Novel cryptomelane nanosheets for the superior catalytic combustion of oxygenated volatile organic compounds.

This work offers a novel pathway to prepare cryptomelane manganese oxides nanosheets as an superior catalyst for the catalytic combustion of oxygenated volatile organic compounds. The tunnel cryptomelane manganese oxides nanosheets were prepared from layered birnessite via simultaneously tuning pH and molar ratio (R) of the redox-precipitation between oxalic acid and KMnO. Thus, few-layered cryptomelane nanosheets possessing the most predominantly exposed (211) facet are generated at low pH (5.2-5.6), which intensifies the surface area of thin crystal cryptomelane nanosheets up to 177 mg and weakens Mn-O bonds. Moreover, high R results in low manganese average oxidation state (AOS), greater oxygen vacancies and better low-temperature reduction and oxygen mobility. Such features significantly maneuver the catalytic activity of the cryptomelane nanosheets catalysts for the complete oxidation of oxygenated volatile organic compound (e.g., 2-propanol, acetone) at low temperature (170-230 °C). Moreover, the catalysts show high stability for 48 h. The presented catalyst discloses an avenue to address current obstacles in the catalytic oxidation of volatile organic compounds.