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

Fabrication methods for functional nanoparticles and interdigitated nanoelectrodes

Esta tesis presenta el desarrollo de nuevos métodos de nanofabricacion para la preparación de nanopartículas funcionales y electrodos interdigitados. El trabajo incluye el diseño, fabricación y caracterización de diferentes métodos que solucionan algunas de los retos que presenta la nanotechnología hoy en día. Estas estrategias aprovechan las ventajosas propiedades que surgen de las dimensiones nanometricas. En primer lugar, se ha desarrollado un método que facilita el estudio de la conductividad de una única nanopartícula. Este método está basado en la preparación de una plataforma donde se deposita una capa muy fina de un nuevo nanocompuesto. El nanocompuesto está formado de nanocristales embebidos en una resina altamente aislante. Esto facilita la conexión de las nanopartículas usando una punta de AFM mientras estas están aisladas eléctricamente del medio. Se exponen el diseño y optimización de la técnica, además de los resultados preliminares obtenidos de las medidas eléctricas. Además, se han fabricado nanopartículas metálicas mediante litografía por nanoimprint. Esta técnica es un avance en el estado del arte, ya que permite la fabricación de nanoestructuras con una alta relación de aspecto, facilita el liftoff, y proporciona una alternativa para obtener nanopartículas de diferentes tamaños, formas y materiales, incluso combinaciones de estos. También se ha evaluado el comportamiento de las partículas como plasmones de resonancia para su aplicación en sensores LSPR (localized surface plasmon resonance). Se ha presentado el desarrollo de la fabricación y caracterización de nanoelectrodos interdigitados para usar como (bio)sensores, incluyendo la adaptación de métodos de nanolitografía y encapsulados. La caracterización funcional de los nanoelectrodos interdigitados demuestra una mejoría en la selectiva detección de dopamina en presencia de ácido ascórbico debido a la miniaturización de los dispositivos. Los resultados experimentales han sido confirmados mediante simulaciones de elementos finitos. En esta tesis, se ha demostrado que los nuevos métodos desarrollados permiten la fabricación de nanoestructuras y nanodispositivos con nuevas y mejoradas funciones. Además, los métodos presentados pueden ser aplicados a otras áreas como los biosensores, la nano/microelectrónica, medicina o energía.This thesis presents the development of novel nanofabrication methods for the preparation of functional nanoparticles and interdigitated nanoelectrodes. The work includes the design, fabrication and characterization of different approaches that overcome some of the current challenges in nanotechnology. These approaches take advantage of the enhanced properties that arise from the nanometer scale dimensions. First, a novel method to study the electrical conductivity of single nanoparticles has been developed. This method is based on the preparation of a platform where a thin film of a new nanocomposite is placed. The nanocomposite is composed of nanocrystals embedded in a highly isolating resist. It facilitated the connection of the particles by AFM tip while keeping them electrically isolated from their surroundings. The design and optimization of the method, as well as the preliminary electrical results have been exposed. Moreover, metallic nanoparticles arrays have been fabricated by nanoimprint lithography. This technique is a step forward in the nanoimprint lithography’s state of the art, since allows the fabrication of high aspect ratio nanostructures, facilitates the lift-off, provide alternative to obtain nanoparticles of different size, shapes and materials, and even combination of them. Plasmonic resonance behavior of the particles has also been evaluated for their application as localized surface plasmon resonance (LSPR) sensors. In addition, fabrication and characterization of interdigitated nanoelectrodes to be used as (bio)sensors have been developed, including the adaptation of nanolithography methods and packaging strategies. The functional characterization of the interdigitated nanoelectrodes showed an improvement on the selective detection of dopamine in presence of ascorbic acid resulted from the miniaturization of the devices. The experimental results are correlated to finite element simulations. In this thesis, it is demonstrated that the new developed methods allow fabricating nanostructures and nanodevices with novel and enhanced functionalities. Moreover, the presented methods can be further applied to different areas, such as biosensors, nano/microelectronics, medicine or energy

Fabrication methods for functional nanoparticles and interdigitated nanoelectrodes

Esta tesis presenta el desarrollo de nuevos métodos de nanofabricacion para la preparación de nanopartículas funcionales y electrodos interdigitados. El trabajo incluye el diseño, fabricación y caracterización de diferentes métodos que solucionan algunas de los retos que presenta la nanotechnología hoy en día. Estas estrategias aprovechan las ventajosas propiedades que surgen de las dimensiones nanometricas. En primer lugar, se ha desarrollado un método que facilita el estudio de la conductividad de una única nanopartícula. Este método está basado en la preparación de una plataforma donde se deposita una capa muy fina de un nuevo nanocompuesto. El nanocompuesto está formado de nanocristales embebidos en una resina altamente aislante. Esto facilita la conexión de las nanopartículas usando una punta de AFM mientras estas están aisladas eléctricamente del medio. Se exponen el diseño y optimización de la técnica, además de los resultados preliminares obtenidos de las medidas eléctricas. Además, se han fabricado nanopartículas metálicas mediante litografía por nanoimprint. Esta técnica es un avance en el estado del arte, ya que permite la fabricación de nanoestructuras con una alta relación de aspecto, facilita el liftoff, y proporciona una alternativa para obtener nanopartículas de diferentes tamaños, formas y materiales, incluso combinaciones de estos. También se ha evaluado el comportamiento de las partículas como plasmones de resonancia para su aplicación en sensores LSPR (localized surface plasmon resonance). Se ha presentado el desarrollo de la fabricación y caracterización de nanoelectrodos interdigitados para usar como (bio)sensores, incluyendo la adaptación de métodos de nanolitografía y encapsulados. La caracterización funcional de los nanoelectrodos interdigitados demuestra una mejoría en la selectiva detección de dopamina en presencia de ácido ascórbico debido a la miniaturización de los dispositivos. Los resultados experimentales han sido confirmados mediante simulaciones de elementos finitos. En esta tesis, se ha demostrado que los nuevos métodos desarrollados permiten la fabricación de nanoestructuras y nanodispositivos con nuevas y mejoradas funciones. Además, los métodos presentados pueden ser aplicados a otras áreas como los biosensores, la nano/microelectrónica, medicina o energía.This thesis presents the development of novel nanofabrication methods for the preparation of functional nanoparticles and interdigitated nanoelectrodes. The work includes the design, fabrication and characterization of different approaches that overcome some of the current challenges in nanotechnology. These approaches take advantage of the enhanced properties that arise from the nanometer scale dimensions. First, a novel method to study the electrical conductivity of single nanoparticles has been developed. This method is based on the preparation of a platform where a thin film of a new nanocomposite is placed. The nanocomposite is composed of nanocrystals embedded in a highly isolating resist. It facilitated the connection of the particles by AFM tip while keeping them electrically isolated from their surroundings. The design and optimization of the method, as well as the preliminary electrical results have been exposed. Moreover, metallic nanoparticles arrays have been fabricated by nanoimprint lithography. This technique is a step forward in the nanoimprint lithography's state of the art, since allows the fabrication of high aspect ratio nanostructures, facilitates the lift-off, provide alternative to obtain nanoparticles of different size, shapes and materials, and even combination of them. Plasmonic resonance behavior of the particles has also been evaluated for their application as localized surface plasmon resonance (LSPR) sensors. In addition, fabrication and characterization of interdigitated nanoelectrodes to be used as (bio)sensors have been developed, including the adaptation of nanolithography methods and packaging strategies. The functional characterization of the interdigitated nanoelectrodes showed an improvement on the selective detection of dopamine in presence of ascorbic acid resulted from the miniaturization of the devices. The experimental results are correlated to finite element simulations. In this thesis, it is demonstrated that the new developed methods allow fabricating nanostructures and nanodevices with novel and enhanced functionalities. Moreover, the presented methods can be further applied to different areas, such as biosensors, nano/microelectronics, medicine or energy

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

Business Model Development for a High-Temperature (Co-)Electrolyser System

There are increasing international efforts to tackle climate change by reducing the emission of greenhouse gases. As such, the use of electrolytic hydrogen as an energy carrier in decentralised and centralised energy systems, and as a secondary energy carrier for a variety of applications, is projected to grow. Required green hydrogen can be obtained via water electrolysis using the surplus of renewable energy during low electricity demand periods. Electrolysis systems with alkaline and polymer electrolyte membrane (PEM) technology are commercially available in different performance classes. The less mature solid oxide electrolysis cell (SOEC) promises higher efficiencies, as well as co-electrolysis and reversibility functions. This work uses a bottom-up approach to develop a viable business model for a SOEC-based venture. The broader electrolysis market is analysed first, including conventional and emerging market segments. A further opportunity analysis ranks these segments in terms of business attractiveness. Subsequently, the current state and structure of the global electrolyser industry are reviewed, and a ten-year outlook is provided. Key industry players are identified and profiled, after which the major industry and competitor trends are summarised. Based on the outcomes of the previous assessments, a favourable business case is generated and used to develop the business model proposal. The main findings suggest that grid services are the most attractive business sector, followed by refineries and power-to-liquid processes. SOEC technology is particularly promising due to its co-electrolysis capabilities within the methanol production process. Consequently, an “engineering firm and operator” business model for a power-to-methanol plant is considered the most viable option

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

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

Gold interdigitated nanoelectrodes as a sensitive analytical tool for selective detection of electroactive species via redox cycling

Redox cycling (RC) is a unique electrochemical technique to selectively detect redox-active species in presence of molecules with similar oxidation potential but whose electrochemical reactions display different electron transfer kinetics. Pairs of interdigitated electrodes (IDEs) working as generator-collector devices have been widely applied in RC. The diffusion of species that takes place between the two IDEs has to be minimized in order to enhance the device sensitivity. Therefore, scaling down the IDE dimensions is carried out to detect very low concentrations of the molecules under study. The application of interdigitated nanoelectrode structures (nano-IDEs) is currently limited by low-yield production and packaging processes. Here, we describe a fabrication approach that enables robust mass production of gold nano-IDEs at wafer scale, along with a packaging strategy to easily operate with the electrodes. The theoretical and experimental detection of dopamine in presence of ascorbic acid demonstrates the superior analytical performance of the resulting devices. Nano-IDEs with dimensions of 150 nm width and 300 nm pitch showed faradaic steady-state currents related to the oxidation of dopamine that were 16.7 times larger than those recorded by standard cyclic voltammetry. By contrast, if the dimensions of the nano-IDEs are increased by a factor of 10, the amplification factor of the redox reaction is decreased to less than one fourth.Peer Reviewe