Ultrathin manganese dioxide nanosheets for formaldehyde removal and regeneration performance

Ultrathin manganese dioxide (MnO 2 ) nanosheets with the thickness of 1–2   nm were synthesized by chemical oxidation of Mn 2+ ions in the presence of tetramethylammonium cations in an aqueous solution. The composite material MnO 2 /PET (polyethylene terephthalate) was prepared by impregnating PET into MnO 2 nanosheets colloid. The impregnation time has a great influence on HCHO adsorption and removal efficiency. When the PET was impregnated in nanosheets colloid for 1   h at room temperature, the concentration of HCHO decreased quickly within initial 10   min and finally reached about 81% removal efficiency with an initial HCHO concentration of ∼200   ppm. Moreover, the used MnO 2 /PET can be simply regenerated by heating at 105   °C without any rinse treatment. Based on in-situ DRIFTS and TG-MS studies, the mechanism of formaldehyde removal and regeneration was proposed. All the results showed that as-synthesized MnO 2 /PET can be used as an effective, affordable, and recyclable materials to removal and oxide toxic HCHO in indoor air.