Effect of Facet on Oxygen Vacancy Properties in δ-MnO₂ for Stable and Efficient Catalytic Ozone Decomposition

Manganese oxides (MnO_x) serve as a classical catalytic material for ozone (O₃) decomposition, while the accumulation of the peroxide intermediate (*O₂) and water (H₂O) significantly degrades its performance. In this study, the exposed (111) facet of δ-MnO₂ was prepared to modulate the properties and content of oxygen vacancies (Vo). Experimental and theoretical results indicate that δ-MnO₂ with the (111) facet possessed a lower Vo content compared to the thermodynamically stable (001) facet. Remarkably, despite the deficiency in Vo content, the rapid *O₂ desorption enables the catalyst to achieve superior performance, along with excellent stability. Additionally, the dynamic adsorption and reaction of H₂O with O₃ significantly enhance the stability and water tolerance of the catalyst. The preferred Mn-0.2 maintained 95% O₃ conversion after 24 h of reaction under harsh conditions (WHSV = 900 L·g^-1·h^-1 and 35% RH). This work provides and validates new insights into strategies for mitigating the rate-determining step in an environmental catalytic reaction.