Presence Of Ce0 Research Articles

Synthesis and characterization of polypyrrole-Ce0.05CoSb3 nanocomposites

Filled Skutterudite CeyCoSb3 (y = 0.05) nanoparticles synthesized by Solvothermal method are incorporated into conducting Polypyrrole (PPy) via in-situ Chemical Polymerization technique to form Polymer Inorganic Nanocomposites (PINs). Further, studies on different weight percent (10, 20, 30 and 40%) of the nanocomposites with respect to pure PPy are conducted. Field Emission Scanning Electron Microscopy (FESEM) equipped with Energy Dispersive X-Ray Spectrometer (EDS), powder X-Ray Diffractometer (pXRD), Fourier Transform Infrared (FTIR) Spectroscopy techniques were employed to study morphological, structural and optical properties of as-synthesized PINs. FESEM confirms uniform distribution of nanoparticles in polymer matrix and increase in atomic weight % of CeyCoSb3 (y = 0.05) shown in EDS analysis confirms the successful fusing of nanoparticles into the PPy chains. pXRD analysis justifies the formation of PPy-Ce0.05CoSb3 nanocomposites indicating the presence of Ce0.05CoSb3 diffraction peaks with broad amorphous background of polypyrrole. FTIR spectra reveal the vibrational modes and the chemical bonds of pure PPy and PPy fused with Ce0.05CoSb3 justifying the formation of expected nanocomposites.

Carbon Deposition and Sulfur Poisoning in SrFe0.75Mo0.25O3-δ and SrFe0.5Mn0.25Mo0.25O3-δ Electrode Materials for Symmetrical SOFCs

Redox stable SrFe0.75Mo0.25O3-δ and SrFe0.5Mn0.25Mo0.25O3-δ electrode materials were studied in terms of their physicochemical properties and electrochemical performance in symmetrical SOFCs, with focus on their tolerance toward carbon deposition and sulfur poisoning. Both materials possess cubic, B-site cation-disordered Pm-3m structure in air up to high temperatures. SrFe0.5Mn0.25Mo0.25O3-δ was found to transform to a B-site cation-ordered structure after reduction in dry 5 vol% H2/Ar at 1100°C, while no structural changes were observed for SrFe0.75Mo0.25O3-δ. Weight change upon annealing up to 850°C in air and in dry 5 vol% H2/Ar indicated an increase in oxygen deficiency on the order of δ = 0.2. Seebeck coefficient and conductivity dependence on the oxygen partial pressure pO2 showed that both oxides exhibit p-type conductivity in air and n-type conductivity under reducing conditions. Carbon deposition was found to depend on temperature, gas composition (CO or CH4), and presence of Ce0.8Gd0.2O1.9 electrolyte in the composite-type electrode. Stable fuel cell performance, without carbon deposition, was obtained for SrFe0.75Mo0.25O3-δ-based SOFC in 10 vol% of CO in CO2. Also, SOFC operation with CH4 as fuel was achieved without coking at temperatures ≤ 700°C. However, both oxides suffer from sulfur poisoning-related effects in atmosphere with 800 ppm H2S.

XPS Study of Pt/CexZr1−xO2/Si Composite Systems

ABSTRACTThis work describes the study of the surface reduction of ceria zirconia mixed oxides (CeZrO) as either thin films or powders, both with and without Pt present. XPS was used to measure the composition of the surface and the oxidation states of all metals contained within the material. The thin films of CeZrO showed little reactivity towards the reducing conditions used. Grazing incidence angle XRD showed the presence of Ce0.75Zr0.25O2. The thin films prepared with Pt showed that surface reduction of Ce4+ occurred under reducing conditions. The size of the Pt clusters was also determined from the data. The Pt was found to always exist in the metallic state. The Zr4+ was not seen to change during all treatments. For the powder samples the Ce4+ was readily reduced to approximately 60%. Pt was found to be initially oxidised with the % of metallic Pt increasing with reduction temperature. Again no change in the Zr was observed.