多相氧载体CoO-MgO和氧分子作用的ESR研究

用ESK研究多相氧载体CoO-MgO表面上氧的吸附作用,发现在77-150K温度范围内表面Co²⁺离子和O₂的结合是可逆的,吸附产生Co³⁺-O₂^-自由基加合物有超精细结构的ESR谱;当温度增加,吸附态O₂^-自由基发生转移并稳定在Mg²⁺离子上形成Mg²⁺-O₂^-自由基,文中着重讨论Co³⁺-O₂^-自由基的电子结构和成键本质,认为自由基是通过自旋成对的方式形成的,由于σ-л键作用引起的自旋极化以及由于电子离域作用而引起的偶极作用与ESR制的超精细结构线产生有关。

ESR STUDY OF THE ADSORPTION OF O2 MOLECULES ON THE SURFACE OF CoO-MgO AS A HEIEROGENEOUS OXYGEN CARRIER

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.