M. Imamura et al., Catalytically active oxygen species in La1-xSrxCoO3-delta studied by XPS and XAFS spectroscopy, J PHYS CH B, 104(31), 2000, pp. 7348-7353
X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge struc
ture (XANES) spectroscopy were used to characterize the oxygen species in p
erovskite-type La1-xSrxCo3-delta with x = 0 and 0.2. The XPS method used sy
nchrotron radiation with variable excitation energies. XPS showed two kinds
of oxygen species: a surface species with a high binding energy and a bulk
species with a low binding energy, Compared with LaCoO3, the surface oxyge
n species in La0.8Sr0.2CoO3-delta was distributed into a deeper region, Com
parison of the XANES spectra measured by partial photoelectron yield, total
photoelectron yield, and fluorescence yield methods identified three featu
res assigned to the surface species, which were identical to those of anion
ic dioxygen. These results indicate that the partial replacement of La by S
r causes the distribution of negatively charged dioxygen species to a deepe
r region. We think that this anionic dioxygen species is related to the hig
h oxidation activity of La0.8Sr0.2CoO3-delta.