Molecular oxygen interaction with Bi2O3: a spectroscopic and spectromagnetic investigation

The interaction of molecular oxygen with polycrystalline Bi2O3 was investigated by infrared (IR) and thermogravimetric (TGA) analyses, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). The results indicate the formation of "end-on" and "bridging" superoxide species, which are trapped in the beta-Bi2O3 oxygen vacant sites, Bi(IV) and Bi(V) centres also being produced. O2- interacts with Bi(IV) centres giving two superoxide adducts with temperature dependent relative amounts, Bi(IV)-O2- and Bi(IV)- O2- -Bi(III), both having a triplet spin state.