La1−xCaxCoO3 perovskite-type oxides: Identification of the surface oxygen species by XPS

A detailed study of the La1−xCaxCoO3 perovskites surface by XPS was carried out since this is a potentially useful tool to identify the oxygen species involved in the catalytic reaction and discriminate them. Mainly, the concentration of surface oxygen vacancies (λ′) can be estimated from the XPS atomic ratio.