Cu Species-Modified OMS-2 Materials for Enhancing Ozone Catalytic Decomposition under Humid Conditions

Manganese oxide octahedral molecular sieves (OMS-2) exhibit an excellent performance in ozone catalytic decomposition in dry atmosphere conditions, which however is severely limited by deactivation in humid conditions. Herein, it was found that the OMS-2 materials modified with Cu species could obviously improve both the ozone decomposition activity and water resistance. Based on the characterization results, it was found that these CuO/OMS-2 catalysts exhibited dispersed CuO nanosheets attached and located at the external surface accompanied with ionic Cu species entering the MnO₆ octahedral framework of OMS-2. In addition, it was demonstrated that the main reason for the promotion of ozone catalytic decomposition could be ascribed to the combined effect of different Cu species in these catalysts. On the one hand, ionic Cu entered the MnO₆ octahedral framework of OMS-2 near the catalyst surface and substituted ionic Mn species, resulting in an enhanced mobility of surface oxygen species and formation of more oxygen vacancies, which act as the active sites for ozone decomposition. On the other hand, the CuO nanosheets could serve as non-oxygen vacancy sites for H₂O adsorption, which could alleviate the catalyst deactivation to some extent caused by the occupancy of H₂O on surface oxygen vacancies. Finally, different reaction pathways for ozone catalytic decomposition over OMS-2 and CuO_x/OMS-2 under humid conditions were proposed. The findings in this work may shed new light on the design of highly efficient catalysts for ozone decomposition with improved water resistance.