)
The accumulation of bacteria over implant surfaces is still the first cause of failure, and the development of antimicrobial surfaces constitutes a first line in implant research. Besides, the durability and mechanical performance of implants, in special in the dental area, are mainly determined by their osseointegration capacity into the maxillofacial bone and the appearance of infections. Consequently, implant osseointegration and infection prophylaxis remain as big challenges to attain so a huge investigation is being developed on the production of bioactive surfaces to achieve improvements in these aspects. In this work we propose the functionalization of titanium surfaces (Ti Cp) with self-assembled monolayers (SAMs) of bioactive organophosphate compounds: phytic acid (Ti-PA) and its metallic phytate de- rivatives bearing Sr2+ and/or Zn2+ (Ti-SrPhy, Ti-ZnPhy and Ti-SrPhy/ZnPhy) which exhibited tunable in vitro osteogenic, antimicrobial and antioxidant properties in a previous work. Thus, phytate compounds are chemically anchored onto Ti discs through a simple procedure consisting of a condensation reaction promoted by heat treatment. EDS and XPS spectroscopies confirm the obtaining of the modified surfaces and the topographic properties and wettability analysed by SEM, AFM, profilometry and contact angle measurements, respectively, are explored. Additionally, phytate-SAMs do not release any cytotoxic compound after 14 days and stimulate in vitro adhesion and proliferation of human osteoblast cells after 14 days of culture. The osteogenic ability of the modified surfaces evaluated by the quantification of ALP activity and matrix mineralization degree shows a significant improvement with respect to unmodified surfaces. Furthermore, the antimicrobial activity of phytate-SAMs against Streptococcus mutans cultures is evaluated. The count of viable cells and the quantification of produced biofilm are significantly reduced by all phytate-SAMs groups (p < 0.001). Cell membrane integrity studies by LIVE/DEAD staining and SEM imaging confirm a decreased viability of adhered bacteria when phytate-based surfaces are tested, due to a disruption in the function and permeability of the cell membrane. Therefore, phytate-SAMs exhibit suitable in vitro features suggesting their promising potential as bioactive coatings of dental implants.
May, 2023 | DOI: 10.1016/j.apsusc.2023.156818
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