Catalytic decomposition of gaseous ozone over todorokite-type manganese dioxides at room temperature: Effects of cerium modification

Abstract

Catalytic decomposition of gaseous ozone (O3) over todorokite-type manganese dioxides (T-MnO2) at room temperature and the effects of cerium modification were investigated. Catalytic activity and stability were greatly improved over Ce-modified MnO2 (Ce-MnO2), which increased with the increase of Ce/Mn atomic ratios from 0.06 to 0.28. The cerium modification made agglomerated MnO2 particles transformed into small sheets of Ce-MnO2 catalyst with Ce/Mn ratio of 0.28, accordingly increasing the specific surface area. Moreover, the crystal boundaries between MnO2 and CeO2 formed at high ratios of Ce/Mn. Larger surface area and the crystal boundaries between MnO2 and CeO2 resulted in the formation of more oxygen vacancies, which act as the active sites for O3 decomposition. Besides, we found the improved catalytic stability was associated with the desorption of oxygen species occupying the positions of oxygen vacancies.