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

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+.