X-ray photoelectron spectroscopic study of direct reforming catalysts Ln(0.5)Sr(0.5)Ti(0.5)Mn(0.5)O(3 +/- d) (Ln = La, Nd, and Sm) for high temperature-operating solid oxide fuel cell

摘要

Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln(0.5)Sr(0.5)Ti(0.5)Mn(0.5)O(3 +/- d) (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln(0.5)Sr(0.5)Ti(0.5)Mn(0.5)O(3 +/- d) were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln(0.5)Sr(0.5)Ti(0.5)Mn(0.5)O(3 +/- d); Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln(0.5)Sr(0.5)Ti(0.5)Mn(0.5)O(3 +/- d), some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln(0.5)Sr(0.5)Ti(0.5)Mn(0.5)O(3 +/- d) from the 0 is spectra; a high portion of lattice oxygen was observed in both Nd0.5Sr0.5Ti0.5Mn0.5O3 +/- d (NSTM) and Sm0.5Sr0.5Ti0.5Mn0.5O3 +/- d (SSTM). In various respects, NSTM and SSTM will be desirable reforming catalysts and anode candidates for high temperature solid oxide fuel cell. (C) 2016 Elsevier B.V. All rights reserved.