Efficient Propane Low-temperature Destruction by Co3O4 Crystal Facets Engineering: Unveiling the Decisive Role of Lattice and Oxygen Defects and Surface Acid-base Pairs

Abstract Low-temperature degradation of short chain alkane is one of the greatest challenges of volatile organic compound purification. Here, rod-, sheet-, and cube-like Co3O4 (Co3O4-R, Co3O4-S, and Co3O4-C) with predominantly exposed (110), (111), and (100) facets respectively were fabricated. Co3O4-R presents excellent activity achieving 90% of propane oxidized at just 195 °C owing to large amounts of lattice defects, oxygen vacancies and low coordinated Co atoms. Theoretical calculation reveals that Co3O4-R has the lowest formation energy of oxygen vacancy on (110) facet (Evo (110) =1.7 eV), which has a higher activation capacity for oxygen due to the largest O2 adsorption energy (-1.30 eV) and thus accelerates propane oxidation. Moreover, largest amount of lewis acid-base pairs existed in Co3O4-R polarizes substrate electron distribution and therefore accelerates the activation of C-H bonds. Electrophilic oxygen species (O22- or O-) caused the degradation of carbon skeleton and formed carboxylate intermediates before mineralized to CO2.