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

Manganese-based materials are prime candidates for ozone (O-3) elimination, but powder materials are suffering from agglomeration and insights into the O-3 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 O-3 for over 75 h at 50 ppm at an ambient temperature. When a large-scale fabricated PAN@NiMn-LDH membrane (100 cm x 30 cm) was applied to a commercial air cleaner, an initial O-3 concentration of 10 ppm could be eliminated to 46 ppb within 6 min in a 36 m(3) room, which was below the World Health Organization (WHO) guideline value (similar to 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 O-3 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 O-3, and thereby facilitated the formation of reactive oxygen species accompanied with the oxidation of Ni2+/Mn2+/Mn3+ to Ni3+/Mn4+.