To initiate water-promoted reaction pathways on CuMnAl catalysts to facilitate ozone decomposition under humid conditions

Efficient catalytic ozone (O₃) purification under low temperature and high relative humidity (RH) conditions with optimal active sites that promotes water molecules to participate in O₃ degradation is essential for sustainable development for human health and ecological environment. This study initiates "water-promoted" reaction pathways on cost-effective and low-toxicity manganese-based catalysts to realize efficient O₃ purification (T ≤ 45 °C) under both dry and humid conditions through simple aging time modulations. Experimental results demonstrate that prolonging aging time transforms the CuMnAl crystalline structure from MnCO₃ and Mn(OH)₂ to MnO₂, concomitantly reducing the catalyst's electron-donating and electron-withdrawing capacities. This adjustment minimizes interactions with intermediate products, enabling 100 % O₃ conversions at ambient temperatures (80 ppm O₃/air, 600,000 mL g^-1 h^-1, 0 % RH). Conversely, reduced aging time of CuMnAl catalyst preserves higher contains of Brønsted acid sites and surface hydroxyl groups, facilitating activation of water molecules to participate in O₃ degradation, resulting in 93 % O₃ conversions at 45 °C (90 % RH), which improves 12 % compared to dry conditions, effectively initiating the "water-promoted" reaction pathways. Additionally, in situ diffuse reflectance Fourier transform (DRIFT) characterization elucidates seven reaction mechanisms on the CuMnAl catalyst surface, pinpointing pivotal active sites involved in water-promoted reactions. This study establishes a theoretical framework for enhancing the moisture resistance of manganese-based catalysts and offers a viable solution for purifying ozone under conditions of low temperature and high humidity.