Samples of Ba1-xSrxCe0.9Y0.1O3-δ, 0 < x < 0.1, with Improved Chemical Stability in CO2-H2 Gas-Involving Atmospheres as Potential Electrolytes for a Proton Ceramic Fuel Cell.

Comparative studies were performed on variations in the ABO3 perovskite structure, chemical stability in a CO2-H2 gas atmosphere, and electrical conductivity measurements in air, hydrogen, and humidity-involving gas atmospheres of monophase orthorhombic Ba1-xSrxCe0.9Y0.1O3-δ samples, where 0 < x < 0.1. The substitution of strontium with barium resulting in Ba1-xSrxCe0.9Y0.1O3-δ led to an increase in the specific free volume and global instability index when compared to BaCe0.9Y0.1O3-δ. Reductions in the tolerance factor and cell volume were found with increases in the value of x in Ba1-xSrxCe0.9Y0.1O3-δ. Based on the thermogravimetric studies performed for Ba1-xSrxCe0.9Y0.1O3-δ, where 0 < x < 0.1, it was found that modified samples of this type exhibited superior chemical resistance in a CO2 gas atmosphere when compared to BaCe0.9Y0.1O3-δ. The application of broadband impedance spectroscopy enabled the determination of the bulk and grain boundary conductivity of Ba1-xSrxCe0.9Y0.1O3-δ samples within the temperature range 25-730 °C. It was found that Ba0.98Sr0.02Ce0.9Y0.1O3-δ exhibited a slightly higher grain interior and grain boundary conductivity when compared to BaCe0.9Y0.1O3-δ. The Ba0.95Sr0.05Ce0.9Y0.1O3-δ sample also exhibited improved electrical conductivity in hydrogen gas atmospheres or atmospheres involving humidity. The greater chemical resistance of Ba1-xSrxCe0.9Y0.1O3-δ, where x = 0.02 or 0.05, in a CO2 gas atmosphere is desirable for application in proton ceramic fuel cells supplied by rich hydrogen processing gases.

Tuning of the Seebeck Coefficient and the Electrical and Thermal Conductivity of Hybrid Materials Based on Polypyrrole and Bismuth Nanowires.

The growing demand for clean energy catalyzes the development of new devices capable of generating electricity from renewable energy resources. One of the possible approaches focuses on the use of thermoelectric materials (TE), which may utilize waste heat, water, and solar thermal energy to generate electrical power. An improvement of the performance of such devices may be achieved through the development of composites made of an organic matrix filled with nanostructured thermoelectric materials working in a synergetic way. The first step towards such designs requires a better understanding of the fundamental interactions between available materials. In this paper, this matter is investigated and the questions regarding the change of electrical and thermal properties of nanocomposites based on low-conductive polypyrrole enriched with bismuth nanowires of well-defined geometry and morphology is answered. It is clearly demonstrated that the electrical conductivity and the Seebeck coefficient may be tuned either simultaneously or separately within particular Bi NWs content ranges, and that both parameters may be increased at the same time.