Boosting toluene destruction by engineering surface acidity–alkalinity in defective cobalt oxide catalyst

Abstract

The surface acidity and alkalinity of catalysts played a decisive role in the destruction of Volatile organic compounds (VOCs). In this study, a series of Co3O4 catalysts were synthesized under different temperatures by calcining metal organic frameworks (MOFs). By controlling the temperature, the organic linkers were effectively eliminated, resulting in catalysts with a high specific surface area due to the preservation of the parent structure of the MOFs. Among the catalysts tested, Co3O4−350 (calcined at 350 °C) demonstrated the highest catalytic activity for toluene oxidation (T90 =231 ℃) and reliable water resistance (3 vol.% water vapor). The efficacy was attributed to the high ratio of reactive oxygen species and high valence Co species, weaken Co−O bond strength as well as high concentration of oxygen vacancies. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) demonstrate that acidity–alkalinity is crucial in the adsorption and activation, while oxygen vacancies were found to be essential for deep oxidation.