ELECTROPHORETIC DEPOSITION AS A METHOD FOR THE PREPARATION OF CERAMIC FUEL CELLS

Solid Oxide Fuel Cells (SOFC) have attracted great attention due to highly efficient electric power generation, system modularity, multi fuel capability and possibility of direct hydrocarbon conversion. Traditional YSZ electrolytes need high operating temperatures at 800-1000°C. Therefore fabrication, long term stability and material costs of these conventional SOFC systems are rather high. Lowering the working temperature is required to make this promising technology commercially viable. YSZ is the standard material to be used as electrolyte in high temperature oxide fuel cells. We developed a simple method for the electrophoretic deposition of electrodes on dense electrolyte substrates. To allow significant temperature reduction new electrolyte materials with higher oxygen ion conductivity below 800°C compared to YSZ are needed. Apatite type lanthanum silicates (ATLS) are a new class of electrolytes which provides good oxygen permeability even at lower temperatures. These new electrolytes necessitate the development of suitable electrode materials. The ATLS electrolyte needs to be dense and gastight allowing only the transport of O2- ions through the electrolyte, whereas the electrodes need to be porous in order to allow gas exchange while maintaining good adhesion to the electrolyte. Another fuel cell class which allows the reduction of the service temperature is based on the use of proton conducting ceramics and we preset the preparation of such fuel cells as well. Electrophoretic deposition of ceramic films has become an attractive alternative for the fabrication of SOFCs, due to the need to control the layer thickness by the order of microns. In this study, we present the preparation of different ceramic fuel cells by electrophoretic deposition

Ultrasound-Assisted Preparation Methods of Nanoparticles for Energy-Related Applications

Ultrasound (US) technology is already into the research field providing a powerful tool of producing nanomaterials or being implicated in decoration procedures of catalyst supports for energy applications and material production. Toward this concept, low or/and high-frequency USs are used for the production of nanoparticles, the decoration of catalytic supported powders (carbon-based, titania, and alumina) with nanoparticles, and the production of metal-organic frameworks (MOFs). MOFs are porous, crystalline materials, which consist of metal centers and organic linkers. Those structures demonstrate high surface area, open metal sites, and large void space. All the above produced materials are used in heterogeneous catalysis, electrocatalysis, photocatalysis, and energy storage. Batteries and fuel cells are popular systems for electrochemical energy storage, and significant progress has been made in nanostructured energy materials in order to improve these storage devices. Nanomaterials have shown favorable properties, such as enhanced kinetics and better efficiency as catalysts for the oxygen reduction reaction (ORR)

Nitrogen diffusion in nitrogen-doped yttria stabilised zirconia

Nitrogen self-diffusion was measured in single crystalline nitrogen-doped yttria-stabilised zirconia (YZrON) containing 10 mol% yttrium oxide. Samples containing two different nitrogen contents (5 and 6 mol% N on the anion sublattice) were investigated as a function of temperature (650–1000 K) using implanted 15N as a stable tracer. For a given temperature, the nitrogen diffusivity was nearly independent of the nitrogen content in the nitrogen-doped yttria-stabilised zirconia, which can be only partially understood using defect chemistry. The activation enthalpy of nitrogen diffusion was between 2 and 2.5 eV with a preexponential factor of the order of 100 cm2 s−1, which corresponds to a migration entropy of 5 kB. The surface exchange reaction between nitrogen and the oxonitride surface was investigated at 1073 K using 200 mbar gaseous 15N2 and was found to be slow but considerable. Decreasing the oxygen content in the gas phase can enhance the nitrogen incorporation into the oxonitrides.Instituto de Física La Plat

Lanthanide transport in stabilized zirconias : Interrelation between ionic radius and diffusion coefficient

The diffusion of all stable lanthanides in calcia stabilized zirconia (CSZ) and in yttria stabilized zirconia (YSZ) was measured. Lanthanide migration enthalpies were calculated using the Mott-littleton approach. The results suggest that the bulk diffusion coefficient depends on the ionic radius of the lanthanide tracer. It was also found that the experimental activation enthalpies are about 6eV for CSZ and between 4 and 5 eV for YSZ and almost constant for all lanthanides.Instituto de Física La Plat

Plasma assisted bio-degradation of poly-lactic acid (PLA)

Plastics are artificial synthetic organic polymers that have been used in every area of daily life. However, because of their slow degradation rate, their use is contentious. The treatment of the surface of the sample is considered necessary as enzymatic or bacterial attach is not possible, if the plastic surface environment is not ideal. The main topic of this work is the investigation of the effect of atmospheric dielectric barrier discharge (DBD) plasma on the near surface structure of polylactic acid (PLA) samples, which, in turn, can promote the adhesion of enzymes or bacteria for further biodegradation. In general, plasma processes can already be considered as inherently environmental technologies. Plasma processes enable resource saving through high energy utilization efficiency and thus, are environ-mentally friendly technologies. Atmospheric pressure discharges (APDs) are useful because of their specific advantages over low-pressure ones. They do not need expensive vacuum equipment, and generate nonthermal plasmas, which are more suitable for assembly line processes. Hence, this category of discharges has significant industrial applications. The use of a dielectric barrier in the discharge gap helps prevent spark formation. DBDs exhibit two major discharge modes: filamentary and glow (homogeneous). The glow discharge mode has obvious advantages over the filamentary one for applications such as treatment of surfaces and deposition of thin films. Glow mode discharges with average power densities comparable to those of filamentary discharges are of enormous interest for applications in which reliable control is required. Here we will present the increased adhesion of bacteria strains on DBD plasma treated PLA foils which can lead to a better degradation of the PLA. X-ray photoelectron spectroscopy (XPS) measurements of the foils prior to and after the treatment proved the changes on the polymer surface. A short discussion of the possibilities the treatment opens is given.CHANIA 2023: 10th International Conference on Sustainable Solid Waste Management Chania, Greece, 21 - 24 JUNE 202

The influence of protecting polyelectrolyte layers on the temperature behavior of NaBD₄

The use of NaBH4 as a hydrogen storage material suffers to some extent from its deficient stability against chemicals and degradation at elevated temperatures. This disadvantage can be overcome by the use of polyelectrolytes as protective layers. Furthermore, the coating of NaBH4 with polyelectrolytes significantly enhances the release of hydrogen from the storage material. In this work, the influences of polyethyleneimine (PEI) and poly(acrylonitrile-co-butadiene-co-acrylic acid), dicarboxy terminated (PABA) as protective polyelectrolytes coatings have been investigated on deuterated sodium borohydride, thus being able to determine hydrogen release from the polyelectrolyte and the hydrogen storage material. The release rates have been investigated by temperature-programmed desorption measurements of significant species as preliminarily identified by mass spectrometry. Furthermore, the geometrical structures of the polyelectrolyte films were characterized by confocal laser scanning microscopy studies prior and posterior to the temperature treatment