Three-Dimensional Hierarchical Membrane with Dual Active Sites for Ozone Decomposition

Abstract

Manganese-based materials are prime candidates for ozone (O₃) elimination, but powder materials are suffering from agglomeration and insights into the O₃ decomposition mechanism at the molecular level remain elusive. Herein, the PAN@NiMn-LDH membrane (PAN = polyacrylonitrile; LDH = layered double hydroxide) was synthesized by adopting an epitaxial growth strategy, resulting in the formation of a robust three-dimensional (3D) interwoven hierarchical structure. The resulting PAN@NiMn-LDH membrane presented a long-lasting 100% conversion efficiency of O₃ for over 75 h at 50 ppm at an ambient temperature. When a large-scale fabricated PAN@NiMn-LDH membrane (100 cm × 30 cm) was applied to a commercial air cleaner, an initial O₃ concentration of 10 ppm could be eliminated to 46 ppb within 6 min in a 36 m³ room, which was below the World Health Organization (WHO) guideline value (∼51 ppb). Compared with the previous studies, such superior activity can be ascribed to the following reasons: (1) the as-prepared PAN@NiMn-LDH membranes were beneficial for the capture of O₃ due to the 3D interwoven hierarchical structure with a high porosity of 63%. (2) The dual sites of Ni–OH/Mn–OH promoted the adsorption and activation of O₃, and thereby facilitated the formation of reactive oxygen species accompanied with the oxidation of Ni²⁺/Mn²⁺/Mn³⁺ to Ni³⁺/Mn⁴⁺.