Facile preparation of α-MnO₂ nanowires for assembling free-standing membrane with efficient Fenton-like catalytic activity

Assembling MnO₂ nanowires into macroscopic membrane is a promising engineered technology for catalyst separation and enhancement of Fenton-like reaction activity, yet its development is limited by the deficiencies in preparation and property modulation of the MnO₂ nanowires. In this work, we developed a facile method using C₂H₅OH and CH₃COOK as reductive and vital control reagents to react with KMnO₄ by hydrothermal reaction at 140 °C for 12 h, to prepare the ultralong α-MnO₂ nanowires up to tens of micrometers with high purity and aspect ratio. Such strategy not only had the advantages of being mild, easily controlled and environmental pollution-free, but also endowed α-MnO₂ nanowires with excellent ability as a Fenton catalyst when assembled into free-standing membrane for degrading phenolic compounds (k_obs = 0.0738 ∼ 0.1695 min⁻¹) in a continuous flow reaction. The reactive oxygen species (i.e., ^•OH) from Fenton-like reaction were enriched within this α-MnO₂ nanowire membrane via nanoconfinement effect, which further enhanced the mass transportation of ^•OH available for phenolic contaminants. MnO₂ nanowire membrane using our method possessed the high practical potential for water purify due to its easy-preparation and enhanced catalytic performances.