Efficient propane low-temperature destruction by Co₃O₄ crystal facets engineering: Unveiling the decisive role of lattice and oxygen defects and surface acid-base pairs

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 (E_vo (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.