کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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46438 | 46439 | 2012 | 11 صفحه PDF | دانلود رایگان |
The influence of nickel and strontium incorporation in LaCrO3 on the crystalline structure, redox behavior and electrochemical performance by impedance spectroscopy using symmetrical cells has been studied. Namely, the La1−xSrxCr1−yNiyO3−δ (x = 0, 0.15; y = 0.05, 0.1, 0.2) system was investigated. Structural and redox evolution has been monitored by X-ray diffraction in oxidized and reduced samples. Reduced samples kept the initial perovskite structure although metallic nickel nanoparticles were detected on the perovskite grain surface by TEM analysis. The re-oxidized surface did not present nickel particles, suggesting the nickel re-incorporation into perovskite lattice coupled with cation diffusion. The perovskites were tested as SOFC anodes and the polarization resistance depended on the nickel stoichiometry and the reduction temperature. La0.85Sr0.15Cr0.9Ni0.1O3−δ reduced at 800 °C showed the lowest polarization resistance, both in hydrogen and methane. In fact this composition showed a 20% methane conversion at 900 °C for the methane steam reforming in a fixed bed reactor. Tolerance to redox cycling was proved electrochemically by in situ treatments of La0.85Sr0.15Cr0.9Ni0.1O3−δ electrode. Materials were further analyzed by TPR and XPS (in oxidized and reduced state) in order to identify the possible species involved in the electrocatalytic processes.
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► Catalysts including La1−xSrxCr1−yNiyO3−δ (x = 0, 0.15; y = 0.05, 0.1, 0.2) were prepared and tested.
► The electrochemical test (EIS) anode was done using both H2 and CH4 as fuels on YSZ electrolyte.
► Structural and redox evolution was monitored by XRD, TEM and XPS in oxidized and reduced samples.
► Upon reduction the perovskite structure is kept and metallic nickel nanoparticles are formed.
Journal: Applied Catalysis B: Environmental - Volumes 115–116, 5 April 2012, Pages 346–356