Birnessite-Type Manganese Dioxide Nanosheets on Metal–Organic Frameworks with High Catalytic Activity in Ozone Decomposition

Ground-level ozone (O 3 ) poses a threat to both human health and ecosystems; the development of O 3 decomposition catalysts is thus of fundamental and practical significance. In the past decades, metal oxides have been widely investigated for O 3 elimination due to their low cost and high catalytic activity. Recently, it has been demonstrated that metal–organic frameworks (MOFs) could also show high performance in the removal of O 3 and even other airborne gaseous pollutants at the same time. Herein, we report a facile synthetic method to prepare the composite of the well-known MOF, UiO-66-NH 2, and birnessite-type manganese dioxide, namely, δ-MnO 2, where the nanosheets of δ-MnO 2 are vertically aligned and densely grown on the crystal surfaces of UiO-66-NH 2 . The δ-MnO 2 /UiO-66-NH 2 composite could completely remove low-concentration O 3 (5 ppm) in both dry and highly humid (RH = 80%) air at ambient temperature and pressure with a space velocity of 2000 L h –1 g –1 . In contrast, a single-phase sample of δ-MnO 2 or the typical O 3 decomposition catalyst, α-MnO 2, showed a much lower O 3 removal efficiency under the same experimental conditions. Due to the ultrathin morphology (high surface area) and well-separated distribution (no aggregation) of δ-MnO 2 nanosheets in the δ-MnO 2 /UiO-66-NH 2 composite, there are rich Mn 2+ /Mn 3+ atoms and oxygen vacancies on its surface, contributing to its high performance in catalytic O 3 decomposition. This work demonstrated a facile method to prepare MOF-based composites with fascinating nanostructures and high catalytic activity in O 3 decomposition, which are also potentially useful in other catalytic reactions.