Fe and Cu co-doping induces abundant oxygen vacancies in MnO2 for efficient ozone catalytic oxidation of toluene at room temperature

Abstract

MnO₂ holds significant potential for room-temperature ozone catalytic oxidation of volatile organic compounds (VOCs), yet it encounters challenges related to low degradation efficiency. This study introduces a co-doping strategy aimed at enhancing the catalytic activity and stability of MnO₂. Specifically, Mn⁴⁺ ions were substituted with low-valence copper and iron dopants via a straightforward one-step hydrothermal method, resulting in the formation of abundant oxygen vacancies on the catalyst surface through driven redox precipitation. The resultant Fe–Cu–MnO₂ catalyst exhibited remarkable catalytic performance at room temperature, achieving 100% toluene degradation and 100% ozone removal efficiency, along with an impressive mineralization ratio of 81.2% and sustained stability over 100 hours. Relevant experiments demonstrated that the improvement in catalytic activity was primarily attributed to the significant increase in oxygen vacancy concentration induced by co-doping. This was accompanied by increased surface oxygen adsorption and enhanced low-temperature reducibility, which facilitated the generation of reactive oxygen species. Additionally, co-doping induced crystal morphology changes and specific surface area expansion contribute to exposing more active sites, thereby enhancing catalytic performance. Consequently, the catalyst exhibited superior ozone catalytic oxidation performance for toluene degradation. In situ DRIFTS analysis further elucidated the degradation pathway and reaction mechanism of ozone catalytic oxidation of toluene. These findings may provide valuable insights for the development of efficient catalysts for low-temperature catalytic ozonation of VOCs.