Characterization by XPS and XAS of supported Pt/TiO₂CeO₂ catalysts

Abstract

the stabilization is more pronounced with lower cerim oxide concentration. X-ray absorption spectroscopy measurements done on the L,,, edge sbow the same variation as a function of cerium oxide concentration, but in the bulk the reduction is mu& lower. Cerium in Pt/TiO,-CeO, catalysts exhibits the same behavim.

Use of CuNi/YSZ and CuNi/SDC Catalysts for the Reverse Water Gas Shift Reaction

“…The fact that similar CO yields were obtained during the second and third cycles indicates that no deactivation was apparent. The thermal stability shown by Pt was expected based on previous reports [16,[27][28][29]. The CO yields obtained with the Pt/SDC catalyst in Figure 6 were superior to those obtained with the Pt/YSZ catalyst in Figure 4.…”

Preparation and Characterization of Ce/N-Codoped TiO2 Particles for Production of H2 by Photocatalytic Splitting Water under Visible Light by Sun et al. (Catal Lett (2010) 135:219)

“…All these calculations successfully explained the complex nature and structure of experimental XPS Ce3d spectra of cerium oxides [2-6, 11, 13], that is, the number of peaks, their relative BE locations and their relative intensities [2,3]. Now, Sun et al's interpretation is impossible to reconcile with these theoretical and experimental findings, because it assumes that both the Ce3d spectrum of Ce 2 O 3 and that of CeO 2 contain two peaks only.…”

“…Now, Sun et al's interpretation is impossible to reconcile with these theoretical and experimental findings, because it assumes that both the Ce3d spectrum of Ce 2 O 3 and that of CeO 2 contain two peaks only. By way of contrast, four and six peaks are, respectively the case, and a Ce3d spectrum recorded on a surface involving both oxides necessarily contains as many as ten peaks [2,3,13], not just the four peaks implied by the authors [1]. Since Sun et al consider Ce3d peaks in isolation, i.e.…”

“…XPS analysis is of useful application to the much studied class of Ce-bearing catalysts [2][3][4][5], because it provides straightforward access to the chemistry of the cerium, and this is also a central issue in both the scope and aims of Sun et al's paper [1]. My comment will focus on the authors' interpretation of the XPS Ce3d spectra of sample Ce(1.2%)-N-TiO 2 analyzed as-inserted (Fig.…”

“…I shall argue that the authors' interpretation of the two spectra is unwarranted, and I shall try to suggest possible explanations for the difference between their profiles. XPS Ce3d spectra of cerium oxides are among the most striking cases of the many-body nature of photoemission which manifests itself with the occurrence of not just one peak, but several peaks for each (5/2 and 3/2) spin orbital component [2][3][4][5][6][7][8][9][10][11][12]. Theoretical work carried out by Kotani et al [8,10,12] and by Le Normand et al [11] showed that, in the ground state of CeO 2 , the cerium has not only the 4f 0 electron configuration, i.e.…”