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Artículos SCI



2024


Nanotecnología en Superficies y Plasma

Growth dynamics of nanocolumnar thin films deposited by magnetron sputtering at oblique angles

Alvarez, R; Garcia-Valenzuela, A; Regodon, G; Ferrer, FJ; Rico, V; Garcia-Martin, JM; Gonzalez-Elipe, AR; Palmero, A
Nanotechnology, 35 (2024) 095705

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The morphology of numerous nanocolumnar thin films deposited by the magnetron sputtering technique at oblique geometries and at relatively low temperatures has been analyzed for materials as different as Au, Pt, Ti, Cr, TiO2, Al, HfN, Mo, V, WO3 and W. Despite similar deposition conditions, two characteristic nanostructures have been identified depending on the material: a first one defined by highly tilted and symmetric nanocolumnar structures with a relatively high film density, and a second one characterized by rather vertical and asymmetric nanocolumns, with a much lower film density. With the help of a model, the two characteristic nanostructures have been linked to different growth dynamics and, specifically, to different surface relaxation mechanisms upon the incorporation of gaseous species with kinetic energies above the surface binding energy. Moreover, in the case of Ti, a smooth structural transition between the two types of growths has been found when varying the value of the power used to maintain the plasma discharge. Based on these results, the existence of different surface relaxation mechanisms is proposed, which quantitatively explains numerous experimental results under the same conceptual framework.


Febrero, 2024 | DOI: 10.1088/1361-6528/ad113d

Nanotecnología en Superficies y Plasma

Harnessing a Vibroacoustic Mode for Enabling Smart Functions on Surface Acoustic Wave Devices - Application to Icing Monitoring and Deicing

Karimzadeh, A; Weissker, U; del Moral, J; Winkler, A; Borrás, A; González-Elipe, AR; Jacob, S
Advanced Materials Technologies, (2024) 2301749

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Microacoustic wave devices are essential components in the radio frequency (RF) electronics and microelectromechanical systems (MEMS) industry with increasing impact in various sensing and actuation applications. Reliable and smart operation of acoustic wave devices at low costs will cause a crucial advancement. Herein, this study presents the enablement of temperature and mechanical sensing capabilities in a Rayleigh-mode standing surface acoustic wave (sSAW) chip device by harnessing an acoustic shear-thickness dominant wave (SD) using the same set of electrodes. Most importantly, this mode is excited by switching the polarity of the sSAW transducer electrodes by simple electronics, allowing for direct and inexpensive compatibility with an existing setup. The method in the emergent topic of surface de-icing is validated by continuously monitoring temperature and liquid–solid water phase changes using the SD mode, and on-demand Rayleigh-wave deicing with a negligible energy cost. The flexibility for adapting the system to different scenarios, and loads and the potential for scalability opens the path to impact in lab-on-a-chip, internet of things (IoT) technology, and sectors requiring autonomous acoustic wave actuators.


Febrero, 2024 | DOI: 10.1002/admt.202301749

Química de Superficies y Catálisis

Optimizing biogas methanation over nickel supported on ceria-alumina catalyst: Towards CO2-rich biomass utilization for a negative emissions society

González-Arias, J; Torres-Sempere, G; Arroyo-Torralvo, F; Reina, TR; Odriozola, JA
Enrironmental Research, 242 (2024) 117735

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Biogas methanation emerges as a prominent technology for converting biogas into biomethane in a single step. Furthermore, this technology can be implemented at biogas plant locations, supporting local economies and reducing dependence on large energy producers. However, there is a lack of comprehensive studies on biogas methanation, particularly regarding the technical optimization of operational parameters and the profitability analysis of the overall process. To address this gap, our study represents a seminal work on the technical optimization of biogas methanation obtaining an empirical model to predict the performance of biogas methanation. We investigate the influence of operational parameters, such as reaction temperature, H2/CO2 ratio, space velocity, and CO2 share in the biogas stream through an experimental design. Based on previous research we selected a nickel supported on ceria-alumina catalyst; being nickel a benchmark system for methanation process such selection permits a reliable data extrapolation to commercial units. We showcase the remarkable impact of studied key operation parameters, being the temperature, the most critical factor affecting the reaction performance (ca. 2 to 5 times higher than the second most influencing parameter). The impact of the H2/CO2 ratio is also noticeable. The response surfaces and contour maps suggest that a temperature between 350 and 450 degrees C and an H2/CO2 ratio between 2.5 and 3.2 optimize the reaction performance. Further experimental tests were performed for model validation and optimization leading to a reliable predictive model. Overall, this study provides validated equations for technology scaling-up and techno-economic analysis, thus representing a step ahead towards real-world applications for bio-methane production.


Febrero, 2024 | DOI: 10.1016/j.envres.2023.117735

Nanotecnología en Superficies y Plasma

Synergistic Integration of Nanogenerators and Solar Cells: Advanced Hybrid Structures and Applications

Hajra, S; Ali, A; Panda, S; Song, HW; Rajaitha, PM; Dubal, D; Borras, A; In-Na, P; Vittayakorn, N; Vivekananthan, V; Kim, HJ; Divya, S; Oh, TH
Advanced Energy Materials, (2024) 2400025

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The rapid growth of global energy consumption and the increasing demand for sustainable and renewable energy sources have urged vast research into harnessing energy from various sources. Among them, the most promising approaches are nanogenerators (NGs) and solar cells (SCs), which independently offer innovative solutions for energy harvesting. This review paper presents a comprehensive analysis of the integration of NGs and SCs, exploring advanced hybrid structures and their diverse applications. First, an overview of the principles and working mechanisms of NGs and SCs is provided for seamless hybrid integrations. Then, various design strategies are discussed, such as piezoelectric and triboelectric NGs with different types of SCs. Finally, a wide range of applications are explored that benefit from the synergistic integration of NGs and SCs, including self-powered electronics, wearable devices, environmental monitoring, and wireless sensor networks. The potential for these hybrid systems is highlighted to address real-world energy needs and contribute to developing sustainable and self-sufficient technologies. In conclusion, this review provides valuable insights into the state-of-the-art developments in NGs and SCs integration, shedding light on advanced hybrid structures and their diverse applications.


Febrero, 2024 | DOI: 10.1002/aenm.202400025

Química de Superficies y Catálisis

Synthetic natural gas production using CO2-rich waste stream from hydrothermal carbonization of biomass: Effect of impurities on the catalytic activity

González-Arias, J; Torres-Sempere, G; Villora-Picó, JJ; Reina, TR; Odriozola, JA
Journal of CO2 Utilization, 79 (2024) 102653

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The utilization of biomass and bio-waste, particularly through hydrothermal processes, has shown promise as a technology for converting these materials into valuable products. While most research has traditionally focused on the solid and liquid byproducts of these hydrothermal treatments, the gaseous phase has often been over-looked. This study specifically investigates the conversion of off-gases produced during hydrothermal carbonation (HTC) into synthetic natural gas, offering a readily marketable product with economic potential. Although the methanation of conventional flue gases has been extensively studied, dealing with non-standard off-gases from processes like HTC presents challenges due to the presence of minor impurities like CO and CH4. This novel research seeks to experimentally evaluate the methanation of HTC off-gases using nickel-based catalysts and analyze how these impurities affect the catalytic performance. The studied catalysts include nickel supported by ceria and alumina, as well as alumina supported nickel-cobalt systems. The results demonstrate that these catalysts exhibit high CO2 conversion and CH4 selectivity under ideal gas conditions. However, when real gas compositions with impurities are considered, CO2 conversion decreases at lower temperatures (ca. 20% lower conversion for real gas vs. ideal), probably due to side reactions such as CH4 cracking. This difference becomes less pronounced at higher temperatures. Nevertheless, the catalysts perform satisfactorily, especially at temperatures exceeding 350 degrees C. In conclusion, this study sheds light on the methanation of HTC off-gases and underscores the significance of understanding how impurities in real gases impact the process, providing potential directions for future research.


Enero, 2024 | DOI: 10.1016/j.jcou.2023.102653

 

 

 

 

 

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