Curve Fitting Analysis of ESCA Ni 2p Spectra of Nickel-Oxygen Compounds and Ni/Al2O3Catalysts

Nonlinear least-squares curve fitting is used to analyze Ni 2p spectra obtained from various nickel-oxygen compounds and Ni/Al 2 O 3 catalysts. Apart from NiO, which shows a characteristic discrete satellite peak 2 eV from the main 2p 3/2 peak, all other spectra exhibit variable peak asymmetry assigned to multiplet splitting effects. By the use of a single extra peak to describe this asymmetry, the relative satellite/main peak intensity ratio can be used as an indication of the chemical state of nickel. Results for Ni/Al 2 O 3 catalysts agree with reduction studies from previous work about the nature of nickel species on the surfaces of these catalysts at various nickel loadings.