Abstract: The adsorption of oxygen molecules on the CoO-MgO as a kind of heterogeneous oxygen carrier has been studicd from 77 to 300K by ESR,It was observed that Co²⁺ ions on the surface of CoO-MgO could combine with oxygen reversibly at low temperature of 77-150K and generate a cobalt-oxygen radical adduct Co³⁺-O₂^- which is responsible for the appearanee of hyperfine stnlctural lines in ESR spectrum.On increasing the temperature O₂^- radical in cobalt-oxygen adduct would be transferred and stabillzed on Mg²⁺ ions,and fomied a new Mg²⁺-O₂^- radical adduct at room temperature,In this paper the electronic structure of the cobalt-oxygen adduct and their bonding nature were discussed by the analysis of ESR spectra.Both the spin polarintion due to σ-л bond interaction and the electron delocalization had been suggested to account for the origin of the hyperfine lines in ESR spectra.

Key words: Heterogeneous Oxygen carrier, CoO-MgO, Adsorption, Superoxygen anion radi-cal, ESR