Thin film oxide-ion conducting electrolyte for near room temperature applications

Stabilized bismuth vanadate thin films are presented here as superior oxide ionic conductors, for application in solid state electrochemical devices operating near room temperature. Widely studied in the 90s in bulk form due to their unbeatable ionic conduction, this family of materials was finally discarded due to poor stability above 500 °C. Here, we however unveil the possibility of using BiVCuO at reduced temperatures in thin film-based devices, where the material keeps its unmatched conduction properties and at the same time shows good stability over a wide oxygen partial pressure range

Electrical properties of individual tin oxide nanowires contacted to platinum electrodes

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties free electron concentration nd, electrical mobility , and conductivity in individual nanowires has been developed. A combined model involving thermionic emission and tunneling through interface states is proposed to describe the electrical conduction through the platinum-nanowire contacts, fabricated by focused ion beam techniques. Current-voltage I-V plots of single nanowires measured in both two- and four-probe configurations revealed high contact resistances and rectifying characteristics. The observed electrical behavior was modeled using an equivalent circuit constituted by a resistance placed between two back-to-back Schottky barriers, arising from the metal-semiconductor-metal M-S-M junctions. Temperature-dependent I-V measurements revealed effective Schottky barrier heights up to BE= 0.4 eV

Membrana electrolítica de óxido sólido soportada sobre nervios de silicio dopado para aplicaciones en micropilas de combustible de óxido sólido

La presente invención se refiere a una pila de combustible de oxido solido que consta de: (a) un sustrato con al menos una cavidad para formar una membrana; (b) una membrana electrolítica basada en una capa delgada de un oxido solido de más de 5 nm pero menos de 5 um de grosor , cubriendo la cavidad formada en el sustrato; (c) una red de nervios de silicio dopado cruzando la cavidad, justo por debajo de la membrana electrolítica, de forma que sirvan como soporte del electrolito; los nervios de silicio determinan membranas electrolíticas singulares de un tamaño siempre mayor que el grosor de los nervios, las cuales sumadas forman la membrana electrolítica de gran superficie; y (d) dos capas finas que actúan como electrodos, depositadas una a cada lado de la citada membrana electrolítica. Asimismo, es objeto de la invención el método para fabricar dicha pila de combustiblePeer reviewedConsejo Superior de Investigaciones Científicas, Fundació Institut de Recerca de Energía de CatalunyaA1 Solicitud de patente con informe sobre el estado de la técnic

Advances in layered oxide cathodes for intermediate temperature solid oxide fuel cells

15 páginas, 5 figuras, 1 tabla.In the context of solid oxide fuel cells (SOFCs) applications, mixed-ionic electronic conductors offer significant advantages over conventional cathodes especially in the intermediate-to-low range of temperatures where the performance of the cathode is of fundamental importance. An increasing number of layered oxide materials have been found to present excellent properties as mixed ionic-electronic conductors. Therefore, considerable efforts have been recently devoted to better understand and evaluate layered ordered structures. This article highlights the most important advances in this topic concentrating on both structural aspects and impact in cathode performance for SOFCs applications.This investigation has been supported by the Spanish Ministry of Science and Education (MAT-2008-04931, CSD-2008-023 and TEC-2007-64669 projects) and the ‘‘Generalitat de Catalunya’’ (2009-SGR-228). A.T. and M.B would like to thank the financial support of different postdoctoral programs: JAE-DOC (CSIC), ‘‘Ramón y Cajal’’ (MICINN) and ‘‘Ayudas para investigación postdoctoral’’ (MICINN).Peer reviewe

Thin film oxide-ion conducting electrolyte for near room temperature applications

Stabilized bismuth vanadate thin films are presented here as superior oxide ionic conductors, for application in solid state electrochemical devices operating near room temperature. Widely studied in the 90s in bulk form due to their unbeatable ionic conduction, this family of materials was finally discarded due to poor stability above 500 °C. Here, we however unveil the possibility of using BiVCuO at reduced temperatures in thin film-based devices, where the material keeps its unmatched conduction properties and at the same time shows good stability over a wide oxygen partial pressure range

Sensor electroquímico de estado sólido y procedimiento para su fabricación

Sensor electroquímico integrado de estado sólido (S) que comprende un primer electrodo (1) en contacto con un primer volumen libre (V1), un segundo electrodo (2) con un segundo volumen libre (V2), un electrolito sólido (3), una estructura de soporte del electrolito, estando los electrodos (1, 2) en contacto con el electrolito (3), un amperímetro o un voltímetro conectado entre los electrodos (1, 2), en el que el primer (V1) y/o el segundo (V2) volumen es susceptible de contener un gas cuya concentración se quiere medir, en el que el electrolito (3) es una membrana de zirconia estabilizada con itria, la estructura (4) es de silicio micromecanizado provista de al menos un orificio atravesante y la membrana (3) está fijada a la estructura de modo que cubre el orificio.Peer reviewedInstitut de Recerca en Energía de Catalunya, Consejo Superior de Investigaciones Científicas, Universitat de BarcelonaA1 Solicitud de adición a la patent

Electrical characterization of thermomechanically stable YSZ membranes for micro solid oxide fuel cells applications

10 páginas, 10 figuras, 3 tablas.Yttria-stabilized zirconia free-standing membranes were fabricated by pulsed laser deposition on Si/SiO2/Si3N4 structures for developing silicon-based micro devices for micro solid oxide fuel cell applications. Their mechanical stability under working conditions was evaluated satisfactorily by applying thermal cycling to the membranes. Membranes mechanically stable at operating temperatures as high as 700 °C were obtained for deposition temperatures in the range between 400 and 700 °C. Thermomechanical behavior as measured by X-ray microdiffraction was correlated with the evolution of the microstructure with the temperature from TEM analysis, comparing as-deposited and post-deposition annealed membranes. Electrical properties of both yttria-stabilized zirconia films and membranes were studied by DC conductivity and impedance spectroscopy, respectively. A difference of almost one order of magnitude was measured between bulk and stressed films while conductivities close to the bulk were observed for YSZ membranes. Values of area specific resistance of 0.15 Ωcm2 were measured at temperatures below 450 °C for 240 nm thick YSZ membranes deposited at 600 °C and annealed at the same temperature for 2.5 h.This investigation has been supported by the Spanish Ministry of Science and Education (MAT-2008-04931, CSD-2008-023 and TEC- 2007-64669 projects) and the “Generalitat de Catalunya” (2009-SGR- 228). A.T., N.S would like to thank the financial support of the postdoctoral program “Ramón y Cajal” (MICINN) and A.C to the postdoctoral program “Juan de la Cierva” (MICINN)Peer reviewe

Standalone micro-reformer for on-demand hydrogen production from dimethyl ether

Entering a new era of sustainable energy generation and consumption, micro-fuel cells are showing great po-tential for providing high energy density to consumer electronics, and micro-reactor technology can indeed enable their integration by providing hydrogen on-demand from hydrocarbons. In this work, we present the design and fully scalable wafer-level fabrication of a MEMS-based catalytic micro-reactor tested in real-life operating conditions by means of a 3D printed ceramic housing. The device consists of an array of thousands of vertically aligned micro-channels, 500 µm in length and 50 µm in diameter, for an overall superficial area per unit volume of 120 cm2 cmPeer ReviewedObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (author's final draft

Membrana de electrolito polimérico híbrida y sus aplicaciones

Membrana de electrolito polimérico híbrida y sus aplicaciones. La invención describe una membrana de electrolito polimérico híbrida que comprende dos polímeros distintos espacialmente dispuestos de tal forma que ambos constituyen una estructura donde uno de los polímeros, que es un polímero de siloxano, hace de base perforada para que el otro polímero, que es un electrolito polimérico, se pueda distribuir en él las perforaciones en forma de canales. Esta membrana es útil para la fabricación de dispositivos de electrolitos poliméricos, como por ejemplo, las pilas de combustible, electrolizadores y pilas microbianas, permitiendo un mayor nivel de integración de la membrana con el resto de los componentes, una reducción en el tamaño de los dispositivos, compatibilidad con materiales rígidos.Peer reviewedConsejo Superior de Investigaciones Científicas (España)A1 Solicitud de patentes con informe sobre el estado de la técnic

A Pd/Al2O3-based micro-reformer unit fully integrated in silicon technology for H-rich gas production

This work reports the design, manufacturing and catalytic activity characterization of a micro-reformer for hydrogen-rich gas generation integrated in portable-solid oxide fuel cells (µ-SOFCs). The reformer has been designed as a silicon micro monolithic substrate compatible with the mainstream microelectronics fabrication technologies ensuring a cost-effective high reproducibility and reliability. Design and geometry of the system have been optimized comparing with the previous design, consisting in an array of more than 7x103 vertical through-silicon micro channels perfectly aligned (50 µm diameter) and a 5 W integrated serpentine heater consisting of three stacked metallic layers (TiW, W and Au) for perfect adhesion and passivation. Traditional fuels for SOFCs, such as ethanol or methanol, have been replaced by dimethyl ether (DME) and the chosen catalyst for DME conversion consists of Pd nanoparticles grafted on an alumina active support. The micro-channels have been coated by atomic layer deposition (ALD) with amorphous Al2O3 and the influence of rapid thermal processing (RTP) on such film has been studied. A customized ceramic 3D-printed holder has been designed to measure the specific hydrogen production rates, DME conversion and selectivity profiles of such catalyst at different temperatures