INVESTIGADORES
CANEIRO Alberto
congresos y reuniones científicas
Título:
Study of BaCe0.8Pr0.2O3-d/BaCe0.4Zr0.4Y0.2O3-d bilayer proton conductor electrolyte
Autor/es:
J. BASBUS; H. WANG; Q. SU; A. CANEIRO; H. TROIANI; L. MOGNI
Lugar:
Buenos aires
Reunión:
Congreso; 20th Topical meeting of the International society of Electrochemistry (ISE); 2017
Institución organizadora:
International Society of Electrochemistry
Resumen:
Barium cerates and zirconates are interesting materials due to their ability for transporting protonsthrough their crystal lattice. This feature and their stability at high temperatures makes them potentialcandidates as hydrogen sensors, membranes for hydrogen purification and isotopic exchange (hydrogen,deuterium, tritium -H/D/T-) and as electrolytes for proton conductor solid oxide fuel and electrolyzer cells(PC-SOFC). In previous works, we studied the BaCe0.8Pr0.2O3-δ (BCP) [1] and BaCe0.4Zr0.4Y0.2O3-δ(BCZY) [2] oxides. We found that, whereas BCP electrical conductivity is dominated by a mixed (ionicand electronic) conductivity, especially under O2-containing atmosphere, BCZY behaves as a pure protonconductor electrolyte. On the other hand, BCZY ionic bulk conductivity is one or two order of magnitudehigher than for BCP, however its grain boundary conductivity is so low that compromises the use of thismaterial as a proton-conductor membrane. Besides, CO2 tolerance is also an important issue for theseoxides. When they operate under low quality H2 atmospheres, the same basicity that promotes H2Oincorporation also induces carbonate formation. In this sense, zirconates show much better stability underCO2 containing atmospheres.Considering this, we propose a novel approximation: the use of a bilayer electrolyte with the aim tocombine the best properties of each material for its use as a complex proton conductor membrane.Therefore, a thin layer (500 nm) of BCZY was deposited by Pulsed Laser Deposition (PLD) on a densethick BCP electrolyte. The microstructure, composition and crystal structure of the thin layer and theBCP-BCZY interface was studied by grazing angle X-ray diffraction (GA-XRD), and electron scanning(SEM) and transmission (TEM) microscopies. The transport properties were studied by electrochemicalimpedance spectroscopy (EIS) as a function of temperature (100 to 600 ºC) and atmosphere (H2-containing atmosphere and H2O or D2O wet air to analyze the isotopic effect). The EIS response of thebilayer electrolyte was analyzed by comparison with that of the BCP and BCZY single-layer membranes.The three systems (BCP, BCZY and BCP-BCZY) were evaluated in a single chamber furnace by using Ptas current collector. The i-V curves of the membranes, working under atmospheric air and H2/Ar-mixture,were also evaluated. The EIS responses were analyzed by using an electrical equivalent circuit, where itcan be confirmed that the electronic conductivity of the BCP is blocked by the thin (and almost singlecrystal) BCZY layer.