One-step synthesis of δ-MnO2 with rich defects for efficient ozone decomposition under humid conditions

The catalytic performance of manganese oxides (MnOx) for ozone (O3) decomposition is affected by moisture and stability, for which MnOx with abundant defects offers a promising solution. In this study, a simple and mild one-step synthesis route was developed for highly defective δ-MnO2 preparation. The optimal catalyst was operated at 35 % relative humidity (RH) for 12 h, and the O3 conversion maintained over 99 %. Characterizations revealed that the K+ insertion into the interlayers preserved a highly defective layered structure. Rich surface defects and grain boundaries facilitated the generation of oxygen vacancies and the migration of oxygen species, stabilizing the elimination of O3. In addition, a combination of characterization and experiments determined that physisorbed water is critical for inhibiting activity, and thus, weak physisorption of water on the catalyst represents excellent water resistance. This work aims to provide guidance and new insights into the design of stable and water-resistant MnOx catalysts.