Engineering of oxygen vacancy defect in CeO₂ through Mn doping for toluene catalytic oxidation at low temperature

Catalytic oxidation is considered a highly effective method for the elimination of volatile organic compounds. Oxygen vacancy defect engineering in a catalyst is considered an effective approach for high-performance catalysts. Herein, a series of doped Mn_xCe_1-xO₂ catalysts (x = 0.05–0.2) with oxygen vacancy defects were synthesized by doping low-valent Mn in a CeO₂ lattice. Different characterization techniques were utilized to inspect the effect of doping on oxygen vacancy defect generation. The characterization results revealed that the Mn_0.15Ce_0.85O₂ catalyst has the maximum oxygen vacancy concentration, leading to increased active oxygen species and enhanced oxygen mobility. Thus, Mn_0.15Ce_0.85O₂ catalyst showed an excellent toluene oxidation activity with 90% toluene conversion temperature (T₉₀) of 197 °C at a weight hourly space velocity of 40,000 mL g⁻¹ h⁻¹ as compared to undoped CeO₂ (T₉₀ = 225 °C) and Ce based oxides in previous reports. In addition, the Mn_0.15Ce_0.85O₂ catalyst displayed strong recyclability, water resistant ability and long-time stability. The in situ DRIFT results showed that the Mn_0.15Ce_0.85O₂ catalyst has a robust oxidation capability as toluene is quickly adsorbed and actuated as compared to CeO₂. Thus, the present work lays the foundation for designing a highly active catalyst for toluene elimination from the environment.