Effect of Morphology-Dependent Oxygen Vacancies of CeO₂ on the Catalytic Oxidation of Toluene

Catalytic oxidation is regarded as an effective, economical, and practical approach to remove volatile organic compounds such as important air pollutants. CeO2 catalysts with different morphologies exhibit different oxygen vacancies content, which plays a vital role in oxidation reaction. Herein, three distinct morphologies of CeO2 i.e., shuttle (CeO2 (S)), nanorod (CeO2 (R)), and nanoparticle (CeO2 (P)), were successfully fabricated by the SEM and TEM results, and investigated for toluene catalytic oxidation. The various characterizations showed that the CeO2 (S) catalyst exhibited a larger surface area along with higher surface oxygen vacancies in contrast to CeO2 (R) and CeO2 (P), which is responsible for its excellent toluene catalytic oxidation. The 90% toluene conversion temperature at 225 °C over CeO2 (S) was less than that over CeO2 (R) (283 °C) and CeO2 (P) (360 °C). In addition, CeO2 (S) showed a greater reaction rate (14.37 × 10−2 μmol∙g−1∙s−1), TOFov (4.8 × 10−4∙s−1) at 190 °C and lower activation energy value (67.4 kJ/mol). Furthermore, the CeO2 (S) also displayed good recyclability, long-term activity stability, and good tolerance to water. As a result, CeO2 (S) is considered a good candidate to remove toluene