Probing the catalytic oxidation of styrene on Co3O4 with different morphologies: Promotion by oxygen vacancies

Oxygen defects (oxygen vacancies) are vacancies formed in metal oxides or other oxygen-containing compounds when oxygen atoms (oxygen ions) in the crystal lattice detach, resulting in a lack of oxygen. In this paper, three Co3O4 catalysts with different morphologies (nanoparticulate, layered, and cubic) were synthesized to control the concentration of oxygen vacancies and applied to the catalytic oxidation of styrene, and the nanoparticulate Co3O4 (Co3O4-N), which has the smallest specific surface area (38.0240 m2/g), showed the best catalytic performance (T100 = 247 °C). Based on various characterization data, the analysis was carried out, and the results showed that the physical structural properties are not the key factor determining the catalytic activity, and more excellent chemical properties such as oxygen vacancies determine the catalytic activity. Finally, the reaction process of styrene adsorption oxidation and the degradation of key intermediates of the reaction were investigated by in situ DRIFTS technique, which demonstrated that a high concentration of oxygen vacancies can accelerate the oxidation of important intermediates, simplify the whole styrene oxidation process, and produce fewer by-products.